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机构地区:[1]武汉工程大学绿色化工过程教育部重点实验室,湖北武汉430074
出 处:《武汉工程大学学报》2013年第12期35-39,共5页Journal of Wuhan Institute of Technology
基 金:湖北省教育厅重点项目(D20081508)
摘 要:加氢精制过程中,有机含氮化合物的存在会使得贵金属催化剂或酸性催化剂中毒,同时抑制加氢脱硫(HDS)催化剂的活性,因此研究含氮化合物在催化剂表面的吸附行为有助于了解含氮化合物对HDS反应的作用机理.本研究构建一个周期性的镍钼硫(NiMoS)催化剂超晶胞模型,应用密度泛函理论的方法计算了平行吸附和垂直吸附状态下的吡啶、喹啉、咔唑和吲哚在NiMoS催化剂表面的吸附构型和吸附能.结果表明:碱性分子吡啶和喹啉通过Ni—N键吸附在催化剂的表面上,主要表现为垂直吸附;而非碱性分子吲哚通过吡咯环的β—C键吸附在催化剂表面上,咔唑则主要通过苯环吸附在催化剂表面上,两者均以平行吸附为主.比较两类不同吸附构型的吸附能发现,在NiMoS催化剂表面碱性氮化物的吸附能比非碱性氮化物的吸附能高.氮化物在催化剂表面的吸附过程为放热过程.Organonitrogen compounds usually have poisoning effects on noble metal or acid catalyst and inhibition effects on hydrodesulfurization in the process of hydrotreating.For this reason,our studies for adsorption of nitrogen compounds on the catalyst surface can make important contributions towards understanding the inhibitory mechanism for the process of hydrodesulfurization.The adsorbed configurations and adsorbed energy of pyridine,quinoline,indole and carbazole were studied by densityfunctional theory on periodic supercell models of the nickel-molybdenum sulfide catalyst surface,with the molecular plane perpendicular or flat on the catalyst surface.The results show that pyridine and quinoline of the basic nitrogen-containing molecules are preferably adsorbed perpendicularly on the catalyst surface through Ni-N bond; however,the non-basic nitrogen-containing molecules are adsorbed parallel on the catalyst surface such as indole preferentially adsorbed on the catalyst surface through the β-C bond,and the phenyl rings of carbazole primarily interacting with the catalyst.It is found that basic nitrogen compounds are adsorbed on the nickel-molybdenum sulfide catalyst surface containing higher adsorption energy than non-basic nitrogen compounds through comparison between the adsorption energy of two configurations.It is an exothermic process for the adsorption of organonitrogen on the nickel-molybdenum sulfide catalyst surface.
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