Mechanistic Studies of Methanol Oxidation to Formaldehyde on Isolated Vanadate Sites Supported on High Surface Area Zirconia

Journal Article · Tue May 12 04:00:00 EDT 2009 · J. Phys. Chem. C112:6404,2008

OSTI ID:958609

Bronkema, J L; Bell, A T

The oxidation of methanol on both ZrO{sub 2} and V/ZrO{sub 2} was investigated using temperature-programmed experiments together with in situ infrared spectroscopy. Characterization of V/ZrO{sub 2} after calcination by Raman spectroscopy and XANES shows that the vanadium is present as isolated VO{sub 4} units in a distorted tetrahedral geometry. Methanol was found to adsorb dissociatively on both Zr-O-Zr and V-O-Zr species to create Zr-OCH{sub 3}/Zr-OH and V-OCH{sub 3}/Zr-OH pairs, respectively. Upon heating, CH{sub 3}OH and H{sub 2}O desorb initially from all samples. Above 423 K, surface formate species are detected while H{sub 2} and CO are the main products formed on ZrO{sub 2}. Upon addition of vanadium, CH{sub 2}O production increases dramatically during temperature-programmed reaction. The absence of CH{sub 2}O during temperature-programmed desorption and oxidation experiments on V/ZrO{sub 2} is likely due to rapid readsorption of the product onto the ZrO{sub 2} support, leading to the formation of formate species and H{sub 2}. The apparent activation energy for V/ZrO{sub 2} is 18 kcal/mol. The activities of isolated vanadate species supported on SiO{sub 2}, TiO{sub 2}, and ZrO{sub 2} are compared and discussed.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 958609
• Report Number(s): SLAC-REPRINT-2009-079
• Journal Information: J. Phys. Chem. C112:6404,2008, Journal Name: J. Phys. Chem. C112:6404,2008 Journal Issue: 16 Vol. 112; ISSN 1932-7447
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
ACTIVATION ENERGY
CALCINATION
DESORPTION
FORMALDEHYDE
FORMATES
GEOMETRY
HEATING
METHANOL
OXIDATION
Other
CHEM
PRODUCTION
RAMAN SPECTROSCOPY
SPECTROSCOPY
SURFACE AREA
VANADATES
VANADIUM