Study on different synthesis methods of Zn_xCe_2-yZr_yO₄/SAPO-34 catalyst and its catalytic performance in syngas to low-carbon olefins

A series of Zn_xCe_2-yZr_yO₄ metal oxides were synthesized by sol gel method, hydrothermal method and co-precipitation method respectively and characterized by XRD, BET, HRTEM, CO-TPD, Raman and XPS. The effects of the synthesis method on the morphology, grain size and oxygen vacancy concentration and the catalytic performance in syngas to low-carbon olefin reaction of the Zn_xCe_2-yZr_yO₄ catalysts were investigated. The results show that the shape, exposed crystal surface, grain size and surface oxygen vacancy concentration of Zn_xCe_2-yZr_yO₄ solid solution are strongly dependent on the synthesis method. Under the reaction conditions of 300 ℃ and 1.0 MPa, the dual-functional catalysts of Zn_xCe_2-yZr_yO₄/SAPO-34 prepared by sol-gel method have the highest low-carbon olefin (C_2-4⁼) selectivity (79.5%), while the selectivities of methane and CO₂ are only 5.5% and 10.7%, respectively. Here the direct conversion of syngas to low-carbon olefins are realized at low temperature and pressure and the formation of methane and CO₂ is greatly reduced.