Performance of coal fly-ash based oxygen carrier for the chemical looping combustion of synthesis gas

• Fly-ash based oxygen carriers were synthesised for chemical looping combustion of synthesis gas.
• Using fly-ash as the support of the oxygen carrier enhanced the thermal stability and oxidant transfer for fuel oxidation.
• Fly-ash based nickel oxide reformed hydrocarbons into carbon monoxide with the presence of carbon dioxide.

The performance of coal fly-ash based oxygen carriers for chemical looping combustion of synthesis gas has been investigated using both a thermogravimetric analyser and a packed bed reactor. Oxygen carriers with 50 wt% active metal compounds, including copper, nickel and iron oxides, supported on coal fly-ash were synthesised using the deposition–precipitation method. Copper oxide and nickel oxide supported on fly-ash showed high oxygen transfer efficiency and oxygen carrying capacity at 800 °C. The fly-ash based nickel oxide was effective in reforming hydrocarbons and for the conversion of carbon dioxide into carbon monoxide; a nickel complex with silicate was identified as a minor phase following the reduction reaction. The fly-ash based iron oxide showed various reduction steps and resulted in an extended reduction time. The carbon emission at the oxidation stage was avoided by reducing the length of the exposure to the reduction gas.