Selective synthesis of gasoline from syngas in near-critical phase

• Syngas was efficiently converted to hydrocarbons via MeOH in near-critical fluid.
• A hybrid catalyst was composed of Cu-ZnO and Pd supported on ZSM-5.
• The hybrid catalyst selectively produced gasoline-range hydrocarbons from syngas.
• Nanosized ZSM-5 selectively produced gasoline-range hydrocarbons.
• Increasing Pd content led to the improvement in the stability of the catalyst.

The conversion of syngas (CO + H2) to hydrocarbons in gasoline fraction over a hybrid catalyst composed of Cu-ZnO and Pd/ZSM-5 in a near-critical n-hexane solvent was investigated. Methanol was synthesized from syngas over Cu-ZnO; subsequently, was converted to hydrocarbons through the formation of dimethyl ether (DME) over Pd/ZSM-5. The yield of hydrocarbons increased from ca. 29% to ca. 54% with increasing the partial pressure of n-hexane from 0 MPa to 1.5 MPa. By contrast, the yields of CO2 and DME decreased with increasing the partial pressure of n-hexane. A decrease in the particle size of ZSM-5 as well as an increase in a Pd loading led to the selective production of hydrocarbons in the gasoline fraction. The hybrid catalyst containing 0.5 wt% Pd/ZSM-5 with ca. 100 nm in size exhibited 51% gasoline fraction yield with 75% CO conversion. The catalyst stability was also improved by increasing the Pd loading during the reaction.

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