植物纤维制备燃料乙醇的关键技术

由于中国人口众多、土地资源紧缺,农林植物纤维是发展燃料乙醇的可靠原料.南京林业大学在日处理原料5 吨、日产乙醇0.8吨的农林植物纤维生产燃料乙醇中试生产线上的研究结果表明,植物纤维经蒸汽爆破预处理后,用里氏木霉制备的纤维素酶进行酶水解,纤维素和半纤维素水解得率达71.3 %.含戊糖己糖的水解糖液经树干毕赤酵母发酵转化,糖利用率为87.2 %,乙醇得率为 0.43 g 乙醇/g消耗的糖,生产成本为每吨乙醇4000元左右.为使该技术形成生产力,有待解决的关键技术有:1)能耗低、损耗少的原料预处理技术,特别是蒸汽爆破预处理技术的研究;2)纤维素酶活力高、酶系结构合理的纤维素酶制备和酶水解技术,包括纤维素酶制备基因工程菌的构建,纤维素酶制备的定向调控,高β - 葡萄糖苷酶活力纤维素酶的合成,以及高糖化率纤维素酶水解模式和技术方法;3)戊糖代谢的研究,包括戊糖代谢调控发酵的研究和戊糖己糖同步发酵微生物基因工程菌株的构建;4)植物纤维资源制取乙醇的关键技术的整合和集成;5)能源木本植物的研究.

Key Technologies for Producing Fuel Ethanol from Lignocelluloses

Lignocelluloses are reliable raw materials available for large-scale fuel ethanol production in China. In the research on a pilot plant, lignocelluloses were steam exploded, cellulose and hemicellulose were hydrolyzed with cellulose enzyme synthesized by Trichoderma reesei strain, and the resulted pentoses and hexoses were fermented to ethanol by Pichia stipitis. This pilot plant handled lignocelluloses 5 t per day to produce ethanol 0. 8 t per day, with a hydrolysis yield of 71. 3% , a sugar utilization ratio of 87.2 % , and an ethanol yield of 0.43 g/g consumed sugars. The cost of ethanol production was estimated to be 4000 yuan/t, or 500 USD/t. In order to tramsform this technology into productivity, further research works are required in the following respects of key technologies; 1) Pretreatment techniques of low energy consumption and low material loss, especially steam explosion and chemical-added explosion; 2) Recombinant strains for high-efficiency cellulose enzyme synthesis, systematic control of enzyme production and enzymatic hydrolysis; 3) Pentose fermentation regulation and genetic modification of yeast strains; 4) Assembling and coordination of the available key technologies for full-scale utilization of lignocelluloses; 5) Research on woody plants as energy resources.