Selective oxidation of CO in rich hydrogen stream over Ag/OMS-2 catalyst

摘要

The Ag/OMS-2 catalysts prepared by the simple reflux method show high activity and stability for the CO selective oxidation in rich H_2 stream. The catalysts are characterized by means of XRD, BET, XRF, XPS, SEM, TEM and H_2-TPR. The results show that the materials have the cryptomelane type structure with a one-dimensional channel and Ag ions are well dispersed in the micropores of the cryptomelane structure. The catalytic activity for CO selective oxidation was increased after Ag introduction. In the longtime stability test under the realistic reaction condition, 100% CO conversion can maintain for 250 h at 120 ℃ with about 90% selectivity. The main reason for the deactivation of the Ag/OMS-2 catalysts is that the fine-dispersed silver species are agglomerated to form Ag_2O and parts of OMS-2 are reduced to Mn_2O_3, accompanied with a structure reordering.