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7/31/2019 Registration Seminar Report-Prince G

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1. IntroductionMetal organic frameworks (MOFs) are one of the latest smart materials that are primarily

studied for gas storage and separation applications. More recent researches also have shown

promises in the area of catalysis. MOFs are synthesized chemically, consisting of inorganic

metal atoms/ions interconnected by organic linkers, forming porous crystalline structures

where porosity varies from meso to nano porous ranges (i.e.


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(PS) alone and in the presence of 4,4'-isopropylidenc bis(2,6-dibromophenol) was

investigated by MacNeilland et al. [1] and had shown product yields ranging from styrene,

carbon dioxide, water, benzaldehyde, alpha-methylstyrene, phenol, phenylacetaldehyde

and acetophenone. Vishal Karmore and Giridhir Madras [2] had shown that degradation in

presence of acid catalysts is more effective, the study was on polystyrene degradation using

p-tolune sulfonic acid for a temperature range from 150-170C. Carnitiand et al. [3] had

shown effect of acid catalyst for the formation of volatile compounds. The study was carried

out on polystyrene in presence of four different zeolites and silica as catalysts for two

different temperatures of 300C and 400C. They have also shown the product distribution

varying from C6C24 series. Catalytic degradation of polystyrene under ZSM-11 was

demonstrated by Lilina et al. [4] and reported complete thermal degradation between a

temperature ranges of 400-500C. The resultant products reported mainly was styrene and 1,

5 hexadiene. Natural clinoptilolite zeolite HNZ was studied as a catalyst in the degradation of

polystyrene (PS) at 400C. Lee et al. [5] had also reported the resultant product of degradation

as styrene and liquid oils in range of C6C12.

De-carboxylation of vegetable oils is another research area which has been gaining grounds

in recent times. The study on the effectiveness of MOFs for such type of reactions is also

challenging because of involvement of high temperature. Some recent activities in this area

are cited as follows. Kinetics for the deoxygenation of glycerol to aliphatic hydrocarbons

over alumina was studied by Vonghia et al. [6] showing dehydration of glycerol at 450 C to

monoalkenes. Nitrides of Molybdenum and Vanadium over supported alumina were

deoxygenated by canola oil at 380-410C and had shown product yield (medium level diesel

oil) by Monnier et al. [7]. Decarboxylation of oleic acid without hydrogen was carried out

using three different MgO contents. Its effect of MgO content in hydrotalcites and reaction

temperature of 623 K on the decarboxylation performance was shown by Jeong-Geol Na et

al. [8]. Fuand et al. [9] had reported the use of activated carbons impregnated with Pd and

supercritical water for the decarboxylation of oleic acid, palmitic acid to their corresponding

lower carbon n-alkanes at temperature of 370C.


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3. Research Objectives

The research objectives can be summarized as follows:

To synthesise and characterize different metal organic frameworks suitable forcatalysis.

To study catalytic activities of different metal organic frameworks on varioussubstrates viz. polymeric materials and vegetable oils.

To theoretically predict catalytic activity of studied metal organic framework. To determine the reaction kinetics for various substrates during catalysis.

4 . Experimental

Synthesisof MOF catalystsSynthesis of Cu-BTC (HKUST-1) [10]: Cu-BTC or HKUST-1 was first reported by Chui et

al. [10].This method reported by Liu et al. and is a modification of previous works by

Rowsell and Yaghi. 1, 3, 5-benzenetricarboxylic acid (1.0 g) was dissolved in 30 ml of a 1:1

mixture of ethanol/N,N-dimethylformamide (DMF). In another flask, Copper (II) Nitrate

trihydrate (2.077 g) was dissolved in 15 ml water. The two solutions were then mixed and

stirred for 10 min. They were then transferred into Teflon-lined stainless steel autoclave and

heated at 373 K for 10 hours. The reaction vessel was cooled to room temperature normally.

The resulting blue crystals were isolated by filtration and extracted with methanol overnight

using a Soxhlet extractor to remove solvated DMF. The product was then dried at room

temperature.

Synthesis of Zn-BDC [11]: Zn-BDC on the other hand was synthesized following the

original procedure described by HenrikFan Clausen et al followed by the modified route of

Jinping Li et al.[14] Zn (NO3)2.6H2O (6 g), and H2BDC (1.7 g) were dissolved in DMF (20ml). The solution was then transferred into Teflon- lined autoclave, which was heated at 373

K for 24 h. The reaction products were cooled to room temperature, and the solid obtained

were collected by centrifugation, washed with DMF, and dried at room temperature.

Synthesis of MIL-53(Fe): Fe-BDC or MIL-53 was synthesized hydrothermally following the

published work of Ferey et al. [12]. The reaction was carried out in Teflon lined stainless

steel autoclave where a stoichiometric mixture of FeCl3.xH2O, DMF and 1, 4-benzene


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dicarboxylic acid was placed for 24 h at 423 K. Post-synthesis treatments of MIL-53 (Fe)

sample was washed with water, DMF, acetone and dried in air.

Synthesis of Pb-BTC: The method of synthesis is a modification of previous works by

Rowsell and Yaghi [10]. 1, 3, 5-benzenetricarboxylic acid (1.0 g) was dissolved in 30 ml of a

1:1 mixture of ethanol/N, N-dimethylformamide (DMF). In another flask, Lead (II) Nitrate

hexahydrate (2.077 g) was dissolved in 15 ml water. The two solutions were then mixed and

stirred for 10 min. They were then transferred into Teflon-lined stainless steel autoclave and

heated at 373 K for 10 hours. The reaction vessel was cooled to room temperature normally.

Characterization: To have a greater understanding of behaviour of MOF against different

solvents as its being proposed for separation studies, all the synthesized samples were

subjected to washing with solvents like methanol, dimethylformamide, ethanol etc. Selection

of solvent was confirmed form literature. Characterization was done for all samples which

included SEM. TGA, XRD and BET.

Thermal degradation of polystyrene: The aim of the thermal degradationexperiment is to lower the thermal degradation temperature of polystyrene in air. Initially

known quantity of polystyrene is taken for thermal degradation, the degradation temperature

is noted.Then followed by equal quantity of known catalysts and polystyrene were taken and

subjected to thermal degradation with temperature restriction. The final weight of the

substrate is measured and final solid end products remaining were to be characterized.

Decarboxylation of vegetable oils: The experiment is the decarboxylation ofvegetable oil (primary study on coconut oil). A closed glass round bottom flask is taken in

which known quantity of vegetable oil is mixed with known quantity of MOF that acts as

catalyst.The flask is heated above 150oC. The vapours are condensed and refluxed back to the

flask. The reaction is stopped after 2hrs.The end products in the flask were washed with n

hexane and centrifuged at 3000 rpm for 30 minutes. The different phases after centrifugation

were characterized for desired products (i.e. hydrocarbons mainly alkanes).

Theoretical prediction of catalytic activity of MOFs with substrates: The PXRDdata obtained experimentally was compared with the PXRD data from the literature. The

matching data in the literature was used to obtain the corresponding crystal structure and

atomic positions (i.e. cif format) .The atomic positions and atoms were used to predict

catalytic activity using software FIREFLY.


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5. Results and Discussion

Characterization of MOF catalystsSurface morphologies of each of the MOFs synthesized show some unique patterns and

corroborate nicely with the reported literature. It has been seen that different solvents have

different effects on the betterment of the structural stability of MOFs and also aid in removal

of impurity of synthesized samples as evident from SEM and XRD pattern. All the

characterization details are briefly shown below.

Figure 1: SEM images of A) Cu-BTC Methanol Washed Sample B) Zn-BDC DMF Washed

Sample

Figure 2: Powder XRD of different samples of MOFs synthesised

Table 1: Surfacearea data of Different Samples of MOFs

Surface AreaCu-BTC

(HKUST-1)

Fe-BDC

(MIL-53 Fe)Pb-BTC

m2/g 785.68 121.36 11.28

A B


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Figure 3: TGA Results of different MOF samples

For Cu BTC, in the range of 25-125oC the weight loss is purely due to removal of moisture

and trapped methanol. The second step from 125oC to 275

oC is a horizontal plateau, where

the weight remains fairly constant. Beyond 275oC the structure collapses.

For Zn BDC in the range of 25-150o

C the weight loss is purely due to removal of moisture

and trapped DMF, from 150oC-400

oC the weight loss remained largely stable. Beyond 400

oC

the structure collapses.

For Fe-BDC and Pb-BTC, there is gradual change in weight of the sampledue to removal of

moisture and solvent (DMF) trapped in the pores of the crystal. The gradual change can also

be explained by change in molecular arrangement of organic linkers thereby liberating

molecules and solvents that have been adsorbed in the pores of the crystal voids. Beyond

380

o

C and 400

o

C the structure collapses for Fe BDC and Pb-BTC respectively.

The temperature restriction above which the MOF structure collapses is listed in the table

below.

Table 1: Temperature profile data from TGA

MOFs Cu-BTC Zn-BDC Fe-BDC Pb-BTC

Breakdown temperature (oC) 275 400 380 400

Experimental Temperature (oC) 250 350 300 350

0

5

10

15

20

25

0 100 200 300 400 500 600 700 800

Weightloss(mg)

Temperature

FeBDC

CuBTC

ZnBDC

PbBTC


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Thermal degradation of polystyrene using MOFsFrom figure 4 the thermal degradation of polystyrene within the limits of temperature

restrictions of particular MOFs can be observed.Condition in the absence of a catalyst the

thermal degradation if polystyrene starts around 290-310oC and complete degradation occur

at about 470oC.

Figure 4: TGA Results of different MOF as catalysts with polystyrene

Condition in presence of catalyst, equal mass of catalyst and polystyrene were taken.

The conversion shown by Cu-BTC-PS, can be explained in two ways either the moisture

adsorbed on the catalyst vaporises causing the loss of weight or the bi-peddle structure of Cu-

BTC acts as Lewis acid [13] thereby initiating an oxidation of polystyrene in presence of

oxygen.

The conversion shown by Pb-BTC is a gradual degradation of polystyrene since moisture losses

can be negligible, it can the oxidation of polystyrene occurs and the degradation is high attemperature of 330

oC.

The conversion shown by Fe BDC is lower than Pb-BTC but higher than Zn BDC.

Decarboxylation of vegetable oils using MOFsOn heating vegetable oil with catalyst, oil changes colour from colourless to dark brown after 2

hrs. After hexane treatment and centrifugation, three phase separation occurs; the bottom solid

phase is carbon black and catalyst, next two phases are liquid that are to be analysed.


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6. Conclusions Synthesis and Characterization of Copper, Lead and Zinc based MOFs are carried out

successfully.

Thermal degradation analysis of polystyrene with all the mentioned MOFs iscompleted.

Cu-BTC and Pb-BTC show promise in degradation of polystyrene. Decarboxylation of vegetable oil (coconut oil) was carried out. The process

parameters for the above reaction have to be fine-tuned for optimum conversion.


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7. Road Map: For research work for two years duration.Activity Time period

January,2011

TO

June,2011

July,2011

TO

December,

2011

January, 2012

TO

March, 2012

April, 2012

TO

June, 2012

July,2012

TO

August,2012

September,2012

TO

October, 2012

November, 2012

TO

December 2012

Literature survey andResearch theme

selection with

Preliminary

Experimental Runs

Course work

Synthesis and

Characterization of

MOFs and Substrates

Running reaction

kinetics and

standardization

Integrating catalysts oninert support

Running kinetics in

pilot scale reactor

Thesis writing


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8. Future Work Determination of suitable and optimum catalyst quantity for thermal degradation of

polystyrene and/or decarboxylation of vegetable oil.

Reusability of the catalyst used for particular reactions.

Predicting the reaction kinetics for the catalytic reaction under study using FIREFLYsoftware.

9. References1. I.C. McNeiil,L. P. Razumovskii, V. M. Goldberg, G. E. Zaikov,The thermo-

oxidative degradation of polystyrene,Polymer Degradation and Stability 45 47-

55,(1994)

2. Giridhar Madras, J. M. Smith & Benjamin J. McCoy,Thermal degradation kineticsof polystyrene in solution,Polymer Degradation and Stability, 58, 131-138,(1997)

3. P. Carniti, A. Gervasini, P.L. Beltrame,G. Audisio, F. Bertini,Polystyrene thermo-degradation. III. Effect of acidic catalysts on radical formation and volatile product

distribution,Applied Catalysis A: General 127 , 139-155,(1995)

4.

Liliana B. Pierella1, Soledad Renzini, Daniel Cayuela, Oscar A. Anunziata,Catalyticdegradation of polystyrene over ZSM-11 modified materials2

ndMercosur Congress

on Chemical Engineering and 4th Mercosur Congress on Process Systems

Engineering.

5. S.Y. Lee, J.H. Yoon, J.R. Kim, D.W. Park,Catalytic degradation of polystyrene overnaturalclinoptilolite zeolite,Polymer Degradation and Stability 74 ,297305,(2001)

6. EnricoVonghia, David G. B. Boocock, Samir K. Konar, and Anna Leung,Pathwaysfor the Deoxygenation of Triglycerides toAliphatic Hydrocarbons over Activated

Alumina,Energy & Fuels ,9, 1090-1096,(1995)

7. Jacques Monniera, HardiSulimmab, Ajay Dalaib, GianniCaravaggio,Hydrodeoxygenation of oleic acid and canola oil over alumina-

supportedmetal nitrides,Applied Catalysis A: General 382 ,176180,(2010)

8. Jeong-Geol Na, Bo Eun Yi, Ju Nam Kim, Kwang Bok Yi, Sung-Youl Park, Jong-HoPark,Jong-Nam Kim, Chang Hyun Ko ,Hydrocarbon production from

decarboxylation of fatty acid without hydrogen,Catalysis Today 156 ,4448(2010).


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9. JieFu,FanShi,L. T. Thompson, Jr.,XiuyangLu,and Phillip E. Savage,ActivatedCarbons for Hydrothermal Decarboxylation of Fatty Acids,ACS Catal., 1, 227

231,(2011).

10.Chui,S.S.-Y., Lo,S.M.-F., Charmant,J.P.H., Orpen,A.G., and Williams,I.D.,AChemically Functionalizable Nanoporous material [Cu3(TMA)2(H2O)3]n, Science,

283, 1148-1150 (1999).

11.HenrikFan Clausen, RasmusDamgaardPoulsen, Andrew D. Bond, Marie-AgnesS.Chevallier, Bo BrummerstedtIversen, Solvothermal synthesis of new metal organic

framework structures in the zincterephthalic aciddimethyl formamide system Solid

State Chemistry 178, 33423351(2005).

12.G. Frey, F. Millange, M. Morcrette, C. Serre, M.-L. Doublet, J.-M. Grenche,Synthesis of metalorganic framework MIL-53 (Fe),Angew. Chem. Int. Ed., 46,

3259, 2007.

13.David Farrusseng, Sonia Aguado, and Catherine Pinel,MetalOrganic Frameworks:Opportunities for Catalysis,Angew. Chem. Int. Ed., 48, 75027513,(2009)

14.Jinping Li, Shaojuan Cheng, Qiang Zhao, Peipei Long, Jinxiang Dong, Synthesis andhydrogen-storage behavior of metalorganic framework MOF-5 hydrogen energy

34, 1377-1382 (2009).

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