Production of a hydrogen-enriched syngas by combined CO2-steam reforming of methane over Co-based catalysts supported on alumina modified with zirconia

5% Co-Pt catalysts modified with 0.25-0.5 mass% Pt supported on alumina modified with zirconia at amounts corresponding to 5-10 mass% of Zr were studied in combined CO2-steam reforming (bireforming) of methane and, for comparison, in dry reforming of methane (DRM) over the temperature interval of 300-755 degrees C, P = 0.1 MPa, CO2/CH4 = 1/1. The addition of certain amounts of zirconia to Co-Pt/Al2O3 caused an increase in the activity of the catalyst in both processes, DRM and bireforming, accompanied with a decrease in the temperature of the complete conversion of CO2 and CH4 by 15-50 degrees C depending on the amounts of modifiers and process type. Introducing 20 vol.% of steam into the CO2-CH4 feed was beneficial to the performance; the temperature, when both reagents reached 100% conversion, was decreased by 40-55 degrees C, while syngas was enriched with hydrogen and the H-2/CO ratio grew from 1 to 1.1 to similar to 1.5 in comparison with DRM. It was concluded that the improved performance of the 5% Co-Pt/Al2O3-ZrO2 catalysts in bireforming was caused by the synergistic effect as result of the combination of two reactions, dry and steam reforming of methane. The long-term continuous testing of the 5% Co-Pt(95: 5)/Al2O3-ZrO2 catalyst confirmed its stability in both DRM and bireforming for 100 h.