Study On Isobutane/1-Butene Alkylation Catalyzed By Trifluoromethanesulfonic Acid Supported On Mesoporous Molecular Sieve

At present,the commercial catalysts for the production of isobutane alkylated gasoline are mainly sulfuric acid?H₂SO₄?and hydrofluoric acid?HF?,which generally have some disadvantages,such as large acid consumption,corrosion equipment,great harm to people and the environment,and high cost of waste acid treatment.In view of the shortcomings of traditional alkylation catalysts,in this paper,three mesoporous solid acid catalysts were designed and applied to the isobutane/1-butene alkylation reaction.The research content is mainly divided into the following three systems:The SBA-15 mesoporous molecular sieve was prepared by hydrothermal synthesis under acidic conditions through using P123 as template and tetraethyl orthosilicate as silicon source,and then,the mesoporous solid acid TfOH-SBA-15 was prepared by solution post-impregnation method by which trifluoromethanesulfonic acid was supported on SBA-15.The molecular sieves before and after the acid loading were characterized by XRD,FT-IR,scanning electron microscopy,transmission electron microscopy,nitrogen adsorption-desorption,etc.,and the acid amount of the load was determined by acid-base titration method.Isobutane/1-butene alkylation reaction was studied catalyzed by TfOH-SBA-15 on the alkylate fixed bed reactor.The optimum reaction conditions were optimized:I/O?alkane/olefine?=48:1,temperature T=80°C,reaction pressure P=3 MPa,reaction feed space velocity WHSV=0.12 h^-1,catalyst dosage m=1 g.Under the optimal reaction conditions,the conversion of 1-butene is above 98.84%,the highest value reaches 99.62%,the C₈ selectivity is above 40.03%,and the highest value is 54.25%.The SBA-16 mesoporous molecular sieve was prepared by hydrothermal synthesis under acidic conditions using F-127 as template,tetraethyl orthosilicate as silicon source,and potassium sulfate as auxiliary agent.Subsquently,the mesoporous solid acid TfOH-SBA-16 was prepared by solution post-impregnation method by which trifluoromethanesulfonic acid was supported on SBA-16.The molecular sieves before and after loading were characterized by XRD,FT-IR,transmission electron microscopy,nitrogen adsorption-desorption,etc.,and the acid amount of the load was determined by acid-base titration method.Isobutane/1-butene alkylation reaction was studied catalyzed by TfOH-SBA-16 on the alkylate fixed bed reactor.The optimum reaction conditions were optimized:I/O=48:1,reaction temperature T=90°C,reaction pressure P=3 MPa,reaction feed space velocity WHSV=0.24 h^-1,catalyst dosage m=1 g.Under the optimal reaction conditions,the conversion of 1-butene is above 99.12%,the highest value reaches 99.92%,the C₈ selectivity is above 49.38%,and the highest value is 65.24%.The hollow mesoporous silica sphere PS-SiO₂ is synthesized under alkaline conditions through using polystyrene microspheres?PS?as hard template,cetyltrimethylammonium bromide?CTAB?as soft template,tetraethyl orthosilicate as silicon source,AETAC?acryloyloxyethyltrimethyl ammonium chloride?as an auxiliary agent,and V-50?azobisisobutyl hydrazine hydrochloride?as an initiator.Subsquently,the mesoporous solid acid TfOH-PS-SiO₂ was prepared by loading trifluoromethanesulfonic acid using acid solution post-impregnation method.The mesoporous silica spheres before and after acid loading were characterized by FT-IR,scanning electron microscopy,transmission electron microscopy,nitrogen adsorption-desorption and other characterization method.The acidity of the supported was determined by acid-base titration method.Isobutane/1-butene alkylation reaction was studied catalyzed by TfOH-PS-SiO₂ on the alkylate fixed bed reactor.The optimum reaction conditions were optimized:I/O=48:1,reaction temperature T=90°C,reaction pressure P=3 MPa,reaction feed space velocity WHSV=0.12 h^-1,catalyst dosage m=0.5 g.Under the optimal reaction conditions,the conversion of 1-butene is above 98.92%,the highest value can reach99.82%,C₈ selectivity is above 60.18%,and the highest value can reach 75.42%.In this paper,three kinds of mesoporous solid acids with different pore channels were synthesized and applied to catalyze the alkylation of isobutane/1-butene.These catalysts exhibit good catalytic perfermance,and they are environmentally friendly and easy to separate form products.The study provides a new idea for the preparation of large pore solid acid catalysts for alkylation.