Preparation, characterisation and catalytic activities of supported Pd-Ce systems
1 and 2% Pd-Ce supported catalysts were prepared by ion-exchange and impregnation methods using PdCl[sub 2] and Pd(NH[sub 3])[sub 4][NO[sub 3]][sub 2] as precursors respectively. Ceria was added as a promoter for the system. The cerium loadings used were between 0.1--0.4% for 2%Pd and 0.1--0.2% for 1%Pd. The samples were all calcined and reduced at 723K. Tpr studies allowed the optimum temperature of sample reduction to be ascertained. The rate and extent of CO chemisorption on various samples were also studied using a volumetric system. The results (with the exception of 2%Pd/SiO[sub 2].3%Ce(I.E) which showed an exception high uptake of CO) indicated that the Pd dispersion and surface area decreased significantly with increased cerium loading. XPS studies were of limited value in indicating the surface compositions of the samples. The activities of the Pd-CoO[sub y] or PdO[sub x]-CeO[sub y] ((x < < < y) ie. x is a very small number and y is less than 2) phases supported on silica for propane dehydrogenation and n-butane hydrogenolysis were investigated. It was found that in both reactions the catalysts prepared by ion-exchange showed higher activity than catalysts prepared by the impregnation method. In general the specific rates of propane dehydrogenation and n-butane hydrogenolysis did not decrease with increased CeO[sub y] loading. Added CeO[sub y] blocks the metal surface and decreases the number of adsorption sites on Pd and hence reduces its surface area. However, surprisingly this did not appear to hinder the catalytic activity and the reasons for this are given.
- Research Organization:
- Brunel Univ., Uxbridge (United Kingdom)
- OSTI ID:
- 5601763
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALKANES
BUTANE
CATALYST SUPPORTS
CATALYTIC EFFECTS
CERIUM
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
DEHYDROGENATION
ELEMENTS
HYDROCARBONS
IMPREGNATION
ION EXCHANGE
METALS
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM METALS
PROPANE
RARE EARTHS
REDUCTION
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SURFACE AREA
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS