Zn改性Sr/γ-Al_(2)O_(3)表面吸附甲醇活化羟基的分子模拟  

Molecular simulation of hydroxyl activated by methanol adsorption on Zn-modified Sr/γ-Al_(2)O_(3) surface

作　　者：郝雅楠 牛胜利[1] 李颖 周文波 厉志鹏 王永征[1] 韩奎华[1] 李英杰[1] 路春美[1] Hao Yanan;Niu Shengli;Li Ying;Zhou Wenbo;Li Zhipeng;Wang Yongzheng;Han Kuihua;Li Yingjie;Lu Chunmei(School of Energy and Power Engineering,Shandong University,Jinan 250061,China)

机构地区：[1]山东大学能源与动力工程学院,济南250061

出　　处：《农业工程学报》2022年第9期253-260,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(51876106)。

摘　　要：为明确Zn原子掺杂强化Sr/γ-Al_(2)O_(3)对吸附甲醇效果的影响,进而提高生物柴油产率,该研究基于密度泛函理论,在Sr单原子掺杂的基础上建立了Sr-Zn双原子掺杂γ-Al_(2)O_(3)(110)表面模型,通过计算掺杂能得到了最稳定催化剂表面;优化模拟了甲醇吸附于催化剂表面的吸附构型,并计算相应的吸附能。模拟结果表明,Sr原子倾向于替换Al_(3c-1)和Al_(4c-2)配位铝,Zn原子倾向与替换Al4c-4配位铝,此时催化剂表面掺杂能最小,其值为945.00 kJ/mol;Zn原子掺杂Sr/γ-Al_(2)O_(3)(110)表面时,甲醇吸附催化剂表面的吸附能绝对值增加,其吸附能值为−305.60 kJ/mol,甲醇上氧原子得电子数增加,羟基上氢原子与催化剂表面成键效果更好。Zn原子掺杂强化Sr/γ-Al_(2)O_(3)催化剂吸附甲醇的稳定性得到强化,有利于后续生物柴油的合成。研究结果可为促进生物柴油的发展、有效调整农业结构、减少化石燃料的燃烧提供理论参考。Biodiesel has been one of the most promising types of renewable and clean energy.Replacing fossil fuels with biodiesel can effectively reduce environmental pollution and the consumption of non-renewable energy.It is often produced by a transesterification reaction between methanol and triglyceride under the action of a catalyst.The catalyst is indispensable during reactions.Homogeneous catalyst has been widely used in industrial applications.But the homogeneous catalyst is difficult to separate and easy to saponify with oil.Fortunately,solid catalysts behave the high activity and are easy separation from the solution.In this study,a solid catalyst was fabricated withγ-Al_(2)O_(3) as a carrier,while Sr and Zn as active atoms.γ-Al_(2)O_(3) has been widely used as the carrier of active substances,due to the high thermal stability and developed micro pore structure.The strontium dopedγ-Al_(2)O_(3) presented a high catalytic activity for transesterification reaction,due to the high basic strength of Sr atom.Zinc atom was added to form the diatomic catalyst.Zn atom served as the dual properties of acid and base,which adsorbed the acid grease for esterification reaction.Doping both Sr and Zn atoms intoγ-Al_(2)O_(3) can effectively improve the yield of biodiesel.Aγ-Al_(2)O_(3)(110) surface model,strontium dopedγ-Al_(2)O_(3)(110) surface model,and Sr-Zn dopedγ-Al_(2)O_(3)(110) surface model were constructed.The surface doping energy of Sr and Sr-Zn doped catalysts was calculated to obtain the most stable surface.A system evaluation was made to clarify the influence of atomic doping on the stability of the catalysts.After that,the catalyst adsorption model of methanol was established to take the most stable surface as the adsorption carrier.The adsorption energy of methanol on different catalysts was calculated to obtain the best adsorption site of methanol on the catalyst surface.An investigation was made to explore the influence of zinc doping on the catalyst adsorption effect of methanol.Mulliken charge layout wa

关 键 词：吸附 催化剂 甲醇 γ-Al_(2)O_(3) 分子模拟 

分 类 号：TQ534[化学工程—煤化学工程]