Pulse and Temperature Programmed Reaction Study of Acetic Acid Conversion to Hydrocarbon On TiO2/ZSM-5

Acetic acid is a major component of pyrolysis oil produced from Biomass. It is also a byproduct when syngas is converted to ethanol on Rh and Mo catalysts. Conversion of acetic acid to hydrocarbon would greatly enhance the viability of biomass conversion to fuel processes. However, acetic acid is shown to coke when reacted on H⁺/ZSM-5 without much hydrocarbon formation. This is because acetic acid is not amenable for cracking reactions on acid catalysts due to its poor H/C ratio. Hence we studied using titania (TiO₂) in conjunction with the zeolite, H⁺/ZSM-5 to convert acetic acid to liquid hydrocarbon. Our strategy utilizes the ability of titania to catalyze condensation reactions where acetic acid can be converted to acetone and acetone can be converted to mesitylene via mesityloxide formation. The condensation products then can react on the zeolite to form wider range hydrocarbon.

Initially, acetic acid was reacted in a pulse reactor connected to a GC-MS on Titania P25 catalyst. The reactions were performed between 300 ^oC and 450 ^oC. The results confirmed our hypothesis when acetone and mesitylene were seen in the product stream. Then 10% TiO₂ impregnated on H⁺/ZSM-5 was tested which showed the formation of several other hydrocarbon like substituted benzenes and naphthalenes.  Hence the combination of titania with the acid zeolite seem to be the way to move forward in converting acetic acid to hydrocarbon. This is further tested in a Temperature programmed reaction system to understand various intermediate formation. Also the catalyst is characterized using pyridine DRIFTS and XRD. Some of the later work is in progress.