Deactivation studies of the SCR of NOx with hydrocarbons on Co-mordenite monolithic catalysts

Promotional effects and mechanism of second cations on activity and stability of Co-MOR for nitrous oxide decomposition: UV–Vis spectroscopy and EXAFS analysis

“…6 and [39]. Moreover, it is found that the distribution of Co ions in the zeolite is not only affected by the preparation process and cobalt loading but also on the co-cation presence [5][6][7][8][9][11][12]14]. As shown in Fig.…”

“…(Fig. 4a) catalyst, an intense reduction peak at high temperature region (675-900°C) is observed, which is ascribed to the reduction of mono-atomic Co 2+ on ion exchange sites [5,9]. In addition, a weak H 2 consumption at 200-400°C is present, which are assigned to the reduction of Co 3 O 4 particles at the external surface of the zeolite crystal [30][31][32][33].…”

“…They were more strongly coordinated to framework oxy- [7][8][9] and our previous research [17], the activity loss of cobalt zeolites under rigorous reaction conditions is generally believed to be related to redistribution of cobalt species. In the presence of water, the hydrolysis of Co 2+ ions species would interact with the nearest Brönsted acid on the zeolite matrix, leading to the formation of small oxide crystallite and causing irreversible activity loss [17,[40][41][42].…”

“…However, the Co ion-exchange level is still very low during the WIE process due to the weak ion diffusion capacity, and the synthesized catalyst with low Co loading often suffer activity loss under rigorous reaction conditions (gas streams containing water at high temperature) [7,8]. It is found that in a stream of air, hydrated species of the mono-atomic Co 2+ on the zeolite exchange sites would interact with the un-exchanged protons, leading to relocation of the Co cations, loss of the dispersion and activity [9]. Besides, the zeolite support may also be deteriorated due to dealumination from the zeolite lattice, and therefore restrict their application [8].…”

Characterization of Electrochemically Deposited Ce1-xZrxO2 Layers Modified with Cobalt Oxide for Electrocatalytic Conversion of NOx and CO

“…It is also obvious that modification with cobalt oxide has no catalytic effect as claimed in. 39 In an attempt to verify the lack of "own" catalytic effect of the cobalt oxide layer, the electrocatalytic curves for CO oxidation and NO x reduction were plotted also for a cobalt layer deposited on a steel substrate (sample No. 10).…”