Renewable Resources Robert-Jan van Putten,†,‡ Jan C. van der Waal,† Ed de Jong,*,† Carolus B. Rasrendra,‡,⊥ Hero J. Heeres,*,‡ and Johannes G. de Vries* †Avantium Chemicals, Zekeringstraat 29, 1014 BV Amsterdam, the Netherlands ‡Department of Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, the Netherlands Department of Chemical Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung 40132, Indonesia

Hydroxymethylfurfural, A Versatile Platform Chemical Made from Renewable Resources

This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts. Because of the huge number of chemical products that can be potentially manufactured, a selection of starting materials and targeted chemicals has been done. Also, thermochemical conversion processes such as biomass pyrolysis or gasification as well as the synthesis of biofuels were not considered. The synthesis of chemicals by conversion of platform molecules obtained by depolymerisation and fermentation of biopolymers is presently the most widely envisioned approach. Successful catalytic conversion of these building blocks into intermediates, specialties and fine chemicals will be examined. However, the platform molecule value chain is in competition with well-optimised, cost-effective synthesis routes from fossil resources to produce chemicals that have already a market. The literature covering alternative value chains whereby biopolymers are converted in one or few steps to functional materials will be analysed. This approach which does not require the use of isolated, pure chemicals is well adapted to produce high tonnage products, such as paper additives, paints, resins, foams, surfactants, lubricants, and plasticisers. Another objective of the review was to examine critically the green character of conversion processes because using renewables as raw materials does not exempt from abiding by green chemistry principles (368 references).

Conversion of biomass to selected chemical products

and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

Chemical modification of lignins: Towards biobased polymers

Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine-tuning of multiple "upstream" (i.e., lignin bioengineering, lignin isolation and "early-stage catalytic conversion of lignin") and "downstream" (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a "beginning-to-end" analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis.

Alcohol (methanol or ethanol) and water showed synergistic effects on biomass direct liquefaction, and the 50 wt % co-solvent of either methanol−water or ethanol−water was found to be the most effective solvent for the liquefaction of eastern white pine sawdust. The 50 wt % aqueous alcohol at 300 °C for 15 min produced a bio-oil yield at approximately 65 wt % and a biomass conversion of >95%. At a temperature higher than 300 °C, conversion of bio-oil to char was significant by repolymerization. The Fourier transform infrared spectroscopy (FTIR) and gas chromatography−mass spectrometry (GC−MS) analyses of the obtained bio-oils confirmed the presence of primarily phenolic compounds and their derivatives (such as benzenes), followed by aldehyde, long-chain (and cyclic) ketone and alcohol, ester, organic acid, and ether compounds. Gel permeation chromatography (GPC) results suggested that hot-compressed ethanol as the liquefaction solvent favored lignin degradation into monomeric phenols. The X-ray diffractio...

Highly Efficient Liquefaction of Woody Biomass in Hot-Compressed Alcohol−Water Co-solvents†

Synthesis of phenol–formaldehyde resol resins using organosolv pine lignins

The complexity of lignin and hemicellulose segmentation has been known since the middle of the ninetieth century. Studies confirmed that all lignin units in coniferous species and 47–66% of lignin moieties in deciduous species are bound to hemicelluloses or cellulose molecules in lignin–carbohydrate complexes (LCC). Different types and proportions of lignin and polysaccharides present in biomass lead to the formation of LCC with a great variety of compositions and structures. The nature and amount of LCC linkages and lignin substructures affect the efficiency of pulping, hydrolysis, and digestibility of biomass. This review paper discusses the structures, compositions, and properties of LCC present in biomass and in the products obtained via pretreating biomass. Methods for extracting, fractionating, and analyzing LCC of biomass, pulp, and spent pulping liquors are critically reviewed. The main perspectives and challenges associated with these technologies are extensively discussed. LCC could be extracted from biomass following varied methods, among which dimethyl sulfoxide or dioxane (Bjorkman’s) and acetic acid (LCC-AcOH) processes are the most widely applied. The oxidation and methylation treatments of LCC materials elucidate the locations and frequency of binding sites of hemicelluloses to lignin. The two-dimensional nuclear magnetic resonance analysis allows the identification of the structure and the quantity of lignin–carbohydrate bonds involved in LCC. LCC application seems promising in medicine due to its high anti-HIV, anti-herpes, and anti-microbial activity. In addition, LCC was successfully employed as a precursor for the preparation of spherical biocarriers.

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Lignin–carbohydrate complexes: properties, applications, analyses, and methods of extraction: a review

Hydrolytic degradation of alkaline lignin in hot-compressed water and ethanol.

Lignin is an abundant renewable feedstock for bioenergy, chemicals and materials production. Numerous review papers have addressed lignin research; though, a limited focus has been given to lignin commercial initiatives and its market applications potential. However, this is an area of great importance, given the growth of commercial lignin production. For instance, expressed in the strategic directions taken by pulp mills with kraft lignin valorization as a primary pathway in their transformation to the biorefinery. This work aims to provide concrete information on the global lignin market and supply, and to discuss its most explored applications - these being phenols and polyols due to their importance in short- and mid-terms lignin market development. Over the years, lignosulfonates have dominated the market. However, kraft lignin production increased by 150% from 2014 to 2018, competing with lignosulfonates to some extent. Even with the increased kraft lignin precipitation, it should remain a bioenergy source for kraft mills in the short- and mid-terms, with only its surplus being directed to biochemicals and biomaterials. The most demonstrated market application of kraft lignin is the production of biophenol, with biopolyol as a prone application in the mid-term. In both cases, lignin modification to obtain uniform and reactive biochemicals could allow faster market penetration. Besides, phenol and polyol markets are expected to grow globally providing an opportunity for biopolymers. The main recommendations are related to scaling up technologies to achieve technical and economic optimization of lignin applications as well as collaborative research efforts connecting stakeholders in the value chain.

Mathew Leitch

Papers

Highly Efficient Liquefaction of Woody Biomass in Hot-Compressed Alcohol−Water Co-solvents†

Synthesis of phenol–formaldehyde resol resins using organosolv pine lignins

Lignin–carbohydrate complexes: properties, applications, analyses, and methods of extraction: a review

Hydrolytic degradation of alkaline lignin in hot-compressed water and ethanol.

Global lignin supply overview and kraft lignin potential as an alternative for petroleum-based polymers