Investigation of Oxygen Diffusivity within Oxygen Carrier In Chemical Looping Process

Energy and Transport Processes
2011 AIChE Annual Meeting
AIChE Annual Meeting
October 17, 2011 - 8:00pm

Chemical looping process is effective in converting carbonaceous fuels into hydrogen and electricity while generating a sequestration-ready CO2 stream. The process scheme is enabled by the cyclic reduction and oxidation reactions of an oxygen carrier (OC). The properties of OCs are of critically importance for the performance of chemical looping process. Our previous experimental studies show that composite iron oxide synthesized by adding support materials to the pure iron oxide can serve as good OCs. Unlike the unsupported iron oxide which deactivates within the first few redox cycles, the composite iron oxide maintains good reactivity over a long time although pore volume decreases significantly in the first few cycles. This phenomenon indicates that traditional understanding on support effect, mainly based on morphological analysis, may not be accurate. In this study, we investigated the role of support through both marker experiments and periodic Density Functional Theory (DFT) calculations. Ilmenite (FeTiO3) was used to model the simplified TiO2 supported iron (II) oxide material. Both the oxygen diffusion barrier and vacancy formation energy in ilmenite (FeTiO3) and wustite (Fe1-xO) were calculated. The diffusivities of oxygen in both materials were estimated based on the calculation results. It was found that the energy barrier for oxygen anion diffusion in ilmenite was significantly lower than that in wustite. The calculated oxygen diffusivity in ilmenite was also higher. This finding was corroborated by the marker experiment which indicates notably enhanced oxygen anion conductivity in the supported iron oxide.

Please Note: Members of the Transport and Energy Processes Division of AIChE are entitled to this content for free. Simply enter the 'promo code' TEPCOD when you are checking out. Only AIChE members are entitled to join the Transport and Energy Processes Division. For more info please click here. click here
Professional Development Hours
0.5 PDHs
You will be able to download and print a certificate for these PDH credits once the content has been viewed. If you have already viewed this content, please click here to login.

Would you like to access this content?

No problem. You just have to complete the following steps.

You have completed 0 of 2 steps.

  1. Log in

    You must be logged in to view this content. Log in now.

  2. Purchase Technical Presentation

    You must purchase this technical presentation using one of the options below.
    If you already purchased this content recently, please click here to refresh the system's record of ownerships.


Credits 0.5 Use credits
List Price $25.00 Buy now
AIChE Members $15.00 Buy now
AIChE Undergraduate Student Members Free Free access
AIChE Graduate Student Members Free Free access
Related Topics: 
Skill Level: