Abstract
Biodiesel is considered to be a promising alternative or additive to fossil fuel. Biodiesel, fatty acid methyl esters (FAME), is produced by transesterification of triglycerides or fatty acids with alcohols (i.e. methanol or ethanol, in the presence of a suitable acidic or alkaline catalyst. The present work is focused on process modelling and simulation of biodiesel production using: i) an innovative method for methanol synthesis, methanol being an important raw-material for biodiesel, as well as ii) an intensified method for biodiesel production (i.e. reactive distillation – RD). Methanol production from CO2 and H2 is considered to be an interesting method for CO2 utilization. The main advantages of this method are the reduction of greenhouse gas emissions and the production of one valuable chemical, methanol. The H2 for the methanol synthesis is obtained from wood chips through chemical-looping gasification. Beside methanol, other raw-materials for biodiesel production are triglycerides and the catalyst. The classical acid method, consisting in reaction and separation, and the intensified method based on RD for biodiesel production are investigated and compared from technical and environmental point of view. The study also considers as benchmark cases biodiesel production using classical and intensified methods, methanol deriving from syngas, syngas being obtained from natural gas (NG) steam reforming (SR). A productivity of 100,000 t/year of biodiesel is set for all cases. Purities higher than 99% are obtained both for the main product, biodiesel, and for the by-product, glycerol. The results of the simulations lead to the conclusion that RD for biodiesel production gives superior performance in terms of raw materials consumption, biodiesel purity, by-product flow-rate and CO2 emissions but energy and steam consumption should be reduced in order to make this technology competitive at industrial scale.
