A green biopolymer catalyst based on natural polysaccharides for the esterification of isosorbide Katrin Staedtke 1 , Michael Theisinger 2 , Alexandra Inayat 2 1 Erlangen Center for Interface Research and Catalysis, Friedrich-Alexander-Universität Erlangen- Nürnberg, Germany, 2 Institute of Chemical Reaction Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany Starbons are mesoporous carbons based on polysaccharides for different applications like catalysis or adsorption. [1,2] In general high amylose corn starch (Hylon) used for the preparation of Starbons that is only occurring in special breeded corn plants.[1,3] The aim of this work was to produce biopolymer catalysts based on natural polysaccharides (e.g. native starch and alginic acid) for the esterification of isosorbide. An acidic Starbon catalyst should replace the petrochemical based catalyst like Amberlyst-15. For that, commercial starches from potato and wheat, sodium alginate are used to prepare Starbon materials. Preparation consisted of four main steps: gelling, drying, pyrolysis and sulfonating. A study about the correlation between retrogradation time and crystallinity of the mesoporous materials showed effects on surface area (10-75m²/g), pore size (5-50nm) and pore volume (0,1-0,5cm³/g), as confirmed by nitrogen physisorption and XRD analysis. Through the pyrolysis and sulfonation (sulphur content 0.4- 2.6%), various catalyst were prepared. The tested catalysts based on alginic acid is less active than Amberlyst-15. However, potato and wheat starch based catalysts performed like the Amberlyst-15 (conversion of isosorbide 100% and selectivity to diester 80- 90% after 26h reaction time). [4]
Fig. 1 Systematic overview of the raw materials for the preparation of sulfonated Starbon materials for the test reaction (esterification of isosorbide) References 1. R. J. White, V. L. Budarin, R. Luque, , D. J. Macquarrie, Chemical Society Reviews, 2009, 38(12), 3401-3418. 2. H.L. Parker, V. L. Budarin, J. H. Clark, A. J. Hunt, ACS Sustainable Chemistry & Engineering , 2013 1(10), 1311-1318. 3. V. L. Budarin, J. H. Clark, J. J. Hardy, R. Luque, K. Milkowski, S.J., Tavener, A. J. Wilson, Angewandte Chemie , 2016, 118 (23), 3866-3870. 4. A. Inayat, A., A. van Assche, J.H. Clark, T. J. Farmer, Sustainable Chemistry and Pharmacy , 2018, 7, 41-49.
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