Pathways for biomass‐derived lignin to hydrocarbon fuels

Abstract

Production of hydrocarbon fuel from biomass‐derived lignin sources with current vision of biorefinery infrastructure would significantly improve the total carbon use in biomass and make biomass conversion more economically viable. Thus, developing specialty and commodity products from biomass derived‐lignin has been an important industrial and scientific endeavor for several decades. However, deconstruction of lignin's complex polymeric framework into low molecular weight reactive moieties amenable for deoxygenation and subsequent processing into hydrocarbons has proven challenging. This review offers a comprehensive outlook on the existing body of work that has been devoted to catalytic processing of lignin derivatives into hydrocarbon fuels, focusing on: (i) the intrinsic complexity and characteristic structural features of biomass‐derived lignin; (ii) existing processing technologies for the isolation and depolymerization of bulk lignin (including detailed mechanistic considerations); (iii) approaches aimed at significantly improving the yields of depolymerized lignin species amenable to catalytic upgrading; and (iv) catalytic upgrading, using aqueous phase processes for transforming depolymerized lignin to hydrocarbon derivatives. Technical barriers and challenges to the valorization of lignin are highlighted throughout. The central goal of this review is to present an array of strategies that have been reported to obtain lignin, deconstruct it to reactive intermediates, and reduce its substantial oxygen content to yield hydrocarbon liquids. In this regard, reaction networks with reference to studies of lignin model compounds are exclusively surveyed. Special attention is paid to catalytic hydrodeoxygenation, hydrogenolyis, and hydrogenation. Finally, this review addresses important features of lignin that are vital to economic success of hydrocarbon production. Published in 2013 by John Wiley & Sons, Ltd

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

“…Several catalytic routes have been proposed to upgrade lignin-derived bio-oil (such as zeolite upgrading to produce hydrocarbons and aqueous phase reforming to produce H 2 ). 227 However, the hydrodeoxygenation process (HDO) is one of the most common methods to achieve oxygen removal. HDO involves the treatment of oxygen-containing molecules with high-pressure H 2 at moderate temperature (200-500°C) in the presence of heterogeneous catalysts.…”

Production of Biofuel via Hydrogenation of Lignin from Biomass

“…Through the binding of arrays of carbon-carbon and ether linkages, a single intermonomeric bonding scafold was formed which is also known as lignin matrix [37]. This complex heterogenous structure of lignin consists essentially from three aromatic alcohols: p-coumaryl, coniferyl and sinapyl alcohols.…”

“…The β-O-4′ (aryl ether) interunit linkage has been identiied as a major lignin substructure where it provides a foundation for polymeric framework deconstruction in industrial processes. Some are known to have some resistant to chemical degradation such as β-5′, β-β′, 5-5′, 5-O-4′ and β-1′ [37,41]. Thus, lignin usually appears in a complicated macromolecule form due to the diversity functional groups and various kinds of linkage of lignin substructures [42].…”

“…Lignin usually exists in the form of lignin-carbohydrate complexes (LCCs) resulted from dehydrogenation of G, S and H monolignols. Hence, the covalently linked to hemicellulose lignin and the occurrence of lignin cross-linked to polysaccharides provide mechanical strength to plant cell wall and additional protection to other structures from external [37].…”

“…It involves the removal of oxygen from oxygen-containing molecules in the presence of catalysts with high-pressure hydrogen at moderate temperature. Oxygen is removed to form water via hydrogenolysis reaction and then saturated by hydrogenation reaction [37]. Catalytic HDO of guaiacol (2-methoxyphenol), an oxygen-rich lignin model compound, has been investigated by Aqsha et al for production of deoxygenated products.…”