J. of Supercritical Fluids 49 (2009) 227232

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The Journal of Supercritical Fluids

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Review

2-Buty alconcen

K. Kriaa,Laboratoire The dusrue Jules Ferry

a r t i c

Article historReceived 29Received in rAccepted 14

Keywords:2-Butyne-1,4HydrogenatiSupercriticalModellingReaction kin

Contents

1. Intro2. Mate

2.1.

2.2.3. Resu

3.1.3.2.3.3.3.4.3.5.

4. ConcAcknRefe

1. Introdu

The usethe elds oopment ofattractivetally accepsolvents d

CorrespoE-mail ad

0896-8446/$doi:10.1016/jl e i n f o

y:August 2008evised form 13 January 2009January 2009

-diolonCO2

etic

a b s t r a c t

Hydrogenation experiments of 2-butyne-1,4-diol, catalysed by carbon-supported palladium, have beenperformed in a batch reactor using high pressurised carbon dioxide as reaction solvent. Carbon dioxidepressure was kept to a constant value of 18MPa. The inuence of the hydrogen pressure, varying from0.2 to 0.8MPa, on the conversion rate was investigated. Under these conditions, the reactive media ismonophasic. Finally, we tted our experimental results with a simple reaction kinetic model.

2009 Elsevier B.V. All rights reserved.

duction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227rials and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2282.1.1. Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2282.1.2. Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228Reaction experiments and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

lts and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Hydrogenation without catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Physical state of reactive mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Hydrogenation in supercritical medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Effect of hydrogen concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Kinetic model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

lusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231owledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231rences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231c

fmftu

nd

.sne-1,4-diol hydrogenation in supercritictration

J.-P. Serin , F. Contamine, P. Czac, J. Mercadierrmique Energtique et Procds, Ecole Nationale Suprieure en Gnie des Technologies InBP 7511, 64075 Pau, Francetion

of supercritical carbon dioxide (scCO2) is of interest inindustrial applications, food industry, pharmacy, devel-aterials and environment [13]. ScCO2 is particularly

or synthesis reaction, because it is an environmen-able replacement to the harmful conventional organice to its non-toxicity, its non-ammability, its moder-

ding author. Fax: +33 5 59407801.ress: jean-paul.serin@univ-pau.fr (J.-P. Serin).

ate criticaladdition, sccibility withtransport pthe selectivcatalysed hscCO2, oftetributions,[1121].

We focubutyne-1,4-well as its h

see front matter 2009 Elsevier B.V. All rights reserved.upu.2009.01.004/ locate /supf lu

CO2: Effect of hydrogen

trielles, Universit de Pau et des Pays de lAdour,parameter and a potentially easy separation [46]. InCO2 affords somepotential advantages: a completemis-hydrogen, high diffusivity, and good mass and thermal

roperties. Thus, it has been attracting much attention ine hydrogenations [710]. A number of heterogeneouslyydrogenations have been successfully carried out inn with higher reaction rates and different product dis-in comparison with hydrogenations in organic solvents

sed in the present study on the hydrogenation of 2-diol which is an important product in ne chemicals asydrogenated derivatives. This reaction is generally car-

228 K. Kriaa et al. / J. of Supercritical Fluids 49 (2009) 227232

ried out in ais the mainis composereactants anover a varielike Ni or Ncatalysts coit possibleSeveral exphydrogenatalyst supposelectivitywcreate side-

The presa homogenethe organicpalladium a

In the frdiol in scCOwith Pd/C chydrogenatnumericalexperiment

2. Materials and methods

2.1. Materials

2.1.1. ChemicalsHydrogen and carbon dioxidewere supplied byAir Liquide,with

a stated purity of 99.998mol%.2-Butyne-1,4-diol (purity: 99%), cis-2-butene-1,4-diol (purity:

95%), butane-1,4-diol (purity:99%), ethanol (purity:99.5%)weresupplied by MERCK,

Glycerol (purity: 98%) was supplied by Prolabo.

2.1.2. Catalyst5wt.% Pd/C catalyst, particle size between 50 and 100m.

2.2. Reaction experiments and methods

The hydrogenation experiment of 2-butyne-1,4-diol is per-with an apparatus consisting of a one-litre stainless steel

r in w3K (tleto lims maconns theratur

hydK, inin be reae reaset.ller mve. Ibecae isressuen isini

le 1.t. IndFig. 1. Photograph of the pilot.

triphasic, gas + liquid + solid catalyst system. Hydrogencomponent of the gas phase whereas the liquid phased of the solvent (aqueous solution or organic solution),d products. This three-phase reaction has been studiedty of different catalysts. The use of catalytic supportsiCu requires severe conditions [22]. Today, the use ofntaining noble metals as palladium or platinum makesto work with more exible operating conditions [22].erimental studies used palladium as catalyst for theion of 2-butyne-1,4-diol [2229]. The impact of the cat-rt nature or the solvent effect on both conversion andere investigated. They all are in a triphasicmediumandproducts such as n-butanol or crotyl-alcohol.ent objective is to carry out hydrogenation reaction inous (supercritical) medium with the aim of decreasingsolvent consumption (environmental standards) using

formedreactoand 47one ouorder tature ijacketagitatetempe

The323.15is usedand thinto thture iscontroautocladucedmixturtotal phydrog

Thein Tabpresens catalyst.amework of our study, hydrogenation of 2-butyne-1,4-2 has been carried out at a xed temperature of 323.15Katalyst. The concentration proles and the inuence ofion pressure have been discussed. Finally, we obtainedparameters of a simple kinetic model which ts oural results.

is initially oindicated acompoundwhen the hregular intemiddle of ththrough am

Fig. 2. Schematic diagram of the reactorhich it possible to implement reaction until 30MPaFig. 1). This autoclave has three potential feeders andline equipped with a gasliquid separator (cyclonic init the drive of the liquid phase). The reaction temper-intained constant by a circulation of oil in an externalected to a thermostat (Fig. 2). A variable speed stirrermixture. Safety arrangements like rupturedisc andhighe cut-off are also provided.rogenation of 2-butyne-1,4-diol is carried out atthe presence of 0.07g of catalyst. In this study the pilotatch mode. First, the reactor is loaded with the catalystctive mixture. Then, liquid carbon dioxide is pumpedctor up to 18MPa while the desired reaction tempera-The propeller stirrer turns at 600 rpm and a mass oweasures the quantity of hydrogen introduced into the

t is important to stir themixturewhilehydrogen is intro-use hydrogen is greatly soluble in carbon dioxide. If thenot agitated during this step, a time evolution of there only due to the slow mixing of carbon dioxide andobserved.

tial composition of the reactive mixture is givenGlycerol, the internal standard, and ethanol are alsoeed, ethanol is used todissolve2-butyne-1,4-diolwhichn a solid form. In addition, ethanol has previously beens a good co-solvent to improve the solubility of organicin carbon dioxide. The start of the reaction is notedydrogen is loaded into the reactor. Samples are taken atrvals through a sampling valve xed to a dip tube in thee reactor. The sample is collected in a vial, and bubbledeasured amount of ethanol. The analysis of the samples

system.

K. Kriaa et al. / J. of Supercritical Fluids 49 (2009) 227232 229

Table 1Composition of the reactive mixture.

Components Concentrations (molm3)

2-Butyne-1,4-dEthanolGlycerolHydrogenCO2

is conductegraph is equcolumn, anThe oven te523.15K atand detectotively. Glycanalysis.

3. Results

Hydrogeent hydroge

3.1. Hydrog

One studof 2-butyneless steel rewe primarilating conditests have bor the reactno conversstart withoments havecatalyst.

3.2. Physica

Since thit is not potive mixturbeen takenmiddle andallowed ushomogeneoexperiment

3.3. Hydrog

This wortion inuen2-butyne-1reactionswperature of

First of agenation oexperimentilar to thosrapidly decdiol admitsproduct rdecreases dthe reactionbutyne-1,4-

rolecriticas (() bd 18M

eactio.

e cone is g

fect o

effef 2-budiedarepletee, thne-1l has0% aes wtheion is ofs are very close when working with a hydrogen concentra-eater than 0.056kmol/m3. The effect of hydrogen pressureutene-1,4-diol concentration prole is similar to the effect on-1,4-diol. The coordinate of the extremum is a characteris-t of the prole. Experimentally, when the hydrogen contentes, this point appears sooner, but its value is smaller. So, theum for the intermediate product content is observed withnimum hydrogen concentration.

netic model

hydrogenation of butynediol consists of two consecutivens (Fig. 4).mass balances for 2-butyne-1,4-diol and the reaction prod-

ve the following system of differential equations:

m1 n1iol 2.3213.20.76327.511317200

d by gas chromatography method. The gas chromato-ippedwith a 30m0.32mm internal diameter TR-waxd a ame ionization detector. The carrier gas is helium.mperature program is: 373.15K for 1min, a ramp to

a rate of 15Kmin1, and 523.15K for 3min. The injectorr temperatures are set to 593.15 and 623.15K, respec-erol is used as internal standard for quantitative GC

and discussion

nations of 2-butyne-1,4-diol were performed at differ-n concentrations. The effect on kinetics was studied.

enation without catalyst

y made by Zhao et al. [30] proves that hydrogenation-1,4-diol in scCO2 medium can be promoted by a stain-actor (SUS 316) wall without any catalyst. That is whyy chose to carry out the reaction reproducing the oper-tions of Zhao. In order to initiate the reaction, severaleen carried out, like increasing the hydrogen pressureion temperature from 323.15 to 353.15K. Nevertheless,ion was observed. Unfortunately, the reaction cannotut catalyst. Consequently, our hydrogenation experi-been done in presence of carbon-supported palladium

l state of reactive mixture

e autoclave is not equipped with a sapphire window,ssible to detect visually the physical state of the reac-e. To answer this problem, samples have concurrentlyfrom different levels of the reactor (from the top, thethe bottom of the reactor). The analyses of the samplesto determine the physical state of the reactive mixture:us or heterogeneous (vapour and liquid phases). In alls introduced here, the mixture is supercritical.

enation in supercritical medium

k focuses on the investigation of hydrogen concentra-ce on the distribution of products obtained from the,4-diolhydrogenationunder supercritical conditions.Allere performed using 5wt.% Pd/C catalyst, at a xed tem-323.15K.ll, no side products have been detected during hydro-f 2-butyne-1,4-diol in supercritical medium. In alls, the distribution proles of the components are sim-e presented in Fig. 3. The 2-butyne-1,4-diol content

Fig. 3. Pin superproductof H2 an

Fig. 4. Rmedium

and thschem

3.4. Ef

Theles owas stresultsis comimagin2-buty1,4-diothan 8increashigherformattrationproletion gron 2-bbutanetic poinincreasmaximthe mi

3.5. Ki

Thereactio

Theucts gi

da(t)

reases. The concentration prole of the 2-butene-1,4-an extremum. Then, the amount of the intermediate

st increases, passes through a maximum value, andown to zero. The butane-1,4-diol is produced as soon asbegins and its content increaseswith time. After 2h, 2-diol and 2-butene-1,4-diol have quantitatively reacted

dt

= k

db(t)dt

= k1dc(t)dt

= k2 and result of numeric simulation of the hydrogenation of butynedioll CO2, expressed as mole percentage of () butynediol and reactionutenediol and (+)butanediol) vs. time (min), at 323.15K,2.75E2molPa of CO2 pressure. RRMSD=34.0%.

n scheme for the hydrogenation of 2-butyne-1,4-diol in supercritical

version rate into butane-1,4-diol is 100%. The reactioniven in Fig. 4.

f hydrogen concentration

ct of hydrogen concentration on the conversion pro-utyne-1,4-diol, 2-butene-1,4-diol and butane-1,4-diolover a range from 0.2 to 0.8MPa and at 323.15K. The

shown in Fig. 5. In all experiments, 2-butyne-1,4-diolly converted into butane-1,4-diol in 2h. As we coulde higher the hydrogen concentration is, the faster the,4-diol reacts. Then, in 20min, only 40% of the 2-butyne-reacted at the lowest hydrogen pressure, against moret the highest one. The overall rate of hydrogenationhen the hydrogen concentration increases. Indeed, theamount of hydrogen, the faster the butane-1,4-diol

s. Nevertheless, this effect seemsweaker at high concen-hydrogen. Experimental butane-1,4-diol concentration1 [H2] a(t) (1)

[H2]m1 a(t)n1 k2 [H2]m2 b(t)n2 (2)

[H2]m2 b(t)n2 (3)

230 K. Kriaa et al. / J. of Supercritical Fluids 49 (2009) 227232

Fig. 5. Concenbutane-1,4-diotions (() 2.75E2kmol/m3,

where a(t),1,4-diol, 2-b

The parathe followin

f obj =3

i=1

j

where i reptal result. yestimated b

Table 2 plated curveequations athe effect odiol, the se

Table 2Kinetic parameters for the hydrogenation of 2-butyne-1,4-diol in supercriticalmedium.

Parameter Value

110.340.670.26mol0.34 l0.34 min1

0.81mol0.67 l0.67 min1

erall rate of hydrogenation. In Figs. 3, 59, the experimentale presented as points; the continuous lines are the results ofmerically resolution of the mass balances (Eqs. (1)(3)). Theean square deviation ranges from 17.9 to 34% according toeriment. This deviation is dened as:

3 1 np(yexpi,j ycalci,j )2n1n2m1m2k1k2

the ovdata arthe nuroot mthe exptration prole for 2-butyne-1,4-diol (A), 2-butene-1,4-diol (B) andl (C), as a function of reaction time for different hydrogen concentra-E2kmol/m3, (*) 3.75 E2kmol/m3, () 5.65 E2kmol/m3, (+) 7.00() 11.30 E2kmol/m3).

b(t) and c(t) represent the concentrations of 2-butyne-utene-1,4-diol and butane-1,4-diol, respectively.meters of kinetic reaction are obtained by minimisingg objective function:

np

=1

yexp

i,j ycalc

i,j

yexpi,j

(4)resents the component, np is the number of experimen-exp and ycalc are the experimental value and the valuey the model, respectively.resents the parameters estimated by tting the simu-

s to the experiment data. The predictions of the modelre in good agreement with the experimental results forf hydrogen pressure on the conversion of 2-butyne-1,4-lectivity of 2-butene-1,4-diol and butane-1,4-diol, and

RRMSD(%) =i=1

npj=1

yexpi,j

(5)

The relative simplicity of the kinetic model explains the values ofthe deviation. Nevertheless, no trend of the deviation with hydro-gen pressure has been noticed.

Fig. 6. Result ocritical carbonof CO2 pressur

Fig. 7. Result ocritical carbonof CO2 pressurf numeric simulation forhydrogenationof2-butyne-1,4-diol in super-dioxide with 3.75 E2kmol/m3 of hydrogen, at 323.15K and 18MPae (() butynediol, () butenediol, (+) butanediol). RRMSD=17.9%.f numeric simulation for hydrogenationof 2-butyne-1,4-diol in super-dioxide with 5.65 E2kmol/m3 of hydrogen, at 323.15K and 18MPae (() butynediol, () butenediol, (+) butanediol). RRMSD=26.2%.

K. Kriaa et al. / J. of Supercritical Fluids 49 (2009) 227232 231

Fig. 8. Result ocritical carbonof CO2 pressur

Fig. 9. Result ocritical carbonof CO2 pressur

4. Conclus

The hydin an homoladium. Thedioxide. Theno side prodiol is comworks madresults showide. Moreothe reactiontration, theto the nalis shorter wthe maximis observedit is difcubiphasic mperature lereaction veple kineticestimated bdata.

wledgements

wish to thank the Conseil Rgional dAquitaine for his nan-pport to this work.EP iscal rescf-P

nces

Yu, RecarboanselercritPerrutInd. E. Jessom. ReAnitesical bi1139icenceical ca03) 99hao, Ytinummetahao, Sndsway 98un, Sr2/n-Bf numeric simulation forhydrogenationof2-butyne-1,4-diol in super-dioxide with 7.00 E2kmol/m3 of hydrogen, at 323.15K and 18MPae (() butynediol, () butenediol, (+) butanediol). RRMSD=26.5%.

Ackno

Wecial su

LaTnologipau.fr/

Refere

[1] J.-J.ical

[2] F. Csup

[3] M.up,

[4] P.GChe

[5] G.crit139

[6] P. Lcrit(20

[7] F. Zplaand

[8] F. ZpouTod

[9] J. SZnBf numeric simulation forhydrogenationof2-butyne-1,4-diol in super-dioxide with 11.30 E2kmol/m3 of hydrogen, at 323.15K and 18MPae (() butynediol, () butenediol, (+) butanediol). RRMSD=25.0%.

ions

rogenation of 2-butyne-1,4-diol has been carried outgenous medium catalysed by carbon-supported pal-solvent of the reaction was high pressurised carbonexperimental results obtained in this work show that

ducts are detected and the conversion to butane-14-plete in a maximum of 2h. Compared to the othere on the hydrogenation of 2-butyne-1,4-diol, these

the interest to work with supercritical carbon diox-ver, the inuence of the hydrogen concentration on

was investigated. The higher the hydrogen concen-shorter the reaction time for the overall conversionproduct is. In addition, the time of total conversionhen the hydrogen concentration increases. However,um of the intermediate product, 2-butene-1,4-diol,for the minimum hydrogen concentration. Even if

lt to compare our results with those obtained inixture, because the conditions (pressure and tem-vels, catalysts,. . .) are different, it seems that thelocity is higher in supercritical media. Finally, a sim-model was proposed. The model parameters werey tting the simulated curves to the experimental

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2-Butyne-1,4-diol hydrogenation in supercritical CO2: Effect of hydrogen concentrationIntroductionMaterials and methodsMaterialsChemicalsCatalyst

Reaction experiments and methods

Results and discussionHydrogenation without catalystPhysical state of reactive mixtureHydrogenation in supercritical mediumEffect of hydrogen concentrationKinetic model

ConclusionsAcknowledgementsReferences