Abstract

Alumina supported Fe2O3 was prepared to evaluate its feasibility as an oxygen carrier for chemical looping using a thermogravimetric analyzer (TGA) and fixed bed reactor. Fe2O3/Al2O3 particles containing 60 wt% Fe2O3 and sintered at 1300°C demonstrated reasonable oxygen conversion. The reduction mechanism of Fe2O3/Al2O3 oxygen carriers was proposed based on the thermogravimetric analysis and XRD characterization. FeAl2O4 is formed and can serve as a supporting material as well as oxygen carrier in practical operations by using a moving bed reactor. The prepared Fe2O3/Al2O3 oxygen carriers demonstrated high CO2 yields in relation to syngas and methane combustion in the fixed bed reactor operated at temperatures higher than 500 and 850°C, respectively. Moreover, hydrogen generation was demonstrated to be feasible by steam oxidation with reduced Fe2O3/Al2O3 oxygen carriers for experiments conducted at temperatures above 800°C. The crush strength and TGA of Fe2O3/Al2O3 were examined, and the results showed that they had an appropriate crush strength and reasonable reactivity as oxygen carriers for use in a chemical looping process.

Highlights

  • Carbon dioxide (CO2) as one of the anthropogenic GHGs has been rapidly grown by 39% above pre-industrial levels at the end of 2010 (IPCC, 2011)

  • The crush strength and thermogravimetric analyzer (TGA) of Fe2O3/Al2O3 were examined, and the results showed that they had an appropriate crush strength and reasonable reactivity as oxygen carriers for use in a chemical looping process

  • For experiments conducted with Fe2O3/Al2O3 oxygen carriers sintered at temperature lower than 1000°C, the conversions of oxygen were independent on sintering temperature

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Summary

INTRODUCTION

Carbon dioxide (CO2) as one of the anthropogenic GHGs has been rapidly grown by 39% above pre-industrial levels at the end of 2010 (IPCC, 2011). The performance of prepared Fe2O3/Al2O3 oxygen carriers on CO2 yield with syngas and methane combustions, and on H2 generation by H2O oxidation were determined in a fixed bed reactor. The procedure of redox cycling was replicated for 50 times with Fe2O3 and Fe2O3/Al2O3 pellets to evaluate the reactivity and recyclability with respect to practical moving bed operation of chemical looping process. For reduction of Fe2O3/Al2O3 oxygen carriers with methane and syngas, 1.5 L/min reducing gas was introducing into the fixed bed reactor at various temperatures, ranging from 100 to 900°C. For H2 generation by steam oxidation of reduced Fe2O3/Al2O3 oxygen carriers, 50 mmol/min of steam was introduced into the fixed bed reactor at various temperatures, ranging from 500 to 900°C. Where FCO2, FCO, FH2 and FCH4 are the molar flow rates of CO2, CO, H2 and CH4 in the outlet stream, respectively

RESULTS AND DISCUSSION
Generation in Fixed Bed Reactor
CONCLUSIONS

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