Direct Observation of Extremely Low Temperature Catalytic Dehydrochlorination of 1,1,1-Trichloroethane over Platinum

Lee, Adam F.; Carr, Paul A.; Wilson, Karen

doi:10.1021/jp046813h

Cited by 9 publications

(13 citation statements)

References 24 publications

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“…Similarly dehalogenation of cis -1,2- and trans -1,2-dichloroethene (DCE) has been reported above 200 K on Pt(111), although a more recent synchrotron study by Cassuto et al found both DCE and 1,1,2-trichloroethene (TCE) simply desorbed at 250 K without any reaction . More recently we have reported that above 130 K dehydrochlorination of 1,1,1-trichloroethane is observed via rapid sequential C−Cl bond scission to form a surface alkylidyne intermediate and HCl. , …”

Section: Introductionmentioning

confidence: 71%

“…The latter is attributed to the strong adsorption of hydrocarbon reaction intermediates and irreversible coke deposition; HCl is not believed to play a significant role in catalyst self-poisoning. We have recently shown that there is a delicate balance between low-temperature poisoning by accumulated surface chlorine and high-temperature coking over a model Pt(111) catalyst, which also extends to practical dispersed Pt/γ-Al 2 O 3 catalysts …”

Section: Introductionmentioning

confidence: 76%

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Sulfate-Enhanced Catalytic Destruction of 1,1,1-Trichlorethane over Pt(111)

Lee

Wilson

2005

J. Phys. Chem. B

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The catalytic destruction of 1,1,1-trichloroethane (TCA) over model sulfated Pt(111) surfaces has been investigated by fast X-ray photoelectron spectroscopy and mass spectrometry. TCA adsorbs molecularly over SO4 precovered Pt(111) at 100 K, with a saturation coverage of 0.4 monolayer (ML) comparable to that on the bare surface. Surface crowding perturbs both TCA and SO4 species within the mixed adlayer, evidenced by strong, coverage-dependent C 1s and Cl and S 2p core-level shifts. TCA undergoes complete dechlorination above 170 K, accompanied by C-C bond cleavage to form surface CH3, CO, and Cl moieties. These in turn react between 170 and 350 K to evolve gaseous CO2, C2H6, and H2O. Subsequent CH3 dehydrogenation and combustion occurs between 350 and 450 K, again liberating CO2 and water. Combustion is accompanied by SO4 reduction, with the coincident evolution of gas phase SO2 and CO2 suggesting the formation of a CO-SOx surface complex. Reactively formed HCl desorbs in a single state at 400 K. Only trace (<0.06 ML) residual atomic carbon and chlorine remain on the surface by 500 K.

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 76%

Sulfate-Enhanced Catalytic Destruction of 1,1,1-Trichlorethane over Pt(111)

Lee

Wilson

2005

J. Phys. Chem. B

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“…In contrast, the m Pd NPs produced more ethylene than ethane, i.e., only the polyhedral and multiply-twinned Pd particles approached the desired selectivity (Figure 12). The deactivation of the Pd NPs, induced by the chlorine poisoning of the surfaces, was beneficial for the selectivity (Figures 11a and 12a), but this was more pronounced for the curved (stepped) s Pd NPs [7,10,21,25,110,[112][113][114][115][116]. The stepped surface structures prefer the π adsorption mode, while smooth (111) planes of m Pd NPs favor the di-σ adsorption mode (Figure 10) [95,101,104,106,109,110,112,117,118].…”

Section: Catalytic Application Of Pt and Pd Nps For Tce Hydrodechlorinationmentioning

confidence: 99%

The Effect of Shape-Controlled Pt and Pd Nanoparticles on Selective Catalytic Hydrodechlorination of Trichloroethylene

et al. 2020

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Tailoring the shape of nanoscale materials enables obtaining morphology-controlled surfaces exhibiting specific interactions with reactants during catalytic reactions. The specifics of nanoparticle surfaces control the catalytic performance, i.e., activity and selectivity. In this study, shape-controlled Platinum (Pt) and Palladium (Pd) nanoparticles with distinct morphology were produced, i.e., cubes and cuboctahedra for Pt and spheres and polyhedra/multiple-twins for Pd, with (100), (111 + 100), curved/stepped and (111) facets, respectively. These particles with well-tuned surfaces were subsequently deposited on a Zirconium oxide (ZrO2) support. The morphological characteristics of the particles were determined by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD), while their adsorption properties were investigated by Fourier transform infrared spectroscopy (FTIR) of CO adsorbed at room temperature. The effect of the nanoparticle shape and surface structure on the catalytic performance in hydrodechlorination (HDCl) of trichloroethylene (TCE) was examined. The results show that nanoparticles with different surface orientations can be employed to affect selectivity, with polyhedral and multiply-twinned Pd exhibiting the best ethylene selectivity.

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“…In an effort to understand PGM hydrodechlorination catalysts, we used TP-XPS to investigate the thermal chemistry of 1,1,1-trichloroethane (TCA), a common commercial solvent until 2005, over Pt (111). 166 TCA adsorbs non-dissociatively at 100 K, bonding through the three Cl atoms in a vertical geometry akin to ethylidyne. Between 120-200 K, around 60% of chemisorbed TCA undergoes rapid, stepwise C-Cl bond cleavage via CH 3 CCl 2 and CH 3 CCl metastable surface intermediates, liberating atomic chlorine and ethylidyne (Fig.…”

Section: C-x Activationmentioning

confidence: 99%

Surface X-ray studies of catalytic clean technologies

2010

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The rational design of new heterogeneous catalysts for clean chemical technologies can be accelerated by molecular level insight into surface chemical processes. In situ methodologies, able to provide time-resolved and/or pressure dependent information on the evolution of reacting adsorbed layers over catalytically relevant surfaces, are therefore of especial interest. Here we discuss recent applications of surface X-ray techniques to surface-catalysed oxidations, (de)hydrogenations, C-C coupling, dehalogenation and associated catalyst restructuring, and explore how these may help to shape future sustainable chemistry.

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Direct Observation of Extremely Low Temperature Catalytic Dehydrochlorination of 1,1,1-Trichloroethane over Platinum

Cited by 9 publications

References 24 publications

Sulfate-Enhanced Catalytic Destruction of 1,1,1-Trichlorethane over Pt(111)

Sulfate-Enhanced Catalytic Destruction of 1,1,1-Trichlorethane over Pt(111)

The Effect of Shape-Controlled Pt and Pd Nanoparticles on Selective Catalytic Hydrodechlorination of Trichloroethylene

Surface X-ray studies of catalytic clean technologies

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