Carbon-13 Nuclear Magnetic Resonance Spectroscopic Studies of 13CO Adsorbed on Platinum Particles in L-Zeolites

Oc Hee Han, Gustavo Larsen, Gary L. Haller, Kurt W. Zilm

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

13CO chemisorbed on platinum particles in L-zeolite has been investigated by static and magic angle spinning NMR spectroscopy. The representative spectra are composed of a broad asymmetric peak with a center of gravity at 230±30 ppm and a sharp symmetric peak at 124±2 ppm which is tentatively assigned to physisorbed CO2 on inner walls of L-zeolite. Overall, the broad resonance component is similar to our previous results of highly dispersed (80-96%) CO/Pt/silica or CO/Pt/alumina samples, still showing metallic characters. The principal difference is in the first moment value. The broad peak in the spectra is assigned to CO linearly bound to Pt particles in the L-zeolites, and indicates a distribution of isotropic shifts from bonding site to bonding site. The NMR results reported here manifest that the Pt particles inside of the L-zeolites channels are not collectively the same with the ones supported on silica or alumina with similar dispersion in terms of Pt particle shape and/or ordering of Pt atoms in a particle. As a result, Pt particles of CO/Pt/L-zeolite were agglomerated accompanying CO desorption upon annealing. There were no definite changes in the NMR spectra due to differences of exchanged cations. Comparison of our observation on CO/Pt/L-zeolite with Sharma et al.'s reveals that even when the first moment, the linewidth, and the relaxation times of the static spectra and the dispersion measured by chemisorption are similar, the properties of Pt particles can be dramatically different. Therefore, it is essential to take advantage of the strengths of several techniques together in order to interpret data reliably, especially for the highly dispersed samples.

Original languageEnglish (US)
Pages (from-to)934-942
Number of pages9
JournalBulletin of the Korean Chemical Society
Volume19
Issue number9
StatePublished - Sep 20 1998

Fingerprint

Zeolites
Carbon Monoxide
Platinum
Carbon
Nuclear magnetic resonance
Aluminum Oxide
Silicon Dioxide
Magic angle spinning
Chemisorption
Linewidth
Relaxation time
Nuclear magnetic resonance spectroscopy
Cations
Desorption
Gravitation
Annealing
Atoms

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Carbon-13 Nuclear Magnetic Resonance Spectroscopic Studies of 13CO Adsorbed on Platinum Particles in L-Zeolites. / Han, Oc Hee; Larsen, Gustavo; Haller, Gary L.; Zilm, Kurt W.

In: Bulletin of the Korean Chemical Society, Vol. 19, No. 9, 20.09.1998, p. 934-942.

Research output: Contribution to journalArticle

@article{fe7c099738fe4ff28723972e4397561b,
title = "Carbon-13 Nuclear Magnetic Resonance Spectroscopic Studies of 13CO Adsorbed on Platinum Particles in L-Zeolites",
abstract = "13CO chemisorbed on platinum particles in L-zeolite has been investigated by static and magic angle spinning NMR spectroscopy. The representative spectra are composed of a broad asymmetric peak with a center of gravity at 230±30 ppm and a sharp symmetric peak at 124±2 ppm which is tentatively assigned to physisorbed CO2 on inner walls of L-zeolite. Overall, the broad resonance component is similar to our previous results of highly dispersed (80-96{\%}) CO/Pt/silica or CO/Pt/alumina samples, still showing metallic characters. The principal difference is in the first moment value. The broad peak in the spectra is assigned to CO linearly bound to Pt particles in the L-zeolites, and indicates a distribution of isotropic shifts from bonding site to bonding site. The NMR results reported here manifest that the Pt particles inside of the L-zeolites channels are not collectively the same with the ones supported on silica or alumina with similar dispersion in terms of Pt particle shape and/or ordering of Pt atoms in a particle. As a result, Pt particles of CO/Pt/L-zeolite were agglomerated accompanying CO desorption upon annealing. There were no definite changes in the NMR spectra due to differences of exchanged cations. Comparison of our observation on CO/Pt/L-zeolite with Sharma et al.'s reveals that even when the first moment, the linewidth, and the relaxation times of the static spectra and the dispersion measured by chemisorption are similar, the properties of Pt particles can be dramatically different. Therefore, it is essential to take advantage of the strengths of several techniques together in order to interpret data reliably, especially for the highly dispersed samples.",
author = "Han, {Oc Hee} and Gustavo Larsen and Haller, {Gary L.} and Zilm, {Kurt W.}",
year = "1998",
month = "9",
day = "20",
language = "English (US)",
volume = "19",
pages = "934--942",
journal = "Bulletin of the Korean Chemical Society",
issn = "0253-2964",
publisher = "Korean Chemical Society",
number = "9",

}

TY - JOUR

T1 - Carbon-13 Nuclear Magnetic Resonance Spectroscopic Studies of 13CO Adsorbed on Platinum Particles in L-Zeolites

AU - Han, Oc Hee

AU - Larsen, Gustavo

AU - Haller, Gary L.

AU - Zilm, Kurt W.

PY - 1998/9/20

Y1 - 1998/9/20

N2 - 13CO chemisorbed on platinum particles in L-zeolite has been investigated by static and magic angle spinning NMR spectroscopy. The representative spectra are composed of a broad asymmetric peak with a center of gravity at 230±30 ppm and a sharp symmetric peak at 124±2 ppm which is tentatively assigned to physisorbed CO2 on inner walls of L-zeolite. Overall, the broad resonance component is similar to our previous results of highly dispersed (80-96%) CO/Pt/silica or CO/Pt/alumina samples, still showing metallic characters. The principal difference is in the first moment value. The broad peak in the spectra is assigned to CO linearly bound to Pt particles in the L-zeolites, and indicates a distribution of isotropic shifts from bonding site to bonding site. The NMR results reported here manifest that the Pt particles inside of the L-zeolites channels are not collectively the same with the ones supported on silica or alumina with similar dispersion in terms of Pt particle shape and/or ordering of Pt atoms in a particle. As a result, Pt particles of CO/Pt/L-zeolite were agglomerated accompanying CO desorption upon annealing. There were no definite changes in the NMR spectra due to differences of exchanged cations. Comparison of our observation on CO/Pt/L-zeolite with Sharma et al.'s reveals that even when the first moment, the linewidth, and the relaxation times of the static spectra and the dispersion measured by chemisorption are similar, the properties of Pt particles can be dramatically different. Therefore, it is essential to take advantage of the strengths of several techniques together in order to interpret data reliably, especially for the highly dispersed samples.

AB - 13CO chemisorbed on platinum particles in L-zeolite has been investigated by static and magic angle spinning NMR spectroscopy. The representative spectra are composed of a broad asymmetric peak with a center of gravity at 230±30 ppm and a sharp symmetric peak at 124±2 ppm which is tentatively assigned to physisorbed CO2 on inner walls of L-zeolite. Overall, the broad resonance component is similar to our previous results of highly dispersed (80-96%) CO/Pt/silica or CO/Pt/alumina samples, still showing metallic characters. The principal difference is in the first moment value. The broad peak in the spectra is assigned to CO linearly bound to Pt particles in the L-zeolites, and indicates a distribution of isotropic shifts from bonding site to bonding site. The NMR results reported here manifest that the Pt particles inside of the L-zeolites channels are not collectively the same with the ones supported on silica or alumina with similar dispersion in terms of Pt particle shape and/or ordering of Pt atoms in a particle. As a result, Pt particles of CO/Pt/L-zeolite were agglomerated accompanying CO desorption upon annealing. There were no definite changes in the NMR spectra due to differences of exchanged cations. Comparison of our observation on CO/Pt/L-zeolite with Sharma et al.'s reveals that even when the first moment, the linewidth, and the relaxation times of the static spectra and the dispersion measured by chemisorption are similar, the properties of Pt particles can be dramatically different. Therefore, it is essential to take advantage of the strengths of several techniques together in order to interpret data reliably, especially for the highly dispersed samples.

UR - http://www.scopus.com/inward/record.url?scp=0342843703&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0342843703&partnerID=8YFLogxK

M3 - Article

VL - 19

SP - 934

EP - 942

JO - Bulletin of the Korean Chemical Society

JF - Bulletin of the Korean Chemical Society

SN - 0253-2964

IS - 9

ER -