基于原位漫反射光谱技术研究Ni/Al_(2)O_(3)催化甲烷化反应机理

STUDY ON METHANATION REACTION MECHANISM OVER Ni/Al_(2)O_(3)CATALYST BASED ON IN SITU DRIFTS TECHNOLOGY

研究了Ni/Al_(2)O_(3)催化剂上CO和H_(2)的暂态反应和稳态反应过程吸附态的变化。结果表明:在250℃下,Ni/Al_(2)O_(3)催化剂在吸附CO形成了线式吸附态(2065 cm^(-1))和桥式吸附态(1913 cm^(-1))。在250℃下CO和H_(2)共吸附时,CO发生了氢助解离而不是直接解离,线式吸附态(2073 cm^(-1))和桥式吸附态(1909 cm^(-1))会和催化剂表面解离吸附的氢发生反应生成羰基氢化物(2060和1895 cm^(-1)),在氢气过量的情况下又进一步生成多氢羰基氢化物(1854 cm^(-1)),而多氢羰基化合物是生成甲烷的中间产物。

The transient and steady-state reactions of CO and H_(2) over Ni/Al_(2)O_(3)catalysts were studied by in-situ DRIFTS.The results showed that the Ni/Al_(2)O_(3)catalyst formed a linear adsorption state(2065 cm^(-1))and a bridge adsorption state(1913 cm^(-1))for CO adsorption at 250℃.When CO and H_(2) were adsorbed at 250℃,CO undergoes hydrogen assisted dissociation rather than direct dissociation.The linear adsorption state(2073 cm^(-1))and bridge adsorption state(1909 cm^(-1))react with the dissociated adsorbed hydrogen on the catalyst surface to generate carbonyl hydrides(2060 and 1895 cm^(-1)).In the case of excessive hydrogen,it will further generate multi carbonyl hydrogen hydride(1854 cm^(-1)),which is an intermediate product of methane generation.