US EPA

1446969 

Journal Article 

Participation of linear methoxy species bonded to Ti4+ sites in the methanol carbonylation catalyzed by TiO2-supported rhodium: An infrared investigation 

Flores-Escamilla, GA; Fierro-Gonzalez, JC 

2012 

Yes 

Journal of Molecular Catalysis A: Chemical
ISSN: 1381-1169 

359 

49-56 

10.1016/j.molcata.2012.03.020 

WOS:000304634300008 

TiO2-supported rhodium samples synthesized from the Rh-6
(CO)(16) complex were catalytically active and selective for the gas-phase methanol carbonylation
at 140 degrees C and atmospheric pressure in the presence of methyl iodide as promoter. Infrared
(IR) spectra recorded during catalysis allowed the identification of molecularly adsorbed
methanol, together with linear, doubly, and triply-bridged surface methoxy species on Ti4+ sites
of the support. IR bands characteristic of rhodium complexes that might be regarded as reaction
intermediates were also observed, in addition to bands assigned to surface acetate species
attributed to the formation of methyl acetate. Our results reveal that only linear methoxy
species on Ti4+ sites react with flowing CO in the presence of CH3I to give methyl acetate,
whereas bridged methoxy species and molecularly adsorbed methanol are only spectators in methanol
carbonylation. (C) 2012 Elsevier B.V. All rights reserved. 

Methanol carbonylation; Supported rhodium; Infrared spectroscopy