Nickel Oxides Supported on Alumina as Oxygen Carriers for Chemical-Looping Combustion and Reforming of Methane

Abstract

Chemical-Looping Combustion (CLC) and Chemical-Looping Reforming (CLR) processes are technologies in development, considered as economically viable alternatives for CO2 mitigation. Both processes employ two interconnected reactors (air reactor and fuel reactor), by which oxides particles (called oxygen carriers) circulate. CLC process produces heat with inherent separation of CO2 from gaseous hydrocarbons combustion. CLR process performs the fuel partial oxidation, generating synthesis gas (H2 and CO), which is the major industrial intermediate for hydrogen (H2) and other hydrocarbons production, thru Fischer-Tropsch reactions. The employment of OCs enables the total or partial oxidation of fuel, in the absence of atmospheric air, which allows great reduction of the separation costs. Nickel-based OCs are the most investigated, showing high performance and reactivity. This work presents the synthesis of OCs composed by different contents of nickel oxides supported on alumina, textural, physical and chemical characterizations by several techniques, and experimental results obtained when these materials were applied to CLC and CLR processes, using CH4 as fuel, mixed or not, with H2O or CO2. The results showed the potential industrial applications of these materials, which are preferentially selective to the CLR process, and the addiction of H2O or CO2 greatly reduces the carbon deposition.