生物柴油通常由植物油和动物脂肪(三甘油酯)经碱催化酯化成为脂肪酸酯类来制取。这一过程需经过预处理从进料中去除游离脂肪酸。因存在游离脂肪酸使反应速率降低,并因脂肪酸酯与甘油产物相分离困难,致使产率降低。碱催化剂从甘油中去除也困难,同时含碱废水必须从过程中予以处理。虽然已经开发了一些替代路线生产生物柴油,如基于超临界醇或酶的工艺,但需要耐高压高温设备或需采用高稳定性和活性的酶类,距离工业化尚远。 Biodiesel is usually prepared from vegetable oils and animal fats (triglycerides) by base catalyzed esterification to fatty acid esters. This process requires pretreatment to remove free fatty acids from the feed. The reaction rate decreases due to the presence of free fatty acids, and the yield is reduced due to difficulty in separating the fatty acid ester from the glycerol product. Base catalysts are also difficult to remove from glycerol, and alkali-containing wastewater must be treated from the process. Although alternative routes have been developed for the production of biodiesel, such as those based on supercritical alcohols or enzymes, enzymes that are resistant to high pressure and temperature or require high stability and activity are still far from industrialized.