Routes to Potential Bioproducts from Lignocellulosic Biomass Lignin and Hemicelluloses

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Routes to Potential Bioproducts from Lignocellulosic Biomass Lignin and Hemicelluloses Xiao Zhang & Maobing Tu & Michael G. Paice

Published online: 20 August 2011 # Springer Science+Business Media, LLC. 2011

Abstract An essential feature of proposed fermentationbased lignocellulose to biofuel conversion processes will be the co-production of higher value chemicals from lignin and hemicellulose components. Over the years, many routes for chemical conversion of lignin and hemicelluloses have been developed by the pulp and paper industry and we propose that some of these can be applied for bioproducts manufacturing. For lignin products, thermochemical, chemical pulping, and bleaching methods for production of polymeric and monomeric chemicals are reviewed. We conclude that peroxyacid chemistry for phenol and ringopened products looks most interesting. For hemicellulose products, preextraction of hemicelluloses from woody biomass is important and influences the mixture of solubilized material obtained. Furfural, xylitol, acetic acid, and lactic acid are possible targets for commercialization, and the latter can be further converted to acrylic acid. Preextraction of hemicelluloses can be integrated into most biomass-to-biofuel conversion processes. Keywords Lignocellulosic biomass . Lignin . Hemicellulose . Extraction . Bioproducts . Conversion . Biofuel . Pulp and paper

Introduction Despite decades of efforts, producing biofuels from lignocellulosic biomass is still not an economically viable proposition. Fuel, regardless of its type, is a low-value product, and using biomass particularly woody biomass to produce fuel economically as a sole purpose poses a great economic challenge. Identifying value-added co-products along with the production of advanced biofuel is key to the success of a viable lignocellulosic biomass conversion process. Lignocellulosic biomass is primarily composed of cellulose, hemicelluloses, and lignin. The technical feasibility of producing various types of biofuels (e.g., ethanol, butanol, and hydrocarbon fuels) from biomass carbohydrates, particularly cellulose, has been well demonstrated. However, converting biomass lignin and hemicelluloses to fuel in high yield remains a much greater challenge. This paper describes some of the opportunities and promising routes for converting biomass lignin and hemicelluloses to bioproducts.

Lignin Lignin and its Current Commercial Applications

X. Zhang (*) School of Chemical Engineering and Bioengineering, Center for Bioproducts and Bioenergy, Washington State University, Richland, WA, USA e-mail: [email protected] M. Tu School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, USA e-mail: [email protected] M. G. Paice MP & Associates, Richmond, BC, Canada e-mail: [email protected]

Lignin is a ubiquitous component in almost all plant biomass [1–3]. Large quantities of lignin are produced annually as a waste product from chemical pulping processes (i.e., kraft and sulfite pulping). Over 118 million metric tons of chemical