Ethyl Levulinate Production From Biomass-derived Carbohydrates And Kitchen Waste

Currently,most of the carbon-based chemicals are still produced from petroleum in petrochemical plants through sophisticated processes.However,it is urgent to find suitable substitutes for the production of carbon-based chemicals due to the depletion of petroleum.As well known,carbohydrates is the major carbon source of biomass and reveals great potential in the production of high value-added chemicals.Meanwhile,carbohydrates are also an important component of food supply chain waste（FSCW）.Therefore,both biomass-derived carbohydrates and FSCW can be used as ideal substitute of petroleum to produce carbon-based chemicals.Recently,the generation of FSCW has increased rapidly with the incerase of the global population and economy.There are many defects when the existing solid waste treatment technologies,such as landfills,incineration and biological treatment,used in the treatment of FSCW,especially kitchen waste（KW）.Therefore,the production of carbon-based chemicals from KW not only provides a new option for the varolization of KW,but also accumulates research experience for the relief of energy crisis.Among various value-added chemicals,ethyl levulinate（EL）is considered a potential fuel additive due to its unique physical and chemical properties.Therefore,the production of EL from biomass-derived carbohydrates and KW using acid catalysts was proposed in this study.The main contents of this study are:1.Firstly,a solid acid Q[6]-H₂SO₄ was prepared,characterized and then used as catalyst to produce EL from fructose,glucose,sucrose,expired probiotic beverage powder and KW in ethanol.The effects of reaction parameters on EL yield were investigated.Reaction pathways of EL production from biomass-derived carbohydrates and KW were discussed by analyzing the main-product,by-products and inter-products.The results showed that EL yields of 83.7%and 47.7%were obtained at 200°C from fructose（8 h）and glucose（10 h）,respectively.When sucrose was ethanolyzed at 180°C for 8 h,EL yield of 49.6%was obtained.Q[6]-H₂SO₄ has a higher activity in catalyzing the conversion of ketose to EL since there only Bronsted acid on its surface.The yield of61.2%was obtained from a furan rich food waste,expired probiotic beverage powder at180°C for 12 h.KW is difficult to ethanolysis due to the complex composition.However,EL yield increases from 1.2%to 35.0%when the ratio of catalyst addition to KW addition increases from 1 to 2.2.In order to increase the EL yield from glucose and KW,three modified multifarious acid sites HMS molecular SO₃H-X-HMS were prepared.The microstructure,crystal structure,acidity,pore size and specific surface area of the catalysts were characterized.Then,the prepared catalysts were used to catalyze biomass-derived glucose to produce EL.Catalytic activity of various acid sites present on the surface of SO₃H-X-HMS in the steps of reaction pathways of glucose to EL were discussed.The influence of reaction parameters on EL yield was investigated.The maximum EL yield of 47.9%was obtained from glucose catalyzed by SO₃H-Al-HMS at 180°C for 12 h.Acid amount,ratio of B/L,specific surface area and pore size of the catalysts have a certain effect on the EL yield of EL.Meanwhile,EL yields in the range of 1.6%-38.9%were obtained from cellobiose,cellulose,wheat flour and KW.3.Bronsted-Lewis solid acid Sn/Zr P-SO₃H was prepared and combined with several metal triflates:（Al（OTf）₃,Fe（OTf）₃,Sm（OTf）₃）to form catalytic system for the efficient preparation of EL from KW.The catalytic mechanism of the catalytic system was explored.EL yield of 52.5%was obtained from KW catalyzed by Sn/Zr P-SO₃H/Al（OTf）₃after optimizing the reaction parameters by a single factor experiment.Four-factor and three-level experiments were performed using response surface methodology to analyze the interaction between each factors.The optimal reaction conditions predicted by the model（163°C,7.63 h,20mg Al（OTf）₃,40mg Sn/Zr P-SO₃H and 79.98 mg of KW）estimated a maximal EL yield for EL of 51.24%.The experimental yield of EL however was 52.03%which confirms the reliability of the model.