Direct and multistep conversion of lignin to biofuels
Direct and multistep conversion of lignin to biofuels
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发表时间：
2012-08
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通讯作者：
M. Kosa
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作者：
M. Kosa
木质素是地球上仅次于纤维素的第二大生物聚合物，其高度复杂的化学结构阻碍了其可能的利用。由于其廉价的性质，以不同方式利用木质素的应用受到极大关注。目前的工作是基于将木质素转化为不同的生物燃料的概念，这些生物燃料与木质素作为直接能源相比只有很少的优势，但是重要的是。目前工作的第一部分（热解）详细分析了来自一个相对较新的木质素分离工艺（称为LignerBoost）的木质素。它是通过从黑液（BL）中CO2沉淀木质素而从纸浆和造纸工业中获得的。该方法是环境友好的，产生具有最小氧化的木质素，消除了硫酸盐法循环的主要瓶颈（回收锅炉容量），并且还在工艺流中留下足够的木质素以回收制浆化学品并为纸浆厂产生能量。热解将这种木质素转化为具有高脂肪含量和低氧化水平的生物油，这些都有利于作为液体燃料的应用。论文第二部分证明了木质素降解和油脂积累代谢途径之间存在着相互联系。使用革兰氏阳性不透明红球菌物种DSM 1069和PD 630来评价木质素至脂质的生物转化，从乙醇有机溶剂和硫酸盐木质素开始。在从细胞中提取脂质之后，这种转化是生物柴油生产的多步骤过程中的第一步，该过程包括酯交换。结果清楚地表明，木质素到脂质的生物转化途径是可行的，细胞在脂质中获得高达其重量的4%，同时仅以木质素作为碳源和能源生长。
Lignin is the second most abundant biopolymer on Earth, right after cellulose, with a highly complex chemical structure that hinders its possible utilizations. Applications that utilize lignin in different manners are of great interest, due to its inexpensive nature. Present work is based on the notion of converting lignin into different biofuels that have only a few, however important, advantages over lignin as a direct energy source. The first part of current work (pyrolysis) details the analysis of lignin from a relatively new lignin isolation process called LignoBoost. It is obtained from the pulp and paper industry via CO₂ precipitation of lignin from black liquor (BL). This method is environment friendly, results lignin with minimal oxidation, eliminates the main bottleneck of the Kraft cycle (recovery boiler capacity), and yet leaves enough lignin in the process stream to recover pulping chemicals and generate energy for the pulp mill. Pyrolysis had converted this lignin into bio-oil with high aliphatic content and low oxidation level, all advantageous for application as liquid fuel. The second part of this dissertation proved the theory that lignin degradation and lipid accumulation metabolic pathways can be interconnected. Gram-positive Rhodococcus opacus species, DSM 1069 and PD630 were used to evaluate lignin to lipid bioconversion, starting with ethanol organosolv and Kraft lignin. This conversion is a first step in a multistep process towards biodiesel production, which includes transesterification, after lipids are extracted from the cells. Results clearly indicated that the lignin to lipid bioconversion pathway is viable, by cells gaining up to 4 % of their weight in lipids, while growing solely on lignin as a carbon and energy source.