不同合成方法制备ZnxCe2-yZryO4/SAPO-34催化剂及其合成气制低碳烯烃催化性能的研究

通过溶胶凝胶法、水热法、共沉淀法合成了不同的Zn_xCe_(2-y)Zr_yO_4金属氧化物,并对其结构性质进行了XRD、BET、HRTEM、CO-TPD、Raman以及XPS等多种技术表征。考察不同合成方法(溶胶-凝胶法、共沉淀法和水热法)所制备的Zn_xCe_(2-y )Zr_yO_4金属氧化物形貌、晶粒粒径和氧空穴浓度变化情况,及其对合成气制低碳烯烃性能的影响。结果表明,Zn_xCe_(2-y)Zr_yO_4固溶体的形貌、暴露晶面、晶粒粒径和表面氧空穴浓度强烈依赖于合成方法。在300℃、1.0 MPa条件下,采用溶胶-凝胶法制备的Zn_xCe_(2-y)Zr_yO_4与SAPO-34组成的双功能催化剂具有最高的低碳烯烃(C_(2-4)~=)选择性(79.5%),同时甲烷和CO_2的选择性分别仅为5.5%和10.7%。实现了低温低压条件直接转化合成气制低碳烯烃,同时大幅降低了甲烷和CO_2的释放。

Study on different synthesis methods of ZnxCe2-yZryO4/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.