摘要
采用密度泛函理论方法从HCN氧化和水解两个方面研究了HCN消除反应机理,并考虑了HCN的直接消除反应(途径Ⅰ和途径Ⅱ)和CuO上的HCN消除反应(途径Ⅲ和途径Ⅳ).途径Ⅰ为HCN与2个O_(2)分子生成CO_(2)、NO和H原子;途径Ⅱ为HCN与1个O_(2)分子和1个H_(2)O分子生成CO_(2)和NH_(3);途径Ⅲ为CuO上HNCO水解为CO_(2)和NH_(3);途径Ⅳ为CuO上HCN水解为CO和NH_(3).研究发现,途径Ⅲ速控步骤的活化自由能垒为157.32kJ/mol,比途径Ⅱ中HNCO水解降低12.34 kJ/mol;比途径Ⅳ降低了63.80 kJ/mol.可见,HNCO是HCN净化过程中的重要中间体,CuO的加入降低了反应能垒,促进了HCN消除.
The reaction mechanism of HCN elimination was studied from two aspects of HCN oxidation and hydrolysis by density functional theory method,and the direct elimination of HCN(pathwayⅠand pathwayⅡ)and the elimination of HCN on CuO(pathwayⅢand pathwayⅣ)were considered.HCN reacted with two O_(2)molecules to form CO_(2),NO and H atom in the pathwayⅠ.HCN reacted with one O_(2)molecule and one H_(2)O molecule to form CO_(2)and NH_(3)in the pathwayⅡ.HNCO was hydrolyzed to CO_(2)and NH_(3)on CuO in the pathwayⅢ.HCN was hydrolyzed to CO and NH_(3)on CuO in the pathwayⅣ.It was found that the activation free energy barrier of the rate-controlling step of pathwayⅢwas 157.32 kJ/mol,which was 12.34 kJ/mol lower than that of HNCO hydrolysis in the pathwayⅡ,and 63.80 kJ/mol lower than that of pathwayⅣ.It can be seen that HNCO is an important intermediate in the purification process of HCN,and the addition of CuO effectively reduces the reaction energy barrier and promotes the elimination of HCN.
作者
彭国建
杨蒙
王国微
刘永军
杨春晓
张艳琨
夏福婷
PENG Guo-jian;YANG Meng;WANG Guo-wei;LIU Yong-jun;YANG Chun-xiao;ZHANG Yan-kun;XIA Fu-ting(Key Laboratory of Resource Clean Conversion in Ethnic Regions,Education Department of Yunnan,Yunnan Minzu University,Kunming 650500,China)
出处
《分子催化》
CAS
CSCD
北大核心
2022年第5期446-455,共10页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金(21966033,21567030)
