On the Environment of the Active Sites in Phosphate Modified Silica–Zirconia Acid Catalysts

Converting biomass into value-added chemicals holds the key to sustainable long-term carbon resource management. In this context, levulinic acid, which is easily obtained from cellulose, is valuable since it can be transformed into a variety of industrially relevant fine chemicals. Here we present a simple protocol for the selective esterification of levulinic acid using solid acid catalysts. Silica supported sulfonic acid catalysts operate under mild conditions and give good conversion and selectivity with stoichiometric amounts of alcohols. The sulfonic acid groups are tethered to the support using organic tethers. These tethers may help in preventing the deactivation of the active sites in the presence of water.

Download Full-text

Insights into the structure of active sites in metal-doped solid acid catalysts

Applied Catalysis A General ◽

10.1016/j.apcata.2007.07.041 ◽

2008 ◽

Vol 336 (1-2) ◽

pp. 109-115 ◽

Cited By ~ 27

Author(s):

Stéphane Walspurger ◽

Benoît Louis

Keyword(s):

Active Sites ◽

Solid Acid ◽

Solid Acid Catalysts ◽

Acid Catalysts ◽

Metal Doped

Download Full-text

Investigating the role of framework topology and accessible active sites in silicoaluminophosphates for modulating acid-catalysis

Catalysis Science & Technology ◽

10.1039/c8cy01370e ◽

2018 ◽

Vol 8 (20) ◽

pp. 5155-5164 ◽

Cited By ~ 7

Author(s):

Matthew E. Potter ◽

Julija Kezina ◽

Richard Bounds ◽

Marina Carravetta ◽

Thomas M. Mezza ◽

...

Keyword(s):

Active Sites ◽

Acid Catalysis ◽

Solid Acid ◽

Acid Sites ◽

Beckmann Rearrangement ◽

Solid Acid Catalysts ◽

Acid Catalysts

Framework topology and the acid sites significantly influence the Beckmann rearrangement, affecting the design of solid-acid catalysts.

Download Full-text

Hybrid organic‐inorganic acid catalysts: The effect of active sites localization on catalytic characteristics in the processes of alcohols' etherification. A review

Journal of Applied Polymer Science ◽

10.1002/app.51926 ◽

2021 ◽

pp. 51926

Author(s):

Nina V. Vlasenko ◽

Peter E. Strizhak

Keyword(s):

Active Sites ◽

Acid Catalysts ◽

Inorganic Acid

Download Full-text

The active sites of microporous solid acid catalysts

Phase Transitions ◽

10.1080/01411599708223730 ◽

1997 ◽

Vol 61 (1-4) ◽

pp. 67-81 ◽

Cited By ~ 18

Author(s):

Rajiv Shah ◽

Julian D. Gale ◽

Michael C. Payne

Keyword(s):

Active Sites ◽

Solid Acid ◽

Solid Acid Catalysts ◽

Acid Catalysts

Download Full-text

What catalysis needs from the electron microscopist

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105539 ◽

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.

Download Full-text

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168104 ◽

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).

Download Full-text