The mechanism characterizations of methane steam reforming under coupling condition of temperature and ratio of steam to carbon.

To elucidate the coupling effects of temperature and ratio of steam to carbon on the methane steam reforming process, the characterizations of methane steam reforming at different temperature and ratio of steam to carbon in term of distribution of H 2 and CO, and the elementary reaction rate were investigated. Meanwhile, the formation mechanisms of H 2 and CO via sensitivity analysis and reaction path analysis were obtained. The results showed that the coupling effects of temperature and ratio of steam to carbon on the methane steam reforming were higher than that of individual factor. The effects of temperature on the methane steam reforming were higher than that of the ratio of steam to carbon. The adsorption and desorption reaction of CH 4 on the surface of Ni-based catalyst had the most obvious effect on the sensitivity of H 2 , CH 4 and CO. Besides, the effects of adsorption and desorption reaction of H 2 O on the sensitivity of H 2 were higher than that of CH 4 and CO. Hydrogen was generated by the desorption reaction of H(s) in the adsorbed state and from three generating paths: a) CH 4 (s) dissociated directly or reacted with O(s) to form H(s); b) The dissociation reaction of H 2 O(s) produced H(s); c) OH(s) dissociated directly or reacted with C(s) to form H(s). Carbon monoxide was generated from single path: CH 4 (s)→CH 3 (s)→CH 2 (s)→CH(s)→C(s)→CO(s)→CO(g). • The coupling effects of temperature and the ratio of steam to carbon on methane steam reforming mechanism were investigated. • The hydrogen and carbon monoxide reaction path route was obtained. • The methane conducted a direct decomposition reaction on the surface of catalyst which showed as following: CH 4 (s)→CH 3 (s)→CH 2 (s)→CH(s)→C(s). [ABSTRACT FROM AUTHOR]