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Title: Polymerization and decarbonylation reactions of aldehydes on the Pd(111) surface

Abstract

The adsorption and reaction of formaldehyde, acetaldehyde, and propanal were compared in temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) studies on a clean Pd(111) surface. Formaldehyde reacted upon adsorption at 170 K via decomposition to CO(a) and H(a) and polymerization to paraformaldehyde. In contrast, decomposition of the higher aldehydes required significantly higher temperatures. Acetaldehyde adsorbed on the clean surface in an /eta//sup 2/ configuration and reacted to form stable acetyl species (CH/sub 3/C/double bond/O), which decomposed above 300 K to produce CO(a), H(a), and C/sub 1/ hydrocarbon fragments. Adsorbed acetyl groups were readily identified by the characteristic frequency of their CO stretch at 1565 cm/sup /minus/1/. In competition with decarbonylation, desorption of acetaldehyde occurred at 220 and 325 K. The CO stretch of /eta//sup 2/-acetaldehyde was observed at 1390 cm/sup /minus/1/. Similarly, the adlayer produced by the adsorption of propanal on Pd(111) was a mixture of /eta//sup 2/-propanal and propanoyl species (CH/sub 3/CH/sub 2/C/double bond/O) produced by removal of the aldehyde hydrogen atom. No evidence was found for polymerization of either acetaldehyde or propanal on the clean Pd(111) surface. A kinetic isotope effect was observed in the decomposition of adsorbed acetyl intermediates, suggesting that C-H cleavage ismore » rate determining for this reaction. These results illustrate the pathways, intermediates, and energetics of aldehyde decarbonylation reactions on group VIII metal surfaces and may provide insights into the mechanism of oxygenate synthesis from CO and H/sub 2/.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of Delaware, Newark (USA)
OSTI Identifier:
5637885
DOE Contract Number:  
FG02-84ER13290
Resource Type:
Journal Article
Journal Name:
J. Am. Chem. Soc.; (United States)
Additional Journal Information:
Journal Volume: 111:5
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALDEHYDES; ADSORPTION; POLYMERIZATION; PLATINUM; SORPTIVE PROPERTIES; CARBONYLS; CATALYSTS; DESORPTION; ENERGY-LOSS SPECTROSCOPY; EXPERIMENTAL DATA; ISOTOPE EFFECTS; LAYERS; OXYGEN; REACTION INTERMEDIATES; RESOLUTION; SURFACE PROPERTIES; SURFACES; TEMPERATURE DEPENDENCE; CHEMICAL REACTIONS; DATA; ELECTRON SPECTROSCOPY; ELEMENTS; INFORMATION; METALS; NONMETALS; NUMERICAL DATA; ORGANIC COMPOUNDS; PLATINUM METALS; SORPTION; SPECTROSCOPY; TRANSITION ELEMENTS; 400201* - Chemical & Physicochemical Properties

Citation Formats

Davis, J L, and Barteau, M A. Polymerization and decarbonylation reactions of aldehydes on the Pd(111) surface. United States: N. p., 1989. Web. doi:10.1021/ja00187a035.
Davis, J L, & Barteau, M A. Polymerization and decarbonylation reactions of aldehydes on the Pd(111) surface. United States. https://doi.org/10.1021/ja00187a035
Davis, J L, and Barteau, M A. Wed . "Polymerization and decarbonylation reactions of aldehydes on the Pd(111) surface". United States. https://doi.org/10.1021/ja00187a035.
@article{osti_5637885,
title = {Polymerization and decarbonylation reactions of aldehydes on the Pd(111) surface},
author = {Davis, J L and Barteau, M A},
abstractNote = {The adsorption and reaction of formaldehyde, acetaldehyde, and propanal were compared in temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) studies on a clean Pd(111) surface. Formaldehyde reacted upon adsorption at 170 K via decomposition to CO(a) and H(a) and polymerization to paraformaldehyde. In contrast, decomposition of the higher aldehydes required significantly higher temperatures. Acetaldehyde adsorbed on the clean surface in an /eta//sup 2/ configuration and reacted to form stable acetyl species (CH/sub 3/C/double bond/O), which decomposed above 300 K to produce CO(a), H(a), and C/sub 1/ hydrocarbon fragments. Adsorbed acetyl groups were readily identified by the characteristic frequency of their CO stretch at 1565 cm/sup /minus/1/. In competition with decarbonylation, desorption of acetaldehyde occurred at 220 and 325 K. The CO stretch of /eta//sup 2/-acetaldehyde was observed at 1390 cm/sup /minus/1/. Similarly, the adlayer produced by the adsorption of propanal on Pd(111) was a mixture of /eta//sup 2/-propanal and propanoyl species (CH/sub 3/CH/sub 2/C/double bond/O) produced by removal of the aldehyde hydrogen atom. No evidence was found for polymerization of either acetaldehyde or propanal on the clean Pd(111) surface. A kinetic isotope effect was observed in the decomposition of adsorbed acetyl intermediates, suggesting that C-H cleavage is rate determining for this reaction. These results illustrate the pathways, intermediates, and energetics of aldehyde decarbonylation reactions on group VIII metal surfaces and may provide insights into the mechanism of oxygenate synthesis from CO and H/sub 2/.},
doi = {10.1021/ja00187a035},
url = {https://www.osti.gov/biblio/5637885}, journal = {J. Am. Chem. Soc.; (United States)},
number = ,
volume = 111:5,
place = {United States},
year = {1989},
month = {3}
}