应用ONIOM计算方法研究了MCM-22分子筛超笼12元环上存在两个酸性位时的酸强度及其与骨架铝之间距离的关系,并研究了乙烯和苯分子吸附的规律.计算采用52T簇模型和B3LYP/6-31G* */MNDO方法.结果表明,存在两个酸性位且两个骨架铝之间间隔1个骨架硅时,酸强度比孤立的酸性位明显降低;当间隔的硅原子数增加时,酸强度呈上升趋势,间隔3个以上骨架硅时,其酸强度与孤立的酸性位几乎没有差别.对于乙烯的吸附,当两个骨架铝之间间隔1~4个骨架硅时,其吸附能几乎没有差别(31~35 kJ/mol);对于苯的吸附,当两个骨架铝之间间隔1个骨架硅时,其吸附能有所提高,因为两个桥羟基同时对苯分子产生氢键吸附作用.当两个骨架铝之间的距离增大时,苯的吸附能几乎相同(21~29 kJ/mol).若两个乙烯分子或苯分子同时吸附在双酸性位上,其吸附能与单个分子在孤立酸性位吸附时几乎没有差别.应用自然键轨道计算分析了吸附配合物的电子结构,进一步探明了乙烯和苯在分子筛酸性位上吸附的本质.
参考文献
[1] | Rubin M K;Chu P .[P].US 4954325,1990. |
[2] | 李英霞,陈标华,孟伟娟,李成岳,王文兴,曹钢.MCM-22沸石的孔结构和酸分布特性对苯与丙烯烷基化反应产物分布的影响[J].催化学报,2003(07):494-498. |
[3] | Camblor M A;Corma A;Diaz-Cabanas M-J;Baerlocher C .[J].Journal of Physical Chemistry B,1998,102(01):44. |
[4] | Sastre G;Fornes V;Corma A .[J].Journal of Physical Chemistry B,2000,104(18):4349. |
[5] | 周丹红,杨明媚,王妍,杨刚,刘宪春.模板剂与MCM-22分子筛匹配作用的分子模拟计算[J].无机化学学报,2004(01):41-47. |
[6] | 鲍莹,周丹红,杨明媚,辛长波,武跃.MCM-22分子筛酸性的DFT理论计算研究[J].无机化学学报,2005(07):971-976. |
[7] | Zhou D H;Bao Y;Yang M M;He N Yang G .[J].Journal of Molecular Catalysis A:Chemical,2006,244(1-2):11. |
[8] | Pine L A;Maher P J;Wachter W A .[J].Journal of Catalysis,1984,85(02):466. |
[9] | Derouane E G;Fripiat J G .[J].Zeolites,1985,5(03):165. |
[10] | Teraishi K;Akanuma K .[J].Journal of Physical Chemistry B,1997,101(08):1298. |
[11] | Tielens F. .Ab initio study of the bridging hydroxyl acidity and stability in the 12-membered ring of zeolites[J].Journal of Molecular Structure. Theochem: Applications of Theoretical Chemistry to Organic, Inorganic and Biological Problems,2000(1/3):153-162. |
[12] | van Santen R A;Kramer G J .[J].Chemical Reviews,1995,95(03):637. |
[13] | Dempsey E;Kühl G H;Olson D H .[J].Journal of Physical Chemistry,1969,73(02):387. |
[14] | Wang Y;Zhou D H;Yang G;Miao Sh J Liu X Ch Bao X H .[J].Journal of Physical Chemistry A,2004,108(32):6730. |
[15] | Maseras F.;Morokuma K. .IMOMM - A NEW INTEGRATED AB INITIO PLUS MOLECULAR MECHANICS GEOMETRY OPTIMIZATION SCHEME OF EQUILIBRIUM STRUCTURES AND TRANSITION STATES[J].Journal of Computational Chemistry: Organic, Inorganic, Physical, Biological,1995(9):1170-1179. |
[16] | Dapprich S;Komáromi I;Byun K S;Morokuma K Frisch M J .[J].Journal of Molecular Structure(Theochem),1999,461-462:1. |
[17] | Raksakoon C;Limtrakul J .[J].Journal of Molecular Structure(Theochem),2003,631(1-3):147. |
[18] | Namuangruk S;Pantu P;Limtrakul J .[J].Journal of Catalysis,2004,225(02):523. |
[19] | Bobuatong K;Limtrakul J .[J].Applied Catalysis A:General,2003,253(01):49. |
[20] | Jiang N;Yuan Sh P;Wang J G;Jiao H J Qin Zh F Li Y W .[J].Journal of Molecular Catalysis A:Chemical,2004,220(02):221. |
[21] | Jiang N;Yuan SP;Wang JG;Qin ZF;Jaio HJ;Li YW .An ONIOM study of amines adsorption in H-[Ga]MOR[J].Journal of molecular catalysis, A. Chemical,2005(1/2):59-67. |
[22] | Jiang N;Yuan Sh P;Wang J G;Qin Zh F Jiao H J .[J].Journal of Molecular Catalysis A:Chemical,2005,242(1-2):105. |
[23] | 蒋南,袁淑萍,秦张峰,王建国,焦海军,李永旺.胺类分子在LiMOR分子筛中吸附的量子化学研究[J].催化学报,2004(10):779-784. |
[24] | Yuan Sh P;Shi W;Li B R;Wang J G Jiao H J Li Y W .[J].Journal of Physical Chemistry A,2005,109(11):2594. |
[25] | Leonowicz M E;Lawton J A;Lawton S L;Rubin M K .[J].Science,1994,264(5167):1910. |
[26] | Evleth E M;Kassab E;Jessri H;Allavena M Montero L Sierra L R .[J].Journal of Physical Chemistry,1996,100(27):11368. |
[27] | Limtrakul J;Nanok T;Jungsuttiwong S;Khongpracha P Truong T N .[J].Chemical Physics Letters,2001,349(1-2):161. |
[28] | Kasuriya S;Namuangruk S;Treesukol P;Tirtowidjojo M Limtrakul J .[J].Journal of Catalysis,2003,219(02):320. |
[29] | Panjan W.;Limtrakul J. .The influence of the framework on adsorption properties of ethylene/H-ZSM-5 system: an ONIOM study[J].Journal of Molecular Structure,2003(1/3):35-45. |
[30] | Rungsirisakun R;Jansang B;Pantu P;Limtrakul J .The adsorption of benzene on industrially important nanostructured catalysts (H-BEA, H-ZSM-5, and H-FAU): confinement effects[J].Journal of Molecular Structure,2005(1/3):239-246. |
上一张
下一张
上一张
下一张
计量
- 下载量()
- 访问量()
文章评分
- 您的评分:
-
10%
-
20%
-
30%
-
40%
-
50%