BENZENE ETHYLATION AND CUMENE DEALKYLATION OVER NICKEL-LOADED Y-ZEOLITES

The alkylation and dealkylation activities of a range of nickel-loaded Y zeolites, prepared by ion exchange and impregnation, have been measured and correlated to the surface Brønsted acidity. The effect on the level of protonic activity of varying the alkali metal co-cation (Li+, Na+, K+, Rb+, or Cs+) and the inclusion of Ce3+ ions is discussed. With a vew to optimising catalytic efficiency, a number of parameters were considered: these were catalyst precursor reduction temperature, catalyst precalcination, reaction temperature, acid poisoning by pyridine adsorption, coke deposition, and catalyst regeneration. The presence of nickel metal on the support served to enhance the ethylation and cracking activities by converting coke precursors. In the case of benzene ethylation, diethylbenzenes were formed over the most active samples; the relative distributions of the ortho-, para-, and metaisomers are reported. For comparative purposes, data on benzene ethylation over nickel-impregnated silica and alumina catalysts are also presented. © 1992.