The AIPO4 polymorphs structure in the light of Raman and IR spectroscopy studies

Rokita, M.; Handke, M.; Mozgawa, W.

doi:10.1016/s0022-2860(00)00620-7

Cited by 89 publications

(77 citation statements)

References 3 publications

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“…Other more subtle features are present in this region, including the ν(P-O) stretch at 1270 cm -1 , which is omnipresent in AlPO materials. [22] Introducing ethanol into the system significantly changes the spectra ( Figures 3 and 4). Focusing first on the hydrogen stretching region (4000 to 3000 cm -1 ) water is displaced by ethanol, as the characteristic broad hydrogen-bonding bands between 3700 -3500 cm -1 are now absent.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Potter

Aswegen

Gibson

et al. 2016

Phys. Chem. Chem. Phys.

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The increased demand for bulk hydrocarbons necessitates research into increasingly sustainable, energy-efficient catalytic processes. Owing to intricately designed structure-property correlations, SAPO-34 has become established as a promising material for the low temperature ethanol dehydration to produce ethylene. However, further optimization of this process requires a precise knowledge of the reaction mechanism at a molecular level. In order to achieve this a range of spectroscopic characterization techniques are required to probe both the interaction with the active site, and also the wider role of the framework. To this end we employ a combination of in situ infra-red and neutron scattering techniques to elucidate the influence of the surface ethoxy species in the activation of both diethyl ether and ethanol, towards the improved formation of ethylene at low temperatures. The combined conclusions of these studies is that the formation of ethylene is the rate determining step, which is of fundamental importance towards the development of this process and the introduction of bio-ethanol as a viable feedstock for ethylene production.

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Section: Resultsmentioning

confidence: 99%

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Potter

Aswegen

Gibson

et al. 2016

Phys. Chem. Chem. Phys.

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“…[61][62][63][64] The most obvious changes upon heating are a decrease in the intensities and sharpening of the broad band between ∼3000 and . These bands represent water molecules associated with hydrated aluminum phosphate, O-H stretching, and H-O-H bending modes, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…63 Finally, the band at ∼700 cm -1 (band no. 10) corresponds to the Al-O mode, [61][62][63][64] and it increases in intensity with increasing temperature (see Figure 6). Spectrum d in Figure 6 represents pure berlinite formed after 12 h at 200°C; the existence of this anhydrous phase is again confirmed by the absence of the water peaks in this spectrum.…”

Section: Resultsmentioning

confidence: 99%

Precipitation of Iron and Aluminum Phosphates Directly from Aqueous Solution as a Function of Temperature from 50 to 200 °C

Roncal-Herrero

Rodríguez-Blanco

Benning

et al. 2009

Crystal Growth & Design

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ABSTRACT:The nucleation and crystallization of Al and Fe phosphate phases directly from aqueous solutions were investigated experimentally in batch reactors at 50 to 200°C and pH 1.6. The mineralogy, elemental composition, and morphology of the formed solids were characterized by X-ray diffraction, spectroscopy, and high-resolution microscopic techniques. The corresponding dissolved aqueous Al, Fe, and P concentrations were analyzed by spectroscopic and chromatographic techniques. In all experiments Al and Fe phosphate phases readily precipitate from supersaturated solutions. Precipitation is initiated by the nucleation and growth of amorphous Al or Fe phosphate precursors. These crystallize at T = 100°C to either variscite and metavariscite or strengite and phosphosiderite, respectively. At T g 150°C, these Al and Fe amorphous phases recrystallize to either berlinite or ferric giniite, respectively. The composition of the aqueous solution in all cases evolves rapidly to near saturation with respect to variscite and strengite. These observations suggest that Al and Fe phosphates may be critical to limiting aqueous phosphate availability in many natural environments.

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“…Therefore, AlPO 4 consists of [PO 4 ] 32 tetrahedra isolated by Al 31 cations and does not present any covalent oxygen bridges between Al and P atoms. [8] This structure may also explain why bonding occurs between PO 4 and RhO x at the RhO x /AlPO 4 interface.…”

Section: Rh Nanoparticle Anchoring On Metal Oxides and Metal Phosphatesmentioning

confidence: 98%

Rh Nanoparticle Anchoring on Metal Phosphates: Fundamental Aspects and Practical Impacts on Catalysis

Machida

2016

The Chemical Record

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Metal phosphates stabilize Rh nanoparticles on their surface via Rh-O-P bonds, in contrast to the Rh-O-M bonds formed on metal oxides (MO ). The local structure, electronic structure, and redox properties of Rh nanoparticles anchored on metal phosphates, and their practical impacts on catalysis, are reviewed based on recent publications from the author's research group. Because of the covalency of the Rh-O-P bond, Rh oxide is readily reduced to metallic Rh having a higher catalytic activity, whereas Rh oxide on metal oxide supports is more difficult to reduce with an increase of the anchoring strength. Furthermore, Rh metal shows a higher tolerance to reoxidation when supported on metal phosphates because the Rh-O-P bond is preserved under reducing atmospheres. The electron deficiency of Rh metal is another feature that affects its catalytic properties, and the extent of the electron deficiency can be tuned by replacing the metal in the metal phosphate with one of higher basicity. Further impacts on practical performance (thermal stability, poisoning stability, and lean NO purification) in automobile catalyst applications are also described.

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The AIPO4 polymorphs structure in the light of Raman and IR spectroscopy studies

Cited by 89 publications

References 3 publications

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Precipitation of Iron and Aluminum Phosphates Directly from Aqueous Solution as a Function of Temperature from 50 to 200 °C

Rh Nanoparticle Anchoring on Metal Phosphates: Fundamental Aspects and Practical Impacts on Catalysis

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