Novel hybrid process for the conversion of microcrystalline cellulose to value-added chemicals: part 3: detailed reaction pathway
In this study, a novel method of hydrothermal electrolysis of microcrystalline cellulose (MCC) under sub-critical water conditions (200 °C) was investigated by applying direct current at constant voltage with the presence of acid catalyst of 5 mM H2SO4. Direct current at constant voltage of 2.5 V, 4.0 V and 8.0 V was applied between cylindrical anode (titanium) and cathode (reactor wall). Hydrothermal electrolysis reactions were carried out in a batch reactor (450 mL-T316) for the reaction time of 240 min. Decomposition products of MCC were analyzed by GC–MS and the decomposition pathway of cellulose under applied voltage was postulated. Levoglucosan and levoglucosenone formations were detected as the first hydrolysis products of MCC and further hydrolysis yielded to formation of glucose and fructose. The major decomposition products of cellulose were detected as levulinic acid (LA), 5-HMF and furfural. Further reactions of LA such as electrochemical decarboxylation, dehydration, hydrogenation, resulted in the formation of 2-butanone, 2-butanone-3-hydroxy, gamma-valerolactone, respectively. Most dramatic results on the product distribution were obtained at applied 2.5 V voltage in which LVA and 5-HMF were selectively produced.
KeywordsCellulose Electrochemical Sub-critical water 5-HMF Levulinic acid Levoglucosan
Research is financially supported by Marie Curie Career Integration Grants (FP7-PEOPLE-2012-CIG) with a Project Number of PCIG11-GA-2012-321741. GC–MS analysis was conducted at ‘‘Environmental Reference Research and Development Center” at Izmir Institute of Technology.
- Klemm D, Philipp B, Heinze T, Heinze U, Wagenknecht W (2004) General considerations on structure and reactivity of cellulose: section 2.1–2.1.4. In: Comprehensive cellulose chemistry. Wiley-VCH Verlag GmbH & Co. KGaA, New York, pp 9–29. https://doi.org/10.1002/3527601929.ch2a