褐煤发酵制生物氢过程中关键液相产物的变化规律

过去对于煤发酵产氢过程中液相中间产物内有机物的变化及相互转化关系鲜有研究,而液相产物的种类和浓度不仅关系到煤转化成生物氢的效率,而且还是研究煤制生物氢生成机理的重要内容之一。为此,以陕西省大柳塔褐煤为研究对象,在适宜环境条件下进行生物发酵产氢实验,利用气相色谱法、气质联用法对煤发酵产氢过程中的氢气浓度及关键液相产物进行阶段性测试,以揭示制氢过程中关键液相产物的转化规律。实验结果表明:①煤制生物氢过程中关键液相产物的变化规律和产氢量变化相对应,饱和烷烃及环烃类的相对丰度先增加后减少再增加,而蛋白质类物质的相对丰度则先减少后增加再减少,分别对应产氢初期、产氢高峰期和产氢末期3个阶段;②小分子挥发性脂肪酸在产氢过程中逐渐积累,芳香小分子酸在产氢过程中发生的增加、减少、再增加、再减少的震荡式变化过程,对应小分子物质释放、微生物利用、烃类氧化及大分子再被降解这一系列生物化学反应过程;③液相产物中检测出的脂类、醛类、酮类物质是产酸的母源物质,其变化量与酸类增长具有一定的关联性。结论认为,研究煤制生物氢过程中液相产物的变化规律,不仅揭示了气—液两相之间相互对应的生物化学效应,而且也进一步丰富了煤发酵产氢理论。

Transformation analysis of key liquid phase products during lignite fermentation to produce biological hydrogen

There was little research on the changes and interconversion of organic compounds in the intermediate liquid-phase products in the hydrogen production by anaerobic fermentation of coal. The types and concentrations of the intermediate liquid-phase products are not only related to the efficiency of coal conversion into biohydrogen, but one of the important contents of study on the generation mechanism of biohydrogen from coal. In order to study the change of key liquid phase products in the process of bio-hydrogen production from coal, the simulation experiments of bio-hydrogen production were conducted under suitable environmental conditions using lignite from Daliuta, Shaanxi province. The hydrogen concentration and key liquid phase products were measured using gas chromatography and GC–MS, respectively, to reveal its change. The results show that: (1) there is correspondence between the key liquid phase products and hydrogen yield. The saturated alkanes and cyclic hydrocarbons show a trend of first increasing, then decreasing, and finally increasing, but the changes of proteinaceous materials are just the opposite, which is correspondent to the initial stage, peak stage and terminal stage of hydrogen production, respectively. (2) The short-chain volatile fatty acids are accumulated gradually in the process of hydrogen production, and the short-chain acids of aromatic show a trend of first increasing, then decreasing, increase again and finally decreasing, which is correspondent to the different biochemical reactions, such as the release of small molecules, the utilization of microorganisms, hydrocarbon oxidation and the redegradation of macromolecule. (3) The lipids, aldehydes and ketones are the parent substances of acid production, and the changes are related to the increased acids to a certain extent. This research not only reveals the biochemical effects between gas and liquid phases, but further enriches the theory of bio-hydrogen production from coal.