Wolframite MgWO4-derived Ni-based catalysts for auto-thermal reforming of acetic acid with high anti-coking properties

Auto-thermal reforming (ATR) process is effective in converting biomass-derived acetic acid (HAc) for hydrogen production, and provides a clean, carbon-neutral approach for green hydrogen supply. However, challenges, such as catalytic deactivation by carbon deposition, sintering of active components, and oxidation, need to be addressed. Therefore, monoclinic wolframite-type Ni/MgWO₄ catalysts were prepared by the Pechini method and applied in ATR for H₂ production. The results indicated that with doping of Mg species in tungsten oxide, mixed phases of monoclinic wolframite-type m-MgWO₄ and tetragonal scheelite-type t-MgWO₄ were formed. During the ATR process, t-MgWO₄ transformed into the more stable m-MgWO₄, and thus the wolframite m-MgWO₄ existed as the main phase. The stability of m-MgWO₄ structure was beneficial for dispersing active component of Ni⁰ over the MgWO₄ support and restraining aggregation of Ni⁰ species. Furthermore, this transformation promoted formation of oxygen vacancies and enhancing lattice oxygen mobility for gasification of coke precursors. As a result, the Ni_0.80W_1.11Mg_2.02O_6.15±δ catalyst with Ni/m-MgWO₄ structure demonstrated high stability and activity during ATR test: the conversion rate of acetic acid and the H₂ yield remained stable at 100 % and 2.78 mol-H₂/mol-HAc, respectively, while no coking was found.