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Title: Effects of metal-support and metal-promoter interactions on rhodium catalysts for carbon monoxide hydrogenation

Abstract

An investigation was conducted to establish the effects of support composition and promoter content on the hydrogenation of CO over rhodium. Comparisons of Rh supported on SiO/sub 2/, La/sub 2/O/sub 3/, Nd/sub 2/O/sub 3/, and Sm/sub 2/O/sub 3/ demonstrated that rare earth oxide supports provide high selectivities for methanol and ethanol synthesis, whereas silica provides a high selectivity to methane. Detailed studies of Rh/SiO/sub 2/ and Rh/La/sub 2/O/sub 3/ indicate that there is a metal-support interaction between Rh and La/sub 2/O/sub 3/. The metal-support interaction is a result of a modification of the catalytic and chemisorptive properties of the surface of the Rh crystallites by the deposition of LaO/sub x/ moieties derived from the support. The effect of Rh particle size was studied by investigating Rh/SiO/sub 2/ and Rh/La/sub 2/O/sub 3/ catalysts varying in Rh loading. The intrinsic effects of Rh particle size on the activity and selectivity were determined from the results for Rh/SiO/sub 2/. The catalytic and chemisorptive properties of a particular Rh/La/sub 2/O/sub 3/ catalyst are determined by a combination of the intrinsic effect of Rh particle size and the extent of coverage of the Rh crystallites by LaO/sub x/ moieties. In order to investigate in moremore » detail the specific effects of LaO/sub x/ decoration in the absence of changes in Rh particle size, Rh/SiO/sub 2/ was promoted with varying quantities of La. La promotion results in increases in the turnover frequencies for the formation of all products and an increase in the selectivity for oxygenates. Activity and selectivity are also found to be strong functions of La content. Chemisorbed CO is believed to occur near the periphery of LaO/sub x/ patches, where lanthanum cations interact directly with the oxygen end of the CO molecule. The effect of the CO-La cation interaction is to weaken the C-O bond, thereby making it more susceptible to cleavage and/or hydrogenation.« less

Authors:
Publication Date:
Research Org.:
California Univ., Berkeley (USA)
OSTI Identifier:
5457699
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
10 SYNTHETIC FUELS; CARBON MONOXIDE; HYDROGENATION; METHANATION; ETHANOL; SYNTHESIS; LANTHANUM OXIDES; CATALYST SUPPORTS; METHANE; METHANOL; NEODYMIUM OXIDES; RHODIUM; CATALYTIC EFFECTS; SAMARIUM OXIDES; SILICA; CATALYSIS; ALCOHOLS; ALKANES; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; CHEMICAL REACTIONS; ELEMENTS; HYDROCARBONS; HYDROXY COMPOUNDS; LANTHANUM COMPOUNDS; METALS; MINERALS; NEODYMIUM COMPOUNDS; ORGANIC COMPOUNDS; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; PLATINUM METALS; RARE EARTH COMPOUNDS; SAMARIUM COMPOUNDS; SILICON COMPOUNDS; SILICON OXIDES; TRANSITION ELEMENTS; 090221* - Alcohol Fuels- Chemical Synthesis- (1976-1989); 090121 - Hydrocarbon Fuels- Chemical Synthesis- (1976-1989)

Citation Formats

Underwood, R P. Effects of metal-support and metal-promoter interactions on rhodium catalysts for carbon monoxide hydrogenation. United States: N. p., 1986. Web.
Underwood, R P. Effects of metal-support and metal-promoter interactions on rhodium catalysts for carbon monoxide hydrogenation. United States.
Underwood, R P. Wed . "Effects of metal-support and metal-promoter interactions on rhodium catalysts for carbon monoxide hydrogenation". United States.
@article{osti_5457699,
title = {Effects of metal-support and metal-promoter interactions on rhodium catalysts for carbon monoxide hydrogenation},
author = {Underwood, R P},
abstractNote = {An investigation was conducted to establish the effects of support composition and promoter content on the hydrogenation of CO over rhodium. Comparisons of Rh supported on SiO/sub 2/, La/sub 2/O/sub 3/, Nd/sub 2/O/sub 3/, and Sm/sub 2/O/sub 3/ demonstrated that rare earth oxide supports provide high selectivities for methanol and ethanol synthesis, whereas silica provides a high selectivity to methane. Detailed studies of Rh/SiO/sub 2/ and Rh/La/sub 2/O/sub 3/ indicate that there is a metal-support interaction between Rh and La/sub 2/O/sub 3/. The metal-support interaction is a result of a modification of the catalytic and chemisorptive properties of the surface of the Rh crystallites by the deposition of LaO/sub x/ moieties derived from the support. The effect of Rh particle size was studied by investigating Rh/SiO/sub 2/ and Rh/La/sub 2/O/sub 3/ catalysts varying in Rh loading. The intrinsic effects of Rh particle size on the activity and selectivity were determined from the results for Rh/SiO/sub 2/. The catalytic and chemisorptive properties of a particular Rh/La/sub 2/O/sub 3/ catalyst are determined by a combination of the intrinsic effect of Rh particle size and the extent of coverage of the Rh crystallites by LaO/sub x/ moieties. In order to investigate in more detail the specific effects of LaO/sub x/ decoration in the absence of changes in Rh particle size, Rh/SiO/sub 2/ was promoted with varying quantities of La. La promotion results in increases in the turnover frequencies for the formation of all products and an increase in the selectivity for oxygenates. Activity and selectivity are also found to be strong functions of La content. Chemisorbed CO is believed to occur near the periphery of LaO/sub x/ patches, where lanthanum cations interact directly with the oxygen end of the CO molecule. The effect of the CO-La cation interaction is to weaken the C-O bond, thereby making it more susceptible to cleavage and/or hydrogenation.},
doi = {},
url = {https://www.osti.gov/biblio/5457699}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1986},
month = {1}
}

Thesis/Dissertation:
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