Enhancing preferential oxidation of CO in H2 on Au/α-Fe2O3 catalyst via combination with APTES/SBA-15 CO2-sorbent

Au/alpha Fe2O3 was combined with a CO2 sorbent (3 aminopropyltriethoxysilane (APTES) grafted on SBA 15 and hereafter denoted as APTES/SBA 15) to enhance preferential oxidation (PROX) of CO in H-2 The CO2 molecules could be rapidly adsorbed on APTES/SBA 15 at low temperatures below 50 degrees C with a capacity of 0 68 mmol CO2/g sample and desorbed at a temperature range of 50 C-80 degrees C Three different configurations of the Au/alpha Fe2O3 catalyst and the CO2 sorbent were tested in the PROX reaction namely (i) the sorbent free (catalyst//SBA 15//catalyst) configuration (ii) the packed three layer configuration (catalyst//CO2 sorbent//catalyst) and (m) the mechanically mixed catalyst and CO2 sorbent configuration Compared to configuration (i) configuration (n) achieved an average 10% higher CO conversion at 50 C and a GHSV of 65000 h(-1) However the CO concentration could not be lowered to below 70 ppm from 2000 ppm using configuration (ii) at a GHSV of 10000 h(-1) Thus a S layer configuration (catalyst//CO2 sorbent//catalyst//CO2 sorbent//catalyst) was used and the CO concentration was lowered to ca 25 ppm The mechanism for enhancement of the PROX reaction by the continuous removal of CO2 by the CO2 sorbent is discussed and attributed to reduction of the surface carbonate on the Au/alpha Fe2O3 catalyst formed during the PROX process (C) 2010 Professor T Nept Veziroglu Published by Elsevier Ltd All rights reserved