Selective catalytic reduction

About: Selective catalytic reduction is a research topic. Over the lifetime, 10502 publications have been published within this topic receiving 226291 citations.

Enhanced catalytic reduction of nitrophenols by sodium borohydride over highly recyclable Au@graphitic carbon nitride nanocomposites

Abstract: In this study, a photochemical green synthesis using thermal exfoliation process is developed to fabricate Au@graphitic carbon nitride (g-C3N4) nanocomposite, highly recyclable and reusable, for the catalytic reduction of nitrophenols by NaBH4. Au nanoparticles (Au NPs) in the diameter of 5–15 nm are deposited onto the surface of g-C3N4 in 3–6 layers of structure. The synthesized Au@g-C3N4 nanocomposites exhibit excellent catalytic activity and stability in the reduction of nitrophenols including 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-nitrophenol, and 2,4,6-nitriophenol. The catalytic performance of Au@g-C3N4 is highly dependent on the initial nitrophenol concentration, Au loading, inorganic anions, and pH. The rate constant of 4-nitrophenol reduction over Au@g-C3N4 (2 wt%) is 26.4 times that of pure Au NP in the presence of 7 mM of NaBH4 at pH 5. Moreover, Au@g-C3N4 can be reused for at least 10 consecutive cycles without considerable loss of catalytic activity. The presence of anions (0.1 M) such as H2PO4−, SO42-, HCO3−, and NO3− decreases the rate of 4-nitrophenol reduction by a factor of 1.2–8.8; whereas there is a 1.2-time increase in rate constant upon the addition of Cl− ion. The detection of H radical adducts indicates that Au NPs adsorbs BH4− ions and forms Au-H species. The porous and conductive g-C3N4 provides large surface area for nitroarene adsorption and subsequent electron transfer from the Au-H species to 4-nitrophenol, which results in accelerating the reduction of 4-nitrophenol. Results clearly demonstrate that Au@g-C3N4 is a promising green catalyst of enormous potential for nitroaromatic reduction, which provides a new venue for tailoring Au-based nanomaterials in elucidation of a wide variety of heterogeneous catalytic reactions.

Mechanism of arsenic poisoning on SCR catalyst of CeW/Ti and its novel efficient regeneration method with hydrogen

Abstract: Deactivation and regeneration of arsenic are studied on novel CeO2–WO3/TiO2 for selective catalytic reduction (SCR) of NOx with NH3. It is found that the activity and N2 selectivity of poisoned catalyst are inhibited immensely at the entire temperature range. The fresh, poisoned and regenerated catalysts are characterized using XRD, BET, XPS, H2-TPR, NH3-TPD, NO + O2-TPD, in situ Raman and in situ DRIFTS. The characterization results indicate that the poisoning of arsenic decrease BET surface area, surface Ce3+ concentration and the amount of Lewis acid sites and adsorbed NOx species but increase the reducibility and number of chemisorbed oxygen species. According to the in situ DRIFTS investigations, the adsorption of surface-adsorbed NH3 and NOx species is suppressed at low temperature, while the reactivity between surface-adsorbed NH3 and NO is prohibited at high temperature. A novel H2 reduction regeneration not only effectively removes arsenic from the poisoned catalysts, but promotes surface Ce3+/Ce4+ ratio and form new NOx adsorptive sites. However, it also affects the chemical properties of catalyst such as crystalline Ce2(WO4)3 forming, surface active oxygen species raise and loss of Bronsted acid sites.

Role of Acetate and Nitrates in the Selective Catalytic Reduction of NO by Propene over Alumina Catalyst as Investigated by FTIR

Abstract: The mechanism of the selective catalytic reduction (SCR) of NO by C3H6 on Al2O3 was investigated using in situ IR spectroscopy. Attention was focused on the reactivity of the adsorbed acetate and n...