Alkylation of Benzene with Formaldehyde over ZSM-5

ISSN： 0021-9517

Source： Journal of Catalysis, Vol.184, Iss.1, 1999-05, pp. : 294-297

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Abstract

Benzyl alcohol is currently produced by hydrolysis of benzyl chloride and the by-products are sodium chloride and carbon dioxide. A “green chemistry” route would be the direct synthesis from benzene and formaldehyde. Therefore, ZSM-5, a medium pore zeolite, was used to evaluate the potential of using shape selective catalysis to control the product distribution obtained by alkylation of benzene with formaldehyde. The restriction of the channels resulted in a synthesis of benzyl alcohol and benzylmethyl ether. Neither of these products is obtained with a Friedel–Crafts' catalyst, such as AlCl₃, nor with HY zeolite. Temperature has an effect on benzene conversion, but essentially none on product distribution. Water increases the selectivity to benzyl alcohol but decreases the conversion. Modification of the zeolite with boric acid increases the selectivity to benzylmethyl ether and benzyl alcohol, while modification with phosphorus acid does not, which may be due to the formation of phosphorus acid in the reaction mixture.