摘要
采用等体积浸渍法制备了不同Ag质量分数(0~12%)的改性ZSM-5分子筛。利用XRD、N_2吸附/脱附、NH_3-TPD和CO脉冲化学吸附对改性前后各催化剂进行了表征分析,并于常压、430℃、水醇比为2,空速(LHSV)为2.2h^(-1)的反应条件下,在固定床反应器中考察了各催化剂催化甲醇制低碳烯烃的性能。结果表明,Ag改性ZSM-5分子筛,提高了其合成低碳烯烃选择性,且其选择性随Ag含量的增加先增大后降低,Ag含量为9%制备的AgZ-9催化剂对合成低碳烯烃选择性最大。Ag改性使催化剂强酸消失,结晶度降低,低碳烯烃选择性提高;其中,AgZ-9催化剂的弱酸量和Ag分散度最大,孔径最小,乙烯+丙烯选择性最高。此外,还考察了焙烧温度和时间对AgZ-9催化剂性能的影响。
The modified ZSM-5 zeolites with different Ag contents（0-12% by mass） were prepared by incipient impregnation method. The samples were characterized by XRD, N_2adsorption/desorption, NH3-TPD and CO pulse chemisorption, and tested for the conversion of methanol to light olefins in a fixed bed reactor under the reaction conditions of atmospheric pressure, 430℃, water/methanol mole ratio of 2 and space velocity（LHSV） of 2.2h^-1. Results showed that using of Ag to modify the ZSM-5 zeolites could improve the selectivity of light olefins, which was first increased and then decreased with Ag loading content, and the catalyst AgZ-9with a Ag mass fraction of 9% had the highest selectivity. Modifying the ZSM-5 zeolites by Ag could lead to the disappearance of strong acid sites and the decreasing of crystallinity of the samples, which resulted in an increase of selectivity. Among all catalysts,the AgZ-9 had the greatest number of weak acid sites, the best metal dispersion and the smallest pore diameter, and exhibited the best catalytic performance. Furthermore, the effects of calcination temperature and time on the activity of the catalyst AgZ-9 were investigated.
出处
《天然气化工—C1化学与化工》
CAS
CSCD
北大核心
2015年第6期7-12,17,共7页
Natural Gas Chemical Industry
基金
国家自然科学基金(21366008)
贵州省自然科学基金(黔科合JZ字[2014]2008号)
贵州省优秀青年科技人才专项(黔科合人字2013-14)
