Chemical Looping Combustion is a novel process that generates sequestration-ready CO_(2) from the combustion of woody biomass without requiring a gas separation step and without diluting the CO_(2) with N_(2) from air...Chemical Looping Combustion is a novel process that generates sequestration-ready CO_(2) from the combustion of woody biomass without requiring a gas separation step and without diluting the CO_(2) with N_(2) from air.This is achieved by oxidizing the fuel with lattice oxygen of a metal oxide oxygen carrier.When using cheap and abundant ilmenite ore(FeTiO3)as the oxygen carrier,the rather low reactivity towards volatiles released from the biomass upon devolatilization,as well as detrimental structural changes due to a segregation of Fe and Ti in the material,are of concern.These issues can be addressed by modifying ilmenite with Ca via melt infiltration.In this work,we demonstrate that this modification results in a good distribution of Ca throughout the ilmenite particles that a)prevents detrimental Fe/Ti segregation,b)improves the mechanical stability of the particle compared to materials prepared by solution impregnation and c)improves the reactivity of this material towards hydrogen and wet methane.Moreover,fixed bed experiments showed that the Ca modification not only resulted in increased methane conversion,but also in an increased degree of oxidation of gaseous intermediates CO and H2.We thus conclude that the performance of ilmenite in Chemical Looping processes can be significantly enhanced by Ca modification of ilmenite either prior to use or in-situ during operation of this bed material with Ca-rich fuels such as woody biomass.展开更多
基金This work was supported by the New Energy and Industrial Technology Development Organization(NEDO,Japan)for the project on technological development for zero-emission coal power generation.
文摘Chemical Looping Combustion is a novel process that generates sequestration-ready CO_(2) from the combustion of woody biomass without requiring a gas separation step and without diluting the CO_(2) with N_(2) from air.This is achieved by oxidizing the fuel with lattice oxygen of a metal oxide oxygen carrier.When using cheap and abundant ilmenite ore(FeTiO3)as the oxygen carrier,the rather low reactivity towards volatiles released from the biomass upon devolatilization,as well as detrimental structural changes due to a segregation of Fe and Ti in the material,are of concern.These issues can be addressed by modifying ilmenite with Ca via melt infiltration.In this work,we demonstrate that this modification results in a good distribution of Ca throughout the ilmenite particles that a)prevents detrimental Fe/Ti segregation,b)improves the mechanical stability of the particle compared to materials prepared by solution impregnation and c)improves the reactivity of this material towards hydrogen and wet methane.Moreover,fixed bed experiments showed that the Ca modification not only resulted in increased methane conversion,but also in an increased degree of oxidation of gaseous intermediates CO and H2.We thus conclude that the performance of ilmenite in Chemical Looping processes can be significantly enhanced by Ca modification of ilmenite either prior to use or in-situ during operation of this bed material with Ca-rich fuels such as woody biomass.
