Study On Preparation Of Biodiesel From Oil With High Acid Value Catalyzed By Ordered Mesoporous Carbons-based Solid Acid

As an ideal substitute for fossil diesel, biodiesel is a kind of green and clean fuelproduced from renewable lipid bioresources. The production and application ofbiodiesel have important significances in constructing green, safe and sustainableenergy modes and alleviating environmental problems derived from excessive use offossil energy. Due to the limits of seasons and infields to edible vegetable oils,non-edible oils such as jatropha oil and microalgae oil as the materials for biodieselhave been attracting more and more attention in recent years. Because these oilsusually contain undesirable free fatty acid (FFA), a deacidification process isnecessary to convert FFA into the corresponding esters before biodiesel production.However, liquid acids are commonly used as the catalyst for pre-esterification,accompanied with corrosion, pollution and complicated post-treatments. Aiming atthe above problem, mesoporous carbons-based solid acid was synthesized to catalyzethe esterification of oleic acid and methanol in order to imitate the deacidificationprocessin this work. The mechanism of side reaction in the esterification catalyzed bymesoporous carbons-based solid acid was also studied. Furthermore, high acid-valuedjatropha oil as the material was converted into biodiesel through transesterificationwith one-step and two-step methods and the technical parameters were optimizedrespectively.Firstly, highly ordered mesoporous carbons were synthesized with triblockcopolymer F127as a soft template and then sulfonated ordered mesoporouscarbons(S-OMCs) were prepared by free radical addition.The optimal condition forthe sulfonation is that the calcination temperature is500oC, the sulfonationtemperature is80oC, the mass ratio of the reactants is1:2:2, the reaction time is12h.The optimal condition for the esterification is that the temperature is100oC, thereaction time is8h, the catalyst amount is8wt%and the molar ratio of methanol andoleic acid is8:1, in which case the oleic acid conversion is95.31%. The mechanismof side reaction in the esterification of oleic acid and methanol catalyzed by S-OMCswas also investigated.Then the S-OMCs were applied to catalyze the deacidification of jatropha oil and the optimal condition is as follows: the deacidification temperature is100oC, themolar ratio of methanol and jatropha oil is16:1, the amount of catalyst is4wt%andthe reaction time is10h. The acid value decreased below1mgKOH/g at this optimalcondition. The solid acid catalyst was also used to one-step catalyze thetransesterification of jatropha oil to prepare biodiesel. The biodiesel yield onlyreached69.8%at200oC for3h.After that, two-step method was used for biodiesel preparation, that is, thedeacidification was first catalyzed by S-OMCs and then the transesterification forbiodieselwas catalyzed by Ca/Al base catalyst. The biodiesel yield could reach up to94.6%at the optimal condition of temperature70oC, catalyst amount10wt%, time3h.This work makes new contributions to the theoretical foundation and datasupport for biodiesel production from high acid-valued oils.