担载型过渡金属催化剂上甲烷活化的TPSR研究

TPSR studies of the activation of methane on supported transition metal catalysts

采用程序升温表面反应（ＴＰＳＲ）手段，系统地探讨了甲烷在过渡金属催化剂上的吸附活化特征，并对甲烷分解后产生的表面碳物种进行了考察。研究表明，ＣＨ４确能在ＳｉＯ２担载的过渡金属（Ｃｏ、Ｎｉ）催化剂表面发生解离吸附，生成复杂的表面碳物种，其中低温（〈４００Ｋ）下的Ｃα是以原子态存在的碳化物型表面物种，它具有较高的配位不饱和度，因而具有较强的Ｃ－Ｃ成键能力。

The adsorptive activation of methane on transition metal catalysts was systematically investigated via TPSR, together with the surface carbonaceous species after the decomposition of methane. The results indicated that three kinds of carbonaceous species with different structures and properties were formed by the decomposition & adsorption of methane on the surface of SiO2 supported transition metal (Co, Ni)catalysts,among which Cα(<400K) was a carbide species in atomic state and its ability in C-C bonding was relatively strong owing to its highly unsaturated coordination ;Cβ( 500-700K) was an amorphous carbonaceous species in the form of M-CHx(x≤3), the characteristics of which .depends on the metal in it; and Cγ(>800K) was a graphite-type inactive carbonaceous species, which is an important factor for catalyst deactivation. High temperature is favourable to its formation. Furthermore, the formation of Cα,a dynamic equilibrium, is restricted by the d.stribution of carbonaceous species on catalyst surface.