Producing Biodiesel From Rapeseed Oil And Ethanol Catalyzed By Lipase

Following the fossil fuel storage decrease, some substitution fuel has been developed. As one kind of clear and renewable fuel, biodiesel was an ideal replacing fuel. Biodiesel produced from animal fats or vegetable oil by alcoholysis of short-chain alcohol. Preserve, it mainly producing by acid or base catalysis. This process has some problems. Such as higher reaction temperature, Saponification, produce a large number of acid or base water, and so on. And the reaction of alcoholysis catalyed by lipase, its conditions is very softly. It hasn't the problem exist in acid or base catalysis. Then it is very important to develop the process of lipase catalyze rapeseed oil ethanolysis to produce biodiesel.In this paper, the components and composition of rapeseed oil has been analyzed by GC-MS. The high active lipase, lipase PS and lipase LVK, has been screened from four lipase, which are lipase D, lipase PS, Porcine pancreas lipase, lipase LVK. And the characteristics of rapeseed oil ethanolysis catalyzed by lipase LVK or lipase PS in organic solvent system has been investigated.The process of biodiesel production from rapeseed oil ethanolysis catalyzed by lipase LVK in hexane was optimized by application of single factor experiment, the factorial design and response surface methodology. The reaction conditions from orthogonal optimization experiment are: molar ratio of ethanol to rapeseed oil is 5:1, concentration of catalyst 10%, solvent concentration 15%, reaction temperature 40℃, reaction time 36h. The transesterification ratio reached 86% when ethanol added in once time. And the transesterification ratio reached 93% when ethanol added in three times. After in hexane system optimized by application of the factorial design and response surface methodology. Optimum conditions for the production of ethyl esters were: molar ratio of ethanol to rapeseed oil 5.3:1, concentration of catalyst 15.0%, solvent concentration 18.4%, reaction temperature 39.8℃, reaction time 34.5h. The transesterification ratio reached 93.48% when ethanol added in once time. And the transesterification ratio increased 8.7%. The result show that the hexane system can improve the dissolve of rapeseed oil and ethanol, and this system can remove the toxicity from ethanol on lipase LVK. But it can't elimination the deactive of lipase by glycerol.To solve the inactivation of lipase by glycerol, the single experiment and orthogonal optimization experiment has been carried on in t-BuOH system. It found that the optimum process of lipase catalyzed rapeseed oil ethanolysis in t-BuOH system were: molar ratio of ethanol to rapeseed oil are 5:1, lipase LVK amount 10%, solvent concentration 10%, reaction temperature 40℃, reaction time 36h. The model of adding ethanol has little effect on the yield of transesterification under this condition. This t-BuOH system eliminated the inhibition of ethanol to lipase LVK completely. And it eliminated the deactivation of by-product glycerol to lipase LVK also.To prove the t-BuOH organic solvent system is a kind of effective system for rapeseed oil ethanolysis catalysis by lipase. This paper investigated the process of lipase PS catalyze rapeseed oil to producing biodiesel. Result shew that the t-BuOH system can remove the toxicity by ethanol on lipase PS and elimination the deactive of lipase by glycerol also.This thesis develops a kind of effective organic solvent system for lipase catalysis rapeseed oil ethanolysis to producing biodiesel. These will contribute to the industrialization of producing biodiesel catalysis by lipase.