Biodiesel and Biolubricant Production from Waste Cooking Oil: Transesterification Reactor Modeling

Biodiesel and biolubricants play strategic roles in green technologies, as they can be produced in biorefineries. The design of industrial facilities is essential to assess the industrial implementation of these processes, with few studies about this subject in the literature. The aim of this work was to produce biodiesel and a biolubricant from waste cooking oil through double transesterification with methanol and trimethylolpropane, obtaining high conversion values (>97 and 98%, respectively). The biolubricant (characterized according to the UNE-14214 standard) had a density of 951 kg·m−3, a viscosity of 127 cSt (at 40 °C), an acidity value of 0.43 mgKOH·g−1, flash and combustion points of 225 and 232 °C, and an oxidation stability of 6 h through the Rancimat method. Also, a kinetic study was carried out (at temperatures ranging from 80 to 140 °C and with catalyst concentrations from 0.3 to 0.9% w/w and working pressures from 210 to 760 mmHg) to establish the main kinetic parameters, obtaining a second-order reaction and an activation energy of 17.8 kJ·mol−1. Finally, a conceptual design was included, considering the main components of the facility. Thus, the projected plant worked in a discontinuous regime (producing 2 cubic meters per day), pointing out the feasibility of this plant at an industrial scale.