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Figure 3 - from "Manganese oxide dissociation kinetics for the Mn2O3 thermochemical water-splitting cycle. Part 1: Experimental"

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arrow_backarrow_forwardFig. 3. O2 generation for Mn203 dissociation. Fig. 5. Contour plot of conversion to MnO.

Fig. 3. O2 generation for Mn203 dissociation. Fig. 5. Contour plot of conversion to MnO.

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Figure 1
Fig. 2. Schematic of the quench tube assembly. After the powder passed through the quench tube, it was collected in a gravity collection vessel. Any powder that remained entrained and left the collection vessel was trapped by a high efficiency particulate air (HEPA) filter. The filter was manufac- tured by General Electric H20 Process Technologies, had a 0.22 um pore size, and was 0.14m in diameter. After passing through the filter, gas was analyzed in an oxygen analyzer (Advanced Micro Instruments Model 201) and was subsequently vented. The
Fig. 3. O2 generation for Mn203 dissociation. Fig. 5. Contour plot of conversion to MnO.
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Dissociation reaction response surface p-values. A typical oxygen generation curve of the dissociation reaction is presented in Fig. 3. The reactor temperature was 1873 K and had a bulk gas flow rate of 7.0 slpm. Several peaks may be seen in the center of the graph. These resulted from a small amount of vibration being applied to the feeder, which periodically increased the amount of powder fed to the reactor. Additionally, there were two discontinuities in the graph. The discontinuities occurred when the change in oxygen was so rapid that the Oz sensor range was not changed quickly enough. It is evident from Fig. 3 that the amount of oxygen in the system rapidly increased when manganese oxide was fed. Table 1
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Fig. 4. XRD product spectra from the AFR. As expected, the conversion increased with an increase in temperature. Somewhat unexpectedly however, was that the conversion also increased with increased gas flow rate. An increase in gas flow rate inherently causes the residence time to
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Alan Weimer,

Paul Lichty

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

Abstract: ABSTRACT 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 ∼0.25% by volume. A dual reaction mechanism for Mn2O3 dissociation was found: RAvrami−Erofeev=−A1e−Ea,1/RTn(1−X)[−ln(1−X)](n−1)/nROrder_of_reaction=−A2e−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 1.8×107±1.3×107 and 5.6×103±4.1×103s−1, respectively, for oxygen concentration

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