Combined Steam and CO2 Reforming of Methane over Ni-Based CeO2-MgO Catalysts: Impacts of Preparation Mode and Pd Addition

Abstract

The sol–gel template technique makes it possible to synthesize a stable and efficient nickel catalyst based on magnesium-modified cerium oxide Ce0.5Mg0.5O1.5 for the combined steam and CO2 reforming of methane. To stabilize dispersed forms of the active component in the matrix of the support, the catalysts were synthesized by changing the support precursor (cerium acetate and chloride), the active component composition (Ni, NiPd) and the method of introducing nanoparticles. The relationship was established between the physicochemical and catalytic characteristics of the samples. The use of cerium acetate as a support precursor provided smaller pore and crystallite sizes of the support, a stabilization of the dispersed forms of the active component, and excellent catalytic characteristics. The introduction of Pd into the Ni nanoparticles (Pd/Ni = 0.03) increased the resistance of the active component to sintering during the reaction, ensuring stable operation for 25 h of operation. The increased stability was due to a higher concentration of defective oxygen, a higher dispersion of bimetallic NiPd nanoparticles, and the Ni clusters strongly interacting with the NiO-MgO solid solution. An efficient and stable Ni0.194Pd0.006Ce0.4Mg0.4O1.4 catalyst for the conversion of CO2 into important chemicals was developed. With the optimal composition and synthesis conditions of the catalyst, the yield of the target products was more than 75%.