摘要
采用不同金属离子对HZSM-5进行离子交换改性,探究不同金属离子和不同浓度锰离子交换改性对尿素转化率、单氰胺和双氰胺选择性的影响。通过XRD、NH_(3)-TPD、ICP-OES等测试对催化剂进行了表征,考察了不同离子和不同离子浓度交换对催化剂结构和酸类型、酸强度、酸中心数量的影响,并对催化剂性质与反应活性和选择性的关系进行了探究。结果表明,弱酸和中强酸为反应活性中心,B/L值高有利于尿素热解制单氰胺和双氰胺。不同浓度Mn离子改性,最佳浓度为0.2 mol/L。CeMn双金属改性ZSM-5具有良好催化效果,单双氰胺总选择性优于单一金属离子交换。
HZSM-5 Treated with different metal salt by ion exchange method,and the effect of different metal ions and different concentration of Mn^(2+)on the selectivity of cyanamide and dicyandiamide was investigated.The catalysts were characterized by XRD,NH_(3)-TPD,ICP-OES and other tests.The influence of ion exchange on the catalyst structure,type and intensity of acid sites was investigated.The results show that more weak acid sites and medium strong acid sites are the reaction active sites,and high B/L value is favorable for the pyrolysis of urea to produce cyanamide and dicyandiamide.Mn ion modification with different concentration,the best concentration is 0.2 mol/L.CeMn bimetal modified ZSM-5 has good catalytic effect,and the selectivity of cyanamide and dicyandiamide is better than that of single metal ion exchange.
作者
卜芮
张浩
沈卫华
方云进
BU Rui;ZHANG Hao;SHEN Wei-hua;FANG Yun-jin(State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)
出处
《应用化工》
CAS
CSCD
北大核心
2023年第4期969-973,985,共6页
Applied Chemical Industry
基金
国家自然科学基金(21576083)。
