Application Of(Pesudo) Ionic Liquid In Catalyzing Hydration Of Cycloexene

Cyclohexanol is an important intermediate for the production of many important chemicals,such as adipic acid,hexamethylene diamine,caprolactam.It can also be used to make plasticizers,surfactants and industrial solvents,etc.As novel environmentally friendly liquid catalyst,the acidic deep eutectic solvent（DES）has the characteristics of non-toxicity,biodegradability,simple preparation,etc,and the atomic utilization rate is100%.In addition,it has similar thermal stability,low volatility,and designability as ionic liquids.Considering the characteristics of cyclohexene hydration reaction,a variety of deep eutectic solvents were prepared,and their catalytic performance of cyclohexene hydration and cyclohexyl acetate hydrolysis was investigated.Three choline-based deep eutectic solvents ChCl/PTA,ChCl/Tf OH,and ChCl/H₂SO₄ were prepared in this paper,the eutectic solvent was characterized by by FT-IR,¹H-NMR and Hammett method combined with UV-vis.ChCl/PTA DES had Bronsted acid center which Hammett function H₀ was 0.66.The hydration reaction of cyclohexene catalyzed by ChCl/PTA was studied.The effects of reaction temperature,reaction time and catalyst amount on the reaction were investigated.When reaction temperature was 130℃,reaction time was 6 h,and amount of ChCl/PTA was 8 g,cyclohexanol yield was 7.3%with 76.8%selectivity.And the catalyst has good catalytic performance after three cycles of use.The hydrolysis of cyclohexyl acetate over ChCl/PTA was studied.The reaction mixture was qualitatively analyzed by GC-MS,there were cyclohexyl acetate,cyclohexanol and cyclohexene in the reaction system,it was considered that cyclohexene come from the thermal decomposition of cyclohexyl acetate.The effects of reaction temperature,reaction time and amount of catalyst on the hydrolysis of cyclohexyl acetate were investigated.When reaction temperature was 100℃,reaction time was 4 h and amount of ChCl/PTA was 8 g,the yield of cyclohexyl acetate was85.0%,and the selectivity of cyclohexanol was 98.1%.Besides,Ionic liuid[BMIm]Br was screened to act as co-catalyst for hydrolyzation of cyclohexyl acetate to cyclohexanol over HZSM-5 catalyst.It was found that[BMIm]Br could inhibit the side-reaction,thermal decomposition of cyclohexyl acetate,and increase the selectivity to cyclohexanol greatly.Moreover,the ion exchange between[BMIm]Br and HZSM-5 could promote the generation of H⁺,which could accelerate the hydrolyzation of cyclohexyl acetate.Under the optimized reaction conditions,cyclohexyl acetate conversion was 87.5%with 97.3%cyclohexanol selectivity over HZSM-5 assisted by[BMIm]Br.The reusability of[BMIm]Br and HZSM-5 was investigated respectively,and the former exhibited good stability.However,the catalytic activity of HZSM-5 decreased gradually with the recycling times.It was due to the decreasing of framework Al content of HZSM-5 during the reaction,which led to the reduction of Brosted acid sites and therefore resutled in the decreased activity.