Investigation of Water and Sulfur Tolerance of Precipitable Silver Compound Ag/Al₂O₃ Catalysts in H₂-Assisted C₃H₆-SCR of NOx

Abstract

Ag/Al2O3 catalysts containing different precipitable silver compounds (AgCl, Ag2SO4, and Ag3PO4) were synthesized and investigated for NOx reduction in H2-assisted C3H6-selective catalytic reduction (SCR). The samples were systematically characterized by N2 adsorption, X-ray diffraction (XRD), UV–Vis, X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HR-TEM). N2 adsorption revealed that the introduction of anions (Cl–, SO4 2–, and PO4 3–) did not significantly affect the surface and structural properties of the Al2O3 support. However, XRD patterns and HR-TEM images indicated that the addition of Cl– anions caused the agglomeration of silver species to form large AgCl particles on the AgCl/Al2O3 catalysts. In contrast, the silver species dispersed well on Ag2SO4/Al2O3 and Ag3PO4/Al2O3 catalysts. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that partial oxidation of C3H6 on Ag2SO4/Al2O3 produced large amounts of reactive enolic species, while it tended to yield inert formate on AgCl/Al2O3. As a result, Ag2SO4/Al2O3 catalysts, especially 3% Ag2SO4/Al2O3, exhibited superior water and sulfur tolerance in H2-assisted C3H6-SCR.

Preparation of Ag‐Al₂O₃ nano structures by combustion method and investigation of photocatalytic activity

“…The γ‐Al 2 O 3 phase with diffraction peaks at 2θ = 37.2, 45.8, and 66.9° are matched with JPCDS card NO. 10‐0425 was observed in the Ag‐Al 2 O 3 nanostructures 42 . The Ag phase was observed at 2θ of 38.2° which corresponds to the (111) lattice planes of metallic Ag in all samples, this might be because Ag species on the Ag‐Al 2 O 3 was crystalline phase 43 .…”

“…10-0425 was observed in the Ag-Al 2 O 3 nanostructures. 42 The Ag phase was observed at 2θ of 38.2° which corresponds to the (111) lattice planes of metallic Ag in all samples, this might be because Ag species on the Ag-Al 2 O 3 was crystalline phase. 43 The average crystallite size of the sample was estimated at around 34 nm using the Scherer equation.…”

“…21 Considering that silveralumina is a kind of metal composite, it can be expected that the mentioned composition has superior properties compared to both Ag and alumina. Ag-Al 2 O 3 nanocomposite powders are interesting due to their excellent properties such as high catalytic activity, water, and sulfur resistance, 22 catalytic properties, 23 thermal resistance, 24 and antimicrobial activity, 25 DeNOx activity, 26 imaging and sensor applications. 27 Thus, various methods have been reported to synthesize silver alumina nano-powders.…”

Rationally tailored redox ability of Sn/γ-Al2O3 with Ag for enhancing the selective catalytic reduction of NOx with propene

“…Two XPS characteristic peaks of Ag 3d, 3d 5/2 and 3d 3/2 , were observed, and they could be deconvoluted into Ag + and Ag 0 (ref. 29) (Fig. 4b).…”

Mechanism of Propane Adsorption and the Following NOx Reduction over an In/BEA Catalyst: A Computational Study

“…The selective catalytic reduction of NO x by hydrocarbons (HC-SCR) has been a research focus of environmental catalysis since the 1990s. − Among the available hydrocarbons, methane was regarded as a special beneficial reducing agent for its cheap cost and abundant resource . For catalysts in the hydrocarbon SCR, indium-containing zeolites, including ZSM-5, BEA, and MOR, have shown significant activity and resistance to water in the process.…”