Benzylation of toluene by benzyl chloride over protonic zeolites

✍ Scribed by Bernard Coq; Valérie Gourves; François Figuéras

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 401 KB
• Volume: 100
• Category: Article
• ISSN: 0926-860X
• DOI: 10.1016/0926-860x(93)80116-8

✦ Synopsis

The henzylation of toluene with benzyl chloride was studied at 383 K in the liquid phase on different protonic zeolites: H-ZSM-5, H-BETA and HY. Monobenzylation tobenzyltoluenes is the main reaction, usually higher than 90% selectivity when a toluene/benzyl chloride molar ratio of 5 is used. Secondary reactions to dibenzyl-and tribenzyltoluenes occur to various extent depending on the reaction conditions and catalysts. The most active~atalysts, and the most selective to monobenzylation, are those possessing mesopores in the 30-200 A range: H-BETA and dealuminated HY (Si/Al = 20). On these zeolites it is proposed that intracrystalline catalysis occurs, shape selectivity then preventing secondary reactions. At variance, on the other zeolites, H-ZSM-5 and nondeahnninated HY, the reaction takes place at the external surface of the grain yielding a lower activity and selectivity to monobenzylation.