The structure and activity of silica-supported palladium-cobalt alloys. I. Alloy homogeneity, surface composition, and activity for neopentane conversion

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1235· OSTI ID:5602045

Juszczyk, W; Karpinski, Z; Lomot, D; Pielaszek, J ^[1]; Paal, Z ^[2]; Stakheev, A Yu ^[3]

---

1. Polish Academy of Sciences, Warsaw (Poland)
2. Hungarian Academy of Sciences, Budapest (Hungary)
3. N.D. Zelinsky Institute of Organic Chemistry, Moscow (Russian Federation)

Chemisorption of H[sub 2] and CO, temperature-programmed reduction (TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and neopentane conversion show that differences in preparation method and overall metal loading lead to the formation of different Pd-Co bimetallic materials (changes in reducibility, metal particle size, and lateral homogeneity). Well-homogenized Pd-Co particles exhibit a very pronounced minimum in the plot of catalytic activity versus Pd-Co alloy composition. At the same time, a maximum exists in the isomerization selectivity vs the alloy composition. These deviations from the catalytic behavior of physical mixtures of the monometallic (Pd and Co) catalysts provide a basis for the estimation of how two metals interact with each other in a supported catalyst. Incipient wetness impregnation of silica by considerable amounts (10 wt%) of metal salts leads to the formation of catalyst precursors which are fully reduced at 380[degrees]C yielding good dispersion and lateral homogeneity. Chemisorption and in situ XRD studies are compatible with the kinetic investigations, but information on metal interaction by these methods is less clear. For high metal-loaded Pd-Co/SiO[sub 2] catalysts, comparison of H[sub 2] chemisorption and XRD data suggests surface enrichment in palladium, which is confirmed by XPS. 26 refs., 6 figs., 4 tabs.

• OSTI ID: 5602045
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 142:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
2-2-DIMETHYLPROPANE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
ALLOYS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
COBALT ALLOYS
COHERENT SCATTERING
CONVERSION
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
HYDROCARBONS
HYDROGEN
ISOMERIZATION
KINETICS
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM ALLOYS
PARTICLE SIZE
PHOTOELECTRON SPECTROSCOPY
PLATINUM METAL ALLOYS
REACTION KINETICS
REDUCTION
SCATTERING
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SIZE
SORPTION
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE DEPENDENCE
X-RAY DIFFRACTION