Four component catalysis for the hydroalkylation of benzene to cyclohexyl benzene

Abstract

Patent claims that benzene can be hydroalkylated to form cyclohexyl benzene — a potential diesel fuel — over a four component catalyst have been verified, and the role of the individual components has been explored. The hydrogenation of benzene over nickel on zeolite 13X produced reasonably high (ca. 30%) yields of cyclohexane, but the product distribution favoured cyclohexyl benzene in the presence of rare earth ions. The addition of small (ca. 1%) of platinum produced good yields and selectivities to cyclohexyl benzene at ca. 450 K, a performance which was matched only at ca. 670 K in the absence of platinum. Temperature programmed studies showed that Pt promoted the low temperature reduction of the catalyst to produce better performance. The acidic 13X molecular sieve promoted alkylation, but acidity was not the only factor involved. Rare earth additions were suggested to induce electron transfer to the nickel, weakening adsorption of benzene and promoting hydroalkylation rather than hydrogenation.