IR study of adsorption and reaction of methylbutynol on the surface of pure and modified MgO catalysts: probing the catalyst surface basicity

Fouad, Nasr E.; Thomasson, P; Knözinger, Helmut

doi:10.1016/s0926-860x(99)00369-5

Cited by 38 publications

(43 citation statements)

References 20 publications

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“…MBOH [(CH 3 ) 2 C(OH)CtCH] has been successfully used to probe reactive surface basic sites. [39][40][41] The absorptions displayed in the RT spectrum occur mostly at frequencies lower than those reported 41 or observed ( Figure S2 and/or Lewis acid sites involving the π-electrons. 40,41 Upon increasing the adsorption temperature to 200°C, remarkable changes occur in the spectra taken from the adsorbed ( Figure S1) and gas-phase species ( Figure S2) of MBOH molecules.…”

Section: Heating In the Absence Of Hcl Vapor 311 The Bulkmentioning

confidence: 64%

“…41,42 The splitting of the ν(HCt) absorption into two absorptions is indicative of MBOH adsorption via two types of acetylenic interactions with the surface: with Lewis acid (Ca 2+ ) and basic (O 2-or OH -) sites. [40][41][42] The latter type of interaction is responsible for the greater red-shift of the ν-(HCt) frequency (to 3258 cm -1 ) relative to that of the former type (to 3325 cm -1 ). [40][41][42] Consistently, the catalytic conversion of MBOH into acetone and acetylene has been reported to occur on surfaces exposing strong basic sites as well as Lewis acid sites.…”

Section: Heating In the Absence Of Hcl Vapor 311 The Bulkmentioning

confidence: 99%

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Structural and Morphological Consequences of High-Temperature Treatments of Hydroxyapatite in the Absence or Presence of HCl Vapor

2005

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Hydroxyapatite [HAP; Ca5(PO4)3(OH)], a biocompatible, osteoconductive material, was perceived, in the present investigation, to mimic a healthy bone mineral. Structural and morphological properties of its bulk and surface were examined versus high-temperature (up to 900 degrees C) thermal treatments in air or wet HCl gas atmosphere, using thermogravimetry, X-ray powder diffractometry, N2 sorptiometry, scanning electron microscopy, X-ray energy dispersive spectroscopy, and ex- and in situ infrared spectroscopy. CO, CDCl3, and methylbutynol were used as infrared probe molecules. Results obtained revealed that, in the absence of HCl, the bulk crystalline structure and the chemical composition of HAP were stable during high-temperature treatments. The surface exposed isolated Lewis acid sites (Ca2+) and reactive base sites (O(x-) and/or OH-) that chemisorbed atmospheric CO2 molecules with the formation of surface carbonate species (CaCO3). It is assumed that surface OH groups may interact with atmospheric oxygen molecules, leading to the formation and incorporation of peroxide (O2(2-) species. In the atmosphere of wet HCl, HAP was shown to suffer loss of chemical integrity, facilitated by its carbonated domains, as well as disintegration (or erosion) of particle aggregates and creation of what appeared to be deep groves.

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Section: Heating In the Absence Of Hcl Vapor 311 The Bulkmentioning

confidence: 64%

Section: Heating In the Absence Of Hcl Vapor 311 The Bulkmentioning

confidence: 99%

Structural and Morphological Consequences of High-Temperature Treatments of Hydroxyapatite in the Absence or Presence of HCl Vapor

2005

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“…MgO and CaO treated at elevated temperature were typical solid bases [20,21]. The XRD pattern of MgO and CaO illustrated that cubic MgO and CaO could be prepared via the dissociation of magnesium hydrate and calcium carbonate, respectively (see Fig.…”

Section: Structuresmentioning

confidence: 99%

Solid base and their performance in synthesis of propylene glycol methyl ether

Zhang

Wang

Wei

et al. 2005

Journal of Molecular Catalysis A: Chemical

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“…Although this fact makes the spectra analysis difficult in terms of distinguishing between unlike adsorbed species, some interesting differences can be pinpointed especially with reference to the saturation degree of the infrared bands observed. The band at 1740 cm -1 , related to the C=O stretching vibration mode of ketones [46,47], is the most significant regardless the material used.…”

Section: Analysis Of the Catalytic Stabilitymentioning

confidence: 98%

Effect of metal modification of titania and hydrogen co-feeding on the reaction pathways and catalytic stability in the acetone aldol condensation

Quesada

Faba

Dı́az

et al. 2019

Journal of Catalysis

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A stable performance of TiO2 catalysts for gas-phase acetone aldol condensation was observed when reduced metals were added (Pt or Ni, 1.5 wt.%) and the reactions were conducted in presence of hydrogen. In both cases, the resulting metal-loaded catalysts are stable for 10 h, whereas continuous deactivation is observed for the parent TiO2 catalyst (573 K). Both the activation of the H2 molecule by metal nanoparticles and the change of the catalytic surface by metal insertion (in the case of Niloaded catalyst) enable suppressing oligomerization (by hindering enolates formation) and the strong adsorption of intermediates (by decreasing the concentration of high-strength acid-basic active sites), respectively. More interestingly, these metals allow to tune the selectivity of the reaction. Indeed, the Ni-loaded titania catalyst is highly selective for the synthesis of α,β-unsaturated ketones (selectivity to unsaturated C6 and C9 species >98 %, at ~12 % acetone conversion), whereas the Pt-loaded one is 2 highly selective to the formation of saturated C6 and C9 ketones (MIBK and DIBK, with selectivities >95 % at ~42 % acetone conversion).The catalytic activity and stability of the two materials (Ni/TiO2 and Pt/TiO2) in both absence and presence of H2 are compared between them and with those of the parent TiO2. The results obtained by the reaction gas-phase analysis are supplemented through different solid characterization techniques (i.e., CO2-TPD and NH3-TPD, HRTEM, XPS, TPO, and DRIFTS).

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IR study of adsorption and reaction of methylbutynol on the surface of pure and modified MgO catalysts: probing the catalyst surface basicity

Cited by 38 publications

References 20 publications

Structural and Morphological Consequences of High-Temperature Treatments of Hydroxyapatite in the Absence or Presence of HCl Vapor

Structural and Morphological Consequences of High-Temperature Treatments of Hydroxyapatite in the Absence or Presence of HCl Vapor

Solid base and their performance in synthesis of propylene glycol methyl ether

Effect of metal modification of titania and hydrogen co-feeding on the reaction pathways and catalytic stability in the acetone aldol condensation

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