Etanólise supercrítica para produção de biodiesel a partir de óleo de soja virgem, óleo de soja usado e rejeito de óleo comestível, usando os líquidos iônicos [HMim][HSO4], [DBU][Ac] e [Bmim][BF4] como catalisadores

Abstract

Supercritical catalytic ethanolysis of soybean oil, waste of soybean oil and waste cooking oil using ionic liquids [Bmim][BF4], [HMim][HSO4] e [DBU][Ac], as catalysts, to yield ethyl esters has been investigated. The ionic liquid (IL), showed stability under supercritical ethanol conditions (temperature = 255 oC and pressure = 95 atm). Transesterification temperature was monitored and was maintained at 255 oC. The content of ethyl esters in all samples were determined through 1H RMN and GC techniques. The highest yields, in weight percentage of main product, to soybean oil, waste of soybean oil, and waste cooking oil were 97,63 %, 97,59 % and 97,79 % respectively, obtained under mentioned T and P conditions and in the presence of 0,35 mL of acid IL [HMim][HSO4]. Using the same conditions but in the absence of the catalyst the transesterification yielding is lower, less than 85%. The presence of water in reaction medium, in the range from 1.0 to 3.0 % (v/v) related to total amount of ethanol, does not affect the ethyl esters yield. The method proposed in this work is advantageous over others reported in the literature due to the lower required reaction time (maximum of 45 min) and to the higher biodiesel yield. The results showed that the biodiesel production by transesterification through supercritical ethanolysis is environmental-friendly and presented promising perspectives