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ARACNE

National Conference on Scienceand Technology of Zeolites

Turin, July, 14 2007

Book of abstracts

edited byLeonardo MarcheseSalvatore Coluccia

Edoardo Garrone

Copyright MMVIIARACNE editrice S.r.l.

[email protected]

via Raffaele Garofalo, 133 A/B00173 Roma

(06) 93781065

ISBN 9788854812253

I diritti di traduzione, di memorizzazione elettronica,di riproduzione e di adattamento anche parziale,

con qualsiasi mezzo, sono riservati per tutti i Paesi.

Non sono assolutamente consentite le fotocopiesenza il permesso scritto dellEditore.

I edizione: giugno 2007

7

Contents

Main Sponsors.. 8 List of contributions 11 International Scientific Board 19 Local Organizing Committe.. 20 Scope of the Congress 21 Programme 23

Contributions Session 1. 29Contributions Session 2. 69Contributions Session 3. 115Contributions Session 4. 129Contributions Session 5. 151Contributions Session 6. 185

Index of Authors 221

8

The Congress is organised with the assistance of:

University of Eastern Piedmont A. Avogradro

Polytechnic School of Turin

University of Turin

Italian Zeolite Association

9

The Congress is organised under the

auspices of:

Comune di Torino

10

VIII AIZ Congress 2007 Main Sponsors

11

PL1............................................................................................................................................35 Synthesis, structure, and reactivity of high-valent metal-oxo species grafted onto microporous solids

E. Iglesia 1O1............................................................................................................................................37

Synthesis, ion-exchanging and structural characterization of stannosilicate EMS-2 S. Zanardi, A. Carati, C. Rizzo, R. Millini, M.C. Dalconi

1O2............................................................................................................................................39

Stabilisation of a microporous amorphous precursor of mordenite by CO2-induced chemical condensation of silanols

A. Morsli, M.F. Driole, T. Cacciaguerra, R. Arletti, B. Chiche, F. Hamidi, A. Bengueddach, F. Quignard, F. Di Renzo

1O3............................................................................................................................................41

Evidence of complex interactions during the selective adsorption of gases and vapours in cationic zeolites: an IR investigation

T. Montanari, G. Busca 1O4............................................................................................................................................43

Surface and catalytic properties of imogolite nanotube I. Bottero, B. Bonelli, N. Ballarini, S. Passeri, L. Pesaresi, M. Armandi, F. Cavani, E. Garrone

1O5............................................................................................................................................45

Liquid-phase thiophene adsorption on MCM-22 zeolite C. Delitala, E. Cadoni, D. Delpiano, D. Meloni, S. Melis, I. Ferino

1O6............................................................................................................................................47

Adsorption properties of highly dispersed copper ions in zeolites and MOFs L. Regli, S. Chavan, G. Ricchiardi, C. Lamberti. G. Spoto, S. Bordiga, A. Zecchina

1P1 ............................................................................................................................................51 Quantitative studies of Brnsted acid sites in microporous materials by combining FTIR and TG analysis

G.A.V. Martins, G. Berlier, G. Gatti, S. Coluccia, L. Marchese, H.O. Pastore 1P2 ............................................................................................................................................55

Structural insertion of carbon and nitrogen into a B-substituted chabazite L. Regli, C. Lamberti, C. Busco, A. Zecchina, C. Prestipino, S. Bordiga

Poster contributions

Plenary Lectures and Oral Contributions

Session 1: Synthesis and characterisation of zeolites and other microporous materials

-VIII AIZ Congress 2007-

12

1P3 ............................................................................................................................................57

Zeolite Y synthesis in seeded systems G. Cugliari, S. Candamano, P. Frontera, F. Crea, R. Aiello

1P4 ............................................................................................................................................59

Structural investigation of cobalt species in CoAPO-5: a spectroscopic study M. Vishnuvarthan, G. Berlier , E. Gianotti , V. Murugesan , S. Coluccia

1P5 ............................................................................................................................................61

Monitoring the formation of H,Na-MCM-22 by a combined TGA, XRD and FTIR of the decomposition of the directing agent

L. Palin, H.O. Pastore, G. Croce, M. Milanesio, L. Marchese, D. Viterbo 1P6 ............................................................................................................................................63

Synthesis of new zeolite composite membranes A. Tavolaro, A. Adimari

1P7 ............................................................................................................................................65

Ceramization of Sr-exchanged zeolite matrices B. Liguori, S. Anaclerio, C.Colella

1P8 ............................................................................................................................................67

Characterization of zeolites exchanged with heavy metals as precursors of metal-ceramic composites

E.A. Turcato, S. Ronchetti, B. Onida, D. Mazza, P. Rivolo, S. Esposito, C. Ferone

PL2............................................................................................................................................75 Synthesis and unique properties of mesoporous organosilicas with crystal-like pore walls

Shinji Inagaki 2O1............................................................................................................................................77

Ni catalyst prepared by intercalation of host layered double hydroxides: influence of the anionic guest entities and reduction treatments

S. Morandi, F. Prinetto, G. Ghiotti, D. Kostadinova, C. Grardin, , D. Tichit 2O2............................................................................................................................................79

Synthesis of folic acid-functionalized mesoporous silica L. Pasqua, F. Testa, R. Aiello, J.B. Nagy

2O3............................................................................................................................................81

Photoactive hybrid mesoporous nanoparticles as a tool for diagnostics C.A. Bertolino, E. Gianotti, G. Caputo, C. Isidoro, S. Coluccia


Session 2: Synthesis and characterisation of mesoporous and layered materials


13

2O4............................................................................................................................................83

Saponite clays: surface modification and its effect on acidity and porosity properties C. Bisio, G. Gatti, E. Boccaleri, H.O. Pastore, L. Marchese

2O5............................................................................................................................................85

Mesoporous materials as stationary phase in liquid chromatography R. Aiello, M.C. Bruzzoniti, E. Garrone, B. Onida, A. Prelle, C. Sarzanini, M. Teodoro, F. Testa, A.M. Torchia, A. Virga

2O6............................................................................................................................................87

Facile preparation of silico-pepsin bioreactors: encapsulation of bulky pepsin molecules within large mesopores of silica

H.G. Manyar, S. Tumbiolo, E. Gianotti, S. Coluccia, Y. Sakamoto, O. Terasaki

2P1 ............................................................................................................................................91 FePO4 nanoparticles supported on mesoporous SBA-15 as cathode material for Li-ion cells

C. Gerbaldi, G. Meligrana, S. Bodoardo, A. Tuel, and N. Penazzi 2P2 ............................................................................................................................................93

CMK type mesoporous carbon as fuel cell electrocatalyst support C. Francia, E.P. Ambrosio, P. Spinelli, M. Manzoli, G. Ghiotti

2P3 ............................................................................................................................................95

Drug release from ordered mesoporous silicas incorporated in bioactive glass-ceramic scaffolds for bone substitutions

V. Cauda, R. Mortera, S. Fiorilli, B. Onida, E. Vern, C. Vitale Brovarone, G. Croce, M. Milanesio, D. Viterbo, E. Garrone

2P4 ............................................................................................................................................97

Synthesis and characterization of sponge mesoporous silica as bio-catalyst F. Sartori, F. Di Renzo, A. Galarneau, M. Cangiotti, M.F. Ottaviani

2P5 ............................................................................................................................................99

Evaluation of Iron States in layered [Fe]-ALPO-kanemite materials G.B. Superti, H.O. Pastore, C. Bisio, L. Marchese

2P6 ..........................................................................................................................................101

Acid Sites Characterization of mesoporous SBA-type Aluminosilicates J.M.R. Gallo, C. Bisio, H.O. Pastore, L. Marchese

2P7 ..........................................................................................................................................103

Intercalation of polyhedral oligomeric silsesquioxanes in synthetic saponite clay F. Carniato, E. Boccaleri, C. Bisio, L. Marchese



14

2P8 ..........................................................................................................................................105 Spectroscopic investigation of the interaction between the silica surface and the structure directing agent in SBA-16 mesoporous material

T. Giavani, C. Bisio, L. Marchese 2P9 ..........................................................................................................................................107

Synthesis and characterization of photoluminescent CdTe/hydrotalcite nanocomposites C. Gieck, F. Ghigliotti, L. Marchese, N. Gaponik, A. Eychmueller

2P10 ........................................................................................................................................109

Adsorption of iron on organically modified RUB-18 T.R. Macedo, C. Bisio, C. Airoldi, L. Marchese

2P11 ........................................................................................................................................111

A polarity study of phenylene-bridged periodic mesoporous organosilica B. Camarota, B. Onida, Y. Goto, S. Inagaki, E. Garrone

2P12 ........................................................................................................................................113

Incorporation of zinc complex in mesoporous materials via direct co-condensation and post-synthesis grafting methods

D. Aiello, F. Testa, R. Aiello, T. Martino, I. Aiello, M. La Deda, M. Ghedini

PL3..........................................................................................................................................121

Crystal chemistry of natural zeolites: rumors and facts Reinhard X. Fischer

3O1..........................................................................................................................................123

Do you need an organic template ? A comparison of man-made and natural synthesis of zeolites

R. Arletti, F. Di Renzo 3O2..........................................................................................................................................125

Pressure induced deformations and elastic behaviour of wairakite S. Ori, G. Vezzalini, S. Quartieri, V. Dmitriev

3O3..........................................................................................................................................127

The dehydraton and rehydration process in gmelinite:an in situ x-ray single crystal study I. Parodi, M.C. Dalconi, G. Crucian, A. Alberti

PL4..........................................................................................................................................135



Session 3: Natural zeolites

Session 4: Adsorption and ion exchange: properties and applications


15

Adsorption and ion exchange properties of natural zeolites: still a subject of high quality and innovative research

Panagiotis Misaelides, Athanasios Godelitsas 4O1..........................................................................................................................................137

The adsorption and degradation of sulfamide veterinary antibiotics on zeolites L. Gigli , S. Blasioli , I. Braschi , A. Martucci , A. Alberti , C.E. Gessa

4O2..........................................................................................................................................139

Synthesis, characterisation and cytochrome c adsorption properties of zeolite crystals and composite membranes

A. Tavolaro, P. Tavolaro

4P1 ..........................................................................................................................................143 Amine modified SBA-15 and MCM-22 as high capacity CO2 adsorbents

E.I. Basaldella, N. Firpo, J.C.Tara, E.L. Soto 4P2 ..........................................................................................................................................145

Evaluation of modified or unmodified MCM-41 mesoporous silica for propane/propylene separation

P. Aprea, D. Caputo, M. Ei, Q. Huang, F. Iucolano, C. Colella 4P3 ..........................................................................................................................................147

Evaluation of sorbents as potential tools for reducing ammonia from mainstream smoke of cigarettes

F. Bellucci, D. Caputo, F. Iucolano, T. Monetta, C. Colella 4P4 ..........................................................................................................................................149

Ion exchange kinetic model of zeolite a [LTA] L. Catalanotti, B. de Gennaro, F. Pepe, C. Colella

PL5..........................................................................................................................................157 Acid-catalysis with zeolites: a CONTINUOUS challenge FOR the control of selectivity

F. Cavani 5O1..........................................................................................................................................159

Acetylation of benzenic and naphthalenic compounds over acid zeolites: an alternative to homogeneous Friedel-Crafts catalysts

M. Guidotti, M. Guisnet, P. Magnoux 5O2..........................................................................................................................................161

Traffic control and shape selectivity in the hydrocarbon chemistry catalyzed by protonic zeolites: infrared studies



Session 5: Catalysis


16

M. Bevilacqua, E. Finocchio, T. Montanari, G. Busca 5O3..........................................................................................................................................163

Liquid-phase alkylation of phenol with t-butanol over various catalysts derived from MWW precursors

D. Meloni, R. Monaci,V. Solinas, E. Dumitriu 5O4..........................................................................................................................................165

Knoevenagel condensation over and Y zeolites in liquid phase under solvent free conditions

S. Saravanamurugan, M. Palanichamy, M. Hartmann, V. Murugesan 5O5..........................................................................................................................................167

Aluminium role in N2O decomposition over Fe-ZSM-5: A comparative study between Fe-ZSM-5 and Fe-silicalite

M. Rivallan, G. Berlier, G. Ricchiardi, A. Zecchina 5O6..........................................................................................................................................169

Olive oil bio-diesel preparation using acid zeolites catalysis in an innovative continous reactor

Blasi, E. Viola, F. Nanna, V. Valerio, G. Braccio, G. Giordano

5P1 ..........................................................................................................................................173 NMR/FT-IR study on the various siliceous catalysts used in the vapour phase Beckmann Rearrangement Reaction

A. Aloise, A Macario, L. Forni, B. Bonelli, G. Giordano, J. B.Nagy, F. Trifir, G. Fornasari, E. Garrone

5P2 ..........................................................................................................................................175

Chromium-MCM-41 as a catalyst for propane oxidative dehydrogenation nature of Active species and functional tests

M.A. Botavina, Yu.A. Agafonov, K. Costabello, E. Gianotti, N.A. Gaidai, A.L. Lapidus, G. Martra

5P3 ..........................................................................................................................................177

The environmentally benign, liquid-phase benzoylation of phenol catalyzed by H- zeolite

M. Ardizzi, N. Ballarini, F. Bortolani, F. Cavani, F. DAlessandro, S. Guidetti, P. Manifesta, S. Passeri

5P4 ..........................................................................................................................................179

Use of layered and metallorganic materials for olive oil milling wastewater purification using H2O2

C. Genovese, S. Caudo, S. Perathoner, G. Centi, G. Giordano, T. Granato 5P5 ..........................................................................................................................................181



17

Supported Polyperoxometallates: Highly Selective Catalyst for Oxidation of Alcohols to Aldehydes

H.G. Manyar, S. Coluccia, A. Kumar 5P6 ..........................................................................................................................................183

Acid sites and catalytic performances of beta zeolite in benzene alkylation with propylene

Stefano Ramello, F. Rivetti, G. Span, A. Carati, G. Girotti

PL6..........................................................................................................................................191 Vibrational dynamics of small molecules adsorbed in confined space of zeolite channels and cavities

Petr Nachtigall 6O1..........................................................................................................................................193

Masked lewis sites in proton exchanged zeolites: a computational and microcalorimetric investigation

C. Busco, V. Bolis, P. Ugliengo 6O2..........................................................................................................................................195

A combined theoretical and experimental approach to layered alkylamine-aluminophosphates

M. DAmore, C. Bisio, G. Talarico, M. Cossi, L. Marchese 6O3..........................................................................................................................................197

Combined synchrotron radiation x-ray powder diffraction and molecular dynamics simulation study of li-abw under high pressure

C. Medici, E. Fois, A. Gamba, G. Tabacchi,S. Quartieri, G. Vezzalini, C. Betti, V. Dmitriev 6O4..........................................................................................................................................199

Dehydration-rehydration processes in zeolite A: crystal-chemical characterization and possible application to improve the selectivity of gas sensors

L. Leardini, A. Martucci, M.C. Dalconi, A. Alberti 6O5..........................................................................................................................................201

First-principles studies of boron sites in zeolites E. Fois, A. Gamba, G. Tabacchi, F. Trudu

6P1 ..........................................................................................................................................205 Improved water-water and water-zeolite potentials for the simulation of structural and dynamical properties

P. Demontis, R. Sale, G.B. Suffritti



Session 6: Structural and computational studies


18

6P2 ..........................................................................................................................................207

The evaluation of the potential of proton- and metal-exchanged chabazites as media for molecular hydrogen storage: an ab initio study

F.J. Torres, B. Civalleri, P. Ugliengo, C. Pisani 6P3 ..........................................................................................................................................209

Ir spectroscopy and modeling of H2 adsorption and single-site catalysed ortho-para conversion on ETS-10

J.G. Vitillo, G. Spoto, G. Ricchiardi, A. Zecchina 6P4 ..........................................................................................................................................211

Synthesis and characterization of organic-inorganic hybrid nanosilicas by sol-gel method

P. Vzquez, E. Basaldella, J.A. Azamar Barrios, J.M. Martn-Martnez 6P5 ..........................................................................................................................................213

The Structural characterization of ferrierite in Ag- and Co, Ag-exchanged forms E. Balboni, A. Martucci, M.C. Dalconi, A. Alberti, D. Sannino, E. Palo, P. Ciambelli

6P6 ..........................................................................................................................................215

Comparison of structural changes upon heating of zorite and Na-ETS-4 by in situ synchrotron powder diffraction

M. Sacerdoti, S. Zanardi, G. Cruciani 6P7 ..........................................................................................................................................217

Structure of sodium layered octosilicateRUB-18: IR spectra and computational modeling M.F. Iozzi, M. Cossi, T.R. Macedo, C. Airoldi, L. Marchese

6P8 ..........................................................................................................................................219

Location of bronsted sites in omega zeolite: a combined x-ray and neutron diffraction study

I. Parodi , A. Martucci , A. Alberti , F. Di Renzo

19

VIII AIZ Congress 2007

Scientific Committee

A. Gamba (Univ. Insubria) President

R.Aiello (Univ. Calabria)

A. Alberti (Univ. Ferrara)

G. Bellussi (ENI Tecnologie S.p.A.)

G. Busca (Univ. Genova)

G. Centi (Univ. Messina)

P. Ciambelli (Univ. Salerno)

C. Colella (Univ. Napoli)

R. Psaro (CNR/ISTM)

V. Solinas (Univ. Cagliari)

A. Vaccari (Univ. Bologna)

A. Zecchina (Univ. Torino)

20

VIII AIZ Congress 2007

Local Organizing Committee

Organizing Committee: Salvatore Coluccia Edoardo Garrone Leonardo Marchese

Local Commitee: Chiara Bisio Barbara Bonelli Ugo Finardi Giorgio Gatti Enrica Gianotti Barbara Onida

Administrator Secretary: Giuseppina Cannatelli Aleteia Martins

21

Scope of the Congress

The Italian Zeolite Association (AIZ), the University of Turin, the University of Eastern Piedmont A. Avogadro and the Polytechnic

of Turin have organised the VIII AIZ Congress with the aim to stimulate academic and industrial researchers to discuss the most

recent advances in all aspects of porous materials.

The conference will be devoted to synthesis, characterization and uses of zeolites and related materials.

State-of-the-art and perspectives of basic and applied research will be highlighted

The major topics of the AIZ Congress will include:

1) Synthesis and characterisation of zeolites and other microporous materials

2) Synthesis and characterisation of mesoporous and layered

materials

3) Adsorption and ion exchange: properties and applications

4) Catalysis

5) Structural and computational studies

6) Natural zeolites

Programme

VIII AIZ Congress

1st July 4th July 2007


24

1st July, Sunday 15.00-19.00 Registration (Villa Gualino Congress Centre) 19.30-22.00 Welcome Party 2nd July, Monday 9.00-9.30 Opening ceremony

Session 1:

Synthesis and characterisation of zeolites and other microporous materials

Gualino Room, Villa Gualino Congress Centre 9.30-10.20 PL1 E. Iglesia (Material Science Division Department of Chemical

Engeneering, University of California at Berkeley (USA)) Synthesis, structure and reactivity of high-valent metal-oxo species grafted onto microporous solids

10.20-10.40 1O1 S. Zanardi, A. Carati, C. Rizzo, R. Millini, M.C. Dalconi

Synthesis, ion-exchanging and structural characterisation of stannosilicate EMS-2

10.40-11.00 1O2 A. Morsli, M.F. Driole, T. Cacciaguerra, R. Arletti, B. Chiche, F. Hamidi, A. Bengueddach, F. Quignard, F. Di Renzo Stabilisation of a microporous amorphous precursor of mordenite by CO2-induced chemical condensation of silanols

11.00-11.30 Coffee-break 11.30-11.50 1O3 T. Montanari, G. Busca


11.50- 12.10 1O4 I. Bottero, B. Bonelli, N. Ballarini, S. Passeri, L. Pesaresi, M. Armandi, F. Cavani, E. Garrone Surface and catalytic properties of imogolite nanotube

12.10-12.30 1O5 C. Delitala, E. Cadoni, D. Delpiano, D. Meloni, S. Melis, I. Ferino Liquid-phase Thiophene Adsorption on MCM-22 Zeolite

12.30-12.50 1O6 L. Regli, S. Chavan, G. Ricchiardi, C. Lamberti. G. Spoto, S. Bordiga, A. Zecchina Adsorption properties of highly dispersed copper ions in zeolites and mofs

12-50-14.30 Lunch


25

Session 2:

Synthesis and characterisation of mesoporous and layered materials Gualino Room, Villa Gualino Congress Centre

14.30-15.20 PL2 S. Inagaki (Toyota Central R & D Labs. Inc., Nagakute, Aichi,

Japan) Synthesis and unique properties of mesoporous organosilicas with crystal-like pore walls

15.20-15.40 2O1 S. Morandi, F. Prinetto, G. Ghiotti, D. Kostadinova, C. Grardin, D. Tichit Ni catalyst prepared by intercalation of host layered double hydroxides: influence of the anionic guest entities and reduction treatments

15.40-16.00 2O2 L. Pasqua, F. Testa, R. Aiello, J.B. Nagy Synthesis of folic acid-functionalized mesoporous silica 16.00-16.45 Coffee-break 16.45-17.05 2O3 C.A. Bertolino, E. Gianotti , G. Caputo, C. Isidoro, S. Coluccia

Photoactive hybrid mesoporous nanoparticles as a tool for diagnostics

17.05-17.25 2O4 C. Bisio, G. Gatti, E. Boccaleri, H.O. Pastore, L. Marchese Saponite clays: surface modification and its effect on acidity and porosity properties

17.25-17.45 2O5 R. Aiello, M.C. Bruzzoniti, E. Garrone, B. Onida, A. Prelle, C. Sarzanini, M. Teodoro, F. Testa, A.M. Torchia, A. Virga Mesoporous materials as stationary phase in liquid chromatography

17.45-18.05 2O6 H.G. Manyar, S. Tumbiolo, E. Gianotti, S. Coluccia, Y. Sakamoto, O. Terasaki Facile preparation of silico-pepsin bioreactors: encapsulation of bulky pepsin molecules within large mesopores of silica

19.00-23.00 Cheese Party & Poster session 3rd July

Session 3: Natural Zeolites Gualino Room, Villa Gualino Congress Centre

9.00-9.50 PL3 R. Fischer (University of Bremen, German)

Crystal chemistry of natural zeolites: rumors and facts 9.50-10.20 3O1 R. Arletti, F. Di Renzo

Do you need an organic template? A comparison of man-made


26

and natural synthesis of zeolites

10.20-10.40 3O2 S. Ori, G. Vezzalini, S. Quartieri, V. Dmitriev Pressure induced deformations and elastic behaviour of wairakite

10.40-11.00 3O3 I. Parodi, M.C. Dalconi, G. Cruciani, A. Alberti The dehydration and rehydration process in gmelinite: an in-situ X-Ray single crystal study

11.00-11.30 Coffee-break

Session 4: Adsorption and ion exchange: properties and applications

Gualino Room, Villa Gualino Congress Centre

11.30-12.20 PL4 P. Misaelides (Department of Chemistry Aristotle University, Thessaloniki - Greece) Adsorption and ion exchange properties of natural zeolites: still a subject of high quality and innovative research ?

11.20-12.40 4O1 L. Gigli, S. Blasioli, L. Braschi, A. Martucci, A. Alberti, C.E. Gessa The adsorption and degradation of sulfamide veterinary antibiotics on zeolites

12.40-13.00 4O2 A. Tavolaro, P. Tavolaro Synthesis, characterisation and cytochrome C adsorption properties of zeolite crystals and composite membranes

13.00-14.30 Lunch

Session 5: Catalysis Gualino Room, Villa Gualino Congress Centre

14.00-14.50 PL5 F. Cavani (University of Bologna)

Acid-catalysis with zeolites: a continuous challenge for the control of selectivity

14.50-15.10 5O1 M. Guidotti, M. Guisnet, P. Magnoux Acetylation of benzenic and naphthalenic compounds over acid zeolites: an alternative to homogeneous Friedel-Crafts catalysts

15.10-15.30 5O2 M. Bevilacqua, E. Finocchio, T. Montanari, G. Busca Traffic control and shape selectivity in the hydrocarbon chemistry catalyzed by protonic zeolites: infrared studies

15.30-15.50 5O3 D. Meloni, R. Monaci, V. Solinas, E. Dumitriu Liquid-Phase Alkilation of phenol with T-Butanol over various catalysts derived from MWW Precursors

15.50-16.10 Coffee-break 16.10-16.40 5O4 V. Murugesan (Anna University, Chennai INDIA)

Knoevenagel condensation over Beta and Y zeolites in liquid


27

phase under solvent free conditions 16.40-17.00 5O5 M. Rivallan, G. Berlier, G. Ricchiardi, A. Zecchina

Aluminium role in N2O decomposition over Fe-ZSM-5: a comparative study between Fe-ZSM-5 and Fe-silicalite

17.00-17.20 5O6 A. Blasi, E. Viola, F. Nanna, V. Valerio, G. Braccio, G. Giordano Olive oil bio-diesel preparation using acid zeolites catalysis in an innovative continuos reactor

17:20-19.00 AIZ meeting 19.30 Social dinner 4th July

Session 6:

Structural and computational studies Gualino Room, Villa Gualino Congress Centre

9.00-9.50 PL6 P. Nachtigall (Institute of Organic Chemistry and

Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Prague, Czech Republic) Vibrational dynamics of small molecules adsorbed in confined space of zeolite channels and cavities

9.50-10.10 6O1 C. Busco, V. Bolis, P. Ugliengo

Masked lewis sites in proton exchanged zeolites: a computational and microcalorimetric investigation

10.10-10.30 6O2 M. DAmore, C. Bisio, G. Talarico, M. Cossi, L. Marchese A combined theoretical and experimental approach to layered alkylamine-aluminophosphates

10.30-11.00 Coffee-break 11.00-11.20 6O3 C. Medici, E. Fois, A. Gamba, G. Tabacchi, S. Quartieri, G.

Vezzalini, C. Betti, V. Dmitriev Combined synchrotron radiation x-ray powder diffraction and molecular dynamics simulation study of Li-ABW under high pressure

11.20-11.40 6O4 L. Leardini, A. Martucci, M.C. Dalconi, A. Alberti Dehydration-rehydration processes in zeolite a: crystal-chemical characterization and possible application to improve the selectivity of gas sensors

11.40-12.00 6O5 E. Fois, A. Gamba, G. Tabacchi, F. Trudu

First-principles studies of boron sites in zeolites 12.00-12.30 Closing ceremony

SESSION 1

Synthesis and characterisation of zeolites and other

microporous materials

31

SESSION 1 INDEX PL1............................................................................................................................................35

Synthesis, structure, and reactivity of high-valent metal-oxo species grafted onto microporous solids

E. Iglesia 1O1............................................................................................................................................37

Synthesis, ion-exchanging and structural characterization of stannosilicate EMS-2 S. Zanardi, A. Carati, C. Rizzo, R. Millini, M.C. Dalconi

1O2............................................................................................................................................39

Stabilisation of a microporous amorphous precursor of mordenite by CO2-induced chemical condensation of silanols

A. Morsli, M.F. Driole, T. Cacciaguerra, R. Arletti, B. Chiche, F. Hamidi, A. Bengueddach, F. Quignard, F. Di Renzo

1O3............................................................................................................................................41


T. Montanari, G. Busca 1O4............................................................................................................................................43

Surface and catalytic properties of imogolite nanotube I. Bottero, B. Bonelli, N. Ballarini, S. Passeri, L. Pesaresi, M. Armandi, F. Cavani, E. Garrone

1O5............................................................................................................................................45

Liquid-phase thiophene adsorption on MCM-22 Zeolite C. Delitala , E. Cadoni , D. Delpiano , D. Meloni , S. Melis , I. Ferino

1O6............................................................................................................................................47

Adsorption properties of highly dispersed copper ions in Zeolites and MOFs L. Regli, S. Chavan, G. Ricchiardi, C. Lamberti. G. Spoto, S. Bordiga, A. Zecchina

1P1 ............................................................................................................................................51

Quantitative studies of Brnsted acid sites in microporous materials by combining FTIR and TG analysis

G.A.V. Martins, G. Berlier, G. Gatti, S. Coluccia, L. Marchese, H.O. Pastore 1P2 ............................................................................................................................................55

Structural INSERTION of carbon and nitrogen into a B-substitued chabazite L. Regli, C. Lamberti, C. Busco, A. Zecchina, C. Prestipino, S. Bordiga

1P3 ............................................................................................................................................57

Zeolite Y synthesis in seeded systems


32

G. Cugliari, S. Candamano, P. Frontera, F. Crea, R. Aiello 1P4 ............................................................................................................................................59

Structural investigation of Cobalt species in CoAPO-5: a spectroscopic study M. Vishnuvarthan, G. Berlier , E. Gianotti , V. Murugesan , S. Coluccia

1P5 ............................................................................................................................................61

Monitoring the Formation of H,Na-MCM-22 by a Combined TGA, XRD and FTIR of the Decomposition of the Directing Agent

L. Palin, H.O. Pastore, G. Croce , M. Milanesio, L. Marchese, D. Viterbo 1P6 ............................................................................................................................................63

Synthesis of new zeolite composite membranes A. Tavolaro, A. Adimari

1P7 ............................................................................................................................................65

Ceramization of sr-exchanged zeolite matrices B. Liguori, S. Anaclerio, C.Colella

1P8 ............................................................................................................................................67

Characterization of zeoliteS Exchanged with heavy metals as precursors of metal-ceramic composites

E.A. Turcato, S. Ronchetti, B. Onida, D. Mazza, P. Rivolo, S. Esposito, C. Ferone

SESSION 1


35

PL1

SYNTHESIS, STRUCTURE, AND REACTIVITY OF HIGH-VALENT METAL-OXO SPECIES GRAFTED ONTO

MICROPOROUS SOLIDS

E. Iglesia Material Science Division Department of Chemical Engeneering, University of California at Berkeley (USA)

ABSTRACT Metal-oxo species with high-valent cations (Zr4+,V5+,Mo6+,Re7+) were anchored within aluminosilicate channels in MFI and FER using vapor deposition of volatile precursors. These methods avoid large solvated ions that prevent exchange of these cations from aqueous media. The presence of metal-oxo structures, anchored as cationic monomers or bridged dimers interacting with one or two exchange sites, respectively, and the metal valancy were determined using combined chemical and spectroscopic methods. Isotopic titration and infrared spectra of residual OH groups and chemical reduction in H2 or CO were used to probe exchange stoichiometries. Raman, UV-visible, and X-ray absorption spectroscopies were used to assess the local structure and oxidation state of anchored metal-oxo species during synthesis and thermal treatment. Each cation replaced (approximately) one proton irrespective of cation valency; this led to isolated monomers on single exchange sites for odd valencies (V5+ and Re7+) and bridged dimers interacting with two exchange sites for even valencies (Zr4+ and Mo6+). These materials catalyze oxidation reactions of alkanols and also act as precursors to encapsulated metal and carbide clusters active in non-oxidative reactions of C1-C3 alkanes, for which containment of active structures within MFI zeolite channels is essential for selectivity and stability. The dynamics of this structural evolution from anchored metal-oxo precursors to active metal and carbide phases were probed by transient chemical analysis of effluent streams combined with X-ray absorption spectra of exchanged samples during activation and steady-state catalysis.

37

1O1

SYNTHESIS, ION-EXCHANGING AND STRUCTURAL CHARACTERIZATION OF STANNOSILICATE EMS-2

S. Zanardi 1, A. Carati 1, C. Rizzo 1, R. Millini 1, M.C. Dalconi.2 1Eni S.p.A., Refining & Marketing Division, San Donato Milanese (MI), Italy 1Harth Sc. Dept., University of Ferrara, Ferrara, Italy [email protected]

ABSTRACT Synthesis, ion-exchange properties and characterization of EMS-2, a new stannosilicate isostructural with the natural zirconosilicate lemoynite, have been are reported. EMS-2 samples were characterized by high resolution synchrotron X-ray diffraction, elemental and thermogravimetric analyses. The crystal structure of each exchanged samples was refined revealing the positions and occupancies of the extra-framework cations and water molecules. After de-hydration, the crystal structure of ion-exchanged EMS-2 was investigated by in-situ high temperature X-ray powder diffraction. The experiments indicated that the materials are stable at least up to 400 C and that the Sr- and Ba-exchanged samples undergo structural modifications at high temperature.

INTRODUCTION In the last years different efforts were carried out by the material scientists in order to obtain new microporous structures with zeolitic properties. Among the large number of compound obtained, mixed microporous Octahedral-Pentahedral-Tetrahedral framework silicates are probably the most appealing [1]. Particularly attractive is the Engelhards synthetic counterpart of the mineral zorite, named ETS-4 [2] that, in the strontium exchanged form, showed remarkable properties in separation of gas mixtures [3]. Following this seminal work the search for mixed microporous silicates containing other metal than titanium was extensively undertaken. The results of these studies were summarized in the outstanding reviews by Rocha and Anderson [1] who cite lemoynite [4] as a mineral with an interesting structure. Recently, the synthesis and the characterization of EMS-2, a new stannosilicate isostructural with the natural zirconosilicate lemoynite, have been reported by our group [5]. The synthesis, ion exchange property and characterization of EMS-2 are here reported.

EXPERIMENTAL In the typical synthesis of EMS-2 the reagent mixture was prepared adding in the order 75.7 g of sodium silicate solution (27 wt% SiO2, 8 wt% Na2O), 7.2 g of sodium hydroxide, 5.9 g of potassium fluoride and 61.1 g of an aqueous solution of tin (IV) chloride 0.28M. The slurry was crystallized in hydrothermal conditions at autogenous pressure at 170 C during 14 days. After filtration the final solid was separated by filtration and dried at 100 C. Cationic (Mg, Ca, Sr, Ba) exchanges were performed by two 1 h treatments under reflux conditions with 0.4 M chloride salt solutions, followed by repeated washings. Synchrotron X-ray powder diffraction data were collected at the beamline BM01 (ESRF, Grenoble) with a short wavelength (= 0.50067). Wavelength dispersive spectroscopy (WDS) analysis was performed on an Oxford WDS-600 spectroscope interfaced with a Jeol JSM-840A scanning electron microscope. Thermogravimetric (TG) analysis was performed at atmospheric pressure with a Mettler M3 thermobalance. Data were collected from 25 to 900 C under a 300 ml/min air flow, with a heating rate of 10 C/min.


38

RESULTS AND DISCUSSION Elemental analyses, carried out on the ion-exchanged EMS-2 samples, indicated a high degree of Na and K exchange by earth-alkali metal ions. This was confirmed by the crystal structure analyses of each exchanged sample. In fact the crystal structure refinements, performed by the Rietveld method, against the high-resolution synchrotron X-ray powder diffraction data, permitted to reveal the positions and occupancies of the extra-framework cations and water molecules. Furthermore the TG profiles of EMS-2 samples showed different phenomena of weight losses, associated to the elimination of water adsorbed on the surface and trapped within the pores. However, the different weight losses were in line with the total amount of water molecules per unit cell obtained by the crystal structure refinements. The stability of ion-exchanged EMS-2 samples was investigated, after de-hydration, by in-situ high temperature X-ray powder diffraction. The experiments indicated that the materials are stable at least up to 400 C and that the Sr- and Ba-exchanged samples undergo structural modification at high temperature. A detailed structural analysis demonstrated that a doubling of the c parameter of the unit cell accompanied by a lowering of the symmetry from C2/m to P21/c occurred.

REFERENCES [1] J. Rocha, M.W. Anderson, Eur. J. Inorg. Chem., (2000) 801. [2] Kuzniki S.M., US Patent ,4 938 989, 1990. [3] S.M. Kuznicki, V.A. Bell, S. Nair, H.W. Hillhouse, R.M. Jacubunas, C.M. Braunbarth, B.H. Toby, M. Tsapatsis, Nature, 412 (2001) 720. [4] M. McDonald, G.Y.Chao, Can. Mineral., 39 (2001) 1295. [5] R. Millini, A. Carati, G. Bellussi, G. Cruciani, W.O. Parker, Jr., C. Rizzo, S. Zanardi, Microporous Mesoporous [6] Mater., 101 (2007) 43-49

39

1O2

STABILISATION OF A MICROPOROUS AMORPHOUS PRECURSOR OF MORDENITE BY CO2-INDUCED

CHEMICAL CONDENSATION OF SILANOLS A. Morslia,b, M.F. Driolea, T. Cacciaguerraa, R. Arlettia, B. Chichea, F. Hamidib, A. Bengueddachc, F. Quignarda, F. Di Renzoa,* a Institut Charles Gerhardt, UMR 5253 CNRS-UM2-ENSCM-UM1, Matriaux Avancs pour la Catalyse et la Sant, ENSCM, 8 rue de lEcole Normale, 34296 Montpellier Cedex 5, France. b Dpartement de Chimie, Facult des Sciences, USTO, B.P. 1505 Elmenaouar, Oran, Algeria. c Laboratoire de Chimie Des Matriaux, Universit Oran Es-Senia, B.P. 1524 Elmenaouar, Oran, Algeria. *[email protected] The amorphous aluminosilicate gels formed at the beginning of the hydrothermal synthesis of mordenite present a microporous volume of the same order as the zeolite obtained later in the synthesis (0.14 cm3 g-1). The disorder of the gel is evidenced by the absence of structure-sensitive IR vibrations and X-ray diffraction lines and by the width of the 29Si MAS-NMR peaks. The microporosity of the hydrothermal gel collapses upon evaporative drying but can be preserved by supercritical CO2 drying.

0

20

40

60

80

100

120

0 0.2 0.4 0.6 0.8 1

p/p

cm3 g

-1 S

TP

a

b

Figure 1. Isotherms (N2 at 77 K) of (a) xerogel and (b) aerogel of the mordenite precursor.

Figure 2. MEB pictures of the samples of Figure 1. NaHCO3 crystals are visible at the outer surface of the aerogel.

The role of CO2 in the stabilisation of the porosity is not limited to the suppression of capillary forces beyond the critical point. A treatment by liquid CO2 allows to stabilise the microporosity in the same way as a treatment in supercritical CO2. In both cases, the stabilisation of the microporosity is accompanied by a decrease in the amount of silanols and by the formation of HNaCO3. The proposed mechanism for the stabilisation of the microporosity is the condensation of silanols at the surface of the micropores with the formation of siloxane bridges. The condensation corresponds to the reaction of CO2 with sodium cations and surface hydroxyls according to the equation: SiO-Na+ + SiOH + CO2 Si-O-Si + HNaCO3. The sodium bicarbonate formed cristallyzes outside the gel. The amount of HNaCO3 formed, evaluated by thermal gravimetry, indicates that 30% of the Na+


40

cations of the gel are extracted by the CO2 treatment. X-ray diffraction patterns and IR spectra confirm the formation of sodium bicarbonate. Nitrogen adsorption as well as 29Si RMN spectroscopy confirm the stabilisation of the microporosity of the amorphous aluminosilicate precursor.

5 10 15 20 25 30 35 40 45deg 2

Inte

nsity

(a.u

.)

(a)

(b)(c)

(d)

Figure 3: X-ray powder diffraction patterns of (a) mordenite, (b) thermally-dried hydrothermal gel, (c) supercritical CO2-dried hydrothermal gel, and (d) literature diffraction lines of NaHCO3. The diffractograms are shifted on the intensity scale.

0

1

2

3

400600800100012001400wavenumber

trans

mitt

ance

(a)

(b)

(c)

Figure 4. IR spectra of (a) hydrothermal xerogel, (b) hydrothermal aerogel, and (c) mordenite in KBr pellets. The spectra are shifted on the transmittance scale for easier comparison. The spectra of the gels do not present the structure-sensitive bands of mordenite. The aerogel presents the bands of partially hydrated sodium bicarbonate. More data in A. Morsli, M.F. Driole, T. Cacciaguerra, R. Arletti, B. Chiche, F. Hamidi, A. Bengueddach, F. Quignard and F. Di Renzo, Microp. Mesop. Mater. in press.

41

1O3 EVIDENCE OF COMPLEX INTERACTIONS DURING THE SELECTIVE ADSORPTION OF GASES AND VAPOURS IN

CATIONIC ZEOLITES: AN IR INVESTIGATION

T. Montanari, G. Busca* Laboratorio di Chimica delle Superfici e Catalisi Industriale, Dipartimento di Ingegneria Chimica e di Processo, Universit di Genova, p.le J. F. Kennedy 1, I-16129, Genova, Italy, Fax:+39 010 353 6028; Tel: +39 010 353 6024; E-mail: [email protected]

ABSTRACT IR studies of the adsorption of CO, CO2 and nitriles of alkali and alkaline earth LTA, MOR and FAU zeolites provide evidence for a relevant role of complex interactions (where more cations and oxygen atoms interact with the probes) in the selective adsorption of gases over zeolites molecular sieves.

INTRODUCTION According to their molecular sieving properties, zeolites act as selective regenerable adsorbants for purification of gaseous streams and separation of vapours and gases, either in the form of powder packed beds or of membranes. In this respect, the so called type A zeolites, denoted with the IZA (International Zeolite Association) code LTA (Linde Type A) have very large industrial application for drying of technical gases and liquids and for the n/i-alkane separation in discontinuous sorption processes. The potassium exchanged form, K-LTA or Linde 3A, finds relevant application in ethanol drying processes, for production of fuel grade bioethanol from starch or cellulosic biomasses fermentation with pressure swing adsorption processes. The sodium exchanged form, Na-LTA or Linde 4A, besides having large use as an ion exchanger in the field of detergency, is largely used for air, methane and natural gas purification and has also been considered for alkane/alkene separation. The calcium exchanged form, Ca-LTA (Linde 5A), finds wide application for N2/O2 air separation, and for separation of CO2 and COS from different gases, such as air in spacecraft cabins, methane, natural gas and biogases. Another relevant application of LTA zeolites is in the field of purification of hydrogen through pressure swing adsorption (PSA) processes. Sodium-faujasites, in the form of either NaX or NaY, are also applied industrially for the the separation of air components (N2/O2) by pressure/vacuum swing adsorption procedures, the separation of CO2 from different gaseous streams, the alkene/alkane, the benzene/cyclohexane and the xylene isomers separations. IR studies of the interaction of molecular probes, such as CO, NO, CO2, etc., with cationic zeolites provided evidence for the formation of well characterized 1 to 1 adducts (e.g. cation monocarbonyls) and also, sometimes, for 2 to 1 and 3 to 1 adducts, such as gem-dicarbonyls and tricarbonyls. We recently reported the spectroscopic evidence of the formation of more complex multiply bonded adducts for probes such as CO and nitriles on alkali mordenites [1,2]. Later we found that similar interactions may also occur on Na-Faujasites [3,4] We recently re-investigated the adsorption behavior of LTA zeolites, and we found, also in these cases, a relevant role of complex interactions, where more than one cation, and also framework oxygen atoms participate to the adsorption.

EXPERIMENTAL Self-supporting pressed disks of pure zeolite powders were activated in situ in the IR cell by outgassing at 723 K before the adsorption experiments. A conventional gas manipulation / outgassing ramp was connected to a IR cell which allowed cooling by liquid nitrogen in an external jacket. The adsorption / desorption process has been studied by transmission FT-IR, using a Nexus Nicolet IR


42

instrument

RESULTS AND DISCUSSION CO adsorption on 3A zeolite is mostly limited at the external surface. In the case of 4A zeolite, terminal Na carbonyls are formed. In the case of 5A zeolite, Ca2+ polycarbonyls and monocarbonyls are observed. In both 4A and 5A zeolites strongly bonded CO characterized by low CO stretching frequencies (2112 and 2107-2099 cm-1) are also observed. These have been identified as CO interacting with more than one cation, through both the C and the O atom. Ca ions in 5A zeolite are also bonded to extraframework hydroxy and carbonate ions, which modify their coordination sphere. These results may be relevant in relation to the use of these zeolites as adsorbents for the removal of CO from fuel gases, such as hydrogen. CO2 adsorption on 3A zeolite is also mostly limited at the external surface, both in the form of linear molecular species and of carbonate-like species. In the case of 4A and 5A zeolites, the adsorption occurs mostly in the cavities. Both linear molecular species and carbonate species are formed. The adsorption in the form of carbonates is definitely stronger. However, much more carbonate-like species are formed on 4A than on 5A. This is explained with the partial poisoning of the cations of 5A zeolite in the form of calcium hydroxy and carbonate species, which are already present in the sample after activation. Evidence for the participation of framework oxygen atoms to the adsorption of carbon dioxide and water is also provided by the perturbation of surface Si-O stretching modes upon adsorption. This perturbation is not found upon adsorption of CO, showing that, in that case, oxygen atoms do not participate to the adsorption. The results will be discussed in parallel with analogous experiments performed on alkali metal mordenites and faujasites.

REFERENCES 1- I. Salla, T. Montanari, P. Salagre, Y. Cesteros and G. Busca, Fourier Transform Infrared Spectroscopic Study of the Adsorption of CO and Nitriles on Na-Mordenite: Evidence of a New Interaction Journal of Physical Chemistry, B, 109, 915-922 (2005) 2- I. Salla, T. Montanari, P. Salagre, Y. Cesteros and G. Busca, A reexamination of the adsorption of CO and nitriles on alkali-metal mordenites: characterization of multiple interactions Physical Chemistry and Chemical Physics, 7, 2526 - 2533 (2005) 3- T. Montanari, P. Kozyra, I. Salla, J. Datka, P. Salagre and G. Busca Properties of sodium ions in zeolite materials: FT-IR study of the low temperature adsorption of carbon monoxide Journal of Materials Chemistry, 16 (2006) 995-1000. 4- P. Kozyra, I. Salla, T. Montanari, J. Datka, P. Salagre and G. Busca FT-IR study of the adsorption of carbon monoxide and of some nitriles on Na-faujasites: Additional insight on the formation of complex interactions Catalysis Today, 114 (2006) 188-196.

43

1O4

SURFACE AND CATALYTIC PROPERTIES OF IMOGOLITE NANOTUBE

1 I. Bottero,1 B. Bonelli, N. Ballarini,2 S. Passeri,2 L. Pesaresi,2 M. Armandi,1 F. Cavani,2 E. Garrone1 1Dip. di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, I -10129, Torino, Italy. INSTM, Research Unit of Torino Politecnico. 2Dip. di Chimica Industriale e dei Materiali, Facolt di Chimica Industriale, Universit di Bologna - Viale Risorgimento 4, I-40136 Bologna, Italy. INSTM, Research Unit of Bologna. [email protected]

ABSTRACT This work reports an insight into acidic properties of imogolite, as studied by means of adsorbed probe molecules, CO at nominal 77 K and NH3 at r.t. The catalytic properties in the acid-catalyzed gas-phase methylation of phenol have also been investigated.

INTRODUCTION Imogolite is an aluminosilicate with formula (OH)3Al2O3SiOH, naturally occurring as nanotubes with inner and outer diameters of 1.0 and 2.0 nm, respectively [1], which can be obtained by means of laboratory synthesis, too. Notwithstanding its intriguing nanotubes structure, with SiOH groups at the inner surface and Al(OH)Al groups at the outer surface of nanotubes, respectively, its surface properties have not been studied in detail.

EXPERIMENTAL Imogolite was synthesized via a sol-gel route based on the co-hydrolysis of aluminum sec-butoxide and TEOS (molar ratio = 2:1) at 20C in HClO4 solution, followed by heating in autoclave, according to Farmer et al. [2]. XRD spectra were collected on a XPert Phillips diffractomer using Cu k radiation; BET surface area and pores size were measured on powders outgassed at 423 K by means of N2 isotherms at 77 K with a Quantacrome Autosorb 1C instrument; FESEM pictures were collected on a High Resolution FE-SEM instrument (LEO 1525) equipped with a Gemini Field Emission Column; FT-IR spectra were recorded with a resolution of 2 cm-1 on a Bruker FTIR Equinox 55 spectophotometer, equipped with a MCT detector.

RESULTS AND DISCUSSION Low angles XRD patterns of imogolite (Figure 1) show that nanotubes are self-organized in an ordered structure: fibrous bundles forming a porous network are seen in the FE-SEM image (inset to Figure 1). At temperatures higher than 573 K, the nanotubes structure is partially lost. The total BET surface area is 240 m2 g-1, whereas the microporous area is 170 m2 g-1, indicating that nanotubes external surface area cannot be neglected. The average micropores diameter, as measured with the NL-DFT method, is 1.1 nm. FT-IR spectra (Figure 2) show hydroxyls engaged in H-bonding on imogolite outgassed at r.t., 373 and 573 K. After outgassing at 573 K, molecular water is removed: adsorption of CO at nominal 77 K shows carbon monoxide adsorbed on internal SiOH species (band at 2156 cm-1), along with CO on traces of Al3+ Lewis sites (2191 cm-1). After outgassing at 773 K, Al3+ ions are formed, due to surface de-hydroxylation (band in the 2200 - 2187 cm-1 range) and several OH species are seen, with bands at 3747, 3717 and 3660 cm-1. The latter suffer a downward shift of ca.


44

210 cm-1 upon CO adsorption, showing remarkable acidity. NH3 adsorption gives rise to the formation of ammonium species, reversible only after outgassing at 573 K. These interesting surface features, along with the intriguing nanotubes structure, render imogolite an interesting material with potential applications in catalysis or gas adsorption. The material prepared has been investigated as catalysts for the gas-phase methylation of phenol: the catalyst showed low activity, but selectivity to the product of ortho-C-methylation. However, the performance was clearly affected by diffusional limitations.

5 10 15 20 25 30

Inte

nsity

(cou

nts/

sec)

2

Figure 1. XRD patterns of synthetic imogolite. Figure 2. FT-IR spectra. Inset to Figure: FESEM picture. In conclusion the acidic properties of imogolite have been studied by means of FT-IR spectroscopy of adsorbed probe molecules. The surface of imogolite is covered by hydroxyls of different nature, strongly interacting with water, which is removed only after outgassing at 573 K. SiOH inside nanotubes are accessible to probes like CO and NH3, but also AlOH species at the outer surface play a role, since the outer surface cannot be neglected with respect to total surface area. When heated at 773 K, nanotubes lose their structure and new acidic species, both Lewis and Brnsted sites, are formed. Acknowledgements INSTM is gratefully acknowledged for financial support (Progetto PRISMA 2005).

REFERENCES [1] S. M. Barrett, P. M. Budd and C. Price, Eur. Pol. J., 1991, 27, 609. [2] V.C. Farmer, J.M. Adams, A.R. Fraser and F. Palmieri, Clay Minerals, 1983, 18, 459.

5 10 15 20 25 300

50

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150

200

250

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nsity

(cou

nts/

sec)

2

3500 3000 2500

1

2

3

4

5

6

7

(4)

(3)

(2)

(1)

(1) r.t.(2) outgassed at 423 K(3) outgassed at 573 K(4) outgassed at 773 K

Ab

sorb

ance

Wavenumbers (cm-1)

45

1O5

LIQUID-PHASE THIOPHENE ADSORPTION ON MCM-22 ZEOLITE

C. Delitala a, E. Cadoni b, D. Delpiano b, D. Meloni b, S. Melis a, I. Ferino b* aSaras Ricerche e Tecnologie SpA, V strada, trav. C, Z.I. Macchiareddu, 09032 Assemini (Italy) bUniversit di Cagliari, Dipartimento di Scienze Chimiche, Complesso Universitario di Monserrato, 09042 Monserrato (Italy) - Corresponding author, e-mail: [email protected]

INTRODUCTION The limitations on sulphur content of gasoline [1] are urging the development of novel technologies for sulphur compounds removal. Adsorption technology is worthy of investigation as an alternative route towards the deep desulphurisation of light cracked naphtha (LCN) streams. Due to the fine tune of both its molecular sieving capabilities and the acidic features of its hydrogen form, MCM-22 zeolite might be an interesting candidate for the selective adsorption of thiophenic compounds from mixtures of hydrocarbons of similar electron density. The present work reports about the synthesis, characterisation and adsorption behaviour of the hydrogen form of MCM-22 for the liquid-phase separation at room temperature of: (i), thiophene from thiophene/iso-octane mixtures; (ii), toluene from toluene/iso-octane mixtures; (iii), thiophene from thiophene/toluene/iso-octane mixtures. Thiophene and toluene were regarded as model compounds for the LCN organosulphur and aromatic fractions, respectively.

EXPERIMENTAL Hydrothermal synthesis of MCM-22 (Si/Al = 21) was carried out by using hexamethyleneimine as organic template, SiO2, NaAlO2, NaOH and deionised water. The hydrogen form of MCM-22 was obtained by exchanging the sodium form with NH4NO3 solution. Sample crystallization was checked by XRD on a 3K5 Italstructure diffractometer using Ni-filtered CuK radiation. Textural analysis was carried out on a Sorptomatic 1990 System (Fisons Instruments). Scanning electron microscopy (SEM) images were obtained on a FEI Quanta 200 microscope operated at 30 kV. Surface acidity was investigated by adsorption microcalorimetry on a Tian-Calvet heat flow equipment (C80, Setaram) using ammonia as a probe molecule. Liquid-phase adsorption experiments were carried out in batch conditions at room temperature in a modified FC6S Jar Test apparatus (Velp Scientifica). The thiophene and toluene contents for thiophene/iso-octane and toluene/iso-octane systems were determined by HPLC (Agilent Technologies, 1100 series). For thiophene/toluene/iso-octane solutions the concentration of thiophene in adsorption experiments was determined as total S by UV fluorescence (ThermoEuroglas TN-TS 3000). To investigate the nature of the organosulphur material retained by the zeolite, the adsorbent was separated from the thiophene/iso-octane mixture by filtration and treated with a 40% hydrofluoric acid solution, followed by extraction of the organic compounds by methylene chloride. The solvent was then evaporated and an oily liquid recovered, which was analysed by GC/MS (HP 5890 gas chromatograph coupled with HP 59721A quadrupole mass spectrometer).

RESULTS AND DISCUSSION The adsorbent was identified as crystalline MCM-22 by XRD analysis. Textural analysis indicated a by far predominant micropous character of the solid, in agreement with its zeolitic nature. The presence of slit-shaped, wide mesopores (or narrow macropores) was also revealed. These are probably originated by the aggregation of plate-like particles, as suggested by SEM images. Micropore analysis showed that the volumes of ultramicropores (0.4-0.7 nm-wide) and supermicropores (0.7-1.8 nm-wide) account for 27 and 73% of the total micropore volume, respectively. These figures are consistent with the volume fraction of the straight and oblique (0.40 x 0.55 nm) and the interconnected sinusoidal (0.40 x 0.50 nm) channels (30%) and that of the large cylindrical (0.71 x 0.71 x 1.84 nm) supercages (70%). The acid features of MCM-22, assessed by calorimetric experiments, can be summarised as follows: (i), the concentration of acid sites,


46

characterised by differential heats of adsorption ranging between ca. 250 and 70 kJ/mol, is ca. 560 mol/g; (ii), the concentration of silanol groups (differential heats of adsorption in the 70-50 kJ/mol range) is ca. 420 mol/g. The toluene adsorption isotherm for toluene/iso-octane mixtures exhibited a wide plateau. The thiophene isotherm for thiophene/iso-octane mixtures, showed a stepwise character: after a short plateau, a second, wide plateau was attained. These trends have been interpreted as follows: (i), both toluene and thiophene interact with the acid sites of MCM-22 (the amount of toluene corresponding to saturation, ca. 625 mol/g, and the amount of thiophene corresponding to the first saturation step, ca. 510 mol/g, are fairly close to the acid sites concentration of the adsorbent, 560 mol/g); (ii), while toluene adsorption ends up once all of the acid sites have been occupied, the onset of a second adsorption step occurs for thiophene, due to the establishing of interactions with silanol groups (the thiophene amount adsorbed during this second step, ca. 470 mol/g, is close to the concentration of the silanol groups, ca. 420 mol/g). As a consequence of tiophene-silanol interactions the local concentration of thiophene increases in proximity of thiophene molecules formerly adsorbed on the acid sites. This might favour the transformation of thiophene through bimolecular reactions. Direct evidence for the occurrence of such reactive adsorption of thiophene was obtained by GC/MS investigation of the nature of the organosulphur material recovered in methylene chloride after the adsorption experiment. The products reported below were identified.

SS

S

S

S

S S

S

S

S

S

CH3S

SS

CH3

S

CH3

CH3

S S S S

CH3 CH3

The products with molecular weight 252, 336 and 302 have been reported to form also upon liquid-phase adsorption of thiophene on HY zeolite [2], whereas the others seem typical of MCM-22. Their structure reflects the supercage conformation of the adsorbent. The complex reactions leading to such products have been outlined. Due to its ability to adsorb thiophene in a reactive way, MCM-22 appeared quite effective for the separation of thiophene from toluene-rich thiophene/toluene/iso-octane solutions.

REFERENCES [1] S. Rossini, Catal. Today 77 (2003) 467, [2] D. Richardeau, G. Joly, C. Canaff, P. Magnoux, M. Guisnet, M. Thomas, A. Nicolaos, Appl. Catal. A: General, 263 (2004) 49.

MW = 252 MW = 336 MW = 302

MW = 208 MW = 332 MW = 456

47

1O6 ADSORPTION PROPERTIES OF HIGHLY DISPERSED

COPPER IONS IN ZEOLITES AND MOFS L. Regli, S. Chavan, G. Ricchiardi, C. Lamberti. G. Spoto, S. Bordiga, A. Zecchina, University of Torino and NIS Centre of Excellence, Via P. Giuria 7, I-10125 Torino, Italy

ABSTRACT IR spectroscopy has been used to characterize the adsorption properties toward hydrogen of a copper exchanged ZSM-5 and a copper MOFs. In the first case only the presence of isolated diluted Cu(I) sites have been evidenced, while in case of copper-MOF (HKUST-1), abundant Cu(II) species with a coordination vacancy have been found.

INTRODUCTION The use of hydrogen physisorption on porous materials is one of the main methods considered for automotive applications. The goals is to store a large amount of hydrogen at near-ambient temperature in safe conditions. Hydrogen adsorption has been investigated on a wide range of carbon, silica, alumina, zeolites, silico-titanates, metal organic framework and polymeric porous materials. The maximum amount adsorbed is limited by the H2 adsorbate density, adsorbent pore structure and pore volume available in the narrowest pores. The interaction energy is in the 5-10 kJ /mol range and this is not enough to ensure a sufficient adsorption capacity at room temperature. The presence of highly dispersed cations able to interact with hydrogen quadrupole, is a possible route to obtain the estimated optimum interaction energy for molecular hydrogen storage at RT. Materials with an interaction energy in the 20-25 kJ/mol range could be proposed for practical utilization. In this contribution a zeolite and a metal-organic framework have been considered and compared as both of them are characterized by the presence of copper ions.

EXPERIMENTAL HKUST-1 was synthesized according to the method reported by Williams and co-workers[1] and provided by colleagues working in St. Andrews. Cu(I)-ZSM-5 was prepared by reaction of H-ZSM-5 (Si/Al~90) with gaseous CuCl,[2] a procedure leading to the 1:1 substitution of the zeolite acidic protons exclusively with isolated Cu(I) ions. Similar results can be obtained in case of ion exchanged zeolite with Cu(NO3)2. A detailed description of the cryogenic cell (consisting of a properly modified closed circuit liquid helium Oxford CCC 1204 cryostat) is given elsewhere.[3] The FTIR spectra were collected in transmission mode (at 1 cm-1 resolution) on a Bruker Equinox-55 FTIR spectrometer, equipped with a MCT detector, whose sample compartment was modified ad hoc to accommodate the cryogenic IR cell. Samples were measured in form of self-supporting thin wafers.

RESULTS AND DISCUSSION As it has been already shown in several publications, IR spectra of adsorbed hydrogen collected in controlled pressure and temperature conditions can be very informative in describing and differentiating the available active sites exposed on a surface of a microporous material since upon interaction with a polarizing center, the (HH) mode of hydrogen becomes IR active and is downward shifted with respect to the gas phase. The shifts observed for the different interactions sites are usually larger than those found in the case of the others diatomic molecules.[2,4] By an fundamental point of view, this peculiarity offers the possibility to distinguish sites that have very similar interaction energy, but implies also sometimes an increase of the spectra complexity. A further reason of complexity in IR spectra of adsorbed hydrogen, is due to the fact that H2 molecule can exists in two forms differing for the relative orientation of the nuclear spins of the two protons: ortho-H2 (parallel nuclear spins) and para-H2 (anti-parallel nuclear spins). Ortho- and para-H2 can be distinguished spectroscopically as they give rise to two distinct (H-H) Raman bands separated by 6 (H2 gas) 9 (H2 solid) cm-1.[5] Since the conversion of ortho- into the more stable para-H2 requires spin inversion, the process is extremely slow in normal conditions, but it can be promoted by spin catalysis.[6] It has been


48

shown that upon dehydration of HKUST-1 sample, the first coordination sphere of Cu2+ sites is significantly modifieds since the appearance of coordinative unsaturation on copper ions is observed.[7]. Dosing 50 mbar of H2 on HKUST-1, upon temperature decreasing (150-80 K), we observe the parallel growth of two bands at 4097 and 4090 cm-1. Their frequency separation, intensity ratio and coverage dependence allows the straightforward assignment of the doublet to ortho and para hydrogen on Cu2+ sites. Upon a progressive temperature decrease till 20 K, this doublet progressively changes in the intensity ratio. In the mean time the formation of new absorptions at higher frequency, at 4133 (with a shoulder at 4128), 4137, 4141 and 4148 cm-1 develop till to reach a maximum, when the cryostat is at 20 K. The shape of these components is very unusual as they are very sharp in a region where more commonly the bands are broad being associated to very weakly perturbed hydrogen molecules.[4,8] In the second part of the experiment, we have waited for sample equilibration at 20 K for reaching the equilibrium state. In the first 30 minutes in which we have left the sample at 20 K, we observe the selective decreases of the band at 4084 cm-1, the parallel growth of the component at 4089 cm-1 (clear isosbestic point at 4087 cm-1), the disappearance of the band at 4133 cm-1 and the small increase of all the others components (4137, 4140 and 4148 cm-1). A tentative explanation of the complex evolution of the spectra considers the formation of species due to hydrogen molecules adsorbed on the same Cu2(CO2)4 unit interacting respectively with the Cu2+ and the oxygens of the carboxylates. Furthermore time-dependent spectral changes are also associated with conversion of ortho- into the more stable para-H2. Completely different results have been achieved in the case of Cu(I)-exchanged zeolites, where hydrogen adsorbed on Cu(I) ions has been associated with a (HH) as low as 3079 cm-1.[9,10] In this case it is a widespread opinion that a (HH) of the order of -1000 cm-1 is due to the formation of dihydrogen molecular complexes in side-on configurations, a symptom of a strong interaction involving weak electrostatic (charge induced dipole and charge quadrupole) and strong chemical (donation from the H2 s orbital and from the 3dp orbitals of Cu(I)) contributions.[11] Unfortunately, no data are available in the case of Cu(II) ions both in zeolites and/or others microporous systems. When Cu(II) is introduced, as a counterion, inside a zeolitic matrix, it is in the hydrated form, thus not accessible to weak ligand molecules. Upon activation in vacuo to remove water molecules, Cu(II) species are reduced to Cu(I)[12,13] that have a much stronger affinity toward H2. All these results taken together, we ascribe the band at 4100 cm-1 to dihydrogen coordinated to Cu(II) species. This assignment is perfectly in line with what has been obtained in the case of CO adsorption.[7]

REFERENCES [1] S. S. Y. Chui, S. M. F. Lo, J. P. H. Charmant, A. G. Orpen and I. D. Williams, Science, 1999, 283, 1148; [2] G. Spoto, E. Gribov, S. Bordiga, C. Lamberti, G. Ricchiardi, D. Scarano and A. Zecchina, Chem. Commun., 2004, 2768; [3] G. Spoto, E. N. Gribov, G. Ricchiardi, A. Damin, D. Scarano, S. Bordiga, C. Lamberti and A. Zecchina, Prog. Surf. Sci., 2004, 76, 71; [4] S. Bordiga, J. G. Vitillo, G. Ricchiardi, L. Regli, D. Cocina, A. Zecchina, B. Arstad, M. Bjorgen, J. Hafizovic and K. P. Lillerud, J. Phys. Chem. B, 2005, 109, 18237; [5] B. P. Stoicheff, Can. J. Phys., 1957, 35, 730; [6] B. F. Minaev and H. Agren, J. Phys. Chem., 1995, 99, 8936; [7] C Prestipino, L. Regli, J. G. Vitillo, F. Bonino, A. Damin, C. Lamberti, A. Zecchina, P. L. Solari, K. O. Kongshaug and S. Bordiga, Chem. Mat., 2006, 18, 1337; [8] A. Zecchina, S. Bordiga, J. G. Vitillo, G. Ricchiardi, C. Lamberti, G. Spoto, M. Bjorgen and K. P. Lillerud, J. Am. Chem. Soc., 2005, 127, 6361; [9] G. Spoto, E. Gribov, S. Bordiga, C. Lamberti, G. Ricchiardi, D. Scarano, A. Zecchina, Chem. Commun. 2004, 2768; [10] A.I. Serykh, V. B. Kazansky, Phys. Chem. Chem. Phys. 2004, 6,5250; [11] E. A. Paukshtis and N. E. Yurchenko, Russ. Chem. Rev., 1983, 52, 426; [12] X. Solans-Monfort, V. Branchadell, M. Sodupe, C. M. Zicovich-Wilson, E. Gribov, G. Spoto, C. Busco, P. Ugliengo, J. Phys. Chem. B 2004, 108, 8278; [13] G. Turnes Palomino, P. Fisicaro, S. Bordiga, A. Zecchina, E. Giamello, C. Lamberti, J. Phys. Chem. B 2000, 104, 4064; [14] F. X. Llabres i Xamena, P. Fisicaro, G. Berlier, A. Zecchina, G. Turnes Palomino, C. Prestipino, S. Bordiga, E. Giamello, C. Lamberti, J. Phys. Chem. B 2003, 107, 7036.

SESSION 1

Poster Contributions

51

1P1

QUANTITATIVE STUDIES OF BRNSTED ACID SITES IN MICROPOROUS MATERIALS BY COMBINING FTIR AND

TG ANALYSIS G.A.V. Martins,a G. Berlier,a G. Gatti,b S. Coluccia,a L. Marcheseb, H. O. Pastorec aDipartimento di Chimica IFM, Universit di Torino, Turin I-10125 Italy, [email protected], bDipartimento di Scienze e Tecnologie Avanzate, Universit del Piemonte Orientale, Alessandria I-15100, Italy, cInstituto de Qumica, Universida de Estadual de Campinas, Campinas.

ABSTRACT H-SAPO-34, a silico-aluminophosphate (SAPO) with chabazite structure and Brnsted functionality, has shown peculiar activity and selectivity in MTO processes, and is now central to the UOP/Norsk Hydro MTO technology. The ability of tuning concentration and strength of Brnsted acid sites in solid catalysts could improve the process performances and catalysts lifetime. As a consequence, a careful characterization of Brnsted sites in terms of acid strength and number represents a fundamental advance in catalysis. In this work we concentrate on H-SAPO-34 material, where the presence of three distinct Brnsted sites (one of them showing an acid strength comparable to zeolite homologues) was recently proved by spectroscopic analysis. In this work, a quantitative method for the determination of total Brnsted content is proposed.

INTRODUCTION The use of zeolites and zeotypes as catalysts for hydrocarbons conversion represents an important tool of the modern chemical and petrochemical industry. In particular, the introduction of microporous solid acids for gasoline conversion[1] and other processes such as methanol transformation to light olefin (MTO)[2] results advantageous in terms of safety and waste reduction. The ability of tuning the amount and acid strength of Brnsted sites in solid catalysts still represents one of the main goals of synthetic chemists. One could in fact synthesize materials with the desired tuned acidity, in order to improve the process selectivity and to minimize coke formation to avoid fast deactivation of the catalysts[2]. Many efforts are being devoted to this aim[3], and a careful characterization of Brnsted sites in terms of acid strength and number would represent an important feedback for the synthetic community[4-6]. In a recent paper, we described how FTIR spectroscopy of adsorbed CO, associated to a very careful work of multi-curve fitting along with hydrogen bonding theory, could be used to estimate the relative fraction of Brnsted sites with slightly different strength in H-SAPO-34 samples[6]. We also evidenced the presence in H-SAPO-34 of three distinct families of Brnsted sites, one of them having an acid strength comparable to zeolites[6]. This work represents a further relevant step in the characterization of Brnsted sites in microporous solid catalysts. In fact, our aim is to manage a quantitative determination of Brnsted sites with different acid character in H-SAPO-34 materials. The combined use of FTIR spectroscopy of adsorbed probe molecules (CO and NH3) and of gravimetric measurement, together with critical evaluation of literature data, allowed us to carefully re-calculate the extinction coefficients related to the three distinct Brnsted sites in H-SAPO-34 materials and to give a precise quantification of their amount by using the Lambert-Beer correlation. These results are of general validity for the quantification of Brnsted acid sites in chabasite-like materials and can thus have a great impact in determining the catalytic efficiency.

EXPERIMENTAL The H-SAPO-34 sample reported in this study was prepared by hydrothermal synthesis using tetraethylammonium hydroxide as structure directing agent. FTIR spectra were recorded on pressed


52

discs placed in a quartz cell allowing thermal treatments, gas dosage and in-situ measurements. Before IR measurements, the samples were activated in vacuum in the same quartz cell. Ammonia desorption was carried out by gradually increasing the temperature in a N2 flow (50 cc/min). The parallel gravimetric experiment was performed in the same conditions on a TGA equipment, after dosage of ammonia on a sample activated at 773 K in vacuum.

RESULTS AND DISCUSSION The adsorption/desorption of ammonia on H-SAPO-34 sample was followed by FTIR, by gradually increasing the sample temperature in a nitrogen flow after room temperature (RT) ammonia dosage (Fig. 1). At RT the protonation of ammonia by reaction with Brnsted sites, is witnessed by the appearance (among the others) of the typical bending mode of 4+ at 1456 cm-1 , the intensity of which is then proportional to the amount of Brnsted sites. The presence of weakly adsorbed NH3 on Lewis sites is instead testified by the (-H) mode at 1637 cm-1. A careful FTIR study allowed to determine the experimental conditions (between 165 and 180 C) where the only adsorbed species are ammonium ions, that is a 1:1 NH4+/Si(O-)Al ratio is present. The same experimental conditions were employed to follow ammonia desorption by TG analysis (Fig. 2). The NH3-TGA shows a first mass loss below 170C due to desorption of weakly adsorbed NH3 and a second mass loss at higher temperatures due to NH4+ decomposition. The latter data could be quantitatively correlated to the intensity of the (-H) mode of NH4+ at 1456 cm-1.

In our recent work, a spectroscopic method for estimation of the relative fraction of the three distinct Brnsted sites (adsorbing at 3630, 3614 and 3600 cm-1) in H-SAPO-34 samples was proposed [6] (Fig. 3). The

quantification of total Brnsted sites by ammonia desorption was then combined with the former data, in order to determine the individual extinction coefficients for the three Brnsted acids sites (Table 1). The calculate values were compared with literature data and the statistical validity was checked. These values are of general validity and can be used to calculate the amount of Brnsted sites in chabazite-like SAPO material.

4000 3500 3000 2500 2000 1500

Abs

orba

nce

Wavenumber / cm-1

0.25 a.u. (NH+4)

(NH3)

-OH Free

a

bc

d

0 60 120 180 240 300 360 420 480 540 600

4.8

5.0

5.2

5.4

5.6

5.8

6.0

200

400

600

800

1000

Tem

pera

ture

ram

p /

C

NNH3 = 10,89 mmol/g

N NH4

+ =

> N O

H =

2,7

0 m

mol/

g

Mas

s lo

se /

mg

Time / min

Stop at 170C for 6 hours

35003550360036503700

Wavenumber / cm-1

0,1OH Free

A

BC

Abs

orba

nce

Figure 1: IR spectra of calcined H-SAPO-34: (a) with 20 torr of ammonia (b) After 23 h at 165C; (c) After 3 h at 180C; (d) After 1 h at 550C treatment. (b) to (d) were recorded under N2 flow.

Figure 2: Thermogravimetric analysis of NH4-SAPO-34 made under nitrogen flow.

Figure 3: FTIR of H-SAPO-34; relative fraction of the three Brnsted sites

Table 1. Extinction coefficient of the three Brnsted acid sites.

OH(cm-1) A (cm-1) OH (%)a NOH (mmol.g-1) (cm.mmol)

3630 10.9 45.1 1.22 2.9 3614 2.5 10.5 0.28 2.9 3600 10.7 44.4 1.20 4.5 a Determined in our recent work [6].


53

REFERENCES [1] Wojciechowski, B. W.; Corma, A. In Catalytic Cracking: Catalyst, Chemistry and Kinetics; Dekker, Ed. New York, (1986), [2] Stocker, M. Microporous and Mesoporous Materials 29 (1999), 3, [3] Pastore, H. O.; Coluccia, S.; Marchese, L. Ann. Rev. Mater. Res. 35 (2005) 351, [4] S. Bordiga, L . Regli, D. Cocina, C. Lamberti, M. Bjorgen, K. P. Lillerud, Journal of Physical Chemistry B 109 (2005), 2779, [5] X. Wang, J. Coleman, X. Jia and J. L. White. Journal of Physical Chemistry B 106 (2002) 4941-4946, [6] G.A.V. Martins, G. Berlier, S. Coluccia, H. O. Pastore, G. B. Superti, G. Gatti and L. Marchese. Journal of Physical Chemistry C 111 (2007), 330-339.

55

1P2

STRUCTURAL INSERTION OF CARBON AND NITROGEN INTO A B-SUBSTITUED CHABAZITE

L. Regli,a C. Lamberti, a C. Busco,b A. Zecchina, a C. Prestipino,c S. Bordigaa a University of Torino and NIS Centre of Excellence, Via P. Giuria 7, I-10125 Torino, Italy b DiSCAFF and NIS Centre of Excellence, Via Bovio 6, 28100 Novara, Italy c ESRF, 6 rue Jules Horowitz, BP220, F-38043, Grenoble CEDEX, France

ABSTRACT As prepared B-SSZ-13 exhibits [B(OSi)4] units in Td-like geometry, upon template burning, the break of a B-O-Si bond results in [B(OSi)3] units in D3h-like geometry, testified by the appearance of the IR fingerprint at 1390 cm-1 and by the evolution of the NEXAFS spectrum. Interaction with CH3OH and NH3 at room temperature results in a rich reactivity with both [B(OSi)3] units and adjacent SiOH species. A gentle thermal treatment at 373 K in CH3OH or NH3 atmosphere results in the formation of OCH3 or -NH2 species bonded directly to boron or to silicon, stable at ambient atmosphere. These observations on one hand justifies on a molecular level the unsuitability of B-CHA system for the MTO process and in the mean time they represent the possibility to insert of basic species (NH2) inside a zeolitic framework, and thus the achievement of a microporous molecular sieve acting as a Brnsted base.

INTRODUCTION Zeolites are well known as acid catalysts. B-substituted zeolites give rise to materials with very low Brnsted acidity. The idea to modulate the Brnsted acidity by the isomorphous substitution of boron inside the zeolitic framework has been previously exploited with success in case of vapor-phase Beckman rearrangement of cyclohexanone oxime to -caprolactam performed on B-ZSM-5 [1, 2]. It is consequently expected that B-substituted Chabazite should be less acidic than the H-SAPO-34 and H-SSZ-13 materials, which are the correspondent silicoaluminophosphate and silicoaluminate, respectively. By the MTO process point of view, a less acidic materials as B-substituted Chabazite should be less prone to form coke. Authors explains the total inactivity of B-SSZ-13 towards methanol to hydrocarbons process in term of its lower Brnsted acidity as singled out by NH3 TPD measurements [3]. More interesting could be the properties of Boron to act as Lewis center and reacting with CH3OH or NH3. First spectroscopic results on such interactions are reported in this contribution.

EXPERIMENTAL B-SSZ-13 with a Si/B ratio of 12 has been synthesized following the description reported elsewhere [4]. Parallel studies on self supported pellets and on thin films of B-SSZ-13 deposited on a Silicon wafer have been performed in order to deeply investigate the behavior of surface OH groups and Boron species upon CH3OH and NH3 interaction, respectively. NEXAFS measurements have been obtained on self supporting pellet previously contacted with CH3OH and NH3. The spectra have been collected at BEAR at the Elettra Synchrotron. Molecular modeling has been performed using the Gaussian03 computer code 36 within the DFT approach. Minimal cluster models have been adopted in order to study the thermochemical relative stability of OCH3 and NH2 surface species anchored on B and Si atoms and to substantiate the experimental vibrational results. Hybrid B3LYP functional with the standard gaussian 6-31+G(d,p) basis set has been adopted to fully optimize the considered structures and to compute the harmonic frequencies, which resulted all positive for the reported equilibrium structures (minima on the potential energy surface).


56

RESULTS AND DISCUSSION For studying the interaction between B-SSZ-13 sample and CH3OH and NH3 molecules, the IR experiment have been performed in three steps: (i) increasing

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