Development of (Mn0.77Fe0.23)2O3 particles as an oxygen carrier for coal combustion with CO2 capture via in-situ gasification chemical looping combustion (iG-CLC) aided by oxygen uncoupling (CLOU)

Abstract

Chemical Looping Combustion (CLC) involves the use of a solid oxygen carrier to transport the oxygen from the air to a fuel. Attention has recently been focused on oxygen carriers based on Mn-Fe mixed oxides because they are cheap materials that are able to release oxygen at high temperature, the so-called oxygen uncoupling step. The aim of this work was to assess the use of (Mn 0.77 Fe 0.23) 2 O 3 material as an oxygen carrier with the ability to transport oxygen both by reduction with gaseous fuels and by oxygen uncoupling, i.e. typical mechanisms in CLC and in Chemical Looping with Oxygen Uncoupling (CLOU), respectively. The particles prepared by mechanical mixing were screened to obtain particles of sufficient reactivity and mechanical strength for use in a fluidized bed

Chemical Looping Combustion of gaseous and solid fuels with manganese-iron mixed oxide as oxygen carrier

“…Consequently, Larring et al [54] postulated that in order to take advantage of the oxygen release capability of these materials, an exhaustive control of oxidation conditions, i.e., temperature and partial pressure of oxygen, is essential. Taking this into account, Pérez-Vega et al [55] delimited operating temperature range for the CLOU process of a Mn-rich oxygen carrier selected after a screening process. The authors determined that it would be necessary set a thermal gradient of about 70 ºC between the reactors in order to take advantage of the oxygen uncoupling properties of the solid.…”

“…In light of the results obtained with Mn-Fe oxygen carriers, it is clear that materials of a high mechanical strength must be developed for use in CLC unit operations, while high reactivity must be maintained in order to achieve high fuel conversion. In a previous study, a promising low-cost MnFe-based oxygen carrier, (Mn 0.77 Fe 0.23 ) 2 O 3 , was found after a screening process on particles prepared by mechanical mixing followed by pelletization [55]. This solid was evaluated in both a TGA and a fluidized bed reactor, and it was found to possess the reactivity and mechanical strength required for use in a CLC unit.…”

“…Oxygen uncoupling capability was evaluated during the decomposition-regeneration of the bixbyite phase by alternating high-purity N 2 (< 2ppm O 2 ) and air at 870 ºC, in a way similar to that described in a previous work [55]. In addition, reactivity with H 2 , CO and CH 4 , as well as oxidation by O 2 , was assessed during the reduction of spinel to mangano-wüstite.…”

Bauxite waste with low Fe 2 O 3 and high Na concentration as a promising oxygen carrier in chemical looping combustion

“…In response to this threat, the international community has reached a consensus that if fossil fuel usage continues to increase, it will become necessary to reduce its carbon footprint by restricting its CO 2 emissions. One potential technology capable of achieving these reductions is carbon capture and storage (CCS), in which the CO 2 generated during combustion is captured and then geologically stored underground …”

“…One potential technology capable of achieving these reductions is carbon capture and storage (CCS), 3,4 in which the CO 2 generated during combustion is captured and then geologically stored underground. 5,6 Chemical-looping combustion (CLC) is a neoteric method that is able to separate and capture CO 2 for CCS implementation. 4,7 Based on a near-zero emission concept, CLC has been proposed for coal-fueled power plants because of its potentially low energy penalty during operation.…”