Technology development for the production of biobased products from biorefinery carbohydrates—the US Department of Energy’s “Top 10” revisited

Sustainable Development Goals

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

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

The demand for petroleum dependent chemicals and materials has been increasing despite the dwindling of their fossil resources. As the dead-end of petroleum based industry has started to appear, today's modern society has to implement alternative energy and valuable chemical resources immediately. Owing to the importance of lignocellulosic biomass being the most abundant and bio-renewable biomass on earth, this critical review provides insights into the potential of lignocellulosic biomass as an alternative platform to fossil resources. In this context, over 200 value-added compounds, which can be derived from lignocellulosic biomass by various treatment methods, are presented with their references. Lignocellulosic biomass based polymers and their commercial importance are also reported mainly in the frame of these compounds. This review article aims to draw the map of lignocellulosic biomass derived chemicals and their synthetic polymers, and to reveal the scope of this map in today's modern chemical and polymer industry.

Succinic acid is predicted to be one of the future platform chemicals that can be derived from renewable resources. The improvements in biotechnological succinic acid production are presented. Chemical conversion pathways to γ-butyrolactone, tetrahydrofuran, 1,4-butanediole, and pyrrolidones are reviewed. An overview of possible new biopolymers (e. g. polyesters, polyamides, and poly(ester amide)s) based on succinic acid and its derivatives is given. Nevertheless, industrial processes using purified succinic acid from fermentation broths are not state of the art yet. Further improvements are needed until succinic acid-based chemical production will be economically favorable.

Succinic Acid: A New Platform Chemical for Biobased Polymers from Renewable Resources

Polylactide (PLA), poly(butylene succinate) (PBS) and blends thereof have been researched in the last two decades due to their commercial availability and the upcoming requirements for using bio-based chemical building blocks. Blends consisting of PLA and PBS offer specific material properties. However, their thermodynamically favored biphasic composition often restricts their applications. Many approaches have been taken to achieve better compatibility for tailored and improved material properties. This review focuses on the modification of PLA/PBS blends in the timeframe from 2007 to early 2019. Firstly, neat polymers of PLA and PBS are introduced in respect of their origin, their chemical structure, thermal and mechanical properties. Secondly, recent studies for improving blend properties are reviewed mainly under the focus of the toughness modification using methods including simple blending, plasticization, reactive compatibilization, and copolymerization. Thirdly, we follow up by reviewing the effect of PBS addition, stereocomplexation, nucleation, and processing parameters on the crystallization of PLA. Next, the biodegradation and disintegration of PLA/PBS blends are summarized regarding the European and International Standards, influencing factors, and degradation mechanisms. Furthermore, the recycling and application potential of the blends are outlined.

Polylactide (PLA) and Its Blends with Poly(butylene succinate) (PBS): A Brief Review

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Blending of Polyhydroxybutyrate-co-valerate with Polylactic Acid for Packaging Applications – Reflections on Miscibility and Effects on the Mechanical and Barrier Properties

Difluorovinylidene, F2C=C

Low pressure flash thermolysis of different precursor molecules containing-ClO, -ClO3 or -OClO3 yield, when highly diluted in Ne or O2 and subsequent quenching of the products in a matrix at 5 or 15 K, ClOx (x = 1, 3, 4) radicals, respectively. If Ne or O2 gas is directed over solid ClO2 at -120 degrees C and the resulting gas mixtures are immediately deposited as a matrix, a high fraction of (OClO)2 is trapped. This enables recording of IR and UV spectra of weakly bonded (OClO)2 dimers and detailed studying of their photochemistry. For Ne or O2 matrix isolated ClO radicals the vibrational wavenumbers and electronic transitions are only slightly affected compared with the gas phase. In this study strong evidence is found for long lived ClO in the electronically excited 2 [symbol: see text] 1/2 state. A comprehensive IR study of Ne matrix isolated ClO3 (fundamentals at 1081, 905, 567, 476 cm-1) yield i) a reliable force field; ii) a OClO bond angle of alpha e = 113.8 +/- 1 degrees and iii) a ClO bond length of 148.5 +/- 2 pm in agreement with predicted data from quantum chemical calculations. The UV/Vis spectrum of ClO3 isolated in a Ne matrix (lambda max at 32,100 and 23,150 cm-1) agrees well with the photoelectron spectrum of ClO3- and theoretical predictions. The origin of the structured high energy absorption is at 22,696 cm-1 and three fundamentals (794, 498, 280 cm-1) are detected in the C2E state. By photolysis of ClO3 with visible light the complex ClO.O2 with ClO in the 2 [symbol: see text] 1/2 state is formed. In an extended spectroscopic study of the elusive ClO4 radical, isolated in a Ne or O2 matrix, three additional IR bands, a complete UV spectrum and a strong interaction with O2 are found. This leads to the conclusion that ClO4 exhibits C2v or Cs symmetry with a shallow potential minimum and forms with O2 the previously unknown peroxy radical O3ClO-O2. All these results are discussed in the context of recent developments in the chemistry and spectroscopy of the important and interesting ClOx (x = 1-4) family of radicals.

Rodion Kopitzky

Papers

Succinic Acid: A New Platform Chemical for Biobased Polymers from Renewable Resources

Polylactide (PLA) and Its Blends with Poly(butylene succinate) (PBS): A Brief Review

Blending of Polyhydroxybutyrate-co-valerate with Polylactic Acid for Packaging Applications – Reflections on Miscibility and Effects on the Mechanical and Barrier Properties

Difluorovinylidene, F2C=C

Chlorine oxide radicals ClOx (x = 1-4) studied by matrix isolation spectroscopy.