On the relation between particle morphology, structure of the metal-support interface, and catalytic properties of Pt/{gamma}-Al{sub 2}O{sub 3}

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0330· OSTI ID:501839

Vaarkamp, M ^[1]; Miller, J T; Modica, F S ^[2]; Koningsberger, D C ^[3]

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1. Eindhoven Univ. of Technology (Netherlands)
2. AMOCO Research Center, Naperville, IL (United States)
3. Utrecht Univ. (Netherlands)

The relation between the catalytic activity, electronic properties, morphology, and structure of the metal-support interface was studied for Pt/{gamma}-Al{sub 2}O{sub 3} after low (300{degrees}C, LTR) and high temperature reduction (450{degrees}C, HTR). EXAFS revealed that after LTR the platinum particles were three-dimensional, contained 11 Pt atoms on average, and were at a distance of 2.7 {Angstrom} from the support oxygen. During HTR, the morphology of the platinum particles changed from three-dimensional to rafts with a structure similar to Pt(100), as indicated by a decrease in the Pt-Pt coordination number and the absence of the third coordination shell in the EXAFS spectrum. After HTR the Pt-O distance was shortened to 2.2 {Angstrom} due to the desorption of hydrogen from the metal-support interface. The shortening of the Pt-O distance upon HTR treatment agrees with previous studies on zeolite supported platinum. However, zeolite supported platinum particles retained their three-dimensional structure upon HTR. The changes in the structure of the catalyst affected the catalytic, chemisorption, and electronic properties. After HTR the selectivity for hydrogenolysis of both neopentane and methylcyclopentane to methane decreased. At the same time the specific activity for neopentane isomerization and methylcylopentane ring opening increased. The hydrogen chemisorption capacity after HTR was lower than after LTR. HTR shifted the asymmetric linear CO infrared absorption from 2063 to 2066 cm{sup -1}. 45 refs., 13 figs., 6 tabs.

• OSTI ID: 501839
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 163; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
40 CHEMISTRY
ALKANES
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHEMISORPTION
HETEROGENEOUS CATALYSIS
HYDROGEN
HYDROGENATION
ISOMERIZATION
MORPHOLOGY
PLATINUM
SORPTIVE PROPERTIES