Conversion of methylesters to hydrocarbons over an H-ZSM5 zeolite catalyst

The conversion of methyl octanoate on an H-ZSM5 zeolite catalyst has been investigated as a model reaction for the production of hydrocarbon fuels and chemicals from biodiesel. The reactivity of methyl octanoate on H-ZSM5 is higher than that observed with a linear alkane of the same chain length as the ester, n-octane. The enhanced activity may be due to the strong adsorption of the ester group on the zeolite sites. The deoxygenation of methyl octanoate yielded a variety of hydrocarbons (C1–C7), with significant amounts of aromatics. Octanoic acid and heavy products, particularly 8-pentadecanone, were formed as primary products from methyl octanoate via acid-catalyzed hydrolysis and condensation, respectively. Both octanoic acid and the condensation products undergo further reaction, producing aromatics. The comparison conducted with n-octane as a feed indicates that aromatics can be formed through a series of reactions, namely cracking, oligomerization, and cyclization. A small amount of ethylbenzene and o-xylene at low conversion of methyl octanoate indicates that direct dehydrocyclization may also take place, but this path was not evident when the feed was n-octane.