On the correlation between microstructural changes of Ag-H-ZSM-5 catalysts and their catalytic performances in the selective catalytic reduction of NOx by methane

Study of the Nature and Location of Silver in Ag-Exchanged Mordenite Catalysts. Characterization by Spectroscopic Techniques

“…To better understand issues as varied as the mechanism of selective reduction of NOx or the hydrocarbon adsorption process of silver based catalysts, it is necessary to determine the chemical state and the location of silver nanoparticles in the zeolitic framework. 3,13,18,19 Recently, a considerable number of studies have explored the catalytic properties of silver-zeolite catalysts for the SCR of NOx by hydrocarbons [20][21][22] or alcohols. [23][24][25] Our research group reported that silver-exchanged Na-mordenite catalysts were active and selective in the removal of nitrogen oxides using butane or toluene as reducing agents.…”

Formation of silver active states in Ag/ZSM-5 catalysts for CO oxidation

“…Ag/ZSM-5 catalysts showed high activity and stability in CO oxidation process exceeding the characteristics of Ag/zeolite catalysts presented in literature and tested under comparable conditions [5][6][7][8][9][10][11][12][13][14][18][19][20][21][22][23][24][25][26][27][28]. Almost complete CO conversion was observed at temperatures <100°C.…”

“…and in other reactions can show high catalytic activity at lower temperatures [5][6][7][8][9][10]. For correct comparison of catalytic properties we have to provide very close operating conditions.…”

“…However, gold samples have some drawbacks preventing wide usage of Au catalysts; one of them is fast deactivation of the catalysts during performance or storage. At the same time some researchers reported high efficiency of silver-based catalyst due to their high stability and catalytic activity in the oxidation processes [4][5][6][7][8][9][10]. The activity of these catalysts depends on their surface structure, the method of catalyst preparation, the calcination temperature and other factors.…”

“…As a rule the active sites are considered as silver nanoparticles, but active ionic states are also discussed [4][5][6][7][8][9][10]. A question about the nature of active sites is one of key problem in catalysis.…”