Heat effects of wet oxidation of glucose: A biomass model compound

Abstract

Glucose, as a representative biomass model compound, was oxidized in an aqueous solution in a temperature range from 298 K to 473 K under pressure of 2.13–5.0 MPa. Results of measurements of heat effects generated during that process are presented and discussed in the paper. The measurements were taken using a heat-flow reaction calorimeter in non-isothermal conditions by heating the reaction mixture from 298 K to a final temperature of 473 K at a rate Rt = 4.0 and 0.5 deg min−1. The oxidation was carried out for 3.5 and 8.5 h using different initial concentrations of glucose, i.e. 2.66, 3.65 and 4.93 g dm−3. As a result of these experiments a 56–64% reduction of TOC was obtained. The products of glucose oxidation in these conditions were also formic and succinic acids. The value of molar enthalpy of glucose oxidation with oxygen in subcritical water was ΔHm = −2077.7 ± 270.1 kJ mol−1 substrate used. Differences observed in the heat effects of oxidation in the experiments resulted from different values of TOC removal and changing composition of final products in the solution after oxidation. The values of the heat of wet oxidation of glucose were consistent with the results of thermochemical calculations and the average error of ΔHm determination was 3.40%.