Pt-based Catalysts in the Dry Reforming of Methane: Effect of Support and Metal Precursor on the Catalytic Stability

Platinum catalysts (1.5 wt. %) supported over CeO2 and gamma-Al2O3 were synthesized via wet impregnation using two different Pt precursors: H2PtCl6 and Pt(acac)(2). Catalysts were tested in the dry reforming of methane (DRM) reaction at stoichiometric conditions (CH4/CO2 molar ratio of 1) with two approaches: as a function of temperature (400-800 degrees C) and as a function of time on-stream (800 degrees C / 24 h). Platinum supported over ceria catalysts showed better catalytic properties, especially in the stability tests, where deactivation was almost negligible. In contrast, alumina-supported catalysts stability was considerably lower due to the increased formation of carbon residues and the significant Pt particle sintering after reaction at 800 degrees C for 24 h. Through different characterization techniques (TEM, CO chemisorption), a strong Pt-Ceria interaction was evidenced, which helped in preventing Pt particle agglomeration under reaction conditions and promoted active interface sites. Both features are proposed to be responsible for the Pt/CeO2 catalysts better catalytic performance. The effect of the Pt precursor depends on the nature of the support. In ceria, Cl species benefited the generation of oxygen vacancies and surface ceria reducibility; both features are responsible for the Pt/CeO2 anti-coke properties, thus impacting positively in the catalytic performance of the Pt(-cl)/Ce sample. Conversely, in alumina, these Cl species triggered particle sintering and carbon deposition during the DRM reaction, affecting the Pt(-cl)/Al catalytic performance.