Expert representation chemical looping reforming: A comparative study of Fe, Mn, Co and Cu as oxygen carriers supported on Al2O3

In this study, a comparison between the performance of alumina supported Fe, Mn, Co and Cu oxygen carriers has been performed in chemical looping reforming (CLR) of methane. This process is consisting of two stages: 'air reactor' and 'fuel reactor', in which the oxygen carriers were placed in a fixed bed tubular reactor. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) were applied to check the carrier specifications before and after the process. Also, response surface method based on central composite design was applied to investigate the operating conditions including reaction temperature, time and oxygen carrier type. The results showed that the effective retention time of oxygen carriers varies for different metals in the air and fuel reactors, which depends on the amount of adsorption and desorption of oxygen in each stage. Results of these experiments revealed that iron based oxygen carrier had the highest resistance against sintering and the maximum capacity for oxygen adsorption among the mentioned carriers. It was also found that copper had a significant oxygen transport capacity; however its resistance against sintering and agglomeration is relatively low. Finally, Design expert software suggested several optimized solutions; among them the best choice was obtained to be Fe-based oxygen carrier with reaction temperature and time of 1014.13 degrees C and 50.5 min in the second cycle respectively. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.