Al2O3晶相组成对Ni-Mo加氢催化剂水热稳定性的影响OA

The influences of different crystal phases of alumina supports on catalyst activity and hydrothermal stability were investigated.Alumina supports with different crystal phase compositions,including γ,γ-θ,and θ-α phases,were prepared,and corresponding catalyst systems were constructed.The crystal phase evolution,pore structure changes,and their effects on the stability of the active phase under hydrothermal conditions were examined using XRD,N2 adsorption-desorption,TEM,XPS,and 27Al MAS NMR characterization techniques.The experimental results indicate that γ-Al2O3 readily undergoes hydration-induced crystal phase reconstruction and pore structure collapse under hydrothermal conditions.The introduction of θ or α phases in mixed-crystal-phase supports significantly suppresses the formation of hydrated phases and markedly improves the stability of both crystal phase and pore structure.The mixed-crystal-phase catalysts are capable of forming relatively stable NiMoS active phase structures in the sulfided state.The pure γ-phase catalyst exhibits high initial activity but insufficient stability under oxygen-containing feedstock conditions.By contrast,the γ-θ mixed-crystal-phase catalyst demonstrates superior activity retention under oxygen-containing feedstock conditions.The enhancement of support hydrothermal stability by means of crystal phase regulation provides a reference for the design of catalyst supports for hydrotreating oxygen-containing feedstocks.