Investigation on the catalytic effect of AAEMs on the pyrolysis characteristics of Changji oil shale and its kinetics

摘要

Changji oil shale in Xinjiang Province of China is abundant and characterized by high ash content and low oil content. While, catalytic pyrolysis is an effective method to improve pyrolysis performance. In this paper, CH3COONa, (CH3COO)(2)Ca and MgO were selected as catalysts of oil shale to investigate the its pyrolysis behavior and pyrolysates characteristics. The results reveal that the three catalysts improve the yields of shale oil and gas. They also promote the release of H-2 and reduce the precipitation of C2H4 and C2H6 in the pyrolysis gas. And CH3COONa and MgO improve the formation of CH4, while, CH3COONa and (CH3COO)(2) Ca enhance the yield of CO. In addition, these catalysts have little influence on the component of the spent shale because of its high ash contents. The existence of CH3COONa increases the relative content of alkanes in the shale oil and declines the relative content of alkenes, while (CH3COO)(2)Ca and MgO play the opposite role. The presence of AAEMs cations increases H/C ratio and the relative content of short-chain aliphatic hydrocarbons in shale oil, making the shale oil lightened. The catalysts of CH3COONa and MgO reduce the activation energy of oil shale during pyrolysis. Because Na+ and Mg2+ as polar centers, change the electron cloud distribution of C-C bond. The E values of CJ, CJ + Na and CJ + Ca during pyrolysis fluctuated with the entire conversion rates and CJ + Mg exhibited a constantly increasing trend.