Transesterificación de triglicéridos en una columna de contacto líquido-líquido

Abstract

The relevance in recent years for the minimization of polluting gases and the search for alternative energy sources apart from oil, has led research in various forms of renewable energy including power generated by wind, hydro, solar, biomass and biofuels; and among them biodiesel. Despite extensive research related to the production of biodiesel, there are some issues that desserve to be addressed from the point of view of engineering, especially in the efficiency of mass transfer between the two organic phases (methanol and oil), which plays a critical role during transesterification and thereby controls the rate of reaction in the initial stage, and the use of heterogeneous catalysts which allows an easy and less expensive separation of the product. This thesis aims at studying the efficiency of a cocurrent downflow bubble column as a liquid-liquid contactor reactor in order to carry out the transesterification reaction of canola oil to biodiesel using heterogenous catalysis. The reactor provides great potential for chemical reactions that are limited by mass transfer and has several advantages over typical reactors used for transesterification. At the reactor inlet a high speed liquid flow is produced by venturi effect and this results in a vigorous agitation system with high shear and energy. This high mixing intensity allowed the production of biodiesel according to EN14214 (content greater than or equal of esters ≥ 96.5%), obtaining a 97% of esters in a time of 300 min at a temperature of 50 °C, using CaO from a rather low cost source (quicklime) as heterogeneous catalyst, with a catalyst loading of 8 % (w/w with respect to the reaction mixture oil-methanol), an oil : methanol molar ratio of 1 : 9. In order to understand the effect of the process variables the reaction was also studied in a batch reactor. The studied variables were reagents addition order, methanol quality, methanol-oil molar ratio, amount of catalyst, temperature dependence, type of catalyst and a reaction kinetic model was established. In general there is a minimal difference in the rate of reaction profiles between the lab scale STR and the pilot scale contactor column; beside the desearible content of FAME’s (97% EN14214) was achieve in both reactors after 300 min of reaction. It is worth to be mentioned that the reaction volume in the liquid-liquid contactor was about 24 times higher than the STR volume.