Sulfuric Acid-Catalyzed Dehydratization of Carbohydrates for the Production of Adhesive Precursors

SUSBIND develops the chemical syntheses for producing the carbohydrate-based amino-plastic, and other wood resin systems. This will polymerise urea and other monomers using intermediates derived from high-purified carbohydrates during WP1. This allows investigation of the reactions of the carbohydrates during resin synthesis and to test other modification reactions. This should deliver precursors suitable for using as bio-based binders for wood board production. Resins can be produced on laboratory scale to investigate properties and the most promising candidates are upscaled to pilot level to allow them to be validated as binders. Our Austrian partner WoodKPlus presents how this is done in its most recent publication. We share an extract below.

Switching to renewables

Today’s chemical industry still strongly relies on oil and other fossil resources as the main source of bulk chemicals and energy. Rising demands and diminishing fossil resources along with rising awareness of environmental problems drive the search for more sustainable alternatives. The interest in fuels and chemicals derived from renewables is therefore growing fast and a lot of R&D is done to convert biomass into valuable products. Biomass is the only widely available carbon source besides oil, gas and coal, and 75% of the available biomass are carbohydrates, such as starch, cellulose, or hemicelluloses.[1]

5-hydroxymethylfurfural (5-HMF) and its great industrial potential

The conversion of these carbohydrates into valuable chemicals, e.g., furanic compounds such as 5-hydroxymethylfurfural (5-HMF), has therefore huge industrial potential. 5-HMF is considered a key platform chemical since it can be converted into a variety of other valuable compounds. It has been called a “sleeping giant” along with furandicarboxylic acid (FDCA), a compound that can be derived directly from 5-HMF and may be a renewable alternative for terephthalic acid in polyester or polyamide production.[2]

Extensive literature on the production of 5-HMF is available, including good overviews of synthesis procedures, solvent systems, and proposed reaction mechanisms (Van Putten et al.[3]). Recently, we have added an outline of the challenging development of industrial 5-HMF production processes.[4]One of the main challenges in 5-HMF production is the formation of side products. In general, hexoses are dehydrated by acid catalysis to form 5-HMF. 5-HMF is easily rehydrated to levulinic and formic acid, on the one hand, and also polymerizes, on the other hand, thereby forming complex, black-colored residues called humins.

Abstract

Carbohydrates and hexose-derived 5-hydroxymethylfurfural (5-HMF) are platform chemicals for the synthesis of sustainable binders. New, greener approaches aim at the development of production systems, which minimize process steps and avoid organic solvents or other auxiliaries that could interfere with subsequent resin synthesis. In our work, carbohydrate solutions rich in 5-hydroxymethylfurfural (5-HMF) were produced using a continuous-flow microreactor and diluted H2SO4 as the catalyst. After optimization of the process conditions (temperature, reaction time, catalyst content), a 5-HMF yield of 49% was obtained at a low reaction time of 0.6 min and a catalyst concentration of 1% at 175 °C and 17 bar pressure. Extensive rehydration of the product was avoided by efficient immediate cooling of the reaction solution. The stability of the reaction system was improved by increasing the inner diameter of the capillary in the flow reactor to 2 mm. Advantageously, the obtained reaction mixtures are used directly as precursors in the development of sustainable binder systems, without the need of additional purification, filtration, or extraction steps. Read the full article here.

(c) Woodkplus

 

Authors of the publication:

Wilfried Sailer-Kronlachner, *Email: w.sailer-kronlachner@wood-kplus.at, w.sailer@boku.ac.at

Catherine Thoma, Stefan Böhmdorfer, Markus Bacher, Johannes Konnerth, Thomas Rosenau, Antje Potthast, Pia Solt, and Hendrikus W. G. van Herwijnen

Wood K plus—Competence Center of Wood Composites and Wood Chemistry, Kompetenzzentrum Holz GmbH, Altenberger Str. 69, A-4040 Linz, Austria

Institute of Wood Technology and Renewable Materials, Department of Material Science and Process Engineering University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad-Lorenz Str. 24, A-3430 Tulln, Austria

 

[1] Röper, H. Renewable Raw Materials in Europe–Industrial Utilisation of Starch and Sugar. Starch/Staerke 2002, 54, 89– 99,  DOI: 10.1002/1521-379x(200204)54:3/43.0.co;2-i [Crossref], [CAS], Google Scholar

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[4] Thoma, C.; Konnerth, J.; Sailer-Kronlachner, W.; Solt, P.; Rosenau, T.; van Herwijnen, H. W. G. Current Situation of the Challenging Scale-Up Development of Hydroxymethylfurfural Production. ChemSusChem 2020, 13, 3544– 3564,  DOI: 10.1002/cssc.202000581 [Crossref], [PubMed], [CAS], Google Scholar