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Biodiesel is an mixture alkyl esters, which is prepared through the ester exchange or esterification reaction of vegetable oils, animal fatty or waste fatty with short chain alcohol. Compared with conventional petrochemical diesel, biodiesel is a new type of alternative energy sources, which has two outstanding advantages of the environmental friendliness and renewable nature. In this article, the small scale experiment and scale up experiment of swill oil into biodiesel were carried out, the main targets of biodiesel tested, and the best volume ratio of biodiesel in 0#diesel oil was studied. At the same time, a preliminary exploration of neutral lipase immobilized ways was also made. The experimental results were as follows:The optimum process conditions of swill oil transformed into biodiesel with catalyst of neutral lipase were studied and the influences of the molar ratio of oil and alcohol, enzyme powder dosage, reaction temperature, solvent amount, reaction time and stirring speed on the conversion ratio of the reaction system were discussed. To 50g swill oil as the benchmark, the result showed that: when the temperature at 45℃, molar ratio of oil to ethanol 1:3, enzyme weight 50g, 30g hexane (namely 45mL), the reaction time of 10h, stirring at medium speed, the conversion ratio of the reaction system could be up to 89.7%.The application conditions of the scale up experiment based on the result of small scale were studied and the levels like 10L, 50L, 100L reactor were used. The results of scale up experiments showed that after 10h reaction, the conversion ratio of the reaction system could be up to 81%, and after 24h, it could be up to more than 85%. The crude biodiesel preparation was purified and the main physical and chemical properties of purified biodiesel were measured and analyzed by different ways. The results showed that: the main parameters of the purified biodiesel met national biodiesel standards. And through stduying the influences of different volume ratios to acid value, density, viscosity and sulfur content of the mixed oil, in the proportion of 5%-10% biodiesel in 0#diesel oil was confirmed, the mixed oil is more effective.To reduce enzyme consumption and improve the utilization rate, in the article method of diatomite as the carrier toimmobilize neutral lipase was developed. and the influences of the amount of supplying enzyme, immobilized temperature, immobilized pH, immobilized time on immobilization result were explored. The results showed that: when the amount of supplying enzyme for 33374U/g, temperature at 35℃, pH 7.5, after adsorped for 4h, the recovery of immobilized neutral lipase could be up to 6733U/g carrier. And according to comparative experiment between immobilized neutral lipase and neutral lipase, it had some advantages to the non immobilized neutral lipase.
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