Evaluation of a Mixed Fe–Mn Oxide System for Chemical Looping Combustion

Abstract

In coal-based chemical looping combustion (CLC) technology, relatively cheap metal oxides, referred to as oxygen carrier materials (OCMs), are required because some of the OCMs will be removed together with the residual ashes after combustion. CLC technology will have an estimated loss in efficiency of around 2% compared to standard combustion technology without capture if a proper OCM is found that can give full combustion, removing the need of an air separation unit (ASU). Materials with a chemical looping oxygen uncoupling (CLOU) effect will even give further benefits in faster gasification and combustion of the fuel. One can already find produced materials that can give such a desirable effect, but fabrication and material cost are still an issue in these cases. If such a material can be delivered by the mining industry, cost savings and plant efficiency will be high. Before selection of the natural minerals with strong inert inherent support that contain Fe and Mn, the need for a better understanding of the Fe−Mn system is needed. This pre-study combined with other literature findings of the Fe−Mn system shows that a Mn content of up to 25−33% will increase the CLOU effect, increase the conversion of CH 4 , and give possibilities for full combustion in a CLC plant.

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

“…This is in agreement with the Lambert et al [53], who observed that bixbyite regeneration reaction kinetics was always very slow for Mnrich solids. 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.…”

Chemical-Looping Combustion and Gasification of Coals and Oxygen Carrier Development: A Brief Review

“…Recently the mixed oxides have been synthesized and tested mostly using gaseous fuels. As Mn content in the oxide increases up to 33% the oxygen uncoupling increase to 2% between 800 and 1100 °C [91]. To optimize the cost of the oxygen carrier in the CLOU process, a long life and/or a low cost of oxygen carrier are considered and still a challenge [92].…”

Microstructural Stability of Tailored CaMn0.875−xFexTi0.125O3−δ Perovskite Oxygen Carrier Materials for Chemical Looping Combustion

“…expensive nickel oxide to low-costing ores, [6][7][8] several hundreds of materials based on Ni, Cu, Fe, Mn, Co,and mixtures of these materials have been studied as potential OCMs for CLC. [9] Lately,t here has been significant interest in mixed transition-metal oxides [10] and complex perovskite-type oxides, [11] especially those derived from the calcium manganite CaMnO 3Àd family.F or CLC applications, substitution of calcium by strontium and barium [12] has been considered. Furthermore,t he substitution of manganeseb ym agnesium, [13] titanium, [4,14] or ac ombinationo fb oth [15] has been investigated.…”