Preparation of Highly Dispersed Ni/γ-Al2O3 Catalysts via the Heat Treatment of Deposited Basic Nickel Nitrate with a Hydrogen-Containing Gas

Abstract The process of preparing a highly concentrated 18% Ni/Al2O3 catalyst by means of γ-Al2O3 impregnation with a nickel nitrate solution, followed by thermal treatment in a hydrogen-containing atmosphere is studied. The heat treatment of deposited Ni3(OH)4(NO3)2, which is mainly formed after the calcination of the impregnated support dried at 200°C in an H2 medium (H2 content, ≥20%) at 230°C, promotes the formation of a highly dispersed NiO phase. In this case, nitrate ions are completely removed without any growth of active component particles as compared to the Ni3(OH)4(NO3)2 phase. Decreasing the H2 concentration in the gas mixture reduces the nitrate decomposition rate and leads to the growth of active component particles at an H2 content ≤5%. A hypothesis regarding the role of hydrogen in the catalyst precursor calcination process is proposed.