Research On New Techniques Of Biodiesel Production Catalyzed By Lipase And Development Of Its High Value-added Chemicals

Biodiesel is one of the newly green bio-fuels with non-edible oils as raw material, and preparation through transesterification. It is an ideal substitution for fossil diesel. Compared with chemical preparation method, enzymatic catalyzed method, owing to mild reaction conditions, less methanol consumption and non-pollution to environment, has been become the mainstream direction of the research and development of biodiesel. However, enzymatic production of biodiesel also has some drawbacks, such as high price of lipase, being easily inactivated of lipase, etc.Sapium sebiferum is a unique woody oil plant in China. Its seed has high oil content. Thus, it has the reputations of "China margarine" or "oil tree". However, its oil is not edible and unfit for human consumption because of toxic polyphenols. Its oil contains18-carbon fatty acid as high as 89% and is an ideal substrate for biodiesel production. In this study, several new techniques for biodiesel preparation catalyzed by immobilized Burkholderia cepacia lipase and compound lipases (Novozym 435/Lipozyme TL IM) were developed, and the innovative technology for synthesis of high value-added chemicals from biodiesel was further explored. Main results and innovations are listed as follows:1. Physio-chemical properties and components of stillingia oil were analyzed. Oil components and physico-chemical properties represent oil quality, and determine the characteristics of biodiesel product. The analysis data showed that the oil contained seven fatty acids, among which 18-carbon fatty acid occupied the most, and their carbon chain length and structures were suitable for biodiesel production. It had modest acid value and a small quantity of phospholipids, but the saponification value and iodine value was fairly high. These provide feasibility for biodiesel production with stillingia oil catalyzed by lipase.2. Experiments were conducted to optimize the conditions of biodiesel production catalyzed by immobilized B. cepacia G63 lipase from stillingia oil in solvent-free system. The obtained optimal conditions were:molar ratio of methanol to oil 4:1, loading of lipase 2.7%(based on oil weight), reaction temperature 41℃, content of moisture 7%, the rate of stirring speed 200rpm, and reaction 12h. Under these conditions, the biodiesel yield was up through the kinetic study, we have validated that the compound-enzyme system has positive synergetism.6. On consideration of the fluctuation of market price of oil materials and commercial profit of biodiesel product, an innovative technique for synthesis of high value-added chemicals based on biodiesel was further explored. We prepared dimmer acid methyl ester from biodiesel and employed bentonite as catalyst. The optimum reaction conditions were optimized, and they are:catalyst loading 9.9%, additives quantity 0.8%, at a temperature of 221℃, reaction 6.1h. Under the optimal conditions, the dimmer acid methyl ester yield was up to 63.2%, which coincided with the predicted value (65.26%). The technique provides a pre-processing process for further development of high value-added chemicals based on dimmer acid methyl ester.7. Herein, the economic benefits of biodiesel and dimmer acid methyl ester were preliminarily analysed, respectively. For example, a factory producing 25,000 tons of biodiesel annually, we estimated its total producution cost on the basis of its initial investment, production and sale costs, and we found that the deep processing product-dimmer acid methyl ester had a better economic benefit than biodiesel. Therefore, development of biodiesel and its high value-added chemicals has a potential prospect.