| Biomass is the most abundant and renewable resource in nature, which can be used to produce levulinic acid through a series of hydrolysis process. As an important platform material, levulinic acid can be decarboxylated to form butanone. Butanone can be converted to ethyl acetate through Baeyer Villiger oxidation, ethyl acetate is further reduced to ethanol. Consequently, the research with respect to the above conversion steps from biomass to versatile fuels develops a new pathway to produce bio ethanol, and also becomes increasingly significant to resolve energy crisis and food shortage and so on, which can also supplement or gradually replace the oil based chemicals or energy.The oxidation reactions of biomass derived butanone to ethyl acetate through Baeyer Villiger oxidation with trifluoroperacetic acid, meta chloroperbenzoic acid(mCPBA), potassium hydrogen persulfate silica gel and oxygen as oxidant were studied respectively. Ethyl acetate was catalyzed by Ni based catalyst and Cu Zn Al catalyst in the presence of hydrogen, and finally was reduced to ethanol. In addition, the mechanisms of butanone oxidation and ethyl acetate reduction were investigated based on reactions process optimization. And the new oxidative and reductive pathways of butanone to bio ethanol were explored in this paper.Trifluoroperacetic acid, which was made with trifluoroacetic anhydride, trifluoroacetic acid(TFA), percarbamide and 30 % peroxide, was firstly used as oxidant for Baeyer Villiger oxidation of butanone. With the prepared oxidants, ethyl acetate as main product and methyl propionate, ethyl trifluoroacetate, acetic acid, TFA and propionic acid as by products could be formed. The effects of butanone oxidation varied with different preparation methods of trifluoroperacetic acid, the order from high to low were as following trifluoroacetic anhydride/percarbamide, trifluoroacetic anhydride/peroxide, TFA/percarbamide and TFA/peroxide, respectively. When trifluoroacetic anhydride/percarbamide as raw materials for preparation of trifluoroperacetic acid, the yield of ethyl acetate could attain to 70.45 % and 76.54 % before and after adding buffer.The butaone oxidation was then studied with mCPBA and potassium hydrogen persulfate silica gel as oxidant. The butanone oxidation with mCPBA could produce ethyl acetate, methyl propionate, methyl 3 chlorobenzoate, propionic acid, ethyl 3 chlorobenzoate and acetic acid with or without adding additives. Both ethyl acetate yield and butanone conversion rate rose with adding additives such as trifluoromethane sulfonic acid, methanesulfonic acid, trifluoroacetic acid and TFA, and among these additives, trifluoromethane sulfonic acid influenced most. The reaction lasted 2 hours and the butanone conversion rate and ethyl acetate yield could attain to 95.72 % and 80.35 %, respectively, which improved by 41.05 % and 42.3 % compared with that without adding of trifluoromethane sulfonic acid. Still, potassium hydrogen persulfate silica gel was made by impregnation method. At the room temperature, butanone was oxidated by potassium hydrogen persulfate silica gel for 30 hours and only ethyl acetate was produced with a yield of about 60.21 %.Butanone was catalyzed with Cu silica gel and Ni silica gel in the presence of oxygen as oxidant and benzaldehyde as pro oxidant, which caused ethyl acetate as the main product and ethyl benzoate, acetic acid, phenol benzoate, benzoic acid, phenol and diphenyl as by products. The effects of pro oxidants and solvents were also studied. It was found that benzaldehyde and benzene were the most effective for the reaction. Ethyl acetate yield could attain to 71.39 % when the reaction was operated at temperature of 80℃for 16h, with oxygen pressure of 5 Mpa, Ni silica gel 2 mass of 0.2 g, benezene volume of 40mL and molar ratio of benzaldehyde and butanone of 3:1. It was also found that the dosage of Ni and Cu in catalyst would affect butnanone oxidation. The butanone conversion rate and ethyl acetate yield catalyzed with nickel oxide and cupric oxide were lower than that of Ni silica gel but higher than Cu silica gel. Moreover, the butanone conversion rate and ethyl acetate yield were 28.42 % and 15.46 % repsectively without any catalyst, and no ethyl acetate was detected about butanone oxidation with Co silica gel and Mn silica gel as catalyst.The oxidation products of butanone by Fe MCM 48 and Fe MCM 41 DHT in the presence of oxygen as oxidant and benzaldehyde as pro oxidant were analyzed by GC/GC MS, and the main product was ethyl acetate and by products included phenol benzoate, acetic acid, benoic acid, phenol and methyl benzoate et al. It was found that with ferric nitrate dosage of 1.8 g, the butanone conversion rate and ethyl acetate yield could attain to 58.08 % and 50.34 % repsectively. The reaction catalyzed by Fe MCM 41 DHT got a lower butanone conversion of 35.89 % and ethyl acetate yield of 30.09 %. At the optimum conditions, the butanone conversion rate and ethyl acetate yield could attain to 42.23 % and 34.51 % repsectively with ferric oxide as catalyst. Meantime, oxygen and benzaldehyde could directly oxidize butanone to form ethyl acetate, the butanone conversion and ethyl acetate yield of were about 25.29 % and 20.51 %, respectively.In the presence of hydrogen, ethyl acetate was effectively reduced to ethanol by Ni based catalyst, especially with RE1NASH 110 3 the selectivity and yield of ethanol could attain to 68.2 % and 61.7 % respectively. The hydrogenated reduction of ethyl acetate to ethanol firstly involved the break of hemiacetal C O bond and then the generated oxyethyl group was hydrogenated. With ethanol as the main product, acetaldehyde, methane, ethane, ethyl ether and butyl acetate were also detected.The hydrogenation of ethyl acetate by Cu Zn Al catalyst was also studied. The results analyzed with GC/GC–MS showed that ehtanol was the main product, and 1 butanol, 2 butanol, butyl acetate, ethyl butyrate and acetic acid were also detected. Catalyzed with RE1CZASR 20 1.5, the reaction was carried out at 280℃for 3 hours with hydrogen pressure of 9Mpa, catalyst mass of 1 g, the ethyl acetate conversion rate and ethanol yield could attain to 88.06% and 85.36% respectively. Among the Cu based catalysts, RE1CZAR 80 20 was the best catalyst for ethyl acetate catalytic hydrogenation, the ethyl acetate conversion and ethanol yield could attain to 90.09 % and 87.89 % respectively. As for other catalysts, such as Raney Ni, aluminonickel, Ni Al houghite, Ru/C, Pd/C, copper chromite(GB) and copper chromite(QB) all could catalyze ethyl acetate to ethanol, but the yield of ethanol was lower than 50 %. |
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