Lignocellulosics hydrolysis

Andric P, Meyer AS, Jensen PA, Dam-Johansen K. (2010a). Reactor design for minimizing product inhibition during enzymatic lignocellulose hydrolysis I. significance and mechanism of cellobiose and glucose inhibition on cellulolytic enzymes. Biotechnol Adv, 28(3), 308-324. 

Andric P, Anne S, Meyer A S, Jensen P A, Johansen K D, (2010b), Reactor design for minimizing product inhibition during enzymatic lignocellulose hydrolysis II. Quantification of inhibition and suitabiUty of membrane reactors . Biotechnology Advances, 28,407 25. 

Parisi F (1989) Advances in lignocellulosics hydrolysis and in the utilization of the hydrolyzates. In Fiechter A (ed) Springer, Berlin, Heidelberg, New York p 53 (Advances in biochemical engineering/biotechnology, vol 38)... 

Viikari, L., Alapuranen, M., Puranen, T, Vehmaanpera, J., Siika-Aho, M. (2007). Thermostable enzymes in lignocellulose hydrolysis. Adv Biochem Eng/Biotechnol, 108,121-145. 

Lignocellulosic material + Acid —Hydrolysis > Sugar + Solid residues... 

Conversion of lignocellulose into transportation fuels via pyrolysis and subsequent oil upgrading [72], via gasification and subsequent Fischer-Tropsch or methanol synthesis [3], via hydrolysis and subsequent fermentation to ethanol or subsequent conversion into ethyl levulinate [45, 46, 73]. 

Lignocellulose biomass is a mixture of phenolic lignin and carbohydrates -cellulose and hemi-cellulose. It grows abundantly on earth and is largely available as agricultural and forestry residues. Lignocellulose can be converted via four major routes pyrolysis, gasification, hydrolysis and fermentation. 

Further research is also needed in this area. Particularly, (a) to create a new generation of cheap enzymes for hydrolysis of cellulose and lignocellulose to fermentable sugars (able to complete the biomass hydrolysis during fermentation) (b) to develop improved biocatalysts that allow us to simplify the process and reduce energy input and (c) to improve separation and recovery. 

Bioconversion platforms for lignocellulosics-to-ethanol are beginning to become commercially viable, but the effectiveness of the pretreatment stage should still be improved, the cost of the enzymatic hydrolysis stage decreased, and overall process efficiencies improved by better synergies between various process stages. There is also a need to improve process economics by creating co-products that can add revenue to the process. 

NREL (National Renewable Energy Laboratory). Lignocellulosic biomass to ethanol process design and economics utilizing co-current dilute add prehydrolysis and enzymatic hydrolysis for com stover. Golden, CO US (2002). Report available on web http //www.mel.gov/ docs/ fy02osti/32438.pdf... 

A hydrolysis step is involved in the pulp industry in order to concentrate the cellulose from wood. This uses large-scale processes whereby a liquid fraction, the lignocellulose, is formed as a by-product in the process, and contains high levels of phenolic components and their derivatives. These compounds also constitute an environmental problem due to their possible introduction into rivers, lakes, and/or seas. Chlorophenols from the cellulose bleaching process have traditionally attracted most of the interest in the analysis of industrial waste because of their high toxicity. 

Figure 1, Multistage hydrolysis of autohydrolyzed-extracted lignocellulosic residue, 2.0% on lignocellulosic residue each stage 20 min at 190°C...

Several definitive reviews on pretreatment of lignocellulosic materials for improving cellulose hydrolysis (1,2,3) appeared a few years ago. More recently, two pretreatment methods (the Purdue process and the Iotech process) have been announced that claim superior perform-... 

---