应用量子力学和分子力学联合的ONIOM2(B3LYP/6-31G(d,p):UFF)方法,采用包含分子筛孔道结构的78T簇模型,对HZSM-5分子筛上乙烯芳构化过程中C4至C6中间体的反应历程进行了研究,探讨了分子筛的酸催化机理和择形催化作用.结果表明,作为乙烯二聚产物的表面正丁基烷氧络合物(C4)直接与乙烯作用得到正己基烷氧络合物(C6),在分子筛孔穴尺寸的限制下,很难实现碳链的折叠环化.按照间歇反应历程,丁基烷氧络合物先发生C-O键断裂,脱质子生成1-丁烯,然后在酸性位上再与乙烯加成,在分子筛表面生成3-甲基戊基烷氧络合物,该烷氧络合物脱除质子给分子筛,同时环化生成甲基环戊烷,后者再与分子筛酸性质子共同脱除氢分子,生成不稳定的碳正离子中间体,然后重构成环己烷正离子.丁基烷氧络合物脱质子的活化能为158.42kJ/mol;1-丁烯与乙烯加成反应的活化能为130.71 kJ/mol;3-甲基戊基烷氧络合物脱氢环化生成甲基环戊烷的活化能为122.06kJ/mol,由于孔穴的限域作用,五员环的甲基环戊烷是重要的中间体.
参考文献
| [1] | Wang L S;Tao L X;Xie M S;Xu G F Huang J S Xu Y D .[J].Catalysis Letters,1993,21:35. |
| [2] | Xu YD.;Bao XH.;Lin LW. .Direct conversion of methane under nonoxidative conditions[J].Journal of Catalysis,2003(1/2):386-395. |
| [3] | Shu Y Y;Ichikawa M .[J].Catalysis Today,2001,71:55. |
| [4] | Crabtree R H .[J].Chemical Reviews,1995,95:987. |
| [5] | Zhang CL.;Yuan Y.;Zhang WX.;Wu TH.;Lin LW.;Li SA. .Aromatization of methane in the absence of oxygen over Mo-based catalysts supported on different types of zeolites[J].Catalysis Letters,1998(4):207-213. |
| [6] | Shu YY.;Wong ST.;Wang LS.;Guo XX.;Xu YD. .PROMOTIONAL EFFECT OF RU ON THE DEHYDROGENATION AND AROMATIZATION OF METHANE IN THE ABSENCE OF OXYGEN OVER MO/HZSM-5 CATALYSTS[J].Journal of Catalysis,1997(1):11-19. |
| [7] | Solymosi F.;Szoke A.;Bansagi T.;Oszko A.;Cserenyi J. .AROMATIZATION OF METHANE OVER SUPPORTED AND UNSUPPORTED MO-BASED CATALYSTS[J].Journal of Catalysis,1997(2):150-161. |
| [8] | Wang DJ.;Rosynek MP.;Lunsford JH. .CHARACTERIZATION OF A MO/ZSM-5 CATALYST FOR THE CONVERSION OF METHANE TO BENZENE[J].Journal of Catalysis,1997(1):347-358. |
| [9] | Ding W P;Meitzner G D;lglesia E .[J].Journal of Catalysis,2002,206:14. |
| [10] | Solymosi F;Erdohelyi A;Szoke A .[J].Catalysis Letters,1995,32:43. |
| [11] | Xu Y D;Shu Y Y;Liu S T;Huang J S Guo X X .[J].Catalysis Letters,1995,35:233. |
| [12] | Shu J;Adnot A;Grandjean B A P .[J].Industrial and Engineering Chemistry Research,1999,38:3860. |
| [13] | Liu S T;Wang L S;Ohnishi R;Ichikawa M .[J].Journal of Catalysis,1999,181:175. |
| [14] | Kasuriya S;Namuangruk S;Treesukol P;Tirtowidjojo M Limtrakul J .[J].Journal of Catalysis,2003,219:320. |
| [15] | 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. |
| [16] | Namuangruk S;Tantanak D;Limtrakul J .Application of ONIOM calculations in the study of the effect of the zeolite framework on the adsorption of alkenes to ZSM-5[J].Journal of molecular catalysis, A. Chemical,2006(1/2):113-121. |
| [17] | Namuangruk S;Pantu P;Limtrakul J .[J].Journal of Catalysis,2004,225:523. |
| [18] | Namuangruk S;Pantu P;Limtrakul J .Investigation of ethylene dimerization over faujasite zeolite by the ONIOM method[J].Chemphyschem: A European journal of chemical physics and physical chemistry,2005(7):1333-1339. |
| [19] | 张佳,周丹红,倪丹.H-ZSM-5分子筛上的乙烯二聚反应机理的理论计算研究[J].催化学报,2008(08):715-719. |
| [20] | Van Koningveld H;Van Bekkum H;Jansen J C .[J].Acta Crystallographica Section B:Structural Science,1987,43:127. |
| [21] | Derouane E G;Fripiat J G .[J].Zeolites,1985,5:165. |
| [22] | Lonsinger S R;Chakraborty A K;Theodorou D N;Bell A T .[J].Catalysis Letters,1991,11:209. |
| [23] | Chatterjee A;Vetrivel R .[J].Microporous Materials,1994,3:211. |
| [24] | Derouane E G;Fripiat J G .[J].Journal of Physical Chemistry,1987,91:145. |
| [25] | Fripiat J G;Berger-Andre F;Andre J M;Derouane E G .[J].Zeolites,1983,3:306. |
| [26] | Derouane E G;Chang C D .[J].Microporous and Mesoporous Materials,2000,35-36:425. |
| [27] | Derouane EG. .Zeolites as solid solvents[J].Journal of molecular catalysis, A. Chemical,1998(1/3):29-45. |
| [28] | Friseh M J;Trucks G W;Schlegel H B;Scuseria G E,Robb M A,Cheeseman J R,Montgomery J A Jr,Vreven T,Kudin K N,Burant J C.Gaussian 03,Revision C.02 ed[M].Wallingford,CT:Gaussian,Inc,2004 |
| [29] | Wang Y;Zhou D H;Yang G;Liu X C Ma D Liang D B Bao X H .[J].Chemical Physics Letters,2004,388:363. |
| [30] | Ryder J A;Chakraborty A K;Bell A T .[J].Journal of Physical Chemistry B,2000,104:6998. |
| [31] | Joshi Y V;Thomson K T .[J].Journal of Catalysis,2005,230:440. |
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%