Interaction of Platinum and Molybdophosphoric Heteropoly Acid under Conditions of Catalyst Preparation for Benzene
Oxidation to Phenol with an O2–H2 Gas Mixture
Full article
| Common |
Language:
Английский,
Genre:
Full article,
Status:
Published,
Source type:
Translated
|
| Journal |
Kinetics and Catalysis
ISSN: 0023-1584
, E-ISSN: 1608-3210
|
| Output data |
Year: 2006,
Volume: 47,
Number: 5,
Pages: 704-714
Pages count
: 11
DOI:
10.1134/S0023158406050089
|
| Authors |
Kuznetsova L.I.
1
,
Kuznetsova N.I.
1
,
Koshcheev S.V.
1
,
Rogov V.A.
1
,
Zaikovskii V.I.
1
,
Novgorodov B.N.
1
,
Detusheva L.G.
1
,
Likholobov V.A.
2
,
Kochubey D.I.
1
|
| Affiliations |
| 1 |
Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences
|
| 2 |
Institute of Hydrocarbon Processing, Siberian Branch, Russian Academy of Sciences
|
|
The transformations of platinum and a heteropoly acid (HPA) in binary systems prepared from H2PtCl6 or H2PtCl4 and H3PMo12O40 were studied using IR and UV-VIS spectroscopy, elemental analysis, XPS, EXAFS, TPR, and HREM. The calcination of platinum chloride with the HPA to 450°C resulted in the formation of a platinum salt of the HPA along with decomposition products (mixture I). The reduction of calcined samples containing Pt: HPA = 1: 1 with hydrogen at 300°C (mixture II) followed by exposure to air resulted in the regeneration of the HPA structure. The resulting solid samples of Pt 1−n 0 Pt n II ClmOxHy) (H3+p PMo 12−p VI Mo p V O40) (III) contained platinum and molybdenum in both oxidized and reduced states. The following association species were isolated from mixtures I and II by dissolving in water: [Pt n II PMo12O40] (I s) (n = 0.3−0.8) and [Pt n 0 PMo 12 red O40] (II s) (n ≈ 1). Under exposure to air, the solutions of I s were stable (pH ∼2), whereas Ptmet was released from II s. After the drying of I s, the solid association species (Pt n II ClmOxHy). (H3PMo12O40), where n = 0.3−0.8, m = 0.2−1, and x = 3−0, (I solid) were obtained. The I solid/SiO2 supported samples were prepared by impregnating SiO2 with a solution of I s and drying at 100°C. Platinum metal particles of size ∼20 Å and a mixed-valence association species of platinum with the HPA were observed after the reduction of I solid/SiO2 with hydrogen at 100–250°C. These samples were active in the gas-phase oxidation of benzene to phenol at 180°C with the use of an O2-H2-N2 mixture.