生物质高压液化制生物油研究进展

以生物质为原料进行高压液化制备生物油是目前生物质能领域研究的一个热点。纤维素在水中的降解是复杂的竞争和连串反应机理;在180℃以上,半纤维素就很容易水解,而且不管是酸还是碱都能催化半纤维素的水解反应;在水热条件下木质素会发生分解,生成多种苯酚、甲氧基苯酚等,这些产物可进一步被水解成甲氧基化合物。影响生物质液化产率及生物油组成的主要因素是温度、生物质类型和溶剂种类;次要因素包括停留时间、催化剂、还原性气体和供氢溶剂、加热速率、生物质颗粒大小、反应压力等。纤维素类生物质通过高压液化可以生产生物油,生物油经物理精制及化学加工可以制取车用燃料、生物气及化工产品等。生物油有轻油和重油之分,都是通过对生物质液化产物的分离精制而得到的。目前用来分析生物油的主要方法包括GC-MS(色-质联用)、EA(元素分析)、FTIR(傅里叶变换红外光谱)、HPLC(高效液相色谱)、NMR(核磁共振)、TOC(总有机碳测定)等。人们对生物质高压液化研究已经进行多年,并建立了几套工业试验示范装置。不过因为操作条件太苛刻,到目前为止还没有建立商业化装置。

Progress in High-Pressure Liquefaction of Biomass to Bio-oil

Using biomass as feedstock to produce bio-oil by means of high-pressure liquefaction is now a hotspot for the research on biomass energy.The degradation of cellulose in water is a complicated competitive and consecutive reaction process.When the temperature exceeds 180℃,hemicellulose will hydrolyze easily and both acid and alkali can catalyze the hydrolysis reaction of hemicellulose.Under hydrothermal conditions,lignin will decompose into phenol,methoxyphenol and some other products,which can be further hydrolyzed into methoxy-compounds.The main factors affecting the yields of biomass liquefaction and the composition of bio- oil include temperature and the types of the biomass and solvents used.Other factors include residence time, catalysts,reductive gas,hydrogen-donor solvents,heating rate,the sizes of biomass granules,reaction pressure, etc.By high-pressure liquefaction,cellulose biomass can be used to produce bio-oil,which can be used to produce auto-use fuels,bio-gas and chemical products by means of physical refining and chemical processing. There are two types of bio-oil - light oil and heavy oil ,both of which are produced by separating and refining the products, from the liquefaction of biomass.The main methods currently available for assaying bio-oil include the GC-MS,EA,FTIR,HPLC,NMR and TOC.The study on high-pressure liquefaction of biomass has been going on for many years and several sets of industrial test pilot units have been established.However, no commercial units have been set up so far due to the very demanding operating conditions.