Biobutanol from lignocellulosic biomass: Bioprocess strategies

The direct utilization of first-generation (coal, woody materials) fossil fuel resources as well as the rapid fluctuations in crude oil prices will lead to the consciousness of environmental problems, so the scientists as well as many researchers focused on the necessity of the liquid biofuels (bioethanol or biobutanol) from various feedstocks. One approach, in this way, some researchers identified, is the generation of clean renewable biofuels or bio-oils or bioliquids from different types of solid lignocellulosic biomass materials, such as forest wood, agricultural, and municipal solid wastes, because they have high potential as well as are valuable substitutes for achieving the conventional (gasoline) fuel security. Generally, the structural framework of any lignocellulosic biomass material comprises 30%-50% cellulose, 15%-35% hemicellulose, and 10%-20% lignin. Initially, the solid biomass materials are crumpled down into small ingredients and followed by hydrolysis to produce simple fermentable reducing sugar moieties, which upon fermentation form biofuels (bioethanol and biobutanol). The obtained biobutanol shows tremendously superior fuel properties as compared to bioethanol. Furthermore, the utilization of biodiesel or bioethanol needs some significant modifications in automobile engine parts, but the use of biobutanol does not require any such modifications in engines, because biobutanol shows superior unique fuel properties as well as is easily blended in any ratio with petrol- or petroleum-based gasoline. The major obstacle for the production of biobutanol from lignocellulosic biomass materials is the efficient pretreatments of biomass followed by enzymatic hydrolysis processes. In this regard an outlook on the major conversion technologies for producing biobutanol from various lignocellulosic biomass feedstocks by focusing on their typical performances has been established along with their applications. The effective pretreatment processes for enhancing the relevant techniques, the genetically engineered and modified acetone, butanol, and ethanol fermentation processes are also evaluated. The different routes, say chemical and microbial fermentation for the production of biobutanol, are generally discussed.