HY分子筛催化异丁烷/丁烯烷基化反应中加成反应的模拟研究
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摘要
建立了120T HY分子筛模型,采用量子力学与分子力学(QM/MM)相结合的方法,揭示了叔丁基烷氧基团(TBA)与异丁烯/2-丁烯发生加成反应的细节,并比较了二者的异同。结果表明,叔丁基碳正离子是加成反应的过渡态,且TBA与2-丁烯分子发生加成反应的能垒值是与异丁烯反应的2倍左右。这是由于过渡态的碳正离子与异丁烯之间的电荷转移明显大于与2-丁烯的,二者之间的相互作用力更强,故过渡态能量更低。另外,由于TBA与2-丁烯发生加成反应后中心C原子稳定性降低,故需要首先生成"三角形结构"中间产物,再形成C8碳正离子,最终形成C8烷氧基团完成加成反应。
The mechanism of addition reaction between t-butyl alkoxide(TBA)and isobutene/2-butene was calculated using an embedded QM/MM(quantum mechanics/molecular mechanics)method on the 120 T HY zeolite model.It is confirmed that carbonium ion is the transition state of the two reactions,and the reaction barrier of addition reaction between TBA and 2-butene(29.0 kJ/mol)is2 times than that of isobutene(14.9 kJ/mol).It is because the electron transfer from isobutene to t-butyle carbonium is much easier than that from 2-butene.Moreover,with respect to 2-butene,to form C8 carbonium ion,the extra generation of triangle-structured intermediate and its corresponding rotation are needed,but their reaction heat is ultra low,thus the formation of triangle-structured intermediate is hard to occurr.Especially,the central C atom of C8+is in the form of secondary carbonium, which is less stable than t-butyle carbonium,owing to the endothermic pathway.Consequently, TBA preferentially reacts with isobutene,rather than2-butene.
The mechanism of addition reaction between t-butyl alkoxide(TBA)and isobutene/2-butene was calculated using an embedded QM/MM(quantum mechanics/molecular mechanics)method on the 120 T HY zeolite model.It is confirmed that carbonium ion is the transition state of the two reactions,and the reaction barrier of addition reaction between TBA and 2-butene(29.0 kJ/mol)is2 times than that of isobutene(14.9 kJ/mol).It is because the electron transfer from isobutene to t-butyle carbonium is much easier than that from 2-butene.Moreover,with respect to 2-butene,to form C8 carbonium ion,the extra generation of triangle-structured intermediate and its corresponding rotation are needed,but their reaction heat is ultra low,thus the formation of triangle-structured intermediate is hard to occurr.Especially,the central C atom of C8+is in the form of secondary carbonium, which is less stable than t-butyle carbonium,owing to the endothermic pathway.Consequently, TBA preferentially reacts with isobutene,rather than2-butene.
引文
[1]GB 17930-2016,中华人民共和国国家标准[S].
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[5]马爱增.连续重整装置设计参数研究[J].石油炼制与化工,2013,44(6):64-69.(MA Aizeng.Study of design parameters of CCR reforming units[J].Petroleum Processing Petrochemicals,2013,44(6):64-69.)
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[13]Presidential Green Chemistry Challenge:2016 Greener Synthetic Pathways Award[EB/OL].https://www.epa.gov/greenchemistry/presidential-green-chemi stry-challenge-2016-greener-synthetic-pathways-award.
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[15]MULLEN G M,JANIK M J.Density functional theory study of alkane-alkoxide hydride transfer in zeolites[J].ACS Catalysis,2011,1(2):105-115.
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[17]鲁玉莹,李永祥,龙军,等.HY催化C4烷基化中异丁烯质子化反应的分子模拟[J].石油学报(石油加工),2014,30(5):765-771.(LU Yuying,LI Yongxiang,LONG Jun,et al.Molecular simulation of isobutene protonation in C4alkylation catalyzed by HY zeolite[J].Acta Petrolei Sinica(Petroleum Processing Section),2014,30(5):765-771.)
[18]OLSON D H,DEMPSEY E.The crystal structure of the zeolite hydrogen[J].Journal of Catalysis,1969,13(2):221-231.
[19]HILL J,FREEMAN C M,DELLEY B.Bridging hydroxyl groups in faujasite:Periodic vs cluster density functional calculations[J].The Journal of Physical Chemistry A,1999,103(19):3772-3777.
[20]JIRK Z,VRATISLAV S,BOSˇCEK V.A neutron diffraction study of H,Na-Y zeolites[J].Journal of Physical Chemistry Solids,1980,41(10):1089-1095.
[21]SHERWOOD P,DE VRIES A H,GUEST M F,et al.QUASI:A general purpose implementation of the QM/MM approach and its application to problems in catalysis[J].Journal of Molecular Structure(THEOCHEM),2003,632(1-3):1-28.
[22]DELLEY B.From molecules to solids with the DMol 3approach[J].The Journal of Chemical Physics,2000,113(18):7756-7764.
[23]GALE J D,ROHL A L.The general utility lattice program(GULP)[J].Molecular Simulation,2003,29(5):291-341.
[24]RAPPE A K,CASEWIT C J,COLWELL K S,et al.UFF,a full periodic table force field for molecular mechanics and molecular dynamics simulations[J].Journal of the American Chemical Society,1992,114(25):10024-100035.
[25]RAPPE A K,GODDARD W A.Charge equilibration for molecular dynamics simulations[J].The Journal of Physical Chemistry,1991,95(8):3358-3363.
[26]BAKOWIES D,THIEL W.Hybrid models for combined quantum mechanical and molecular mechanical approaches[J].The Journal of Physical Chemistry,1996,100(25):10580-10594.
[27]HENKELMAN G,JNSSON H.Improved tangent estimate in the nudged elastic band method for finding minimum energy paths and saddle points[J].Journal of Chemical Physics,2000,113(22):9978-9985.
[28]SUN Y,YANG J,ZHAO L,et al.A two-layer ONIOM study on initial reactions of catalytic cracking of1-butene to produce propene and ethene over HZSM-5and HFAU zeolites[J].The Journal of Physical Chemistry C,2010,114(13):5975-5984.
[2]朱玉琴,司云航,朱忆宁,等.我国车用汽油标准现状及发展趋势[J].天然气化工(C1化学与化工),2014,39(6):77-81.(ZHU Yuqin,SI Yunhang,ZHU Yining,et al.Current situation and development trend of motor gasoline standards in China[J].Natural Gas Chemical Industry,2014,39(6):77-81.)
[3]王吉云,张清新.开好烷基化装置促进汽油质量升级[J].石油石化节能与减排,2012,2(5):25-28.(WANG Jiyun,ZHANG Qingxin.Energy gasoline quality upgrade by alkylation operation[J].Conservation and Emission Reduction in Petroleum and Petrochemical Industry,2012,2(5):25-28.)
[4]许友好,屈锦华,杨永坛,等.MIP系列技术汽油的组成特点及辛烷值分析[J].石油炼制与化工,2009,40(1):10-14.(XU Youhao,QU Jinhua,YANG Yongtan,et al.Analysis of octane number and composition characteristics of MIP naphtha[J].Petroleum Processing Petrochemicals,2009,40(1):10-14.)
[5]马爱增.连续重整装置设计参数研究[J].石油炼制与化工,2013,44(6):64-69.(MA Aizeng.Study of design parameters of CCR reforming units[J].Petroleum Processing Petrochemicals,2013,44(6):64-69.)
[6]耿英杰.烷基化生产工艺与技术[M].北京:中国石化出版社,1993.
[7]张剑秋.降低汽油烯烃含量的催化裂化新材料探索[D].北京:石油化工科学研究院,2001.
[8]林世雄.石油炼制工程[M].第三版.北京:石油工业出版社,2000:507-515.
[9]欧阳健,郑明光,张绍良,等.DUPONT工艺硫酸烷基化装置的腐蚀与防护[J].石油化工腐蚀与防护,2012,29(6):31-35.(OUYANG Jian,ZHENG Mingguang,ZHANG Shaoliang,et al.Corrosion of sulfuric acid alkylation unit of DUPONT process and protection[J].Corrosion&Protection in Petrochemical Industry,2012,29(6):31-35.)
[10]梁毅.硫酸法烷基化处理段冲蚀腐蚀分析及处理[J].石油化工设备,2014,43(5):104-107.(LIANG Yi.Erosion corrosion analysis and treatment of sulfuric acid alkylation processing section[J].Petro-chemical Equipment,2014,43(5):104-107.)
[11]LULY M H,POINTNER B E.Hydrogen fluoride compositions:US,2011152432A1[P].2011-06-23.
[12]FELLER A,LERCHER J A.Chemistry and technology of isobutane/alkene alkylation catalyzed by liquid and solid acids[J].Advances in Catalysis,2004,48:229-295.
[13]Presidential Green Chemistry Challenge:2016 Greener Synthetic Pathways Award[EB/OL].https://www.epa.gov/greenchemistry/presidential-green-chemi stry-challenge-2016-greener-synthetic-pathways-award.
[14]ROSENBACH N,DOS SANTOS A P A,FRANCO M,et al.The tert-butyl cation on zeolite Y:A theoretical and experimental study[J].Chemical Physics Letters,2010,485(1-3):124-128.
[15]MULLEN G M,JANIK M J.Density functional theory study of alkane-alkoxide hydride transfer in zeolites[J].ACS Catalysis,2011,1(2):105-115.
[16]任奎,龙军,任强,等.HY分子筛催化异丁烷/丁烯烷基化反应中氢负离子转移过程的模拟[J].石油学报(石油加工),2017,33(6):703-713.(REN Kui,LONG Jun,REN Qiang,et al.A computational study on the hydride transfer process in butene alkylation with isobutane over HY zeolite[J].Acta Petrolei Sinica(Petroleum Processing Section),2017,33(6):703-713.)
[17]鲁玉莹,李永祥,龙军,等.HY催化C4烷基化中异丁烯质子化反应的分子模拟[J].石油学报(石油加工),2014,30(5):765-771.(LU Yuying,LI Yongxiang,LONG Jun,et al.Molecular simulation of isobutene protonation in C4alkylation catalyzed by HY zeolite[J].Acta Petrolei Sinica(Petroleum Processing Section),2014,30(5):765-771.)
[18]OLSON D H,DEMPSEY E.The crystal structure of the zeolite hydrogen[J].Journal of Catalysis,1969,13(2):221-231.
[19]HILL J,FREEMAN C M,DELLEY B.Bridging hydroxyl groups in faujasite:Periodic vs cluster density functional calculations[J].The Journal of Physical Chemistry A,1999,103(19):3772-3777.
[20]JIRK Z,VRATISLAV S,BOSˇCEK V.A neutron diffraction study of H,Na-Y zeolites[J].Journal of Physical Chemistry Solids,1980,41(10):1089-1095.
[21]SHERWOOD P,DE VRIES A H,GUEST M F,et al.QUASI:A general purpose implementation of the QM/MM approach and its application to problems in catalysis[J].Journal of Molecular Structure(THEOCHEM),2003,632(1-3):1-28.
[22]DELLEY B.From molecules to solids with the DMol 3approach[J].The Journal of Chemical Physics,2000,113(18):7756-7764.
[23]GALE J D,ROHL A L.The general utility lattice program(GULP)[J].Molecular Simulation,2003,29(5):291-341.
[24]RAPPE A K,CASEWIT C J,COLWELL K S,et al.UFF,a full periodic table force field for molecular mechanics and molecular dynamics simulations[J].Journal of the American Chemical Society,1992,114(25):10024-100035.
[25]RAPPE A K,GODDARD W A.Charge equilibration for molecular dynamics simulations[J].The Journal of Physical Chemistry,1991,95(8):3358-3363.
[26]BAKOWIES D,THIEL W.Hybrid models for combined quantum mechanical and molecular mechanical approaches[J].The Journal of Physical Chemistry,1996,100(25):10580-10594.
[27]HENKELMAN G,JNSSON H.Improved tangent estimate in the nudged elastic band method for finding minimum energy paths and saddle points[J].Journal of Chemical Physics,2000,113(22):9978-9985.
[28]SUN Y,YANG J,ZHAO L,et al.A two-layer ONIOM study on initial reactions of catalytic cracking of1-butene to produce propene and ethene over HZSM-5and HFAU zeolites[J].The Journal of Physical Chemistry C,2010,114(13):5975-5984.