Robust Ni<sub><i>x</i></sub>Sn/ZSM-12 Catalysts with Zeolite as the Support and Sn as the Promoter for Acetylene Semi-hydrogenation
Dashan Wang, Runping Ye, Chong Zhang, Chengkai Jin, Zhang‐Hui Lu, Mohsen Shakouri, Bingying Han, Tao Wang, Yihuan Zhang, Rongbin Zhang, Yongfeng Hu, Jian Zhou, Gang Feng
Abstract
The synthesis of ethylene from semi-hydrogenation of acetylene is significant for the upgrading of coal. Different kinds of materials (SiO 2, γ-Al 2 O 3, and ZSM-12)-supported Ni catalysts were prepared and evaluated for the acetylene hydrogenation. It demonstrated that the Ni/ZSM-12 catalyst with synergistic effect of B (Brönsted) acid and L (Lewis) acid sites can promote semi-hydrogenation of acetylene better than those over Ni/SiO 2 and Ni/γ-Al 2 O 3 catalysts, in which both only have L acid sites. However, the pure Ni/ZSM-12 still exhibited low selectivity of ethylene and poor stability; thus, the Sn promoter was introduced into the Ni/ZSM-12 catalyst. Due to the geometric and electronic effects, the Ni 7 Sn/ZSM-12 sample achieves higher yield of ethylene (92.51%) with ethylene selectivity of 92.51% and acetylene conversion of 100% at 250 °C, which is an increase of 19.38% over the samples without Sn addition. Moreover, the stability of the Ni 7 Sn/ZSM-12 catalyst (100 h) is much better than those catalysts without Sn (14 h). This is because the carbon deposition over the Sn-containing catalyst was light hydrocarbons that could be removed at high temperature while the pure Ni/ZSM-12 catalyst produced heavy hydrocarbons. The outstanding performance of Ni 7 Sn/ZSM-12 was further illustrated by DFT calculations, which originates from its facilely accessible hydrogen dissociation, lower ethylene adsorption energy, and higher energy barrier for the formation of C 2 H 5 * intermediate.