梁志铭,聂小娃,郭新闻,宋春山.镍掺杂对Fe催化剂上CO2加氢制烃影响的理论计算研究[J].分子催化编辑部,2020,34(4):293-303
镍掺杂对Fe催化剂上CO2加氢制烃影响的理论计算研究
DFT Insight into the Effect of Ni Doping on Hydrocarbons Synthesis from CO2 Hydrogenation over Fe Catalyst
投稿时间:2020-06-22  修订日期:2020-07-12
DOI:
中文关键词:  二氧化碳加氢  烃类  Ni-Fe双金属催化剂  密度泛函理论  反应机理
英文关键词:CO2 hydrogenation  hydrocarbons  Ni-Fe bimetallic catalysts  density functional theory  reaction mechanism
基金项目:国家自然科学基金面上项目(21872012)
作者单位E-mail
梁志铭 精细化工国家重点实验室 PSU-DUT联合能源研究中心 大连理工大学化工学院, 辽宁 大连 116024, 中国  
聂小娃 精细化工国家重点实验室 PSU-DUT联合能源研究中心 大连理工大学化工学院, 辽宁 大连 116024, 中国 niexiaowa@dlut.edu.cn 
郭新闻 精细化工国家重点实验室 PSU-DUT联合能源研究中心 大连理工大学化工学院, 辽宁 大连 116024, 中国 guoxw@dlut.edu.cn 
宋春山 EMS能源研究所 PSU-DUT联合能源研究中心 美国宾夕法尼亚州立大学, 宾州 16802, 美国  
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中文摘要:
      为研究镍掺杂对铁基催化剂上二氧化碳加氢生成C1和C2烃类产物的影响,应用密度泛函理论进行了相关计算.在Fe(110)和Ni-Fe(110)表面上,CH*物种是最有利的生成CH4和C2H4的C1物种(CHx*),其最可能的生成路径为CO2→ HCOO* → HCO* → CH*.尽管CO2直接解离为CO*在动力学上相较于加氢生成HCOO*和COOH*是较为有利的,但CO*进一步加氢生成HCO*在能量上是不利的,其倾向于逆向解离回到CO*.CH*物种可以通过三步加氢反应生成CH4或者经C—C耦合及两步加氢生成C2H4.在Fe(110)表面上,对甲烷和乙烯产物选择性起决定作用的基元反应能垒之间差异仅为0.10 eV,因此两者选择性相近.在将Ni原子引入Fe(110)表面后,生成甲烷与乙烯的选择性差异变大,导致乙烯的选择性提高.计算结果表明,添加少量金属Ni能够促进CO2转化为CH*,及两个CH*物种发生C—C耦合和进一步加氢转化为乙烯.
英文摘要:
      Density functional theory (DFT) calculations were performed to investigate the effect of Ni doping on C1 and C2 hydrocarbons production from CO2 hydrogenation on the Fe catalyst. The CH* species was found to be the most favorable monomeric CHx* species leading to both CH4 and C2H4 formation on Fe(110) and Ni-Fe(110) surfaces. The plausible pathway went through CO2→ HCOO* → HCO* → CH*. Although CO* formation from direct dissociation of CO2 was kinetically more favorable than CO2 hydrogenation to HCOO* and COOH* intermediates on the two surfaces, the subsequent hydrogenation of CO* to HCO* was energetically detrimental, resulting in the reverse conversion of HCO* to CO* preferred. Further conversion of CH* species led to either CH4 via several hydrogenation steps or C2H4 through C—C coupling followed by two hydrogenation steps. On monometallic Fe(110), the barrier difference associated with the selectivity determining step was only 0.10 eV, suggesting similar selectivity to CH4 and C2H4. In contrast, when a Ni atom was doped onto Fe(110), the selectivity difference became more pronounced, leading to an enhanced C2H4 production on Ni-Fe(110). These results revealed that adding a small amount of Ni could promote CH* formation from CO2 hydrogenation, C—C coupling of two CH* species and the further hydrogenation of C2 intermediates to ethylene.
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