Alkylation of benzene with formaldehyde over ZSM-5

Benzyl alcohol is currently produced by hydrolysis of benzyl chloride and t he by-products are sodium chloride and carbon dioxide. A "green chemistry" route would be the direct synthesis from benzene and formaldehyde, Therefor e, ZSM-5, a medium pore zeolite, was used to evaluate the potential of usin g shape selective catalysis to control the product distribution obtained by alkylation of benzene with formaldehyde. The restriction of the channels r esulted 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 t o 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. (C) 1999 Acad emic Press.