Chemical looping gasification of solid fuels using bimetallic oxygen carrier particles – Feasibility assessment and process simulations

• A novel, chemical looping based coal-to-hydrogen scheme is proposed.
• The redox process uses a CuO promoted iron oxide for H2 production and CO2 capture.
• The CuO promoted iron oxide exhibits excellent reactivity for coal conversion.
• CuO promotion leads to simpler energy integration and higher efficiency.

The chemical looping gasification (CLG) process utilizes an iron-based oxygen carrier to convert carbonaceous fuels into hydrogen and electricity while capturing CO2. Although the process has the potential to be efficient and environmentally friendly, the activity of the iron-based oxygen carrier is relatively low, especially for solid fuel conversion. In the present study, we propose to incorporate a secondary oxygen carrying metal oxide, i.e. CuO, to the iron-based oxygen carrier. Using the “oxygen-uncoupling” characteristics of CuO, gaseous oxygen is released at a high temperature to promote the conversion of both Fe2O3 and coal. Experiments carried out using a Thermal-Gravimetric Analyzer (TGA) indicate that a bimetallic oxygen carrier consisting of a small amount (5% by weight) of CuO is more effective for coal char conversion when compared to oxygen carrier without copper addition. ASPEN Plus® simulations and mathematical modeling of the process indicate that the incorporation of a small amount of copper leads to increased hydrogen yield and process efficiency.