Hydrogen production by dry reforming of methane on hydrotalcite Ni-based catalysts

Layered Double Hydroxides (LDHs), a class of anionic clay materials with typical hydrotalcite structure, are offer ideal precursors for preparation of high-performance catalysts, due to their designable composition and excellent structural flexibility Chem. Commun. 2010, 46, 5912; Chem. Sci. 2017, 8, 590． In this study, Ni-Ge/(Mg, Al)O_x catalysts with different Ge/Ni molar ratios (0, 0.10, 0.30, 0.50, 1.0) were prepared by co-precipitation using hydrotalcite-type LDHs as precursors． Their activity and stability for hydrogen production via dry reforming of methane (DRM) were evaluated at 700 ℃, under atmospheric pressure, and with GHSV = 42 000 mL h⁻¹ g⁻¹． Catalysts before and after the reaction were systematically characterized by N₂ adsorption-desorption, FTIR, XRD, H₂-TPR, TGA-DTA, TPO, and Raman spectroscopy． Introduction of Ge did not alter mesoporous structure of the catalyst, but significantly enhanced metal-support interaction, and formed Ni-Ge alloy active sites． Among the five catalysts used, Ni-Ge/(Mg, Al)O_x (Ge/Ni = 0.3) exhibited the best DRM performance: initial conversions of CH₄ and CO₂ reached 65% and 74%, respectively, with no deactivation after 20 hours of continuous reaction; carbon deposition was reduced to 13%, graphitization degree of deposited carbon was the lowest． Improved performance was mainly due to Ge-promoted CO₂ adsorption-activation and carbon gasification cycle, which effectively inhibited sintering and graphitic carbon deposition．