Direct synthesis of LPG from carbon dioxide over hybrid catalysts comprising modified methanol synthesis catalyst and β-type zeolite

• CZZA/Pd-β catalyst was effective for LPG synthesis.
• Reaction pathway of CO2 to LPG was expressed.
• Iso-butane can be obtained in extra-ordinary high selectivity.

Hydrogenation of carbon dioxide to C3 and C4 paraffins (LPG) was studied by using hybrid catalysts composed of Zr-modified Cu–Zn catalyst with Pd-modified β zeolite. Various factors that affect catalyst activity, including reaction temperature, space velocity, pressure, and the ratio of H2 to CO2 were investigated thoroughly. The hybrid catalysts exhibited stable activity over 100 h and extraordinary high selectivity of LPG synthesis (especially iso-butane) even under low temperature (260 °C) and low pressure (2 MPa). Conversion of CO2 and the yield of hydrocarbon reached 25.2% and 13.3%, respectively, while keeping the selectivity of LPG and CH4 75% and 1%, respectively. The iso-butane/n-butane ratio was about 16/1, whose value was much higher than that of thermodynamic equilibrium (about 1/1).

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