Estudo e avaliação do processo eletroquímico para obtenção do catalisador metilato de sódio utilizado na produção de biodiesel.

Abstract

Sodium methylate is a catalyst used in the production of biodiesel. Currently, this catalyst is produced by two conventional methods that present high production costs. The main objective of the present Doctoral Thesis is the study of the production of the sodium methylate catalyst in methanol in an electrochemical route, through ion-selective commercial cationic membranes. This innovative methodology to produce the catalyst through electrolysis in electrochemical reactors with cationic membranes appears as one of these technologies; which may become effective to obtain the catalyst. It is considered an attractive technology, since it presents some advantages over traditional processes, such as: (1) The reaction occurs directly from the sodium ions with the alcohol (methanol), eliminating the water from the pre-solubilization of the hydroxides (NaOH, KOH) in Alcohol (methanol); (2) Does not generate residues of mercury and chlorine gas; in the production of sodium methylate from a sodium amalgam produced from the electrolysis of sodium chloride in a mercury cell, (3) it does not present high costs; as occurs in the production of the catalyst using metallic sodium. The study was carried out in different stages: Initially, the physical properties of the CMV and CSO membranes were studied, such as: sodium induced diffusivity, chemical stability, resistivity, water absorption, ion exchange capacity, Fourier transform infrared spectroscopy FTIR). Subsequently, tests were carried out on the cross-sectional electrochemical reactor and the catalyst yield with the two membranes, the process limiting current, the sodium extraction and the potential variation were investigated. At the same time, a dimensional analysis was carried out in which different empirical models were proposed for mass transfer efficiency for the DSA electrode reactor (De Nora), with G60 Nickel Foam electrode, followed by the time distribution study of residence-DTR. It can be concluded that for 48 hours of operation of the electrochemical cell the CSO and CMV membranes have a maximum value of 12% v / v and 11% v / v of sodium methylate in methanol. In relation to the CSO membrane, the yield obtained was 2.8% v / v more than the CMV membrane using a nickel foam electrode (G60). In general, the change of the DSA electrode in the reactor for the Nickel Foam Electrode (G60) can be used to maximize the cost efficiency, balancing the electrical efficiency with the low electrode cost. In the DTR study the reactor has a short circuit.