Hydrotalcite-Derived Catalysts Based on Al, Mg, and Ni Hydroxides with Untypical Nickel Loadings: Effects of Ni Loading on Textural Properties and Catalytic Performance in Dry Reforming of Methane to Syngas

Abstract

A series of low-nickel (0.7–2.9 wt %) catalysts for dry reforming of methane (DRM) were prepared from specially synthesized hydrotalcite-derived nickel–aluminum–magnesium hydroxo salts. The texture and catalytic performance of these materials were found to depend on the Ni loading in the precursor hydroxo salts. Under DRM conditions, the 2.9 wt % Ni precursor evolved into a layered catalyst that contained non-uniformly dispersed metallic Ni nanoparticles. The catalysts developed from lower-Ni samples showed dense homogeneous textures and uniform dispersion of metallic Ni. While the 2.9 wt % Ni catalyst achieved high product yields at 900°C (94–97% CO, 92–96% H₂), it was particularly susceptible to carbon deposition. The catalysts evolved from the 0.7 and 1.8 wt % Ni precursors demonstrated lower coking levels. Moreover, while lowering the Ni loading somewhat decreased syngas yields, it enhanced the CO and H₂ productivity per gram of nickel. Even at 600°C the catalysts still exhibited appreciable productivity.