Effect of water vapor on the activity and stability of Pd/SZ and Co/ZrO2 in dual-catalyst treatment of simulated exhaust from lean-burn natural gas engines

Mechanism of NO-SCR by methane over Co,H-ZSM-5 and Co,H-mordenite catalysts

“…Similar promoting effect was already suggested to contribute to the NO-SCR activity of different Co and Pd catalysts [22,26,37,56].…”

High Zr-loaded SBA-15 cobalt catalyst for efficient NOx reduction in lean-burn exhaust

“…This trend demonstrates that the structural modification was more pronounced in the presence of a higher content of the cobalt species. Despite this reduction, the surface area of the catalysts was still higher than those of the zeolites and noble metal-based catalysts [15,35,36]. The large surface area of the prepared catalysts, resulting in more active sites for the chemisorption of the reactants and thus higher reaction rate, can be considered as one of the main advantages of the DP synthesis technique [37].…”

“…In the direct synthesis method (D), Zr is introduced to the SBA-15 structure during the hydrothermal synthesis of SBA-15 [23], while in the post synthesis method (P), incorporation of the metal is carried out through the chemical grafting on the synthesized SBA-15 as a second step [24]. Although high amounts of Zr is favored to achieve increased acidity and to enhance the interaction between the support and the active components, both techniques have limitations in Zr loading content, while retaining the intact structure of the SBA- 15. High Zr loading brings about structural collapsing in the case of the former and pore blockage and surface area reduction in the case of the latter.…”

“…However, zeolite-based catalysts suffer from instability in hydrothermal conditions leading to catalysts deactivation [14]. Therefore, other catalytic systems such as zirconium oxide-based catalysts have been attracted more attention for HC-SCR due to high acidity, hydrothermal stability and water tolerance [15,16]. Nonetheless, their low surface area and weak interaction with active components [5,6] keep them far from being a proper catalyst for industrial applications.…”

Pt-Rh/CeO2-Al2O3 for Controlling Emissions from Natural Gas Engines: Three-Way Catalytic Activity at Low Temperatures and Effects of SO2 Aging

“…This imposes a further challenge for controlling emissions from natural gas engines. The selective catalytic reduction of NO x with methane (CH 4 -SCR) coupled with lean combustion can be an alternative solution and has been studied extensively [10][11][12][13][14][15]. However, activities of the reported catalysts are not sufficient to obtain NO x and CH 4 conversions required in practical applications.…”