Comparison Between Chemical And Enzymatic Hydrolysis Of Lignocellulosic Biomass For Bioethanol Production: A Review

The dependence on oil and other fossil resources raises global concerns and questions, as they are not considered sustainable from an economic and environmental point of view. The excess availability of residual agricultural material, the growing need for energy in the transport sector and the environmental benefit, due to the possible reduction of greenhouse gases, have boosted the development of liquid biofuels, including second generation bioethanol. Bioethanol is produced by hydrolysis of lignocellulosic materials, to obtain sugars that are later converted into alcohol by fermentation. This process involves the stages of pre-treatment of biomass, saccharification of cellulose, fermentation of hydrolyzate and distillation of alcohol. This work presents and discusses the different technological routes for cellulose hydrolysis, exposing the contrasts between enzymatic hydrolysis and acid hydrolysis, covering parameters such as reaction conditions, cost, yield and applicability. Showing that enzymatic hydrolysis, in general, is superior to homogeneous acid hydrolysis, however, heterogeneous acid hydrolysis presents itself as the most promising hydrolysis route to reduce the weak points found in the production process of this biofuel.