Investigation of Supercritical Isooctane as a Reaction Medium in the Conversion of Methanol to Hydrocarbons over H-ZSM-5

Supercritical fluid (SCF) reaction media have been previously shown to facilitate heat removal and heavy product extraction from catalyst active sites in a variety of heterogeneous catalytic reactions, such as Fischer–Tropsch synthesis (FTS). This work explores the feasibility of using SCF media to enhance methanol-to-hydrocarbons (MTH) reaction performance relative to traditional, gas-phase operation. Conversion of methanol over H-ZSM-5 was carried out in a continuous fixed-bed reactor in the presence of supercritical isooctane. Isooctane was selected as the SCF medium primarily because of its low reactivity over H-ZSM-5. The performance of SCF-assisted MTH was compared with that of gas-phase MTH at both 300 and 370 °C. Relative to gas phase operation at the same conditions, the use of supercritical isooctane resulted in improved catalyst maintenance and increased hydrocarbon productivity with increasing time on stream.