Preparation Of Poly Acidic Ionic Liquid And Study Of Alkylation Catalysis Performance

As a new branch of ionic liquid,the polymerized ionic liquid has particularity in structure and properties,and it has been widely used in the fields of adsorption and separation,material science,electrochemistry and catalyst.The poly-ionic liquid has the inherent low vapor pressure and higher thermodynamic stability of ionic liquid.It has higher specific surface area and suitable pore size,and has the advantages of good polymer stability,easy modification and easy separation,and its existence form is mostly solid or gel.By introducing acidic groups to synthesize acidic ionic liquids,the properties of the polymerized ionic liquids and acids are combined,which can greatly reduce the use of ionic liquids and improve their utilization rate,which is extremely beneficial to the acid catalytic reaction of large molecules.Diaryl ethane?PXE?is a good solvent for producing pressure sensitive carbon paper,which is mainly obtained through the alkylation of o-xylene and styrene.A series of polymerization acidic ionic liquids were prepared by means of free radical polymerization and ion exchange.The effects of different synthetic conditions on the structure of poly-acidic ionic liquids were investigated,including synthesis solvent,initiator addition,strong acid type,ionic liquid addition,and cationic chain length,and the catalytic performance of the alkylation reaction of diaryl ethane?PXE?was investigated.In the first place,1-vinyl imidazole,N,N-methylene diacrylamide crosslinking agent was used as monomer,and the synthesis of acidic ionic liquid was prepared by the preparation of N-hexane alkylation and trifluoromethane sulfonate ion exchange.The effects of synthetic solvents on the structure and properties of catalysts were investigated,and the optimum catalyst addition and reaction temperature of o-xylene and styrene alkylation were investigated.The results showed that the solubility of the monomer was affected by the polar effect of the solvent,and the MPM-C₆V-SO₃CF₃-IL?DMF?prepared with DMF as the solvent presented a network mesoporous structure,with a larger specific surface area(103.83 m²·g^-1),a larger pore volume(0.72 cm³·g^-1),with more acid content and the active bits were distributed on the skeleton of the grid.The optimal catalytic conditions as follows:3 h reaction time,reaction temperature 120?,the 0.17 g for the amount of catalyst dosing ratio?0.5%?,raw material allyl ratio7.5:1.Eventually,the conversion rate of styrene is approaching 100%,and the PXE conversion rate is above 99%.After determining the appropriate reaction conditions,the effects of other preparation conditions on the poly acidic ionic liquids were investigated.1-vinyl imidazole,N,N-methylene diacrylamide cross-linking agent was used as monomers,and sulfonic acid and acid root ions were introduced through 1,3-propionic acid and different acid acidification.The effects of initiator dosage and strong acid type on catalyst structure and catalytic performance were investigated.It was found that that degree of polymerization influence the degree of polymerization,so that the polymerization was incomplete and the pore diameter was not uniform.It is too easy to cause the detonation,which leads to the blockage of the channel,and the most suitable catalyst is 3wt%of the total feeding,forming a uniform network mesoporous structure,with a large specific surface area and pore volume,and a stable pore structure.Acid acidification purpose is for ion exchange,the introduction of acidic group sulfonic group.In the case of trifluorocarbine sulfonate,the intense electronicity of fluorine atoms in the molecules produces a field effect and inducement,which makes sulfuric acid a very strong acidity,and it has a lot of acid,and the sample MPM-SO₃H-[C₃V][SO₃CF₃]is the best catalytic performance of the PXE rate and the rate of phenethylene conversion.Considering that the first two catalysts were not very stable in thermal stability because of the presence of amide bonds,the diethylbenzene was used as crosslinking agent.1-ethylenimidazole and ionic liquid 1-ethyl-3-butyl imidazole bromide was introduced,and alkylation was carried out under the action of different chains of N-bromoalkane,finally,binary and ternary polymerization acidic ionic liquids was synthesized by the acidification of trifluoromethane.The differences between binary and ternary polymer acidic ionic liquids were compared,besides,the influence of ionic liquid addition and cationic chain length of poly ionic liquid was investigated.It was found that that ternary polymerize acidic ionic liquid has a clear spongy porous structure with a more stable mesoporous structure,a great specific surface area,more sulfonic acid group character peak and more active sites under the conditions of D:V:[VBIM][Br]=2:1:1.Cationic chain length influences the crosslinking pore diameter of polymer ionic liquid.The shorter chain length,the more favorable to the formation of macroporous structure.Pore diameter shorten as the increase of cationic chain.While,overgrowth of cationic chain leads to a high degree of crosslinking polymerization,which leads to the blockage of the channel,as a result,the optimal chain length is C₄.It shows that the amount of ionic liquid and the length of alkyl chain determine the degree of polymerization,cross-linked structure with mesopores and macropores is more favorable to the alkylation reaction.To sum up,the polymerization of acidic ionic liquids with the combination of free radical polymerization and ion exchange has a network or sponge mesoporous structure,which has a higher specific surface area and pore volume,and more acid content.These advantages are beneficial to the polymerization of acidic ionic liquids as catalysts for the preparation of PXE alkylation of o-xylene and styrene.