Research On Technologies Of Preparation Of Biodiesel From Waste Cooking Oil

With the Energy resource becoming more and more serious, biodiesel as a renewable energy resource which could replace the fossil fuel get attention from the world gradually. It is good for energy and environment problem to prepare biodiesel from waste cooking oil, and which could also prevent waste cooking oil back to our food.In the first part of this paper, the traditional process has been researched. The emphasis of the advance was the purification process. This study showed that waste cooking oil was more suitable for use in the preparation of biodiesel after heated and precipitated, adsorbed with activated carbon, filtrated and dehydrated. Orthogonal design show the best reaction condition:At first, the waste cooking oil was heated2h, the up layer was adsorbed12h with activated carbon, the filtrated to remove the activated carbon, then, remove the water in vacuum; Then using sulfuric acid occupy5%of waste cooking oil as catalyst, the molar ratio of methanol and oil is30:1, the reaction temperature is65℃, and the reaction time is3h; the third step use alkali as catalyst, the amount of the alkali is0.15%, the levels of methanol to oil ratio is25:1, levels of reaction temperature is60℃, reaction time is1h. The yield is93.24%in this condition, and the fatty acid methyl ester mount could reach94.83%which was measured by gas chromatograph; At last, density (20℃),viscosity(40℃), flash point, water, sulphur, Cu corrosion max (50℃,3h), carbon residue, mechanical admixture and heat value all were measured and compared with GB/T20828-2007,which showed that all the indicator satisfied the GB/T20828-2007.In second part of this paper, the solid catalyst was studied to overcome the disadvantage of the traditional method, because it’s hard to reuse the catalyst, and the cost is very huge, and the effluent is harmful to the equipment and environment in the traditional method. In this part, SO42-/TiO2-ZrO2was prepared by coprecipitation and infusion methods, and characterized by FTIR, BET surface area measurement and NH3-TPD, and those results demonstrate the SO42-was loaded on the catalyst and the catalyst have enough surface area, pore size and catalytic performance. After the same purification process of the first part, the best reaction condition of preparation of biodiesel from waste cooking oil by SO42-/TiO2-ZrO2. From the orthogonal experiments, the optimum reaction condition was shown as follows:At first, the waste cooking oil was heated2h, the up layer was adsorbed 12h with activated carbon, the filtrated to remove the activated carbon, then, remove the water in vacuum; Then methanol oil mole ratio is25:1, catalyst dosage is5%of oil, reaction temperature is120℃, reaction time is8h, the yield reached96.68%, and the catalyst could be reused three times.In third part of this paper, an acidic ionic liquid was studied for its high catalytic performance and recyclability. In the study,[HSO3-pmim]+[HSO4]-was synthesized with N-methylimidazole,1,3-propyl sulfonic acid lactone and H2SO4, The raw materials and ionoic liquid were characterised by FTIR with KBr, then the absorption peak was analysed serially, the absorption of the C=N has enhanced and C=C has weakened, so it showd that the molecular structure of the product was matched the theoretical structure, so the accurate structure was confirmed. After the same purification process of the first part, the reaction condition of preparation biodiesel from waste cooking oil was optimized. From the experiment, the optimum reaction conditions were shown as follows:At first, the waste cooking oil was heated2h, the up layer was adsorbed12h with activated carbon, the filtrated to remove the activated carbon, then, remove the water in vacuum; Then methanol oil mole ratio is20:1, catalyst dosage is7.5%of oil, reaction temperature is120℃, reaction time is8h, the yield reached90.82%, the acid value is just0.3931mgKOH/g which satisfied the GB/T20828-2007, and the fatty acid methyl ester reach82.34%. The acidic ionic liquid shows good reusability, the acid value is0.492mgKOH/g and the fatty acid methyl ester reach79.445%after reused three times.In fourth part of this paper, this study made use of the advantages of the acidic ionic liquid and the solid catalyst. A new acidic ionic liquid was immobilized on silica-gel. The new ionic liquid was synthesized with1-allyl imidazole,1,3-propyl sulfonic acid lactone and H2SO4, then it was immobilized on silica-gel silical-gel by y-Mercaptopropyltrimethoxysilane as coupling agent to obtain the new catalyst which was characterized by FTIR,DSC/TGA and SEM, those analysis indicated the molecular structure of the product was matched the theoretical structure. After the same purification process of the first part, the reaction condition of preparation biodiesel from waste cooking oil was optimized. From the experiment, the optimum reaction conditions were shown as follows:At first, the waste cooking oil was heated2h, the up layer was adsorbed12h with activated carbon, the filtrated to remove the activated carbon, then, remove the water in vacuum; Then methanol to oil mole ratio is25:1, catalyst dosage is5%of oil, reaction temperature is60℃, reaction time is20h, the yield reached87.58%, and the yield reached70.02%after reused5times. The mcthanol to oil mole ratio and the catalyst dosage were the most important factors to influence the yield.In fifth part of this paper, the stable system of biodiesel-ethanol-water and the emulsification of biodiesel were studied. To get the stable system of biodiesel-ethanol-water, high quality biodiesel was prepared, and the phase behavior of biodiesel-ethanol-water system was researched by measuring the most moisture content of the stable system through dropping method, the result indicated that there existed a single-phase region and two-phase region in the phase diagram. The effect of moisture content was investigated under different emulsifiers, emulsifier content and the content of ethanol, the result indicated that the optimum condition in the experiment as follows:the emulsifier is the blend of oleic acid and nonylphenol polyoxyethylene ether, the mass ratio of oleic acid and nonylphenol polyoxyethylene ether is3:7, the dosage of emulsifier and ethanol are15%and40%of the weight of biodiesel respectively, the moisture content could reach8.82%.