CLC in packed beds using syngas and CuO/Al2O3: Model description and experimental validation

• Published in: Applied energy 2014-04, Vol.119, p.163-172
• Main Authors: Hamers, H.P., Gallucci, F., Cobden, P.D., Kimball, E., van Sint Annaland, M.
• Format: Article
• Language: English
• Subjects: ALUMINUM OXIDE; Applied sciences; Carbon; Carriers; Chemical-looping combustion; CO2 capture; COPPER OXIDE; CuO/Al2O3; DEPOSITION; Energy; Exact sciences and technology; MATHEMATICAL ANALYSIS; Mathematical models; Oxidation; Packed beds; Reactors; Reduction
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2013.12.053

•CLC with CuO/Al2O3 and syngas and air has been demonstrated experimentally.•Model predicts accurately only if kinetics describe the complete solid reduction.•CuO/Al2O3 is proven to catalyze the reversed water gas shift reaction.•H2O is more effective to suppress carbon deposition on CuO/Al2O3 than CO2.•The OC reaction rate is not permanently affected by exposure to H2S. The objective of this work is to study the performance of the oxygen carrier in a packed bed with periodic switching between oxidizing and reducing conditions. In this paper the performance of CuO/Al2O3 as the oxygen carrier in a packed bed reactor with syngas as the fuel are investigated, while also studying the (possible) carbon deposition and the effect of sulphur impurities on the stability of the carrier. Both experiments and simulations are used in this work. Cyclic experiments (oxidation with air and reduction with syngas) have been carried out in a lab scale packed bed reactor with 13wt% CuO/Al2O3. The experimental results were well described by a 1D reactor model, provided that critical attention was given to the reaction rate for the complete reduction reaction, including a dramatic decrease in reaction rate at high solid conversions. Feeding syngas (pH2=pCO=0.1bar) resulted in 1.1% carbon deposition of the feed. Steam was proven to be more effective in reducing carbon deposition than CO2. Moreover, it has been found that CuO/Al2O3 catalyzed the water gas shift reaction and the reaction rate was not permanently affected by exposure to H2S, two key factors for CLC operation. The results of this work imply that CuO/Al2O3 is an effective oxygen carrier as the first packed bed reactor in a TSCLC process and that the developed model is able to describe the performance at larger scales accurately.