One-Pot Synthesis of Full-Featured Mesoporous Ni/Al2O3 Catalysts via a Spray Pyrolysis-Assisted Evaporation-Induced Self-Assembly Method for Dry Reforming of Methane

Abstract

Dry reforming of methane (DRM) is an attractive route to simultaneously consume both methane (CH4) and carbon dioxide (CO2) for the production of valuable syngas. Although nickel catalysts are considered to be the most promising in both cost and activity, catalysts having high stability with low coke formation are highly coveted for commercialization. Here, we report a one-pot synthesis for mesoporous supported nickel catalysts with high activity and stability in a DRM reaction by using a spray pyrolysis-assisted evaporation-induced self-assembly (EISA) method. Two different strategies were introduced to prepare the catalysts of mesoporous alumina supports with highly dispersed active nickel sites from one pot of precursor solutions. One is phase segregation of nickel from alumina supports already in the self-assembly step by using a hydrophobic nickel oleate precursor, a hydrophilic alumina precursor, and an amphipathic triblock copolymer, which was achievable owing to the unique characteristics of spray pyrolysis, especially its fast drying-pyrolysis-mediated kinetic quenching, which was used to form catalysts with highly dispersed active sites of nickel (3 nm). The other strategy is exsolution, entailing the release and anchoring of nickel from the bulk to the surface of the alumina phase in the reduction step while using a hydrophilic nickel precursor. Compared with nickel catalysts prepared by conventional wet impregnation, the one-pot catalysts, especially the nickel oleate-based catalyst, showed high coke resistance, maintaining conversion for 30 h with 92% CH4 conversion and 97% CO2 conversion, which originated from the smaller well-dispersed nickel particles, the strong metal-support interaction, and the suppressed particle agglomeration. We envisage the development, by the one-pot processing of multicomponent precursor solutions, of heterogeneous supported catalysts with superior performances for a wider range of applications.