Alkylation of Diphenyl Oxide with Long Chain Olefins Using Smectite Clay Catalysts

Abstract

Smectite clays were examined as catalysts for the alkylation of diphenyl oxide with long-chain olefins in liquid phase. A clay treated with sulfuric acid was characterized to have a mesopore structure and found to act as an efficient catalyst especially in the alkylation of a hindered substrate. Thus the clay can be used as a substitute for AlCl₃. Saponite with a card-house structure showed the catalytic activity similar to that of a Y-type zeolite. On the other hand, a sheet type clay (Al-Mont) showed similar activity with the acid-treated one (H-Mont) when heated at around 120 °C but lost its activity when heated at higher temperature probably because of the sheet shrinking. The following relationship between the pore size of catalyst and product distribution was noted. The catalysts with a wider pore size tend to produce more polyalkylated products and ortho isomers. Isomer distribution of arylated alkanes spread wider in the p-isomer than those in the o-isomer, which can be explained in terms of steric hindrance and olefin isomerization during the reaction. Mordenite with one dimensional micropore channel structure showed a high selectivity toward straight shape molecules. From the viewpoint of products selectivity, smectite clays were situated between homogeneous and micropore-heterogeneous catalysts, and was found to be useful for alkylation of a bulky substrate.