Gasification lignocellulose

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

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]. 

Conversion of lignocellulose into electricity via combustion or gasification [3, 74],... 

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. 

One can envisage the future production of liquid fuels and commodity chemicals in a biorefinery Biomass is first subjected to extraction to remove waxes and essential oils. Various options are possible for conversion of the remaining biofeedstock, which consists primarily of lignocellulose. It can be converted to synthesis gas (CO + H2) by gasification, for example, and subsequently to methanol. Alternatively, it can be subjected to hydrothermal upgrading (HTU), affording liquid biofuels from which known transport fuels and bulk chemicals can be produced. An appealing option is bioconversion to ethanol by fermentation. The ethanol can be used directly as a liquid fuel and/or converted to ethylene as a base chemical. Such a hiorefinery is depicted in Fig. 8.1. 

When perfected, synthesis-gas-to-ethanol technology can be expected to have a large impact on fermentation ethanol markets. It is likely that thermochemical ethanol would then be manufactured at production costs in the same range as methanol from synthesis gas, which can be produced by gasification of virtually any fossil or biomass feedstock. Applying the advances that have been made for conversion of lignocellulosic feedstocks via enzymatically catalyzed options, it has been estimated that the production cost of fermentation ethanol... 

Aznar, M.P. Corella, J. Delgado, J. Lahoz J. (1993) Improved Steam Gasification of Lignocellulosic Residues in a Fluidized Bed with Commercial Steam Reforming Catlysts. Ind. Eng. Chem. Res., 32, 1-10. 

Deglise X Richard C., Rolin A., Franfois H. (1980). Fast Pyrolysis/Gasification of Lignocellulosic Materials at Short Residence Time, In Proc. Energy from Biomass , T EC Conference, PALI, CHARTIER and HALL ed., Applied Science Pub., 548-553. 

Phillips SD, Aden A, Jechura J, Dayton D, Eggeman T. (2007). Thermochemical ethanol via indirect gasification and mixed alcohol synthesis of lignocellulosic biomass. National Renewable Energy Laboratory, Golden, CO. NREL/TP-510-41168. 

In industry, activated carbons are essentially produced by carbonization (pyrolysis at temperatures up to 900°C under neutral atmosphere) of various precursors (lignocellulosic, polymers, anthracites,. ..), followed by physical and chemical activation [1], Physical activation is generally realized around 900°C through partial gasification of carbon, using CO2 or steam, according to Eqs. 12.1 and 12.2 ... 

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