摘要
针对CO_(2)热催化转化制甲醇过程中CO_(2)吸附、活化较困难及副产物较多的问题,提出采用单原子Ge助剂修饰Cu(111)晶面的解决思路,通过密度泛函理论(DFT)计算研究了CO_(2)在Ge-Cu(111)晶面上加氢合成甲醇的反应机理。结果表明,单原子Ge助剂的电子调控增加了与其相邻的Cu原子的电子云密度,使CO_(2)分子在含Ge活性界面上的吸附能力显著增强:CO_(2)在GeCu(111)晶面上的吸附能约为Cu(111)晶面的1.5倍,约为Pd改性Cu(111)晶面的2.4倍,进而使逆水煤气变换(RWGS)反应路径速控步骤的活化能降低了近20 kJ·moL^(-1),同时衍生出3条生成甲醇的RWGS新路径;此外,Ge-Cu(111)晶面上甲酸盐路径由于速控步骤活化能大幅上升而被禁阻,进而CO及烃类等副产物选择性大幅降低,Ge-Cu(111)晶面上CO_(2)加氢制甲醇选择性升高。
In this work,we proposed a novel strategy,doping single atom Ge promoter to the Cu(111)surface,to overcome the shortcomings such as the difficulties in the adsorption and activation of CO_(2) molecules and the complex by-products produced in both the reverse water gas shift(RWGS)and the formate reaction pathway.The electron modulating effect of single atom Ge species on the reaction mechanism of CO_(2) hydrogenation to methanol over Ge-Cu(111)surface was detailly investigated by the density functional theory(DFT)method.The results show that the electron supply ability of Cu atoms adjacent to the single Ge atom is greatly enhanced due to the electron modulating effect of Ge species,which leads to the improved interaction between the CO_(2) molecule and the active interface:the adsorption energy of CO_(2) over the single atom Ge promoted Cu(111)surface was approximately 1.5 times that over the pure Cu(111)surface and approximately 2.4 times that over clustered Pd modified Cu(111)surface,respectively.The enhanced CO_(2) adsorption ability further resulted in a decline in the activation energy of the reaction rate control step for the RWGS pathway by about 20 kJ·mol^(-1),meanwhile,there emerged three new potential RWGS reaction routes that only produced methanol.Moreover,the formate reaction pathway is kinetically inhibited over the Ge-Cu(111)surface,leading to the reduced by-products such as CO and hydrocarbons to improve both the selectivity of methanol in the CO_(2) hydrogenation to methanol reaction.
作者
周文武
韦晓艺
徐梦宇
樊飞
陈治平
康洁
张乐
周安宁
ZHOU Wen-Wu;WEI Xiao-Yi;XU Meng-Yu;FAN Fei;CHEN Zhi-Ping;KANG Jie;ZHANG Le;ZHOU An-Ning(College of Chemistry and Chemical Engineering,Xi′an University of Science and Technology,Xi′an 710054,China;State Key Laboratory of Green and Safe Coal Development in Western China,Xi′an 710054,China)
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2023年第7期1261-1274,共14页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.21908174,22178283)
陕西省重点研发计划(No.2020GY-136)资助。
