Transition-Metal-Promoted Cu-SSZ-13 Catalysts for Continuous Selective Oxidation of Methane to Methanol Using Molecular Oxygen

ACS Catalysis, Год журнала: 2023, Номер 14(1), С. 292 - 298

Опубликована: Дек. 15, 2023

Chabazite-type Cu-SSZ-13 zeolites can catalyze the continuous selective oxidation of methane (CH4) to methanol (CH3OH) under mild conditions using molecular oxygen (O2) as oxidant. Here, we demonstrate that addition Fe and Zn into zeolite led an increase in space–time CH3OH yield by 138% 68%, respectively, CH4-to-CH3OH reaction. Comparative investigations were conducted over pristine Fe-loaded various ex situ methods, including X-ray absorption spectroscopy, infrared ultraviolet–visible Raman etc., revealed promoted transformation Cu2+ sites [Cu(OH)]+, precursor binuclear [Cu(trans-μ-1,2-O2)Cu]2+ species, which is highly active for oxidation.

Язык: Английский

Unraveling the NH3‐SCR‐DeNOx Mechanism of Cu‐SSZ‐13 Variants by Spectroscopic and Transient Techniques

ChemSusChem, Год журнала: 2024, Номер 17(21)

Опубликована: Июль 30, 2024

Abstract Commercial SSZ‐13 zeolite with different n (Si)/ (Al) ratios and from suppliers were subjected to a post‐synthetic treatment in order create mesopores of up 15 nm. Furthermore, the materials modified copper ions thoroughly physico‐chemically characterized. The textural properties varied nature species, thus, activity selective catalytic reduction NO x ammonia (NH 3 ‐SCR‐DeNO ). Pulsed‐field gradient nuclear magnetic resonance (PFG‐NMR) studies hexane as probe liquid revealed improved intracrystalline diffusion for some Cu‐containing materials. NH pathways are verified via situ DR UV‐Vis, FT‐IR EPR, temperature‐programmed well SSITKA that provide mechanistic understanding reaction. Kinetic modelling results demonstrate highest reaction rates 20 % lower energy barriers ratio 6.5 all forms (i. e., 4 )Cu‐SSZ‐13_6.5 Cu‐SSZ‐13_6.5_NaOH/0.1) cause only negligible parasitic oxidation. stop‐flow experiments further demonstrates SCR pathway HONO surface intermediate is present but barely contributes overall conversion compared dominant path between adsorbed gas phase.

Язык: Английский

CaMnO3 perovskite-derived porous γ-MnO2 for highly efficient oxidation of NH3 and NO

Catalysis Today, Год журнала: 2024, Номер 437, С. 114779 - 114779

Опубликована: Май 1, 2024

Язык: Английский