| Waste cooking oil quality was extremely poor and very unhygienic. Its peroxide value, acid value and mowasture were beyongd the limit seriously. It was occupied by a lot of corruption factor, Aspergillus flavus and unclean substances, so it was a great danger to persons after its consumption. Waste cooking oil returning to the table, let people talk with a changed look.Biodiesel was one important part of bioenergy, which was one green fuel made from plant oil and animal fats transesterificated with methanol. Biodiesel can compete with diesel on most of fuel characters. It was a long chain fatty acid ester formed of seventy seven percent carbon, twelve percent hydrogen, eleven percent oxygen. Main baffle in biodiesel business was cost, especially material lock in about seventy percent of all. While none-edible oil and fat, especially waste cooking oil was very cheap including watsted plant oil and animal fats, which were made into biodiesel will be a great value in energy exploitation and be benefiting enviorment and food safe.Research of material property was been done in the paper, which would help select process and improve quality and reduce cost. Waste cooking oil was classified into three types according to acid value, one was below 10 mgKOH/g, second was between 10 and 120mgKOH/g, third was more than 130mgKOH/g. All material can accord with three types with standardization. Different type has different process. One type process was transesterificattion, second type process was two-step way including esterification and transesterification reaction. Third was process reaction after free acid fatty acid were separated. The acid value of waste cooking oil was 79.02 mgKOH/g, so two-step way was taken and idione was taken as catalyzer in the first step instead of oil of vitriol.Several ternary phase diagrams comprwasing waste cooking oil, methanol and solvent were obtained. Experiments proved that ethyl ether, tert-butyl alcohol and tetrahydrofuran were good solvents, but the esterification reaction in homogeneous phase to form methyl esters were not faster than the traditional esterification reaction.In this work, a novel two-step catalyzed process was adopted to prepwere biodiesel from waste cooking oil (WCO). At the first step, iodine with methanol was introduced to catalyze the esterification reaction. At the second step, KOH was added to catalyze the transesterification reaction in which the triglyceride reacted with methanol. The optimal parameters of esterification obtained by orthonormal experiment were as follows: 1.3wt% of iodine (w/w, iodine/ WCO), 1.75:1 of molar ratio of methanol to waste oil, 3h of reaction time, and 80°C of reaction temperature. The reaction temperature (85℃) and the weight ratio of methanol to triglyceride (0.3:1) was recommended in the transesterification reaction.The impact of water to the esterification and the repeated use of iodine were studied, founding that there was little influence on the catalytic effect of iodine when when water content below 6%.When appropriate amount of 3 A zeolite was added, iodine could be used 9 times repeatedly.Physical and chemical indicators of waste cooking oil-based biodiesel were determined. Main performance indicators of product were in line with national standards and ASTM-2004 standards. Emwassion characterwastics of diesel engine used biodiesel were studied and analyswased, which provide a theoretical baswas of the possibility that biodiesel insead of fossil diesel.The stability of biodiesel were studied and found biodiesel within a certain range in the less water content, the lower the storage temperature, the higher the stability of biodiesel. In addition, the use of stainless steel containers and antioxidants adding also could increase the shelf life of biodiesel.One facility to biodiesel was also drawed. And a biodiesel plant economy analyse was made with fifty thousand tons capacity annually. Result revealed that tax was forty million yuan every year, and net profit was about forty-four million yuan.
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