HEUO分子筛酸中心性质的理论模拟研究  

THEORETICAL STUDY ON PROPERTY OF BR NSTED ACID SITES OF HEUO MOLECULAR SIEVE

作　　者：王冰灿 关慧敏 李强 秦玉才 Wang Bingcan;Guan Huimin;Li Qiang;Qin Yucai(School of Petrochemical Engineering,Liaoning Petrochemical University,Fushun,Liaoning 113001)

机构地区：[1]辽宁石油化工大学石油化工学院,辽宁抚顺113001

出　　处：《石油炼制与化工》2025年第4期140-147,共8页Petroleum Processing and Petrochemicals

基　　金：国家自然科学基金资助项目(U20A20120);辽宁省兴辽英才计划项目(XLYC2203165)。

摘　　要：分子筛的Br nsted酸(简称B酸)中心性质是影响其催化性能的关键因素。本研究以硅铝比[n(SiO_(2))/n(Al_(2)O_(3))]为110的H改性EUO结构分子筛(简称HEUO分子筛)为模型分子筛,采用密度泛函理论的方法考察HEUO分子筛B酸位的酸强度、结构特性和电子性质。结果表明:HEUO分子筛中最易被Al原子取代的位点为T7位点,孔道中的B酸位点具有相似的酸强度和结构性质;位于T5位点的B酸位受到周围骨架O原子的影响,O—H键键长增大,Si—O—Al键角增大,H原子正电荷增多,O原子负电荷减少。轨道性质分析发现,B9位的HOMO轨道能量明显高于其他B酸位,导致了其具有比其他B酸位更低的HOMO、LUMO轨道能量差。研究从量子化学层面揭示HEUO分子筛B酸位的本征特性,为深入认识HEUO分子筛中B酸的性质提供理论支持。The acid properties of Br nsted acid(B acid)sites inmolecular sieves are key factors influencing their catalytic performance.Using H-modified EUO-structure molecular sieve(HEUO molecular sieve)with a silica-to-alumina ratio[n(SiO_(2))/n(Al_(2)O_(3))]of 110 as a model system,the acid strength,structural characteristics,and electronic properties of B acid sites in HEUO molecular sieve were investigated using the density functional theory(DFT)calculation method.The results indicate that the T7 site is the most favorable position for Al atom substitution,and B acid sites within the channels exhibit similar acid strengths and structural properties.The B acid site at the T5 position is influenced by surrounding framework oxygen atoms,leading to an elongated O—H bond,an increased Si—O—Al bond angle,enhanced positive charge on the H atom,and reduced negative charge on the O atom.Orbital analysis reveals that the HOMO orbital energy at the B9 site is significantly higher than that of other B acid sites,resulting in a smaller HOMO-LUMO energy gap compared to other sites.This work elucidates the intrinsic characteristics of B acid sites in HEUO molecular sieve at the quantum-chemical level,providing theoretical insights into their acid properties.

关 键 词：HEUO分子筛 密度泛函理论 结构特性 电子性质 

分 类 号：O64[理学—物理化学]