Production Of Biodiesel From Waste Cooking Oil In One-step Process Using Acid Catalysts

Biodiesel is a renewable and environmental friendly substitute to fossil fuels,for it can be used as the fuel for diesel engines without any changing of the engine original structure to keep its performance.The two key factors that constrain the wide use of biodiesel are the price of feedstocks and the production cost.In this work,the one-step process for producing biodiesel from the cheaper waste cooking oil(WCO)were studied using sulfuric acid and p-toluenesulfonic acid(PTSA)as catalysts.The remarkable advantage for this method is that the WCO is converted into biodiesel in a single process in less time at low cost compared with the traditional biodiesel production technologies.Biodiesel production process was enhanced and speed up by elevating of reaction temperature.The highest biodiesel yield was 89.8% obtained by converting of WCO with acid value of 23.04 mg KOH/g directly at the reaction temperature over the mormal boiling point of methanol in a closed reactor under a pressure of 0.65 MPa using concentrated sulfuric acid as catalyst,at the optimum reaction conditions with the dosage of sulfuric acid of 2.0 wt%,molar ratio of methanol to WCO is 8:1,and the reaction is carried at 120? for 120 min.The effect of reaction temperature,reaction time,catalyst dosage and molar ratio of methanol to WCO on the yield of biodiesel were studied.The reaction showed a secondary order reaction charater,with the activation energy Ea=49.67 k J/mol.The highest biodiesel yield was 89.2% using PTSA as catalyst,at the optimum reaction conditions with the dosage of sulfuric acid of 3.0 wt%,molar ratio of methanol to WCO is 10:1,and the reaction is carried at 140? for 120 min,and the activation energy is 52.83 k J/molIn order to make sure this one-step process is feasible to most of the low valve feedstocks,kernel fatty acid distillate(KFAD),soybean oil deodorizer distillate(SODD)and other WCOs were also used as the feedstocks to produce biodiesel.The results showed that all of these feedstocks could be converted into biodiesel with high yield quickly.It is the particularly important demand for the method to process the low grade oil feedstocks with different properties,such as the cooking waste oil.