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In this series of articles, the board members of ChemSusChem discussrecent research articles that they consider of exceptional quality and importance for sustainability.T his entry features Dr.P ieter Bruijnincx, who discusses bio-based approaches to new and existing chemicals for large-scale polymera pplications, highlighting that the development of methodologies to obtain key monomers from biomass leads to new chemistry, aids the transition to am ore sustainable chemical industry, and fostersnew interdisciplinary approaches. New and Drop-in Bio-based ChemicalsNature offers many opportunities for the production of renewable platform molecules (i.e.,b uildingb locks for am ore sustainable chemical industry). Of particulari nterest, in terms of impact,a re those biomass-derivedp latformm olecules that can be used as monomersf or large-scale polymer applications. [1] Indeed, world plastics consumption showsaconsistenta nnual growth, reaching 311Mti n2 014. These polymers are unfortunately stilll argely made from fossil resources. Bio-based polymers do find their way into the market and show faster annual growth rates than the fossil-derived ones, yet stillcontribute to less than 5% of the total production volume. Much research and development efforts are currently being devoted, both in industry and in academia, to develop conversion technology and polymer materials to increasethis share. An obviousincentive of using high-value, renewable monomers for large-scale polymer applications lies in the concomitant reduction of the carbon footprint of the chemical and polymer industry.T he use of renewable resources, such as biomass,also offers another,d istinct opportunity:c hemical diversity.T he high functionalgroup density and overall oxidation state of many of the main components of biomass offer versatility in terms of reactivity and access to chemical structures and compounds that can be much less easily and efficientlym ade from conventionalf ossil resources. The building blocks that can be obtainedf rom biomass can then be classifieda se ither drop-in (i.e.,m olecularly identicalt oc urrent petrochemical-derived monomers) or new monomers. The former hold the advantage of access to existing markets and applications, but need to be ablet oc ompete on price (there being no real premium on 'green'). The latter offer ac ompetitive advantage that is based on performance, rather than on price, but require applicationsa nd markets to be developed.

The electrocatalytic conversion of furanic compounds, i.e. mainly furfural and 5-hydroxymethylfurfural, has recently emerged as a potentially scalable technology for both oxidation and hydrogenation processes because of its highly valuable products. However, its practical application in industry is currently limited by low catalytic activity and product selectivity. Thus, a better understanding of the catalytic reactions as well as a strategy for the catalyst design can bring solutions for a complete and selective conversion into desired products. In this perspective, we review the status and challenges of electrocatalytic oxidation and hydrogenation of furanic compounds, including thermodynamics, voltammetric studies, and bulk electrolysis with important reaction parameters (i.e., catalyst, electrolyte, temperature, etc.) and reaction mechanisms. In addition, we introduce methods of energy-efficient electrocatalytic furanic synthesis by combining yields of anodic and cathodic reactions in a paired reactor or a reactor powered by a renewable energy source (i.e., solar energy). Current challenges and future opportunities are also discussed, aiming at industrial applications.

The reactivity and physicochemical properties of lignins are partly governed by their molar mass distribution. The development of reliable standard methods for determination of the molar mass distribution is not only relevant for designing technical lignins for specific applications, but also for monitoring and elucidating delignification and pulping processes. Size-exclusion chromatography (SEC) offers many advantages, such as wide availability, short analysis time, low sample demand, and determination of molar mass distribution over a wide range. A collaborative study has been undertaken within the “Eurolignin” European thematic network to standardise SEC analysis of technical lignins. The high-molar-mass fraction of polydisperse lignins was shown to be the main source of intra- and interlaboratory variations, depending on the gel type, elution solvent, detection mode, and calculation strategy. The reliability of two widespread systems have been tested: one based on alkali and a hydrophilic gel (e.g., TSK Toyopearl gel) and the other based on THF as solvent and polystyrene-based gels (e.g., Styragel). A set of practical recommendations has been deduced.

This paper deals with a biorefi nery classifi cation approach developed within International Energy Agency (IEA) Bioenergy Task 42. Since production of transportation biofuels is seen as the driving force for future biorefi nery developments, a selection of the most interesting transportation biofuels until 2020 is based on their characteristics to be mixed with gasoline, diesel and natural gas, refl ecting the main advantage of using the already-existing infrastructure for easier market introduction.This classifi cation approach relies on four main features: (1) platforms; (2) products; (3) feedstock; and (4) processes. The platforms are the most important feature in this classifi cation approach: they are key intermediates between raw materials and fi nal products, and can be used to link different biorefi nery concepts. The adequate combination of these four features represents each individual biorefi nery system. The combination of individual biorefi nery systems, linked through their platforms, products or feedstocks, provides an overview of the most promising biorefi nery systems in a classifi cation network. According to the proposed approach, a biorefi nery is described by a standard format as 'platform(s) -products -and feedstock(s)'. Processes can be added to the description, if further specifi cation is required. Selected examples of biorefi nery classifi cation are provided; for example, (1) one platform (C6 sugars) biorefi nery for bioethanol and animal feed from starch crops (corn); and (2) four platforms (lignin/syngas, C5/C6 sugars) biorefi nery for synthetic liquid biofuels (Fischer-Tropsch diesel), bioethanol and animal feed from lignocellulosic crops (switchgrass).This classifi cation approach is fl exible as new subgroups can be added according to future developments in the biorefi nery area.

Around the world, signifi cant able steps are being taken to move from today's fossil-based economy to a more sustainable economy based on biomass. A key factor in the realization of a successful bio-based economy will be the development of biorefi nery systems allowing highly effi cient and cost-effective processing of biological feedstocks to a range of bio-based products, and successful integration into existing infrastructure. The recent climb in oil prices and consumer demand for environmentally friendly products has now opened new windows of opportunity for bio-based chemicals and polymers. Industry is increasingly viewing chemical and polymer production from renewable resources as an attractive area for investment. Within the bio-based economy and the operation of a biorefi nery, there are signifi cant opportunities for the development of bio-based building blocks (chemicals and polymers) and materials (fi ber products, starch derivatives, etc). In many cases this happens in conjunction with the production of bioenergy or biofuels. The production of bio-based products could generate US$10-15 billion of revenue for the global chemical industry. The economic production of biofuels is often a challenge. The co-production of chemicals, materials food and feed can generate the necessary added value. This paper highlights all bio-based chemicals with immediate potential as biorefi nery 'value added products'. The selected products are either demonstrating strong market growth or have signifi cant industry investment in development and demonstration programs. The full IEA Bioenergy Task 42 report is available from http://www.iea-bioenergy.task42-biorefi neries.com Perspective: Product developments in the bio-based chemicals arena E de Jong et al.

Electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfuran (DHMF) or other species, such as 2,5-dimethylfuran, on solid metal electrodes in neutral media is addressed, both in the absence and in the presence of glucose. The reaction is studied by combining voltammetry with on-line product analysis by using HPLC, which provides both qualitative and quantitative information about the reaction products as a function of electrode potential. Three groups of catalysts show different selectivity towards: (1) DHMF (Fe, Ni, Ag, Zn, Cd, and In), (2) DHMF and other products (Pd, Al, Bi, and Pb), depending on the applied potential, and (3) other products (Co, Au, Cu, Sn, and Sb) through HMF hydrogenolysis. The rate of electrocatalytic HMF hydrogenation is not strongly catalyst-dependent because all catalysts show similar onset potentials (-0.5 ± 0.2 V) in the presence of HMF. However, the intrinsic properties of the catalysts determine the reaction pathway towards DHMF or other products. Ag showed the highest activity towards DHMF formation (up to 13.1 mM cm(-2) with high selectivity> 85%). HMF hydrogenation is faster than glucose hydrogenation on all metals. For transition metals, the presence of glucose enhances the formation of DHMF and suppresses the hydrogenolysis of HMF. On poor metals such as Zn, Cd, and In, glucose enhances DHMF formation; however, its contribution in the presence of Bi, Pb, Sn, and Sb is limited. Remarkably, in the presence of HMF, glucose hydrogenation itself is largely suppressed or even absent. The first electron-transfer step during HMF reduction is not metal-dependent, suggesting a non-catalytic reaction with proton transfer directly from water in the electrolyte.