Precious Metal Doped Ni-Mg/Ceria-Zirconia Catalysts for Methane Conversion to Syngas by Low Temperature Bi-reforming

摘要

Low temperature (450-600 A degrees C) bi-reforming of methane was studied over platinum (0.16 wt%) or palladium (0.13 wt%) along with nickel (1.4 wt%) and magnesium (1.0 wt%) immobilized onto a ceria-zirconia support (termed 0.16Pt and 0.13Pd). Bi-reforming studies using a feed ratio of 3:1:2 for CH4:CO2:H2O, respectively, showed that the H-2:CO ratio neared the desired ratio of 2 between 500 and 600 A degrees C for the 0.16Pt catalyst and consistent with bi-reforming at more traditional conditions. This H-2:CO ratio was desirable (near 2) compared to dry or steam reforming alone, as well as to other CH4:CO2:H2O ratios. Reaction studies showed that CH4 conversion decreased with increasing GHSV (68,000-272,000 h(-1)) at 500 A degrees C and increased with increasing temperature at a GHSV of 136,000 h(-1) for both catalyst systems. However, the Pt-based catalyst had more consistent H-2:CO ratios between 1.9 and 2.2 (T aeyen 500 A degrees C) compared to its Pd counterpart (H-2:CO ratios of 1.6-3.0), which was linked to the increased rWGS activity and stronger CO2 adsorption. This study indicates reasonable CH4 conversions and H-2:CO ratio near 2 can be achieved despite operating in this low temperature regime and may enable intensified processes for the conversion of methane to value-added products.