Preparation And Catalytic Performance Of Liquid Acid Catalysts For Long-chain Olefin Alkylation

In recent decades,long-chain alkylbenzene,as an important raw material for detergents and oil displacing agents,have attracted widespread attention.Long-chain alkylbenzenes are usually obtained by reacting long-chain olefins with benzene compounds.In conventional industrial processes,the catalysts which were used to synthesize heavy alkylbenzenes are typically toxic and corrosive catalysts such as HF or AlCl₃.However,conventional catalysts are very hard to be recycled because of the high cost of equipment corrosion and post-treatment.Therefore,many studies have focused on the development of catalysts for several years,which own highly efficient catalytic activity and environment-friendly.Among them,the solid acid catalysts with good catalytic activity and selectivity are considered as the first potential substitutes for eliminating the disadvantages of conventional alkylation catalysts.Many scientists have designed and synthesized a series of environmentally friendly solid alkylation catalysts,such as zeolite,heteropoly acid?-Al₂O₃,etc.,which have been widely used in alkylation and esterification reactions.But solid acid catalysts are difficult to achieve mass production due to difficult regeneration,high cost,and complicated reprocessing.Therefore,it is of great significance to design a highly efficient and recyclable liquid acid catalyst for long chain olefin alkylation.In this paper,a series of ionic liquid catalysts were synthesized by quaternary amination reaction and ion exchange reaction.The preparation of catalysts,reaction conditions and regeneration methods were systematically studied in order to evaluate the effect of catalysts on the alkylation of long-chain olefins.In addition,the catalytic performance of the catalyst was further studied by amplification experiments.The full text of the research is as follows:?1?A series of ionic liquids were synthesized with 1-methylimidazole,1-vinylimidazole,chloro-n-butane,chloro-n-hexane,chlorooctane,3-chloropropyltriethoxysilane and aluminum trichloride.The precursors,catalysts and reaction products were characterized by FT-IR spectroscopy,specific gravity,²⁷Al NMR and bromine value.The results showed that[PMIM]Cl-2AlCl₃ has the strongest Lewis acidity,with a specific gravity of 1.39876 and a peak of ²⁷Al NMR of 103.95 ppm.In the alkylation of toluene with hexadecane,the bromine value of the alkylation product catalyzed by[PMIM]Cl-2AlCl₃ is lower than the bromine value of the alkylation product catalyzed by[BMIM]Cl-2AlCl₃,[OMIM]Cl-2AlCl₃,[BVIM]Cl-2AlCl₃ and[PMIM-Si?OEt?₃]Cl-2AlCl₃ and can be as low as 0.024 g/100 mL.?2?The effect of different catalyst structures,different catalyst dosages and different reaction conditions?reaction temperature,reaction time,benzene ratio?on long-chain olefins alkylation and the catalytic performance of catalysts were studied.The results showed that[PMIM]Cl-2AlCl₃ had the best catalytic activity.And the octadecene conversion of 99.85%and the selectivity of 32.99%of high-carbon alkylbenzene could be achieved at a reaction temperature of 50°C,a molar ratio of toluene to olefin of 10:1,a molar ratio of catalyst to olefin of 0.3:1 and a reaction time of 20 minutes.Besides,the runs of[PMIM]Cl-2AlCl₃could reach up to 10 times.In addition,the effect of[PMIM]Cl-2AlCl₃ on the long-chain olefins alkylation was studied,the results showed that the shorter the olefin chain length,the better the catalytic activity of[PMIM]Cl-2AlCl₃.?3?The effect of[PMIM]Cl-2AlCl₃ on the alkylation of octadecene with benzene under different reaction conditions was studied.The results showed that the bromine value of the product of long chain olefins alkylation with toluene could be gone down to 0.064 g/100 mL at a reaction temperature of 50°C,the molar ratio of benzene to olefin of 15:1,and the molar ratio of catalyst to olefin of 0.3:1 and a reaction time of 20 minutes.And it could be found that the bromine value of the alkylation products of o-xylene and octadecylene catalyzed by[PMIM]Cl-2AlCl₃ under the optimal reaction conditions were lower than those of m-xylene,p-xylene,xylene and octadecylene,and could be as low as 0.040 g/100 mL.In addition,the effect of[PMIM]Cl-2AlCl₃ on the alkylation of long-chain olefins was further investigated by amplifying.The results showed that the number of cycles of[PMIM]Cl-2AlCl₃ was gone down from 10 to 7 times after amplifying.At the same time,the regeneration experiment was carried out on the deactivated catalyst.It was found that the regenerated catalyst still had good catalytic activity and the number of cycles was up to 6 times.