Zn-Ag双金属改性丝光沸石催化剂在二甲醚羰基化反应中的性能研究OA

In response to the problem of easy deactivation of mordenite(MOR)catalyst in the dimethyl ether(DME)carbonylation reaction,the ion-exchange method was adopted to introduce Zn and Ag bimetals for the modification of MOR to optimize the distribution of acidic sites and the pore structure so as to enhance the catalytic performance.A series of catalysts were prepared by hydrothermal synthesis method,and their physicochemical properties were analyzed by characterization techniques,such as XRD,ICP-AES,SEM,NH3-TPD and Py-IR.The catalytic activity was evaluated in a fixed bed reactor.The results show that after the introduction of Ag,both the amount and strength of Brønsted acid in eight-membered ring channels of the catalyst increase significantly.After the introduction of Zn,the amount of Lewis acid in the twelve-membered ring channels increases,which synergistically promotes the adsorption of CO and the reaction kinetics.Under the conditions of 200℃,1.0 MPa and space velocity of 2400 mL/(g·h),the 1Ag/2Zn-MOR catalyst demonstrates the optimal catalytic performance.After reaction for 3 h with the catalyst,the conversion rate of DME reaches 98%.Even after reaction for 25 h,the DME conversion rate still remains 90%,and the selectivity of methyl acetate is always greater than 99%.The modification with Zn-Ag bimetals can effectively enhance the catalytic activity and stability by regulating the distribution of acid sites and the pore structure of the catalyst,which provides a theoretical foundation for the development of highly efficient catalysts for DME carbonylation.