The Preparation Of Zirconium-based Materials And Their Catalysis For The Synthesis Of γ-valerolactone From Ethyl Levulinate

Currently,the demand of mankind to petroleumis increasing,but oil reserves are decreasing,which enforces us to find basic chemical raw materials and substitutes for liquid fuels.Biomass is the only renewable organic carbon resource in the world,with a number of favorable characters including rich reserves,low prices,and wide sources.Gamma-valerolactone(GVL)is an important biomass-derived small platform molecule,which is one of the recognized important substitutes for basic chemical raw materials.GVL can be converted to various bio-based hydrocarbon liquid fuels such as gasoline and diesel.However,there are many other by-products in the course of the reactions for the synthesis and further upgradation of GVL.Therefore,the construction of a highly efficient catalytic system for the GVL-involved reactions is the current research focus.This project intends to prepare a zirconium-based material catalyst for the conversion of ethyl levulinate to GVL using alcohol as the hydrogen source of reaction system.Meanwhile,the catalyst preparation method,structure characterization,catalytic activity,and catalyst reusability are also discussed.Besides,the application of different zeolitic catalysts in the condensation of furfural(GVL precursor)with mercapto ethyl acetate was also explored.The following conclusions have been made:(1)Zr-Ti microsphere catalysts with different Zr/Ti molar ratios are prepared using hexadecylamine as template agent.Zr-Ti catalysts were prepared from titanium tetraisopropoxide and zirconium n-propoxide,which had microporous structure,regularity and thermal stability characteristics,as clarified by a series of characterization analyses.The catalyst was used for the conversion of ethyl levulinate to GVL.Through screening different reaction conditions,the optimal ones were: 1 mmol ethyl levulinate,5 mL isopropanol as solvent,0.072 g catalyst,180 ℃,and 6 h,where the substrate was completely converted and the GVL yield was 90.1%.Notably,the yield of GVL was not significantly reduced(>85%)after the catalyst was reused for six times under optimal reaction conditions.(2)The Zr-organic inorganic hybrid catalyst was prepared from biphenyl diphosphonic acid and zirconium tetrachloride by hydrothermal method.Through a series of characterization analyses,the catalyst had regulatable acid and alkaline bifunctional features.The biphenyl diphosphonate zirconium catalyst was used foe the conversion of ethyl levulinate to GVL.Through screening different reaction conditions,the optimal reaction conditions were: 1 mmol ethyl levulinate,5 mL isopropanol as solvent,0.072 g catalyst,180 ℃,6 h,the substrate was completely converted,and the GVL yield was 91%.(3)The performance study for the condensation of furfural(GVL precursor)with ethyl thioacetate to form thioacetal.The application of different zeolite catalysts and the effect of the nature of the zeolite catalysts(such as acidity,basicity and pore size)in the reaction of thioacetal were explored.Different reaction conditions were screened,and the best reaction conditions were: 1 mmol of furfural,2.2 mmol of ethyl thioglycolate,and 50 mg of H-beta(19)catalyst where 98% of dithiothrealdehyde was obtained after reaction for 6 h at room temperature.Meanwhile,different substrates were screened under optimal reaction conditions in order to investigate the universality of the catalyst.The yield of the dithiosemialdehyde did not decrease(>90%)in the presence of the regenerating catalyst.