The Theory Of Benzene Alkylation With Ethylene On Ga Modified Zeolite Catalysis

With the recent advances of computer science and software technique, theoreticalcomputational simulation has become an important method for research into themicroscopic of chemical reactions. It has brought about major changes and progressesin the whole chemistry field. Theoretical calculation had shown some advantages inthe study of catalytic reaction, thus becoming a complementary tool for experimentalcatalysis research.In this thesis, the DFT theoretical calculation method was employed to study theGa modified HZSM-5and Hbeta zeolites. By studying Br nsted acid of zeolites andmodified zeolites by proton affinity, adsorption energy and the O-H frequency ofvibration, the Ga/HZSM-5、s acidity is weaker than Al/HZSM-5`s and Ga/Hbeta、sacidity is weaker Al/Hbeta`s were clarified.The ONIOM3and DFT theoretical calculation methods were employed to studythe absorption behavior of benzene and ethylene on the four different types of zeolites.We establish four zeolites cluster model, and benene and ethylene were separatelycalculated on the zeolite adsorption, by examining molecular geometry and adsorptionenergies，we obtained that benzene and ethylene were more easilier adsorbed on Gamodified zeolite.The zeolite and Ga modified zeolite catalyzed alkylation of benzene with ethyleneare investigated at the B3LYP/6-31G(d,p) level of calculation with a12T-clusterrepresenting the Br nsted acid site of the zeolite. The Al/Hbeta, Ga/Hbeta zeolitesB-acid-catalyzed alkylation of benzene with ethylene was investigated by studyingmolecular geometry of reactants and the transition state, activation energy and soon.The energy of coadsorption of benzene with ethylene on Al/Hbeta and Ga/Hbetazeolite are-17.17Kcal/mol,-16.06Kcal/mol. The reaction activation energy thereaction mechanism are43.53kcal/mol and39.74kac/mol on Al/Hbeta and Ga/Hbetazeolite respectively, which indicate to that alkylation reactant favored Ga modifiedHbeta zeolite and the conversion rate of the alkylation reaction has been improved.