Hydrogenation of 1-butene and 1,3-butadiene mixtures over Pd/ZnO catalysts
- Institute of Isotopes of the Hungarian Academy of Sciences, Budapest (Hungary)
- Rice Univ., Houston, TX (United States)
Several palladium catalysts supported on ZnO with different loadings and dispersions have been prepared, characterized, pretreated, and tested for the selective hydrogenation of small amounts of 1,3-butadiene in 1-butene. Hydrogen treatment at temperatures above 423 K caused a marked decrease in catalytic activity and a simultaneous increase in selectivity for reduction of butadiene primarily to olefins. Such treatment also caused partial reduction of the ZnO support which resulted in the formation of PdZn intermetallic phases (XRD results). XPS measurements suggested that the Pd crystallites were [open quotes]decorated[close quotes] with reduced Zn metal which significantly decreased the availability of the Pd adsorption sites, as determined by hydrogen and carbon monoxide chemisorption. Alternate oxidation and temperature-programmed reduction cycles could distinguish between the formation of (PdO)[sub s] and oxidation of the reduced Zn. Even though the overall activity was decreased after high-temperature exposure to hydrogen, the turnover frequency for the smaller number of active sites remained virtually unchanged. Moreover, the activation energy and reaction orders were not altered. High-temperature reduction also decreased the trans/cis-2-butene ratio formed from the butadiene; this may reflect slow interconversion between the syn and anti conformation of the 1,3-butadiene adsorbed on the Zn-decorated surface. These experiments have identified some of the important roles of the support and pretreatment conditions on the performance of such catalysts. 50 refs., 9 figs., 8 tabs.
- OSTI ID:
- 6153626
- Journal Information:
- Journal of Catalysis; (United States), Vol. 141:2; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
BUTADIENE
HYDROGENATION
BUTENES
PALLADIUM
CATALYTIC EFFECTS
ZINC OXIDES
ACTIVATION ENERGY
ALKENES
CARBON MONOXIDE
CATALYST SUPPORTS
CATALYSTS
CHEMICAL REACTION KINETICS
CHEMISORPTION
OXIDATION
PHOTOELECTRON SPECTROSCOPY
REDUCTION
STRUCTURAL CHEMICAL ANALYSIS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
DIENES
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
HYDROCARBONS
KINETICS
METALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
POLYENES
REACTION KINETICS
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
TRANSITION ELEMENTS
ZINC COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing