Dry reforming of methane over ceria supported catalysts produced by direct impregnation with Leachate solution from spent diesel auto‐catalysts

Pt-based catalysts were fabricated by impregnating both commercial and synthesized cerium oxide powders with platinum precursors from a leachate solution coming from hydrometallurgical processing of spent diesel oxidation catalysts. Catalysts were characterized by different techniques to evaluate the amount of Pt and other impurities, the reducibility, and other physico-chemical characteristics. The effect of platinum on the crystalline structure of catalysts was investigated using Williamson-Hall and size-strain methods. H2 temperature programmed reduction revealed a synergistic effect between platinum and CeO2. Dry reforming of methane tests were carried out in a fixed bed reactor at gas feed ratio of CO2/CH4/N2= 40:40:120. The removal of residual NaCl from the leachate solution led to improved catalytic performances: catalysts prepared using commercial and synthesized CeO2 supports showed high conversions of CH4 and CO2, reaching values of ∼94% and ∼96%, respectively, and a H2/CO ratio up to 0.9 at 850 °C. Catalysts were also tested toward the reverse water gas shift reaction, reaching CO2 conversion values of 60%–70%, with nearly 100% selectivity to CO. The best-performing catalyst was tested in a time-on-stream experiment designed to stress the catalysts, and, as a result, negligible amount of carbon was detected and stable conversions over time were achieved.