Manganese oxide dissociation kinetics for the Mn2O3 thermochemical water-splitting cycle. Part 1: Experimental

摘要

It is shown that the dissociation of Mn2O3 to MnO in a short residence time aerosol flow reactor can achieve high conversions approaching 75% when the concentration of oxygen is kept below 0.25%. Significant recombination reaction occurs when the oxygen content exceeds similar to 0.25% by volume. A dual reaction mechanism for Mn2O3 dissociation was found: RAvrami-Erofeev = A(1)e(-Ea,1/RT)n(1 X)[ ln(1 X)]((n-1)) R-Order_of_reaction = -A(2)e(-Ea,2/RT)(1 - X)(n) with the transition from one mechanism to the other occurring at an extent of reaction of approximately 0.6. Rate constants for the two mechanisms were calculated to be 1.8 x 10(7) +/- 1.3 x 10(7) and 5.6 x 10(3) +/- 4.1 x 10(3) s(-1), respectively, for oxygen concentration <0.25%. High levels of dissociation are achievable when the reaction is carried out in an inert gas environment using a reactor configuration that limits the reverse reaction.