Production of biodiesel: possibilities and challenges

Abstract

Biodiesel, defi ned as monoalkyl fatty acid ester (preferentially methyl and ethyl esters), represents a promising alternative fuel for use in compression-ignition (diesel) engines. Biodiesel fuel comes from renewable sources as it is plant-not petroleum-derived and as such it is biodegradable and less toxic. In addition, relative to conventional diesel, its combustion products have reduced levels of particulates, carbon oxides, sulphur oxides and, under some conditions, nitrogen oxides. Enzymatic production of biodiesel has been proposed to overcome the drawbacks of the conventional chemically catalyzed processes. The main obstacle facing full exploitation of the enzyme, lipase, potential is its cost. Therefore, reuse of lipase is essential from the economic point of view, which can be achieved by using the lipase in immobilized form. In addition, immobilized lipase displays improved stability and activity. Common immobilization techniques include attachment to solid supports and entrapment within the matrix of a polymer. This article presents a comparison between conventional processes and enzymatic processes and different possible feedstocks for biodiesel production. In addition, possible ways to overcome the problems facing the use of lipase are described.

The Protagonism of Biocatalysis in Green Chemistry and Its Environmental Benefits

“…However, this route has some drawbacks, such as production of a high quantity of highly alkaline wastewater and difficulty of catalyst recovery. Moreover, the high-price/high-quality raw materials (acidity less than 0.5%) required in such process is economically inconvenient, hindering for biodiesel to economically compete with petro-diesel [157][158][159]. Lipases (glycerol ester hydrolase, EC 3.1.1.3) are alternative biocatalysts that can be used to overcome the drawbacks related with the currently homogeneous alkaline transesterification route [158].…”

Biodiesel Fuel Production by Enzymatic Transesterification of Oils: Recent Trends, Challenges and Future Perspectives

“…S-2 efficiently catalyzed the methanolysis of vegetable oil even in a water-containing system without an organic solvent and in a single step, avoiding the stepwise addition of methanol. In general, lipases produced from yeast and fungi are most commonly used due to their low price and accessibility, although several bacterial lipases such as those from Pseudomonas sp., Enterobacter aerogenes, Bacillus subtilis, and others have been thoroughly investigated because of their superior methanol resistance (Al-Zuhair, 2007;Jaeger and Eggert, 2002;Noureddini et al, 2005). The main characteristic of lipases for biodiesel production from triacylglycerols is that they should be nonstereospecific so that all tri-, di-and monoglycerides can be converted to fatty acid alkyl esters.…”

Biodiesel: visão crítica do status atual e perspectivas na academia e na indústria

“…[154][155][156] Essas dificuldades podem ser superadas pelo uso dessas enzimas na sua forma imobilizada, permitindo o reuso desse biocatalisador várias vezes, reduzindo custos e ainda melhorando a qualidade do produto obtido. 32,33 o confinamento ou localização física de uma enzima em uma determinada região de um espaço definido, com a manutenção das suas atividades catalíticas, podendo ser usada repetida e continuamente devido à facilidade de sua separação do meio reacional é que caracteriza a "imobilização" da mesma.…”