氮取代对环状烃在H-FAU分子筛中吸附性能的影响  

EFFECT OF NITROGEN SUBSTITUTION ON ADSORPTION PROPERTIES OF CYCLIC HYDROCARBONS IN H-FAU ZEOLITE

作　　者：姚远 于双林 党宇 周立元 刘熠斌[2] Yao Yuan;Yu Shuanglin;Dang Yu;Zhou Liyuan;Liu Yibin(Petrochemical Research Institute,CNPC,Beijing 102206;College of Chemical Engineering,China University of Petroleum(East China))

机构地区：[1]中国石油石油化工研究院,北京102206 [2]中国石油大学(华东)化学工程学院

出　　处：《石油炼制与化工》2019年第9期33-39,共7页Petroleum Processing and Petrochemicals

摘　　要：催化裂化原料中的含氮杂环化合物吸附能力强、扩散阻力大,是造成分子筛催化剂中毒失活的重要因素。选取吡啶和哌啶两种含氮杂环化合物及与其结构相似的苯和环己烷两种环状烃为模型化合物,采用蒙特卡罗(GCMC)和密度泛函(DFT)方法考察了4种化合物在H-FAU分子筛孔道和酸性位上的吸附行为。结果表明:4种分子主要分布在超笼孔道中,其中两种氮化物的分布更加集中;吸附强度由高到低的顺序为:哌啶>吡啶>苯>环己烷,并且氮化物与分子筛活性位之间是化学吸附,苯和环己烷的吸附是物理吸附。电荷密度分布结果揭示了两种氮化物分子与H质子之间发生不同程度的电荷转移。模拟结果可为分子筛催化剂氮中毒机理的研究提供理论指导。Nitrogen-containing heterocyclic compounds in FCC feedstock have strong adsorption capacity and diffusion resistance,which are important factors for the poisoning and deactivation of zeolite catalysts.In this paper,two nitrogen-containing heterocyclic compounds,pyridine and piperidine,and two cyclic hydrocarbons with similar structures,benzene and cyclohexane,were selected as model compounds,and the adsorption behaviors of the four compounds on H-FAU zeolite channels and acid sites were investigated by GCMC and DFT methods at 298K.The results showed that the four molecules were mainly distributed in the supercage,and the distribution of two of them was more concentrated.The order of adsorption energy was:piperidine>pyridine>benzene>cyclohexane,and the adsorption of nitrides was chemical adsorption,while benzene and cyclohexane was physically adsorpted.The results of charge density maps revealed that the charge transfer occurs in different degrees between two alkali nitrogen molecules and H protons.The results provide theoretical guidance for the study of nitrogen poisoning mechanism of zeolite catalyst.

关 键 词：氮化物 H-FAU分子筛 蒙特卡罗方法 密度泛函方法 吸附 

分 类 号：O64[理学—物理化学]