Issue 2, 2017

Energetics of cellulose and cyclodextrin glycosidic bond cleavage

Abstract

Thermochemical conversion of lignocellulosic materials for production of biofuels and renewable chemicals utilizes high temperature to thermally decompose long-chain cellulose to volatile organic compounds. Cellulose undergoes two distinct kinetic regimes of intra-chain scission: low-temperature glycosidic bond cleavage (T < 467 °C) associated with a low apparent activation energy and high-temperature glycosidic bond cleavage (T > 467 °C) associated with a high apparent activation energy. In this work, the initial breakdown kinetics of cellulose were examined from 385 °C to 505 °C using a millisecond, thin-film reactor called PHASR (pulse-heated analysis of solid/surface reactions). Using the cellulose surrogate, α-cyclodextrin, the energetics of each kinetic regime were characterized by measuring the conversion between 20 ms and 2.0 seconds. The low temperature kinetic regime exhibited glycosidic bond cleavage (Ea,1 = 23.2 ± 1.9 kcal mol−1, k0,1 = 2.0 × 107 s−1), while the high temperature kinetic regime (Ea,2 = 53.7 ± 1.1 kcal mol−1, k0,2 = 2.4 × 1016 s−1) was consistent with four reaction mechanisms including concerted transglycosylation. Apparent energetics were compared with computed literature values.

Graphical abstract: Energetics of cellulose and cyclodextrin glycosidic bond cleavage

Supplementary files

Article information

Article type
Paper
Submitted
28 Sep 2016
Accepted
06 Jan 2017
First published
06 Jan 2017

React. Chem. Eng., 2017,2, 201-214

Energetics of cellulose and cyclodextrin glycosidic bond cleavage

C. Zhu, C. Krumm, G. G. Facas, M. Neurock and P. J. Dauenhauer, React. Chem. Eng., 2017, 2, 201 DOI: 10.1039/C6RE00176A

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