Decomposition of perfluoro-1-methoxy-2-ethoxy ethane on iron surfaces chemically modified with oxygen

Mary E. Napier, Peter C Stair

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of a model perfluorinated ether, perfluoro-1-methoxy-2-ethoxy ethane, CF3OCF2CF2OCF2CF3, on oxidized polycrystalline iron surfaces and polycrystalline iron surfaces, modified with an overlayer of chemisorbed oxygen. Low temperature adsorption of the perfluorinated ether on both surfaces was molecular. Chemisorption of an oxygen overlayer lowered the reactivity of the surface to adsorption and decomposition of the perfluorinated ether, by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction, which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface via a different pathway from that seen on the clean iron surface. A reaction mechanism is proposed which involves Lewis acid assisted cleavage of the carbon-oxygen bond, with preferential attack at the methoxy carbon.

Original languageEnglish
Pages (from-to)317-328
Number of pages12
JournalSurface Science
Volume316
Issue number3
DOIs
Publication statusPublished - Sep 10 1994

Fingerprint

Ethane
ethane
Iron
Oxygen
Decomposition
decomposition
iron
oxygen
ethers
Ether
Ethers
defluorination
Carbon
Metals
adsorption
Adsorption
carbon
Lewis Acids
High temperature applications
lubricants

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Decomposition of perfluoro-1-methoxy-2-ethoxy ethane on iron surfaces chemically modified with oxygen. / Napier, Mary E.; Stair, Peter C.

In: Surface Science, Vol. 316, No. 3, 10.09.1994, p. 317-328.

Research output: Contribution to journalArticle

@article{139f84f0a8a54254bc3ef761cb2ebccd,
title = "Decomposition of perfluoro-1-methoxy-2-ethoxy ethane on iron surfaces chemically modified with oxygen",
abstract = "Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of a model perfluorinated ether, perfluoro-1-methoxy-2-ethoxy ethane, CF3OCF2CF2OCF2CF3, on oxidized polycrystalline iron surfaces and polycrystalline iron surfaces, modified with an overlayer of chemisorbed oxygen. Low temperature adsorption of the perfluorinated ether on both surfaces was molecular. Chemisorption of an oxygen overlayer lowered the reactivity of the surface to adsorption and decomposition of the perfluorinated ether, by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction, which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface via a different pathway from that seen on the clean iron surface. A reaction mechanism is proposed which involves Lewis acid assisted cleavage of the carbon-oxygen bond, with preferential attack at the methoxy carbon.",
author = "Napier, {Mary E.} and Stair, {Peter C}",
year = "1994",
month = "9",
day = "10",
doi = "10.1016/0039-6028(94)91224-6",
language = "English",
volume = "316",
pages = "317--328",
journal = "Surface Science",
issn = "0039-6028",
publisher = "Elsevier",
number = "3",

}

TY - JOUR

T1 - Decomposition of perfluoro-1-methoxy-2-ethoxy ethane on iron surfaces chemically modified with oxygen

AU - Napier, Mary E.

AU - Stair, Peter C

PY - 1994/9/10

Y1 - 1994/9/10

N2 - Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of a model perfluorinated ether, perfluoro-1-methoxy-2-ethoxy ethane, CF3OCF2CF2OCF2CF3, on oxidized polycrystalline iron surfaces and polycrystalline iron surfaces, modified with an overlayer of chemisorbed oxygen. Low temperature adsorption of the perfluorinated ether on both surfaces was molecular. Chemisorption of an oxygen overlayer lowered the reactivity of the surface to adsorption and decomposition of the perfluorinated ether, by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction, which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface via a different pathway from that seen on the clean iron surface. A reaction mechanism is proposed which involves Lewis acid assisted cleavage of the carbon-oxygen bond, with preferential attack at the methoxy carbon.

AB - Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of a model perfluorinated ether, perfluoro-1-methoxy-2-ethoxy ethane, CF3OCF2CF2OCF2CF3, on oxidized polycrystalline iron surfaces and polycrystalline iron surfaces, modified with an overlayer of chemisorbed oxygen. Low temperature adsorption of the perfluorinated ether on both surfaces was molecular. Chemisorption of an oxygen overlayer lowered the reactivity of the surface to adsorption and decomposition of the perfluorinated ether, by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction, which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface via a different pathway from that seen on the clean iron surface. A reaction mechanism is proposed which involves Lewis acid assisted cleavage of the carbon-oxygen bond, with preferential attack at the methoxy carbon.

UR - http://www.scopus.com/inward/record.url?scp=0028496477&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028496477&partnerID=8YFLogxK

U2 - 10.1016/0039-6028(94)91224-6

DO - 10.1016/0039-6028(94)91224-6

M3 - Article

AN - SCOPUS:0028496477

VL - 316

SP - 317

EP - 328

JO - Surface Science

JF - Surface Science

SN - 0039-6028

IS - 3

ER -