Stabilizing the framework of SAPO-34 zeolite toward long-term methanol-to-olefins conversion
Yang Liu, Chang Wang, Lina Zhang, Weili Dai, Yueying Chu, Jun Xu, Guangjun Wu, Mingbin Gao, Wenjuan Liu, Zhaochao Xu, Pengfei Wang, Naijia Guan, Michael Dyballa, Mao Ye, Feng Deng, Weibin Fan, Landong Li
Abstract
Abstract As a commercial MTO catalyst, SAPO-34 zeolite exhibits excellent recyclability probably due to its intrinsic good hydrothermal stability. However, the structural dynamic changes of SAPO-34 catalyst induced by hydrocarbon pool (HP) species and the water formed during the MTO conversion as well as its long-term stability after continuous regenerations are rarely investigated and poorly understood. Herein, the dynamic changes of SAPO-34 framework during the MTO conversion were identified by 1D 27 Al, 31 P MAS NMR, and 2D 31 P- 27 Al HETCOR NMR spectroscopy. The breakage of T-O-T bonds in SAPO-34 catalyst during long-term continuous regenerations in the MTO conversion could be efficiently suppressed by pre-coking. The combination of catalyst pre-coking and water co-feeding is established to be an efficient strategy to promote the catalytic efficiency and long-term stability of SAPO-34 catalysts in the commercial MTO processes, also sheds light on the development of other high stable zeolite catalyst in the commercial catalysis.