Catalytic Properties Of Supported Transition Bimetallic Nitrides

Transition metallic nitrides show excellent catalytic behaviors resembling noble metals in a number of involved-hydrogen reactions. Accompanying the emphasis of environmental protection, the research of transition metallic nitrides has attracted much attention. In the work, a series of bimetallic nitrides were prepared by temperature-programmed reaction of the corresponding oxides precursor with flowing NH₃. Effects of multi-treatments of passivation and regeneration on the species and composition of the nitrides surface and their changes have been explored by the employments of XRD, TPSR-MS in situ and TEM-EDS, and the catalytic activity for ammonia decomposition and thiophene HDS were also tested. The results were listed as follows:Catalytic activity of supported bimetallic nitrides is significantly dependent upon acidity, alkalinity and pore structure of support. The nitrides supported on MgA10(Al:Mg=1:3) show the highest activity for ammonia decomposition and thiophene HDS.The order of impregnation and regeneration conditions is important factors that affect the catalytic activity of bimetallic nitrides. Exposure of activity sites could enhance the activity of nitrides.Effects of multi-treatment of passivation and regeneration on supported bimetallic nitrides are explored. Some NH_X species that are strongly bonded on the surface of the nitrides are found. The NH3 formation from NH_X species reaction with H₂ in H₂-TPSR obeys the Temkin-Pyzhev mechanism. Passivation and regeneration treatment would influence the surface state and active sites of the bimetallic nitrides or the ratio of sites of Co, γ-Mo₂N and C03M03N significantly. With the passivation and regeneration treatment, Co and γ-Mo₂N phases are decreased due to the formation of C03M03N phase through intermediate species oxynitride Co-Mo-O-N on the surface of the...