Alkylation of Diphenyl Oxide with Benzyl Alcohol over HZSM-5

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Information about Alkylation of Diphenyl Oxide with Benzyl Alcohol over HZSM-5
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Published on November 18, 2008

Author: ran_nwd

Source: slideshare.net

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Study of solid catalyst's action of HZSM-5 in alkylation reaction is presented. Why solid catalyst is better than Friedal-Craft reaction? Detail kinetic study is carried out, this paper was selected and presented in CHEMCON 2005.

Study of Alkylation of Diphenyl Oxide with Benzyl Alcohol over HZSM-5 as Catalyst Ranjeet Kumar, D. Venkatesan and S. Sengupta* Department of Chemical Engineering IIT Kharagpur- 721302

ALKYLATION REACTIONS Used in Pharmaceuticals, Agrochemicals, Resins, Additives, Polymerization inhibitors, Antioxidants, etc

Used in

Pharmaceuticals, Agrochemicals,

Resins, Additives,

Polymerization inhibitors,

Antioxidants, etc

Catalysts used for alkylation of aromatics Friedel-Craft catalysts- AlCl 3 , BF 3 , H 3 PO 4 , H 2 SO 4 Super acid catalysts Cation-exchange resins Zeolite type catalysts

Friedel-Craft catalysts- AlCl 3 , BF 3 ,

H 3 PO 4 , H 2 SO 4

Super acid catalysts

Cation-exchange resins

Zeolite type catalysts

Problems with Friedel-Craft alkylation :--- ---heavy environmental pollution due to waste generation ---troublesome product recovery & purification, ---catalysts cannot be reused, ---lower stability at higher temperature ---poor selectivity ---use of expensive acid-resistant material of construction

Cation exchange resins lower stability at higher temperature low activity and selectivity

lower stability at higher temperature

low activity and selectivity

Zeolites as an alternative Molecular-sieve properties -Selective adsorption of reaction product -Displacement of equilibrium in chemical transform Higher surface area & absorption capacity These increase rate of Hydrogen transfer thus reduce unsaturation

Molecular-sieve properties

-Selective adsorption of reaction product

-Displacement of equilibrium in chemical transform

Higher surface area & absorption capacity

These increase rate of Hydrogen transfer thus reduce unsaturation

Fig 3.1 Schematic Diagram of Experimental Set-Up M Motor C Condenser R Glass Reactor T Thermometer OB Oil Bath TI Temperature Indicator / Controller Experimental Set-up Fully baffled glass reactor with electrically heated oil bath

Experimental procedure diphenyl oxide benzyl alcohol. a speed of agitation of 1100 rpm at 120 0 C for 3hrs catalyst loading was 100kg/m3 of total reactants.

diphenyl oxide

benzyl alcohol.

a speed of agitation of 1100 rpm

at 120 0 C for 3hrs

catalyst loading was 100kg/m3 of total reactants.

Method of Analysis gas chromatogram HPLC and TLC two peaks on HPLC chromatogram and two spots in TLC plate So an isomeric mixture (ortho and para) of benzyl-diphenyl-oxide in reaction product.

gas chromatogram

HPLC and TLC

two peaks on HPLC chromatogram and two spots in TLC plate

So an isomeric mixture (ortho and para) of benzyl-diphenyl-oxide in reaction product.

Chemical equation (B) (A) HZSM-5 120 0 C benzyl alcohol is protonated and the carbocation formed, then it combines with diphenyl oxide in ortho and para position to give two isomeric mixtures as products

Kinetic Studies solid –liquid reaction involving the transfer of benzyl alcohol (A) and diphenyl oxide (B) to the surface of the catalyst particles followed by intraparticle diffusion, adsorption, surface reactions and desorption of the products

solid –liquid reaction involving the transfer of benzyl alcohol (A) and diphenyl oxide (B) to the surface of the catalyst particles

followed by intraparticle diffusion, adsorption, surface reactions and desorption of the products

Kinetic Studies To develop a true kinetic model Experimental analyses were done

To develop a true kinetic model

Experimental analyses were done

Kinetic Studies Effect of Speed of agitation on conversion of Benzyl alcohol Absence of solid-liq MT resistance as stirring went beyond 1100rpm

Kinetic Studies Effect of particle size on conversion of benzyl alcohol The conversion remained practically same within the range of the catalyst sizes. So intraparticle mass transfer resistance is insignificant & this support rxn as surface controlled.

Kinetic Studies Effect of catalyst loading on conversion of benzyl alcohol Due to increase in available acid sites, conversion increases linearly with increase In catalyst loading.

Kinetic Studies Plot of initial rate of reaction (r0i) against catalyst loading (w) Due to increase in available acid sites, initial rate of reaction increases linearly with increase in catalyst loading.

Kinetic Studies Effect of mole ratio on conversion of Benzyl alcohol Mole ratio is diphenyl oxide to benzyl alcohol, no effect on diphenyl oxide conversion, whereas benzyl Alcohol conversion increased With increase in ratio

Kinetic Studies Effect of temperatures on conversion of Benzyl alcohol Clearly, conversion increases with increase in temperature

Kinetic Studies Kinetic plots for various temperatures Rate constants, k1 = 2.26*10 -5 (373K), 2.93*10 -5 (383K), 3.689*10 -5 (393K), 4.265*10 -5 (403K), s -1

Kinetic Studies Arrhenius plot From the slope of this graph Apparent activation energy was calculated, Ea=26.74KJ/mol High value of Ea shows that rxn is kinetically controlled & occurs at the surface of catalyst

Kinetic Studies First order reaction plots: effect of catalyst loading plot of –ln (1-X A ) vs. time was made for this reaction at various catalysts loading. All of these plots show straight lines passing through the origin. Their linearity confirms the first order reaction

Kinetic Studies Effect of reuse of catalyst Reusability of catalyst… Filtered from rxn mixture & heated at 550 o C to burn off the reactants & products from pores. Conversion of Benzyl alcohol became 31.82 to 18.77% from fresh to 1 st reuse

CONCLUSIONS Kinetics of alkylation of diphenyl oxide with benzyl alcohol catalysed by HZSM-5 was established. Reaction is pseudo 1 st order. Internal mass transfer resistance was negligible External mass transfer can be eliminated by adjusting proper stirring rate. Activation energy is 26.74 kj/mol Catalyst is reusable.

Kinetics of alkylation of diphenyl oxide with benzyl alcohol catalysed by HZSM-5 was established. Reaction is pseudo 1 st order.

Internal mass transfer resistance was negligible

External mass transfer can be eliminated by adjusting proper stirring rate.

Activation energy is 26.74 kj/mol

Catalyst is reusable.

References 1. H.Scott Fogler., Elements of Chemical Reaction Engineering (3 rd edition). 2. Smith J.M., Van Ness H.C and Abbott M.M., Introduction to Chemical Engineering Thermodynamics (Fifth edition). 3. R. T. Morrison and Robert Neilson Boyd., Organic chemistry (6 th edition). 4. S.M.Mukherji and S.P.Singh., Reaction mechanism in organic chemistry (3 rd edition). 5.G.D.Yadav and S. Sengupta, Friedel-Crafts Alkylation of Diphenyl oxide with Benzyl chloride , Organic process research &Development . 6 , 252-262, (2002). 6. Bhat. Y. S. and Halgeri. A. B Kinetics of toluene alkylation With methanol on HZSM-8 zeolite catalyst , Ind.Eng.Chem.Res . Res . , 28, 894-899, (1989). 7.Chandavar K. H, et al. Alkylation of benzene to propyl and isopropyl benzenes over ZSM-5 zeolite . J.Chem.technol. J. Chem. 34, 165-173, (1984). 8.Chandavar. K. H., Kulkarni. S. B and Ratnaswami. P., Alkylation of benzene with ethanol over ZSM-5 zeolites . Appl.cata. 4, 287-295, (1982). 9.Chandra. K. G and Sharma M. M., Alkylation of phenol with MTBE and other tert- butyl ethers, Cation exchange resins as catalyst .Catal.lett, 19, 309-317, (1993). 10.Chaudhuri, B and Sharma, M. M., Alkylation of phenol with α-methylstyrene , propylene, butenes, isoamylene, I-octene, and diisobutyle heterogeneous vs homogeneous catalysts. Ind .Eng.Chem.Res . 30 , 227-231, (1991).

1. H.Scott Fogler., Elements of Chemical Reaction Engineering (3 rd edition).

2. Smith J.M., Van Ness H.C and Abbott M.M., Introduction to Chemical Engineering Thermodynamics (Fifth edition).

3. R. T. Morrison and Robert Neilson Boyd., Organic chemistry (6 th edition).

4. S.M.Mukherji and S.P.Singh., Reaction mechanism in organic chemistry (3 rd edition).

5.G.D.Yadav and S. Sengupta, Friedel-Crafts Alkylation of Diphenyl oxide with Benzyl chloride , Organic process research &Development . 6 , 252-262, (2002).

6. Bhat. Y. S. and Halgeri. A. B Kinetics of toluene alkylation With methanol on HZSM-8 zeolite catalyst , Ind.Eng.Chem.Res . Res . , 28, 894-899, (1989).

7.Chandavar K. H, et al. Alkylation of benzene to propyl and isopropyl benzenes over ZSM-5 zeolite . J.Chem.technol. J. Chem. 34, 165-173, (1984).

8.Chandavar. K. H., Kulkarni. S. B and Ratnaswami. P., Alkylation of benzene with ethanol over ZSM-5 zeolites . Appl.cata. 4, 287-295, (1982).

9.Chandra. K. G and Sharma M. M., Alkylation of phenol with MTBE and other tert- butyl ethers, Cation exchange resins as catalyst .Catal.lett, 19, 309-317, (1993).

10.Chaudhuri, B and Sharma, M. M., Alkylation of phenol with α-methylstyrene , propylene, butenes, isoamylene, I-octene, and diisobutyle heterogeneous vs homogeneous catalysts. Ind .Eng.Chem.Res . 30 , 227-231, (1991).

THANKS!

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