Propylene Dimerization Catalyzed By Supported Ionic Liquid And Ni-based Coordination Compounds Complex

Six carbon olefins are important chemical raw materials in many fields. One of the important sixcarbon olefins preparation methods is catalyzed dimerization of propylene. Within progresses of thecatalysis research for propylene dimerization, Ni-based complexes have been repeatly emerged in researchwork for propylene dimerization because of its excellent activity and stability. However, catalyst withcontrollable high selectivities for isomers and suitable continuous production performances has alwaysbeen the key target. So, developing novel supported catalysts for dimerization of propylene is becomingmore and more important. In this dissertation, four Ni-based complexes catalysts and some supported ionicliquid and Ni-based composite catalysts have been prepared.Both batch propylene dimerizationperformances of Ni-based complexes catalysts in homogeneous mode and supported ionic liquid andNi-based composite catalysts in heterogeneous were investigated, respectively. The main contents andconclusions are as follows:Firstly, Ni-based complexes, functionalization ionic liquid, supported ionic liquid and supported ionicliquid-Ni-based complexes composite catalysts were synthesized. Among the four synthesized Ni-basedcomplexes of acetylacetone nickel, bis(salicylaldehyde) nickel, bis(salicylald(o-methylbenzene)iminate)nickel and bis(salicylald(p-nitrobenzene)iminate) nickel, chemical structures are proved by the infraredspectrometry detection and melting point determination and element analyses. Also, the chemical structureof intermediate and target functionalization ionic liquid synthesised by two step methods werecharacterized by means of Infrared(IR) Spectrometry and Nuclear Magnetic Resonance (NMR)Spectroscopy. Four supported materials such as TS-1, MCM-41, SBA-15and silica gel with different size pore and abundant hydroxide radicals on surface were selected to supported ionic liquid. InfraredSpectrometry and Thermo-gravimetry (TG) analyses results show that ionic liquid was covalent-anchoredon the support matrials surface. Then, supported ionic liquid and Ni-based coordination compoundscomplex catalysts were prepared by immersion method.Moreover, performances using bis(p-nitrobenzene-N-salicylaldimine)-nickel complex as propylenedimerization catalyst have been investigated by semi-batch reaction. Results indicate that reactiontemperature, pressure and the amount of co-catalyst influence the conversion of propylene, selectivity forsix carbon olefins isomers and turnover frequency of catalyst. Propylene conversion and turnoverfrequency increase with the reaction pressure and the amount of co-catalyst added. The conversion rate ofpropylene and turnover frequency both attained ideal level simultaneously on conditions including ambienttemperature, pressure0.4MPa, and the molar ratio of Al/Ni300, respectively. The selectivities of targetisomer products could be improved providing increased amount of co-catalyst and reaction pressure on thesame time reduced reaction temperature.Then, propylene dimerization performances of the other three kinds of catalysts of Ni-basedcomplexes were investigated comparisonly. Results show that selectivity of target product isomer andconversion of propylene have no obvious difference among the four Ni-based complexes catalysts. But theturnover frequency of acetylacetonate nickel cayalyst was the lowest one.Bis(p-nitrobenzene-N-salicylaldimine)nickel catalyst with electron withdrawing group could cause highersingle pass conversion and turnover frequency. The upmost conversion of propylene and turnoverfrequency of catalyst are98.2%and2.9×105in one of the propylene dimerization test.Finally, supported ionic liquid and Ni-based composite catalysts was used to investigate the propylenedimerization performances in the heterogeneous semi-batch operation mode. Preliminary results show that supported ionic liquid-Ni-based complexes composite catalysts could improved the selectivity of4-methylpentene and2,3-dimethylbutene isomer distinctly. Using MCM-41as supporter, the increasedselectivity of4-methylpentene is8.2%and2,3-dimethylbutene10.0%with respect to homogeneouscatalysis. As to SBA-15as support, the net increased selectivity of4-methylpentene is18.0%. Thesewitness indicates that the MCM-41and SBA-15support materials play the so-called shape-selective rolesin the heterogeneous propylene dimerization catalysis processes.