Chemical Looping Reforming with Perovskite-Based Catalysts for Thermochemical Energy Storage

Abstract

The performance of a perovskite-based oxygen carrier for the partial oxidation of methane in thermochemical energy storage applications has been investigated. A synthetic perovskite with formula La0.6Sr0.4FeO3 has been scrutinized for Chemical Looping Reforming (CLR) of CH4 under fixed-bed and fluidized-bed conditions. Temperature-programmed reduction and oxidation steps were carried out under fixed-bed conditions, together with isothermal reduction/oxidation cycles, to evaluate long-term perovskite performance. Under fluidized-bed conditions, isothermal reduction/oxidation cycles were carried out as well. Results obtained under fixed-bed and fluidized-bed conditions were compared in terms of oxygen carrier reactivity and stability. The oxygen carrier showed good reactivity and stability in the range 800–1000 °C. An overall yield of 0.6 Nm3 of syngas per kg of perovskite can be reached per cycle. The decomposition of CH4 catalyzed by the reduced oxide can also occur during the reduction step. However, deposited carbon is easily re-gasified through the Boudouard reaction, without affecting the reactivity of the material. Fluidized-bed tests showed higher conversion rates compared to fixed-bed conditions and allowed better control of CH4 decomposition, with a H2:CO ratio of around 2 and CO selectivity of around 0.8. However, particle attrition was observed and might be responsible for a loss of the inventory of up to 9%w.

Keywords

• fixed bed
• fluidized bed
• syngas
• hydrogen
• methane partial oxidation
• isothermal cycles