283184 Cu Based Oxygen Carriers for Chemical Looping Processes

Thursday, November 1, 2012: 10:30 AM
316 (Convention Center )
Egwono Okpoko1, Paul S Fennell2 and Klaus Hellgardt1, (1)Chemical Engineering, Imperial College London, London, United Kingdom, (2)Chemical Engineering and Chemical Technology, Imperial College London, London, United Kingdom

Chemical looping combustion (CLC) is a process developed to efficiently burn gaseous fuels and at the same time capture CO2 without an additional energy intensive separation unit. CLC is a two stage processes which involves supplying oxygen to the fuel for combustion using an oxygen carrier and the subsequent regeneration of the oxygen carrier back to its original state with air. CLC might be economically viable and depending on the design, specific reaction products can be obtained. Hydrogen and syngas are two very important products useful for power generation and intermediates production in the chemical industry. This project focuses on the investigation of Cu based oxygen carriers for the CLC process with particular respect to the stability and kinetics of the synthesised materials. Particles composed of 40, 60 and 80 % CuO supported on Al2O3 have been prepared by co-precipitation methods with Na2CO3 and NH4OH. X-ray analysis (XRD) reveals the presence of a mixture of CuO and CuAl2O4, both being reducible as evidenced by CO/CH4-TPR analysis. The reduction and oxidation kinetics where investigated in a TGA system for particle sizes < 355 μm. Reaction orders for CO, CH4 and O2 were determined as 2, 1.5 and 0.7, respectively and activation energies were in the order O2 > CO > CH4 at temperatures T ≤ 700 oC. The reactivity of the Cu-based oxygen carriers during 20 cycles was investigated both by TGA and fixed-bed reactor operation at temperatures ≤ 700 oC. SEM analysis revealed no sign of sintering with the carriers prepared with Na2CO3 but little sintering effects were observed with carriers prepared with NH4OH. The experimental results suggest that Cu-based oxygen carriers prepared by co-precipitation appear to be very suitable for CLC operation.

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