Carbonylation of Dimethyl Ether on Rh/Cs2HPW12O40: Solid-State NMR Study of the Mechanism of Reaction in the Presence of a Methyl Iodide Promoter
Full article
| Common |
Language:
Английский,
Genre:
Full article,
Status:
Published,
Source type:
Original
|
| Journal |
Journal of Catalysis
ISSN: 0021-9517
, E-ISSN: 1090-2694
|
| Output data |
Year: 2012,
Volume: 291,
Pages: 9-16
Pages count
: 8
DOI:
10.1016/j.jcat.2012.03.024
|
| Tags |
12-Tungstophosphoric acid, 13C solid-state NMR, Carbon monoxide, Carbonylation, Dimethyl ether, Mechanism, Methyl iodide promoter, Rh methyl, Rhodium carbonyls |
| Authors |
Kazantsev Maxim S.
1
,
Luzgin Mikhail V.
1
,
Volkova Galina G.
1
,
Stepanov Alexander G.
1
|
| Affiliations |
| 1 |
Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
|
|
Using C-13 solid-state nuclear magnetic resonance, the carbonylation of dimethyl ether (DME) with carbon monoxide has been studied on solid Rh/Cs2HPW12O40 in the presence of a methyl iodide promoter. The observed decrease in the reaction temperature in comparison with halide-free systems is caused by a change of the reaction mechanism. At first, the activation of the promoter and CO on Rh/Cs2HPW12O40 produces methyl rhodium carbonyl species. Carbon monoxide is then embedded into the Rh-CH3 bond to afford Rh acetyl. Rapid migration of the acetyl group from the Rh center to a Bronsted acid site of Rh/Cs2HPW12O40 gives rise to an acetate group attached to the Keggin unit (Keggin acetate). Bronsted acid sites provide dimethyl ether activation with the formation of a surface methoxy group. The latter, through reaction with hydrogen iodide, which is produced at the stage of Rh acetyl-to-Keggin acetate transformation, restores methyl iodide for subsequent carbonylation stages. Methyl acetate formation from a Keggin acetate and DME closes a catalytic cycle.