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...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%。展开更多
The catalytic decomposition of NO over Ag-ZSM-5 catalyst prepared by ion-exchange was investigated. The exchanged silver in the zeolite was reduced and it collected in the course of the reaction to form silver particl...The catalytic decomposition of NO over Ag-ZSM-5 catalyst prepared by ion-exchange was investigated. The exchanged silver in the zeolite was reduced and it collected in the course of the reaction to form silver particles of about 20 nm. The catalytic reaction induced a pronounced restructuring of the Ag particles through preferential formation of the (111) facets. These facets were shown to hind a tightly bound oxygen species (O-gamma). The O-gamma species occupies the active sites for NO adsorption resulting in catalyst deactivation. It could be removed by appropriate reducing agents, such as CO, to recover the active sites at elevated temperatures.展开更多
文摘以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%。
文摘The catalytic decomposition of NO over Ag-ZSM-5 catalyst prepared by ion-exchange was investigated. The exchanged silver in the zeolite was reduced and it collected in the course of the reaction to form silver particles of about 20 nm. The catalytic reaction induced a pronounced restructuring of the Ag particles through preferential formation of the (111) facets. These facets were shown to hind a tightly bound oxygen species (O-gamma). The O-gamma species occupies the active sites for NO adsorption resulting in catalyst deactivation. It could be removed by appropriate reducing agents, such as CO, to recover the active sites at elevated temperatures.
