Preparation Of Biodiesel From Waste Cooking Oil Using Solid Acid And Base Catalyst

Biodiesel was prepared by waste cooking oil (WCO) in this paper. A solid acid-basemethod was used due to WCO containing amount of free fatty acids (FFAs). Firstly, solid acidcatalyst was used in pre-esterification of FFAs. And then transesterification took place withsolid base catalyst. Three solid acid catalysts TPA/ZrO2, TPA/TiO2-SiO2, sulfonatedpolydivinylbenzene (PDVB-SO3H) and two solid base catalysts KF/CaO, K2CO3/Al2O3wereprepared. The technological parameters of solid acid-base method were discussed. And themain contents were as follows.1. ZrO2and TiO2-SiO2were prepared by precipitation, and phosphotungstic acid (TPA)was taken as an active component. Activities of TPA/ZrO2and TPA/TiO2-SiO2were discussedin the paper. The result showed that TPA/TiO2-SiO2was more active. And the optimal processconditions were gotten by single-factor experiments and orthogonal experiment: the load ofTPA was40%, calcination temperature of TiO2-SiO2was600℃, catalyst dosage was5wt%,reaction time was5h, and mass ratio (MeOH:WCO) was0.8:1. FFA conversion was98%inthe optimal process conditions.2. PDVB-SO3H was prepared by chlorosulfonic acid and divinylbenzene (DVB); andPDVB was dried by the supercritical carbon dioxide extraction technology. PDVB-SO3Hhad high hydrophobicity, large specific surface area and high thermal stability.PDVB-SO3H was used in the pre-esterification of WCO. The results indicated thatPDVB-SO3H was the most active acid catalyst in the paper. The optimum conditions werediscussed by single-factor experiments and Box-Behnken Design. The optimum conditionswere reaction time,3h; mass ratio,0.85:1; catalyst dosage,3.2wt%. Conversion of FFAswas98.7%under this condtions. After PDVB-SO3H was used three times, the conversionwas greater than87%.3. KF/CaO was prepared by impregnation method. The active site KCaF3which decidedcatalytic activity of KF/CaO was formed after heat activation. The optimum conditions ofKF/CaO were as follows. The load of KF was20%, calcination temperature of KF/CaO was600℃and baking time was4h. KF/CaO was used in transesterification of WCO. Catalyst dosage of KF/CaO, reaction time and mass ratio (MeOH: WCO) were discussed.4. K2CO3/Al2O3was synthesized. KAlO2was formed by heat activation. And internalstructures of Al2O3and K2CO3/Al2O3were porous.K2CO3/Al2O3was used in transesterification of WCO. And the best condtions were asfollowed: catalyst dosage,5wt%; reaction time,6h; mass ratio,1.2:1; calcinationtemperature of K2CO3/Al2O3,600℃; and load of K2CO3,30%. The conversion was up to88%under this condition. Compared to KF/CaO, K2CO3/Al2O3was less active. However,soap was made due to the strongly basic catalyst, KCaF3.5. Physical and chemical properties of biodiesel were tested in the paper. Biodieselcouldn’t replace diesel oil due to WCO containing a large of saturated fatty acids. Biodeselwas prepared by soybean oil. The mixing biodiesel was tested. The results showed that theaddition of biodiesel based on WCO was less than10wt%; the mixing biodiesel had betterperformance.