【摘要】 木质纤维基生物质是一类新的能够生产液体燃料和化学品的可再生资源.本文研究了木质纤维生物质在水热条件下,以少量无机酸作为酸催化剂,氧气作为氧化剂(2.0 MPa),经过"一锅两步法"转化成乙酸的反应.以玉米秸秆作为反应原料时,最高可以获得21.3 wt%的乙酸,占据整个液体产物质量比例的84.6%(选择性).同时,将反应推广到玉米芯,甘蔗渣,竹子,杨木和松木等多种生物质原料的转化,同样取得了较高的乙酸产率.最后,我们对木质纤维生物质转化到乙酸的反应过程进行了研究.研究表明木质纤维生物质中的碳水化合物六碳糖是乙酸的主要来源,六碳糖经过脱水和水解生成乙酰丙酸中间体,乙酰丙酸在氧化条件下断裂C—C键生成乙酸.更多还原

【Abstract】 Nowadays, lignocellulosic biomass is considered as renewable source for the substitute of traditional fossil energy resources. The production of biofuel intermediates such as 5-hydroxymethylfurfural(5-HMF), levulinic acid and γ-valerolactone(GVL), and commercially interesting compounds such as lactic acid and ethylene glycol from biomass has become an important issue for world-wide researchers. In this work, we focused on the conversion of lignocellulosic biomass into acetic acid through a "one-pot two-step" method over inorganic acids in aqueous media. The first step was the hydrolysis of the raw biomass with sulfuric acid at 190 ℃, 1.0 MPa N2 for 1 h. After that, the reaction was changed to 2.0 MPa O2 and allowed to react for another 9 h. HPLC analysis of the result mixture showed that mass yield of acetic acid from corn stover was up to 21.3%, and the selectivity of acetic acid was as high as 84.6% of the total liquid products. Besides, the other lignocellulosic biomass feedstocks such as corn cob, bagasse, bamboo, poplar and pine were also successfully converted into acetic acid in good yields under the optimized reaction condition. In addition, the stability of the catalyst acid was examined, and the recovery of the catalyst acid is about 95%. Thus, to achieve the reuse of the catalyst acid, the addition of extra 10% catalyst acid after each catalytic cycle was needed. Finally, the reaction pathway was explored by using the components of the lignocellulosic biomass feedstocks as the starting materials(sugars etc.). The results showed that the carbohydrates especially hexoses were the main source of acetic acid. It was dehydrated and hydrolyzed into the intermediate levulinic acid, which was then oxidized into acetic acid by C—C bond oxidative cleavage. The current method provided a new access to the bulk acetic acid from sustainable raw biomass.更多还原