B、Al、La同晶取代EU-1分子筛酸性的密度泛函理论计算  

Acidity of EU-1Zeolites With Isomorphous Substitution of B,Al,La Calculated by Density Functional Theory

作　　者：冯晓娜[1] 杨冬花[1] 武正簧[1] 杨瑞娟[1] 窦涛[2,3] 常瑜[1] 王凡[1] 韩培德[4] 

机构地区：[1]太原理工大学化学化工学院,山西太原030024 [2]太原理工大学精细化工研究所,山西太原030024 [3]中国石油大学化工学院CNPC催化重点实验室,北京102249 [4]太原理工大学材料科学与工程学院,山西太原030024

出　　处：《石油学报（石油加工）》2013年第4期647-654,共8页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家重点基础研究发展规划"973"项目(2012CB215002);国家自然科学基金项目(20973123);煤转化国家重点实验室开放基金项目(11-12-603)资助

摘　　要：采用量子力学的密度泛函理论(DFT)方法,研究了B、Al、La同晶取代EU-1分子筛骨架的Si后可能的存在位置,确定了与平衡电荷质子结合的骨架O位置,考察了杂原子B、La进入骨架后对EU-1分子筛Brnsted酸(B酸)强度的影响。计算所采用的26T簇模型均在DFT的BLYP方法和DNP基组下完成。对合成的分子筛进行了NH3-TPD表征。能量分析表明,Al和B取代EU-1分子筛骨架最可能的位置为T(1)、T(2)、T(3)、T(6)、T(7)和T(8)位,La取代最可能的位置为T(1)、T(2)和T(8)位。B酸落位点分别为Al(1)-O(12)H-Si(2)和Al(1)-O(13)H-Si(6)位,B(8)-O(29)H-Si(10)位,La(1)-O(12)H-Si(2)、La(1)-O(13)H-Si(6)、La(2)-O(12)H-Si(1)位。与硅铝EU-1分子筛相比,B和La进入骨架会导致EU-1分子筛的B酸强度有所减弱,Al-EU-1、La-EU-1、B-EU-1三者中,Al-EU-1的B酸强度最强,B-EU-1的最弱。B和La进入EU-1分子筛骨架后,酸性减弱,弱酸量增加,理论计算与实验结果一致。The siting of B, A1, La and the bridging hydroxyl group in EU-1 zeolite framework were studied by using density functional theory（DFT） method. The influence of the presence of B or La in the framework on the Bronsted acidity of EU-1 zeolite was investigated. The calculations of 26T cluster model performed with BLYP hydride functional and DNP basis. EU-1 zeolites were synthesized by traditional method and characterized by NH3-TPD. It was shown that energetically,as heteroatoms re placing Si in EU-1 zeolite framework, B or A1 preferred to the same T-sites, T（I,, T7and T〈8） , but La preferred to the T-sites, T（. , T（2 and Tca. The preferable Bronsted acid sites located at Al.-（）（12 H-Si（） , A1.）-Oc13 H-Si（6） , B（8）-O（29） H-Si10 , La（.-O（127 H- Si（2）, IJal-（）{：a）H-Si（s and I-ac2）-O（lz）H-Si（.. The acidity of isomorphously substituted EU-1 zeolite decreased in the order of A1 EU-1, La-EU-1 and B-EU-1. The acidity became weak and the amount of weak acidity declined, when the B or La was presented in the framework. The experimental results were consistent with the theory calculation.

关 键 词：B、Al、La同晶取代 EU-1分子筛 Bronsted酸 从头计算法 

分 类 号：O641[理学—物理化学] O614.33[理学—化学]