Steam/CO2 Reforming of Methane Over Impregnated Ni/CeO2 Catalysts: Effect of Sample Composition on Their Activity and Stability

Steam/CO2 reforming of methane was studied at 600–900 °C, molar ratio CO2/H2O 0–2 and contact time 0.04–0.15 s over impregnated Ni/CeO2 catalysts of various compositions. It has been established that with an increase in the Ni content from 2 to 10 wt.%, both the conversion of reactants (X) and the yield of products (Y) increase in the range XCH4 25→80%, XCO2 35→72%, YH2 30→80%, YCO 30→75% (at 750 °C). With a further increase in the nickel content to 15%, the process parameters changed slightly, reaching a plateau. Higher nickel content (10 vs. 2 wt.%) ensures stable operation of the catalyst over time. The functional performance of the catalysts was correlated with physicochemical properties of as-synthesized, activated and spent samples using X-ray fluorescence analysis, low-temperature nitrogen adsorption, X-ray diffraction analysis, electron microscopy, and thermal analysis. It was shown that the Ni content affects the thermal stability, the textural, structural and redox characteristics of the samples. The 10% Ni/CeO2 catalyst was chosen as the optimal one due to higher H2 productivity, and sufficient resistance to sintering and coking. This sample provides a stable hydrogen yield of 85% in steam/CO2 reforming of methane at 800 °C, CO2/H2O = 2 and a contact time 0.15 s.