【作者】 张蓓笑；

【导师】 林鹿；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2011， 博士

【摘要】 木质纤维素类生物质作为地球上资源量最丰富的一类可再生资源,其水解后可用于生产重要平台化合物乙酰丙酸,乙酰丙酸经脱羧反应可以得到丁酮,丁酮经Baeyer Villiger氧化得到乙酸乙酯,乙酸乙酯还原可生成乙醇。因此,通过上述方法探讨木质纤维素原料的有效能源化利用途径,对于拓展燃料乙醇的多元化生产方法,缓解我国能源危机、粮食危机等具有重要的意义。论文以来源于生物质的丁酮为原料,在Baeyer Villiger氧化体系中以过氧三氟乙酸、间氯过氧苯甲酸、过硫酸氢钾硅胶及氧气为氧化剂,氧化丁酮为乙酸乙酯,乙酸乙酯在镍基催化剂和铜锌铝催化剂的催化加氢作用下被还原得到乙醇。论文在丁酮氧化和乙酸乙酯还原工艺优化的基础上,对相关反应的机理进行了初步探讨,探索生物质基丁酮转化为燃料乙醇的新工艺。论文首先以三氟乙酸酐、三氟乙酸、过碳酰胺和30 %过氧化氢为原料制备液体过酸过氧三氟乙酸,将制备的过氧三氟乙酸用于丁酮的Baeyer Villiger氧化。研究发现用不同原料组合制备出的过氧三氟乙酸,对丁酮均具有氧化效果,过氧三氟乙酸对丁酮的氧化,除得到了目标产物乙酸乙酯外,还得到了副产物丙酸甲酯、三氟乙酸、三氟乙酸乙酯、乙酸、三氟乙酸甲酯和丙酸等。不同原料组合氧化效果由高到低依次为:三氟乙酸酐/过碳酰胺>三氟乙酸酐/过氧化氢>三氟乙酸/过碳酰胺>三氟乙酸/过氧化氢。以三氟乙酸酐/过碳酰胺为原料时制备出的过氧三氟乙酸对丁酮氧化能力最强。在缓冲剂添加前后,乙酸乙酯的得率分别为70.45 %和76.54 %,远高于其它组合。以间氯过氧苯甲酸和过硫酸氢钾硅胶两种固体过氧酸为氧化剂,研究其对丁酮的氧化效果。在添加和不添加助剂的情况下,间氯过氧苯甲酸氧化丁酮,除得到目标产物乙酸乙酯外,还生成了副产物丙酸甲酯、乙酸乙酯、间氯苯甲酸甲酯、丙酸、间氯苯甲酸乙酯和乙酸。添加助剂后,丁酮的转化率和乙酸乙酯得率均得到不同程度的提高。各种助剂促氧化效果由高到低的顺序依次为:三氟甲烷磺酸>甲烷磺酸>三氟乙酸酐>三氟乙酸。其中添加三氟甲烷磺酸后,反应2 h丁酮转化率和乙酸乙酯得率最高可达95.72 %和80.35 %。与未添加三氟甲烷磺酸的反应相比,丁酮转化率和乙酸乙酯得率最大值分别提高了41.05 %和42.3 %。通过浸渍法制备的非均相催化剂过硫酸氢钾硅胶,在室温下氧化丁酮时,仅得到目标产物乙酸乙酯,没有其它的副产物生成,但反应的得率不高,室温下反应30 h,乙酸乙酯得率为60.21 %。以氧气为氧化剂,苯甲醛为助氧化剂,丁酮在铜硅胶和镍硅胶的催化下,除了生成主要产物乙酸乙酯外,还生成了副产物苯甲酸乙酯、乙酸、苯甲酸苯酯、苯甲酸、苯酚和联苯。以镍硅胶2为催化剂,研究了不同醛为助氧化剂的效果,助氧化效果由高到低顺序依次为:苯甲醛>异戊醛>乙醛>异丁醛>特戊醛。在所有反应溶剂体系中,以苯作溶剂乙酸乙酯的得率最高。以镍硅胶2为催化剂氧化丁酮的最佳反应条件为:温度80℃、氧气压力5 MPa、苯甲醛:丁酮摩尔比为3:1、催化剂0.2 g、溶剂苯为40 mL,反应时间16h。在最优条件下,12 mmol的丁酮转化为乙酸乙酯的得率最高可达71.39%。研究还发现Ni和Cu的3个不同负载量的催化剂中,负载中间剂量的Ni和Cu催化剂催化活性最好。氧化镍和氧化铜催化氧化丁酮,丁酮转化率和乙酸乙酯的得率低于镍硅胶催化剂,高于铜硅胶催化剂。不添加任何催化剂时,得到28.42 %的丁酮转化率和15.46 %的乙酸乙酯得率。以钴硅胶和锰硅胶为催化剂时,得不到乙酸乙酯。以Fe MCM 48和Fe MCM 41 DHT为催化剂,氧气为氧化剂,苯甲醛为助氧化剂催化氧化丁酮,得到的产物与金属硅胶的催化产物相同。除生成主产物乙酸乙酯外,还生成了副产物苯甲酸苯酯、乙酸、苯甲酸、苯酚及苯甲酸甲酯等。对比6种不同Fe含量的介孔分子筛Fe MCM 48和1个Fe MCM 41 DHT,发现硝酸铁用量为1.8 g时,丁酮转化率和乙酸乙酯得率最大,分别为58.08 %和50.34 %。Fe MCM 41 DHT催化氧化效果并不高,仅得到35.89 %的丁酮转化率和30.09 %的乙酸乙酯得率。优化条件下,以三氧化二铁为催化剂时,仅得到42.23 %的丁酮转化率和34.51 %的乙酸乙酯得率。空白实验表明,不使用催化剂时,丁酮的氧化也会发生,但仅得到25.29 %的丁酮转化率和20.51 %的乙酸乙酯得率。在反应中添加壬烷时,反应的氧化效果会降低。来自于镍铝水滑石的镍基催化剂在催化氢化条件下能有效地催化乙酸乙酯的加氢还原。在所制备出的镍基催化剂中,RE1NASH 110 3的催化氢化效果最好,对乙酸乙酯氢化还原生成乙醇的选择性和得率分别可达68.2 %和61.7 %。乙酸乙酯催化加氢还原生成乙醇,乙醇的生成经过半缩醛C O断裂和乙氧基加氢过程。在镍基催化剂的催化作用下,乙酸乙酯的加氢除得到主产物乙醇外,还生成了副产物乙醛、甲烷、乙烷、乙醚和乙酸丁酯。乙酸乙酯在铜锌铝催化剂的催化加氢还原作用下,不但得到主产物乙醇,还得到少量的副产物正丁醇、仲丁醇、乙酸丁酯、丁酸乙酯和乙酸。以RE1CZASR 20 1.5为催化剂,最佳催化氢化条件为:温度280℃、氢气压力9 MPa、催化剂用量1 g、反应3 h。在最优条件下,乙酸乙酯的转化率和乙醇得率分别可达88.06 %和85.36 %。在制备出的所有铜基催化剂中,RE1CZAR 80 20是催化氢化活性最高的催化剂,其乙酸乙酯转化率和乙醇得率分别高达90.09 %和87.89 %。其它的催化剂,如雷尼镍、铝镍合金、镍铝水滑石还原物、钌碳、钯碳、亚铬酸铜(国标)、亚铬酸铜(企标)催化乙酸乙酯的氢化反应醇得率均低于50 %。更多还原

【Abstract】 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 %.更多还原