Ag负载量对I-Ag/ZSM-5催化剂物化性质和催化性能的影响

Effect of different Ag loadings on the physicochemical properties and MTO catalytic performance of the I-Ag/ZSM-5 catalyst

以I2为修饰剂,采用等体积浸渍法成功改性制备了I-Ag/ZSM-5催化剂,考察了不同Ag负载量对催化剂物化性质和MTO反应催化性能的影响。采用XRD、NH3-TPD、XRF等手段对不同Ag负载量I-Ag/ZSM-5催化剂微观结构、表面酸性质及反应前后元素组成等进行分析表征。结果表明,I负载量9%时,不同Ag负载量对I-Ag/ZSM-5催化剂物化性质和MTO反应催化性能影响较大;Ag负载量9%时,Ag与I形成适宜化学吸附,提高了催化剂稳定性,产生了部分较弱中强酸;在常压、反应温度330℃、氮气流速20 m L/min、进料空速为2.4 h-1反应条件下,9%I-9%Ag/ZSM-5催化剂表现出良好催化性能,甲醇转化率和低碳烯烃选择性分别达90.13%和87.44%。

Using I2 as modifier,I-Ag / ZSM-5 catalyst was successfully prepared by the incipient wetness impregnation method,and effect of different Ag loadings on the physicochemical properties and MTO catalytic performance of the catalyst was investigated. These obtained products were extensively characterized by XRD,NH3-TPD,XRF techniques to investigate their microstructure,surface acidic property and elemental compositions of fresh and spent catalysts. The results showed that as the iodine loading of 9%,the different Ag loadings posed significant impact on the physicochemical properties and MTO catalytic performance of the I-Ag / ZSM-5 catalyst. The present of relative weak medium-acid and enhancement of loading stability simultaneously appear due to the appropriate chemisorptions between Ag and I as the Ag loading of 9%. 9% I-9% Ag / ZSM-5 catalyst exhibited excellent catalytic performances with methanol conversion of 90. 13% and light olefins selectivity of 87. 44% under the conditions of reaction temperature330 ℃,nitrogen flow rate 20 m L / min and feed speed 2. 4 h- 1.