Quantification and redox property of the oxygen-bridged Cu2+ dimers as the active sites for the NO decomposition over Cu-ZSM-5 catalysts

2004 ◽  
Vol 21 (3) ◽  
pp. 611-620 ◽  
Author(s):  
Deuk Ki Lee
Keyword(s):  
Active Sites ◽  
Redox Property ◽  
No Decomposition

scholarly journals Synthesis and characterization of Cu-MFI catalyst for the direct medium temperature range NO decomposition

2016 ◽  
Vol 34 (1) ◽  
pp. 177-184 ◽  
Author(s):  
Karolina Maduna Valkaj ◽  
Vesna Tomašić ◽  
Andrea Katović ◽  
ElżBieta Bielańska
Keyword(s):  
Ion Exchange ◽  
Active Sites ◽  
Catalytic Properties ◽  
Direct Synthesis ◽  
Copper Acetate ◽  
Nitrogen Adsorption ◽  
No Decomposition ◽  
Medium Temperature ◽  
Exchange Method ◽  
Mfi Zeolites

AbstractIn this study the physico-chemical and catalytic properties of copper bearing MFI zeolites (Cu-MFI) with different Si/Al and Si/Cu ratios were investigated. Two different methods for incorporation of metal ions into the zeolite framework were used: the ion exchange from the solution of copper acetate and the direct hydrothermal synthesis. Direct synthesis of a zeolite in the presence of copper-phosphate complexes was expected to generate more active copper species necessary for the desired reaction than the conventional ion exchange method. Direct decomposition of NO was used as a model reaction, because this reaction still offers a very attractive approach to NOX removal. The catalytic properties of zeolite samples were studied using techniques, such as XRD, SEM, EPR and nitrogen adsorption/desorption measurements at 77 K. Results of the kinetic investigation revealed that both methods are applicable for the preparation of the catalysts with active sites capable of catalyzing the NO decomposition. It was found out that Cu-MFI zeolites obtained through direct synthesis are promising catalysts for NO decomposition, especially at lower reaction temperatures. The efficiency of the catalysts prepared by both methods is compared and discussed.

Dimeric Cu(I) species in Cu-ZSM-5 catalysts: the active sites for the NO decomposition

2005 ◽  
Vol 232 (2) ◽  
pp. 476-487 ◽  
Author(s):  
G MORETTI ◽  
G FERRARIS ◽  
G FIERRO ◽  
M JACONO ◽  
S MORPURGO ◽  
...  
Keyword(s):  
Active Sites ◽  
No Decomposition

Characterization of active sites on copper ion-exchanged ZSM-5-type zeolite for NO decomposition reaction

1999 ◽  
Vol 1 (4) ◽  
pp. 649-656 ◽  
Author(s):  
Yasushige Kuroda ◽  
Ryotaro Kumashiro ◽  
Takefumi Yoshimoto ◽  
Mahiko Nagao
Keyword(s):  
Active Sites ◽  
Copper Ion ◽  
Decomposition Reaction ◽  
No Decomposition ◽  
Type Zeolite

Nature of active sites in decane-SCR-NOx and NO decomposition over Cu-ZSM-5 zeolites

2006 ◽  
Vol 307 (1) ◽  
pp. 156-164 ◽  
Author(s):  
Jiří Dědeček ◽  
Libor Čapek ◽  
Blanka Wichterlová
Keyword(s):  
Active Sites ◽  
No Decomposition

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

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