用XPS和H2化学吸附研究钝化Mo2N的还原作用

作为催化新材料，高比表面的Mo2N的催化特性已经引起催化科学家的极大关注［1，2］．在加氢反应中，Mo2N表现出很高的活性，类似贵金属催化剂．在加氢精制反应中，发现高比表面Mo2N对含杂原子的环加氢和脱除杂原子具有较高的选择性，而对芳香环加氢活性较低［2，3］．高比表面的Mo2N通常是由MoO3和NH3（或H2／N2混合气）反应得到，新鲜Mo2N很活泼，一接触空气就发生燃烧，导致催化剂烧结，其表面积大大降低．一般情况下，为了研究过程中样品处理方便，合成后的新鲜Mo2N需经过钝化处理．在钝化过程中，Mo2N表面会吸附氧，这种表面吸…

Reduction Effects of the Passivated Mo_2N Studied by XPS and H_2 Chemisorption

XPS has been applied to study the reduction influence of the passivated Mo2N sample on H2 chemisorption at room temperature. It is found that most of the Mo6+ species was reduced to low valence molybdenum species (Moδ+:δ≦4) when reduction temperature was raised up to 673K, meanwhile sharp increases of both the irreversible and reversible hydrogen uptakes were measured. The irreversible amount increased to a larger extent. Accordingly, the active sites towards hydrogen adsorption are tentatively proposed to the low valence molybdenum species with nitrogen deficient.