Two-Step Catalysis Of Waste Cooking Oil To Produce Biodiesel And Feasibility Study

With the increase of environmental awareness and depletion of energy resources, a novel energy source that has little environmental damage must be found out to replace of petroleum. And vegetable oil has been used for diesel substitution. However, this conflicts with people's demand for food, although there is great breakthrough in using vegetable oil for diesel substitution. Waste cooking oil is discarded oil, which can be used as raw materials for biodiesel production. And this can also protect our environment. So producing biodiesel with waste cooking oil as raw materials is an efficient way.Compared with other new renewable and clean engine fuel alternatives, methyl esters of vegetable oils have many outstanding advantages. The transesterification process is most likely to be an industrial process method in future. Producing biodiesel by transesterification of waste cooking oil and methanol was studied and a two-step acid-base catalyzed route for producing biodiesel was established in the paper. The main factors that affecting the yields of fatty acid methyl ester, such as the molar ratio of methanol to oil, catalyst concentration, reaction temperature, pressure, reaction time, and the contents of free fatty acids and water in oils, were also discussed. The task of this paper was how to change waste vegetable oils to biodiesel for a substitute of 2# diesel by using acid & base catalyst ,and analyzed the transform ratio of the waste oils by gas chromatography (GC),so determined the optimum experimental conditions of base-catalyzed transesterification through orthogonal experiments. Moreover, the properties of biodiesel products were analyzed according to the national diesel standard of China, and the performance of combustion was also tested. The result showed that biodiesel has a large possibility to replace the 2# diesel. According to the formula of Grunberg-Nissan, the relationship of the biodiesel viscosity and conversion rate was clarified and justifying the biodiesel yield based on viscosity change was established.The acid value of waste cooking oils is as high as 7.25, that is 8.8% (wt%). Firstly it important to transform the free fatty acid in oils to methyl ester by acid catalyst add-in , and avoid free fatty acid have a reaction with base catalyst. The optimum experiment conditions of acid-catalyzed esterification is determined as follows : using oil of vitriol with concentration as 98% for acid catalyst ,the dosage of acid is 14.6%(wt/wt) in 60 centigrade for 6 hours , the molar ratio of methanol to oils is 50:1,so the transform ratio of biodiesel is 65.9%. Secondly the triglycerides transformed into fatty acid methyl ester with base catalyst add-in. The optimum experiment conditions of base-catalyzed esterification is determined as follows : the molar ratio of methanol to oils is 9:1,the dosage of base catalyst is 1.3%(wt/wt) in 50 centigrade for 90 minutes , so the transform ratio of biodiesel is 75.3%. the relationship of the biodiesel viscosity and conversion rate was clarified and was established. According to the formular of Grunberg-Nissan, it determined the value of GMG is -2.41026mPa?s by experiment.The paper also studies the feasibility of technology and economy for producing biodiesel using waste cooking oils, which based on related industry standards and combined with market developments of biodiesel. And the feasibility study has analyzed the capacity and choice of project and equipments. It also evaluated comprehensively the social and economic profits of the project. The total investment of this project is 32,520,000 RMB. The total income of this project is 45,050,000 RMB per year. And the profit is 6,050,000 RMB per year. This project has made a widely applying foreground for waste cooking oil, and also solved the environmental pollution of waste cooking oil.