Study of Adsorption and Reactions of Methyl Iodide on TiO2

Su, Chun; Yeh, Jia‐Hau; Chen, C.-C.; Lin, J.‐C.; Lin, Ja‐Chen

doi:10.1006/jcat.2000.2909

Cited by 34 publications

(13 citation statements)

References 54 publications

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“…However, in the presence of oxygen H 2 O, CO, and CO 2 were also generated. The adsorption and reaction of CH 3 I on powdered TiO 2 and TiO 2 (110) single crystals has been the subject of several studies, which are well documented in the paper of Su et al In our laboratory, we found that Cr 2 O 3 -doped SnO 2 is an active catalyst for the oxidative and nonoxidative decomposition of CH 3 Cl . Supported Pt metals were also applied to catalyze the destruction of these compounds. , McGee et al studied the decomposition of ethyl chloride on supported Pt catalysts.…”

Section: Introductionmentioning

confidence: 65%

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO₂Catalysts

Óvári

Solymosi

2002

Langmuir

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The adsorption and surface reactions of C2H5I on SiO2, Al2O3, MgO, TiO2, and Rh/SiO2 were monitored with Fourier transform infrared spectroscopy. Molecular adsorption was found on all the oxides examined at 206 K. Only reversible adsorption was observed on SiO2, while on the other oxides an ethoxide group was detected from ∼263 K. Surface OH groups and possibly Lewis acidic and/or basic centers are involved in the process. In the case of alumina, one part of C2H5O(a) was formed on a special configuration of active sites (ensemble effect). Spectroscopic identification of C2H5O(a) was confirmed by ethanol adsorption. Ethoxide formation was rather limited on MgO probably due to the lack of strong Lewis acid sites. Dissociative adsorption of C2H5I occurred on Rh/SiO2 at 206 K. Ethylidyne (CCH3(a)) was formed, very probably through an ethyl intermediate. CCH3(a) was stable up to 373 K. In addition, the formation of ethoxide species bonded to the SiO2 support was observed, which was explained with a spillover process of ethyl species from the Rh onto silica.

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Section: Introductionmentioning

confidence: 65%

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO₂Catalysts

Óvári

Solymosi

2002

Langmuir

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“…To confirm the hypothesis, FTIR spectroscopic analyses were employed to investigate the working Rh sites in methanol carbonylation. As shown in Figure 5, the introduction of CH 3 I to Rh@ZSM-5 at 423 K resulted in the appearance of a series of IR bands due to methyl vibrations (Table S6) 42,43 as well as a pair of bands at 1375 and 1315 cm −1 , which should be due to the symmetric and asymmetric stretchings of metal−halogen bonds. In comparison to the reference RhI 3 sample (Figure S21), these two bands shifted to lower frequencies by ∼70 cm −1 , probably induced by the local electric field of MFI zeolites.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

Stabilizing Isolated Rhodium Cations by MFI Zeolite for Heterogeneous Methanol Carbonylation

et al. 2021

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Methanol carbonylation is known as a classic reaction of homogeneous catalysis with large-scale industrial applications. The heterogenization of homogeneous catalysts is being pursued to address the issues of catalyst deactivation and separation encountered in homogeneous systems. Herein, we report the strategy of stabilizing isolated rhodium cations by MFI zeolite to construct highly active Rh@MFI zeolite catalysts for heterogeneous methanol carbonylation. The formation of a zeolite-stabilized [Rh(CO)2I2] analogue during the reaction has been identified to catalyze methanol carbonylation. Moreover, the structure of the zeolite can significantly promote methanol carbonylation within channels through electronic confinment. As a result, a state of the art turnover frequency of 3950 molacetyl/(molRh h) is achieved with the Rh@ZSM-5 catalyst at a low reaction temperature of 423 K. This work presents a simple and general approach toward the heterogenization of homogeneous catalysts for targeted chemical transformations.

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“…The reason for this may be (1) that the 1,4-dioxane formed on the Cu(100) surface below 167 K moves into the FCH 2 CH 2 OH multilayer and makes the active sites on Cu(100) for 1,4-dioxane formation still available, (2) that the presence of the multilayer changes the adsorption geometry of monolayer molecules and lowers the barrier for 1,4-dioxane formation, (3) that the 1,4-dioxane can be generated from the reaction between two FCH 2 CH 2 OH molecules present in the monolayer and multilayer respectively, or (4) that the presence of the multilayer stabilizes the activated complex for the formation of 1,4-dioxane. In the previous studies, it has been shown that dimethyl ether is only generated in the reaction of methyl iodide on TiO 2 (110) at multilayer coverage, and cyclobutane is dissociated at multilayer coverage on Ru(001) at a temperature where the monolayer molecules do not dissociate . Furthermore, alkyl coupling occurs for alkyl iodides on Cu(111) near a monolayer coverage, but not at lower coverages .…”

Section: Resultsmentioning

confidence: 96%

Thermal Decomposition and Adsorption Orientation of 2-Fluoroethanol on Clean and Oxidized Cu(100)

et al. 2003

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Temperature-programmed reaction/desorption and reflection−absorption infrared spectroscopy have been employed to investigate the thermal reactions and adsorption geometry of FCH2CH2OH molecules on clean and oxygen-preadsorbed Cu(100) surfaces. Molecular desorption predominates in heating FCH2CH2OH adsorbed on clean Cu(100). However, ∼20% adsorbed FCH2CH2OH molecules at about half-monolayer coverage dissociate on the surface to form water, ethylene, and 1,4-dioxane. On the other hand, monolayer FCH2CH2OH completely dissociates on oxidized Cu(100) to form 1,4-dioxane and the surface intermediate of FCH2CH2O(a), which further decomposes to evolve FCH2CHO(g) at temperatures higher than ∼350 K. The decomposition of FCH2CH2OH to form FCH2CH2O(a) on oxidized Cu(100) begins at ∼160 K and is completed by 220 K. On clean Cu(100), FCH2CH2OH molecules at ∼0.25 monolayer coverage are adsorbed with the C−C−O skeleton approximately parallel to the surface. The C−C−O skeleton tilts away from the surface as the exposure is increased to a half-monolayer coverage. However, the parallel C−C−O orientation is not observed on the oxidized surface, even at the FCH2CH2OH exposure for a 0.25 monolayer coverage.

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Study of Adsorption and Reactions of Methyl Iodide on TiO2

Cited by 34 publications

References 54 publications

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO₂Catalysts

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO₂Catalysts

Stabilizing Isolated Rhodium Cations by MFI Zeolite for Heterogeneous Methanol Carbonylation

Thermal Decomposition and Adsorption Orientation of 2-Fluoroethanol on Clean and Oxidized Cu(100)

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Study of Adsorption and Reactions of Methyl Iodide on TiO2

Cited by 34 publications

References 54 publications

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO2Catalysts

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO2Catalysts

Stabilizing Isolated Rhodium Cations by MFI Zeolite for Heterogeneous Methanol Carbonylation

Thermal Decomposition and Adsorption Orientation of 2-Fluoroethanol on Clean and Oxidized Cu(100)

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FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO₂Catalysts

FTIR Study of the Interaction of Ethyl Iodide with Different Oxides and Rh/SiO₂Catalysts