A comparative study of the conversion of ethanol and of ethylene over the "Mobil" zeolite catalyst, H-ZSM-5. An application of the Benzene Sequestration Test

Ethanol and ethylene both convert to gasoline over the pentasil zeolite catalyst, H-ZSM-5, at 250 °C, but yields are lower for ethanol. Adding benzene produces different arrays of alkylbenzenes for the two feeds, propylbenzene being absent using ethanol feed but present using ethylene feed. Neither feed gives rise to toluene or xylene yield increments on adding benzene, showing methylating intermediates to be absent. Hence methylation of C 2 species is ruled out as a route to C 3 intermediate production, and cracking of built-up molecules must be invoked. These results may be understood by postulating stronger sorption of ethanol than of ethylene on the catalyst surface, blocking both carbon chain lengthening sites and cracking sites. Keywords: conversion, ethanol, ethylene, sequestration by benzene, H-ZSM-5.