Green processes to biofuel additives production from glycerol over heterogeneous catalysts

Abstract

The glycerol is a by-product in the biodiesel production. For every 9 kg of biodiesel produced, about 1 kg of a crude glycerol is formed. Due to the increase of biodiesel production, an increase of glycerol production has been observed. The glycerol can be converted into solketal, by acetalization reaction with acetone, which can be used as fuel additive. Usually, homogeneous acid catalysts have been used in the acid reaction. However, due to enviromental problems, homogeneous catalysts have been replaced by heterogeneous catalysts, which are reusable and easy to be separated from liquid products, become the process as a “Green Process.” This present review focuses on solid acid catalysts as potential heterogeneous catalysts for glycerol conversion into biofuel additives (solketal), replacing homogenous ones. It is also studied the acetalization of glycerol with acetone over heteropolyacids immobilized on Beta zeolite.