The interest in the development of efficient and environmentally benign catalysts for esters synthesis has increased exponentially, mainly due to the demand for biodiesel. In general, fatty esters are used as bioadditive, cosmetic ingredients, polymers, and, more recently, biofuel. Nevertheless, most of the production processes use nonrecyclable and homogenous alkaline catalysts, which results in the reactors corrosion, large generation of effluents, and residues on the steps of separation and catalyst neutralization. Heterogeneous acid catalysts can answer these demands and are an environmentally benign alternative extensively explored. Remarkably, solid acid catalysts based on tin have been shown highly attractive for the biodiesel production, mainly via FFA esterification reactions. This review describes important features related to be the synthesis, stability to, and activity of heterogeneous tin catalysts in biodiesel production reactions.
Energy balance for biodiesel production processes using microbial oil and scum
