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Title: Adsorption and Reaction of Methanol on Thin-film Cerium Oxide

Abstract

Formaldehyde adsorption and reaction have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The formaldehyde behavior was examined as a function of temperature, exposure and Ce oxidation state. Formaldehyde chemisorbs on fully oxidized CeO{sub 2} as dioxymethylene, CH{sub 2}O{sub 2}. The dioxymethylene decomposes and desorbs as formaldehyde between 200 K and 400 K. No other products are formed. On reduced ceria, formaldehyde also adsorbs as dioxymethylene. In addition to the formaldehyde desorption between 200 K and 400 K, a more strongly bound form of dioxymethylene is formed that produces formaldehyde at 440 K. Above 400 K, some of the dioxymethylene reacts to form formate and methoxy on the surface. These species decompose to produce H{sub 2}, CO and CH{sub 2}O above 500 K.

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
913977
Report Number(s):
BNL-78545-2007-JA
Journal ID: ISSN 0039-6028; SUSCAS; TRN: US0801444
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Surf. Sci.; Journal Volume: 600
Country of Publication:
United States
Language:
English
Subject:
10 SYNTHETIC FUELS; 43 PARTICLE ACCELERATORS; ADSORPTION; CERIUM OXIDES; DESORPTION; FORMALDEHYDE; FORMATES; METHANOL; THIN FILMS; NSLS; national synchrotron light source

Citation Formats

Mullins,D., Robbins, M., and Zhou, J. Adsorption and Reaction of Methanol on Thin-film Cerium Oxide. United States: N. p., 2006. Web. doi:10.1016/j.susc.2006.02.011.
Mullins,D., Robbins, M., & Zhou, J. Adsorption and Reaction of Methanol on Thin-film Cerium Oxide. United States. doi:10.1016/j.susc.2006.02.011.
Mullins,D., Robbins, M., and Zhou, J. Sun . "Adsorption and Reaction of Methanol on Thin-film Cerium Oxide". United States. doi:10.1016/j.susc.2006.02.011.
@article{osti_913977,
title = {Adsorption and Reaction of Methanol on Thin-film Cerium Oxide},
author = {Mullins,D. and Robbins, M. and Zhou, J.},
abstractNote = {Formaldehyde adsorption and reaction have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The formaldehyde behavior was examined as a function of temperature, exposure and Ce oxidation state. Formaldehyde chemisorbs on fully oxidized CeO{sub 2} as dioxymethylene, CH{sub 2}O{sub 2}. The dioxymethylene decomposes and desorbs as formaldehyde between 200 K and 400 K. No other products are formed. On reduced ceria, formaldehyde also adsorbs as dioxymethylene. In addition to the formaldehyde desorption between 200 K and 400 K, a more strongly bound form of dioxymethylene is formed that produces formaldehyde at 440 K. Above 400 K, some of the dioxymethylene reacts to form formate and methoxy on the surface. These species decompose to produce H{sub 2}, CO and CH{sub 2}O above 500 K.},
doi = {10.1016/j.susc.2006.02.011},
journal = {Surf. Sci.},
number = ,
volume = 600,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Formaldehyde adsorption and reaction have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The formaldehyde behavior was examined as a function of temperature, exposure and Ce oxidation state. Formaldehyde chemisorbs on fully oxidized CeO{sub 2} as dioxymethylene, CH{sub 2}O{sub 2}. The dioxymethylene decomposes and desorbs as formaldehyde between 200 K and 400 K. No other products are formed. On reduced ceria, formaldehyde also adsorbs as dioxymethylene. In addition to the formaldehyde desorption between 200 K and 400 K, a more strongly bound form of dioxymethylene is formed that produces formaldehyde at 440more » K. Above 400 K, some of the dioxymethylene reacts to form formate and methoxy on the surface. These species decompose to produce H{sub 2}, CO and CH{sub 2}O above 500 K.« less
  • The adsorption and reaction of hydrogen sulfide, H{sub 2}S, have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The behavior of the H{sub 2}S was examined as a function of Ce oxidation state. H{sub 2}S weakly chemisorbs on fully oxidized CeO{sub 2} desorbing near 155 K. Hydrogen from the H{sub 2}S reacts with the surface O to desorb as water between 200 K and 450 K. When ca. 20% of the Ce{sup 4+} is reduced to Ce{sup 3+} more H{sub 2}S dissociates to -OH and -SH and water is produced near 580more » K. When the ceria is ca. 70% reduced, water formation is suppressed and H{sub 2} desorbs near 580 K. S 2p photoelectron spectroscopy indicates the decomposition of H{sub 2}S into -SH and then -S as the sample is annealed from 100 K to 600 K. O 1s photoemission indicated the presence of H{sub 2}O and -OH.« less
  • The adsorption and reaction of methanethiol, CH{sub 3}SH, have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The behavior of the CH{sub 3}SH was examined as a function of the Ce oxidation state. CH{sub 3}SH weakly interacts with fully oxidized CeO{sub 2}(1 1 1) forming both chemisorbed CH{sub 3}SH and CH{sub 3}S + OH. OH forms through the reaction of the sulfhydrol H with the surface O. These species recombine and desorb near 180 K leaving the surface virtually clean. When the ceria is ca. 50% reduced, the chemisorbed CH{sub 3}SH desorbsmore » near 150 K while the CH{sub 3}S + OH are stable to 400 K. These species react above 450 K to produce predominantly CH{sub 4} and CH{sub 3}SH. A small amount of CH{sub 2}O and water are also formed through reaction with the O in the ceria. Atomic S is left on the surface. S 2p, C 1s and O 1s soft X-ray photoelectron spectroscopy were used to identify the nature of the chemisorbed species and the adsorption site of the CH{sub 3}S or S.« less