5/5/2023 0 Comments Density of copper![]() ![]() Automotive NO x abatement using zeolite-based technologies. Influence of ion mobility on the redox and catalytic properties of Cu ions in zeolites. Signorile, M., Borfecchia, E., Bordiga, S. Mechanism of the Wacker oxidation of alkenes over Cu–Pd-exchanged Y zeolites. Elucidating the mechanism of heterogeneous Wacker oxidation over Pd-Cu/zeolite Y by transient XAS. Ethene dimerization on zeolite-hosted Ni ions: reversible mobilization of the active site. The Cu–CHA deNO x catalyst in action: temperature-dependent NH 3-assisted selective catalytic reduction monitored by operando XAS and XES. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia. Catalysis in a cage: condition-dependent speciation and dynamics of exchanged Cu cations in SSZ-13 zeolites. Condition-dependent Pd speciation and NO adsorption in Pd/zeolites. ![]() Solvation and mobilization of copper active sites in zeolites by ammonia: consequences for the catalytic reduction of nitrogen oxides. Confining isolated atoms and clusters in crystalline porous materials for catalysis. Combining in-situ transmission electron microscopy and infrared spectroscopy for understanding dynamic and atomic-scale features of supported metal catalysts. Resasco, J., Dai, S., Graham, G., Pan, X. Rh single atoms on TiO 2 dynamically respond to reaction conditions by adapting their site. Dynamic formation of single-atom catalytic active sites on ceria-supported gold nanoparticles. Dynamic restructuring drives catalytic activity on nanoporous gold–silver alloy catalysts. Ensembles of metastable states govern heterogeneous catalysis on dynamic interfaces. Continuous partial oxidation of methane to methanol catalyzed by diffusion-paired copper dimers in copper-exchanged zeolites. Dynamic multinuclear sites formed by mobilized copper ions in NO x selective catalytic reduction. Dynamic interconversion of metal active site ensembles in zeolite catalysis. Solid catalysts and reaction rates-general principles. ![]() The Kinetics of Chemical Change (Oxford Clarendon Press, 1940). Increasing the Al density leads to systematic increases in both the fraction of Cu I ions that are SCR active (that is, O 2 oxidizable) and Cu I oxidation rate constants (per Cu), revealing insights into how anionic Al centres in zeolite frameworks regulate the mobility of ionically tethered Cu cations and their dynamic reactivity during low-temperature NO x SCR. Here we combine statistical simulations, steady-state kinetics and operando X-ray absorption spectroscopy to interrogate Cu–chabazite (Cu–CHA) zeolites of varying framework Al density (0.2–1.7 Al centres per cha cage). Cu I oxidation requires the pairing of two mobilized Cu I(NH 3) 2 complexes to form binuclear intermediates, implying that Cu I oxidation kinetics should depend on framework Al density, given that Cu ions are ionically tethered to anionic charges at Al sites in zeolite lattices. Cu zeolites catalyse low-temperature (<523 K) selective catalytic reduction (SCR) of nitrogen oxides (NO x) via a redox cycle involving dynamic interconversion between NH 3-solvated mononuclear Cu I and binuclear Cu II complexes. ![]()
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