利用微藻热化学液化制备生物油的研究进展

微藻是制备生物质液体燃料的良好材料,利用微藻热化学液化制备生物油在环保和能源供应方向都具有非常重要的意义。目前国内外研究者主要采用快速热解液化和直接液化两种热化学转化技术进行以微藻为原料制备生物油的研究。快速热解生产过程在常压下进行,工艺简单、成本低、反应迅速、燃料油收率高、装置容易大型化,是目前最具开发潜力的生物质液化技术之一。但快速热解需要对原料进行干燥和粉碎等预处理,微藻含水率极高,会消耗大量的能量,使快速热解技术在以微藻为原料制备生物油方面受到限制。直接液化技术反应温度较快速热解低,原料无需烘干和粉碎等高耗能预处理过程,且能产生更优质的生物油,将会是微藻热化学液化制备生物油发展的主流方向,极具工业化前景。国内外研究者还尝试利用超临界液化、共液化、热化学催化液化、微波裂解液化等多种新型液化工艺进行微藻热化学液化制备生物油的实验研究。今后的主要研究方向应是将热化学液化原理研究、生产工艺开发、反应器研发、反应条件优化、产品精制等有机地结合起来,进行深入研究。同时应努力节约成本、降低能耗。

Progress in Producing Bio-oil by Thermochemical Liquefaction of Microalgae

Microalgae is an excellent feedstock for producing liquid bio-fuel. Producing bio-oil by thermochemical liquefaction of microalgae is of great significance to both environmental protection and energy supply.Domestic and foreign researchers currently mainly focus on the research into producing bio-oil from mi- croalgac using two thermochemical conversion methods--rapid pyrolysis liquefaction and direct liquefaction. Rapid pyrolysis takes place at atmospheric pressure.This technology is characterized by simple process,low cost,rapid reaction,high yield of fuel oils and good compatibility with large units and is one of the most promising biomass liquefaction technologies by far.However,rapid pyrolysis requires pretreatment to feedstock, including drying and pulverization.As microalgae contain a very high content of water,pretreatment of it will consume a large amount of energy,limiting the application of microalgae in the production of bio-oil.Direct liquefaction requires lower reaction temperature than rapid pyrolysis,no energy-gobbling pretreatment processes such as drying and pulverization are involved in this technology,and higher quality of bio-fuel can be produced.This technology will be the main direction for producing bio-oil by thermochemical liquefaction of mi- croalgae and has great potential for commercialization.Domestic and foreign researches have also conducted laboratory tests on producing bio-oil using some other new types of liquefaction technologies such as super- critical liquefaction,co-liquefaction,thermochemical catalytic liquefaction and microwave pyrolysis.The main direction for future research should be combining the research on the thermochemical liquefaction mechanism, the development of production technology ,the research and development of reactors,the optimization of reaction conditions and the production of fine products in intensive study.In addition,effort should be made to save cost and reduce energy consumption.