silaneclay TEOS is more amenable than silicaclay - PowerPoint PPT Presentation
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Title: silaneclay TEOS is more amenable than silicaclay
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Nanoporous Silicate Catalyst Design
Nanocomposite Aspects
Giselle Sandí and Kathleen Carrado Chemistry
Division, Argonne National Laboratory, Argonne,
Illinois
Motivation Develop a fundamental understanding
between synthesis and the resulting structure,
reactivity, and selectivity of a catalyst.
Tailored silicates comprise the focus of
elucidating the role of supported metal metal
sulfide particle morphology.
Pt(0) NANOPARTICLES ON SILICA-CLAY
- for oxidation, hydrogenation,
- dehydrogenation reactions
- 2.4 wt Pt(0)
- two morphologies
- RAFTS - within galleries
- (1.7 x 9.4 nm ave.) unusual
- occurrence on clays
- SPHERES - interlayer and
- surface (2.8 nm ave.)
- Accomplishments
- In situ SAXS successfully used for the first
time to probe layer silicate formation. - Metal nanoparticle dispersions (Pt, Au) on
synthetic clays PCNs rare raft formation
observed in one system. - Hydrodesulfurization (HDS) activity of
CoMoS- silicates measured a unique CoMoS
particle morphology is observed. - A grafted organo-hybrid was synthesized
these allow for more versatility in
functionalization. - An enzyme mimic (cyt c) was immobilized on an
organo-modified synthetic clay surface.
Pt(0) NANOPARTICLES ON POLYMER- CLAY
NANOCOMPOSITES (PCNs)
- no evidence of rafts
- spheres are only in polymer phase
- spheres also on most natural clays
- compare Pt(0) morphology wrt reactivity
silica-clay
silane-clay
- catalysts compared wrt silica sol size (11, 15,
24 nm) - probed effects on mesostructuring wrt support
integrity - CoMoS phase
- 15 nm silica-clays were optimum for HDS, deep
HDS - collaborations w/ C. Marshall (ANL) C. Song
(PSU) - conversion, selectivity similar to commercial
IN SITU SAXS STUDIES OF FORMATION
- silane-clay (TEOS) is more amenable than
silica-clay - collaboration w/ S. Seifert (XSD-APS) P.
Thiyagarajan (PNS) - customized flow cell design
optimum clay morphology optimum CoMoS phase,
optimum HDS activity?
Li, Appl. Catal. A Gen (2004) 273, 233
H3
- 15 nm silica-clays were most crystalline
- (XRD, TEM-ED)
- textural morphology collapsed for 11 nm
- sample after CoMoS loading
Less active CoMoS-Al2O3 typical monolayers
More active CoMoS-ZrO2-Al2O3 multilayers more
active sites
- different equations from silica-clay
- all parameters plateau at 10 hrs
- size information radius of gyration (Rg)
grows from 110 to 350 Å - size information length scale factor
increases, ? particle volume2 - shape information surface fractal dimension
(multiscale)
- Future Directions
- In situ SAXS methods for monitoring catalyst
formation and operando - methods for catalytic reactivity.
- Tailored spacing of grafted
- organics for biomolecule
- metal catalysis,
- immobilization.
- Applications lie in catalysis,
- adsorption, polymer
- nanocomposites (PCN)
- films/membranes, etc.
DERIVATIZED I/O-HYBRID FUNCTIONALIZED LAYERS
Acknowledgment DOE contract W-31-109-ENG-38
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