Study On Chloroform Coupling Reaction Catalyst

Chloroform is an important raw material in chemical industry.In recent years,a lot of large extension projects and new-built units were performed,and thus the excess supply of chloroform appeared.Therefore,It is of great significance that the industrial residual chloroform could be reasonably converted into high-valued industrial chemicals.In recent years,great attention has been paid to the research of the dechlorination of Ci chlorinated hydrocarbon or forming C-C bond between hydrogen chloride molecules,by which C2 or more carbon molecules can be produced and applied in industrial chemistry.In this study,various catalysts including FeCl3/AC catalsyt,AlCl3/AC catalyst,and multicomponent catalysts with several metal chlorides as active sites and activated carbon as the support,were prepared and employed in the C1 chlorinated hydrocarbon coupling process.The effect of different process condition on the catalytic performance was systematically investigated.1.The research on the coupling reaction of trans-1,2-dichloropropane and chloroformThe 1,1,2,3,3-pentachloropropane was synthesized by the coupling reaction with trans-1,2-dichloroethylene and chloroform as raw material and metal chloride as catalyst.In this study,the influence of several factors on the conversion of trans-1,2-dichloropropane and selectivity of 1,1,2,3,3-pentachloropropane were investigated.The factors include the kinds of catalyst,the content of catalyst,the molar ratio of raw material,the reaction temperature and the reaction time.The AlCl3 catalyst shows a relatively high activity,and the conversion of trans-1,2-dichloropropane reaches 91.8%and the selectivity of 1,1,2,3,3-pentachloropropane achieves 78.0%.However,with only the aluminium chloride as catalyst,the reaction is severe and the tar can easily generated with a content of 16.6%in the final product.In our work,the preparation of the AlCl3/AC catalyst was optimized by a vapor deposition method with cylindrical carbon(ACi)as the support and aluminium chloride as the active component.In addition,we investigated the effect of the content of aluminium chloride,the content of catalyst,the molar ratio of raw material,the reaction temperature and the reaction time on the conversion of trans-1,2-dichloropropane and selectivity of 1,1,2,3,3-pentachloropropane.It turned out that under the condition of the content of aluminium chloride 40%,the content of catalyst 10wt%,molar ratio of raw material 1:1,the reaction temperature of 85℃ and the reaction time of 4 h,the as-prepared catalyst has the highest initial activities.And the conversion of trans-1,2-dichloropropane in this condition reaches 19.7%,the selectivity of 1,1,2,3,3-pentachloropropane achieves 92.1%.The catalysts were fully characterized by XRD,FT-IR,BET and SEM techniques.The XRD results showed that the metal chlorides were uniformly dispersed on the surface of activated carbon,and the graphite structures of activated carbon were not damaged.The FT-IR results showed that most of the catalyst aluminium chloride was chemically bonded with activated carbon but not a simple physical adsorption.The BET results showed that the specific surface area was 1081.4 m2/g,the pore volume was 0.23 cm3/g,and the pore structure were mainly composed by micropores with also some mesopores detected.2.Tetrachloroethylene was synthesized by chloroform coupling reactionWith chloroform as raw material,tetrachloroethylene was synthesized by chloroform coupling dehydrochlorination process.The supported catalysts were prepared by impregnation method with cylindrical carbon(ACi),coconut shell charcoal(AC2),and molecular sieve as the supports and CuCl2,FeCl3,PdCl2,BaCl2,CaCl2,AlCl3,TiCl4 as the active components.We investigated the effect the catalyst kinds,the content of ferric chloride,the reaction temperature and the weight hourly space velocity on the catalytic performance,and obtained the FeCl3/AC catalyst with a high catalytic activity.It turned out that for the chloroform coupling to tetrachloroethylene process,at weight hourly space velocity(WHSV)of 1 h-1,the content of ferric chloride 3%and the reaction temperature of 400℃,the catalysts have the perfect initial activities.Moreover,the conversion of chloroform in this condition reaches 94.1%,and the selectivity of tetrachloroethylene achieves 30.9%.In order to solve the easily decoposing problem of the raw material,we tried to modify the catalysts by the lewis acid.The rection results shows that the selectivity of tetrachloroethylene slightly increased when FeCl3/AC catalysts were prepared by potassium chloride as additives,which was consistent with characterization results of NH3-TPD for FeCl3/AC.