Preparation Of Biodiesel And Improving Its Cold Flow Properties

Biodiesel is a clean fuel produced from renewable sources such as vegetable oils and animal grease. It is an environmentally benign source of energy, as it is non-toxic, biodegradable, and has a high flash point. These properties make biodiesel a good alternative fuel to petroleum-based diesel oil, and it can used directly on the engine without any modify. Developing biodiesel can reduce the environmental polluction and have a promisingsociety impact and economy benefit.In this research, two processes of producing biodiesel from waste cooking oil with high acid value have been investigated. In the first step, Free fatty acid (FFA) of the waste cooking oil (WCO) was esterified with methanol catalyzed by polyferric sulfate ([Fe2(OH)n(SO4)(3-n)/2]m).In the second step, the esterified WCO was transesterified with methanol catalyzed by potassium hydroxide to produce crude biodiesel. During the esterification process, using the method of response surface with the index of acid value of esterification, the optimal parameters were obtained as follows:the mass ratio of methanol to WCO 108.7%, catalyst addition 5.87%(w/w),reaction temperature 80℃, reaction time 6.0 h. FFA in WCO was converted to fatty acid methyl ester(FAME) with a efficiency of 98.4%. The yield of FAME from the crude biodiesel by molecular distillation reached 98.2% at an evaporator temperature of 110℃.Solid super acid (SO42-/ZrO2-Al2O3) was used to catalyze esterification of WCO, the conversion of FFA in the WCO withcrude glycerol,the esterification of FFA in the WCO with an acid value of 88.39 mg KOH/g to acylglycerols was 98.4%.Under optimal conditions:(mole ratio of glycerol to FFA=1.4:1; reaction time=4 h; reaction temperature=200℃; catalyst loading=0.3%(w/w)) were obtained through an orthogonal experiment. Then the esterified WCO was transesterified with methanol catalyzed by potassium hydroxide to produce biodiesel.The factors affecting solid super acid SO42-/ZrO2-SiO2 preparation was alsoinvestigated. The conversion of FFA in WCO to acylglycerols in the esterification process with glycerol was used to estimate the activity of the catalyst. It is found that the SO42-/ZrO2-SiO2 exhibits high catalytic activity for esterification under the conditions of:aging time:4.0 h, sulfuric acid load:30.0 ml, calcination time3.0 h, and calcination temperature600℃. Under this condition, SO42-/ZrO2-SiO2 prepared to as the catalyst for esterification showed an esterification efficiency of 96.8% of FFA in WCO intoacylglycerols.The use of surfactants and detergent fractionation to improve the cold flow properties of biodiesel from waste cooking oil and palm oil(POB) were studied. The effect of five types of surfactants, including sugar esters (S270 and S1570), silicone oil (TSA 750S), polyglycerol ester (LOP-120DP) and diesel conditioner (DDA) on the reduction of the cold filter plugging point (CFPP) of the WCOB and POB, were evaluated, with the greatest reduction to the CFPP of the WCOB (from -10℃to -16℃) and POB(from 1℃to -7℃) being were achieved by the addition of 0.02%(w/w) of polyglycerol ester (LOP-120P). The orthogonal experimental design was utilized to investigate the effects of the various parameters on detergent fractionation. The optimal parameters to WCOB, as obtained by range analysis, were as follows: detergent loading 0.3%(w/w), electrolyte loading 1.0%(w/w), and water loading 150%(w/w). The CFFP of the liquid biodiesel from waste cooking oil was -17℃with a yield of 73.1% when the detergent fractionation was performed under these conditions. The optimal parameters toPOB were as follows:detergent loading 0.2%(w/w), electrolyte loading 1.5%(w/w), and water loading 150%(w/w). The CFFP of the liquid biodiesel from POB was -5℃with a yield of 73.1% when the detergent fractionation was performed under these conditions.