Reactions of methanol and higher alcohols over H-ZSM-5

The reaction of methanol to gasoline range hydrocarbons over H-ZSM-5 was studied as a function of time, temperature, total pressure and H2 partial pressure in a batch reactor. Total gasoline yields were studied as a function of these process variables. The gasoline yield was improved at higher pressures in inert He. The presence of H2 increased the gasoline yield and decreased the formation of polyaromatic compounds. The presence of H2 also led to less coking and lighter gasoline color. The methanol to gasoline (MTG) reaction was also studied over a composite catalyst containing H-ZSM-5 and mixed oxide (Cu–Co–Cr) alcohol synthesis catalyst. The use of segregated beds of zeolite + mixed oxide catalyst gave good gasoline yields whereas the use of a single well mixed bed containing zeolite + mixed oxide catalyst gave negligible gasoline yields. Other alcohols (C2–C4) were also studied for their reaction over H-ZSM-5. Higher alcohols were found to produce higher yields of gasoline compared to methanol. It was found that tertiary and secondary alcohols had an increased tendency to form aromatics compared to primary alcohols. A continuous flow reactor was employed to produce a sufficient quantity of gasoline so as to perform an engine knock test.

***H+ZSM-5 has been found active for alcohol conversion to gasoline-range hydrocarbons mainly composed of alkyl-substituted aromatics and lower branched and cyclized alkanes. Higher yields of hydrocarbon liquids were realized when the substrates were either propyl or butyl alcohols in place of methanol.Figure optionsDownload as PowerPoint slide