Influence of the starting aluminum salt on the surface and acid properties of AlPO/sub 4/ catalysts precipitated with ammonium hydroxide

Journal Article · Sun May 01 00:00:00 EDT 1988 · J. Catal.; (United States)

OSTI ID:6961624

Campelo, J M; Garcia, A; Luna, D; Marinas, J M

In this paper, the influence of the starting aluminum salt (chloride, nitrate, or sulfate) and the pretreatment temperature (773-1273 K) on textural properties, crystal structure, and surface acidity of AlPO/sub 4/ (Al/P = 1) catalysts was studied in order to learn how preparation conditions affect catalyst activity in organocationic reactions. The catalysts were characterized using nitrogen adsorption, X-ray diffraction, infrared spectroscopy, and thermogravimetric analyses. The surface acid properties were determined using a dynamic method that consists of determining the AlPO/sub 4/'s catalytic activity in cyclohexene skeletal isomerization (CSI), a reaction that requires the presence of strong surface acid sites. Catalytic activity (as apparent rate constants), activation energies, and selectivities to 1-methylcyclopentene (1-MCP) were calculated in terms of Bassett-Habgood's kinetic model for first-order processes in which the surface reaction is the controlling step and the partial pressure of the reactant is low. Significant differences in structure, texture, surface acidity, and catalytic activity in CSI were found, showing that the aluminum starting salt plays an important role in the final properties of AlPO/sub 4/ (Al/P molar ratio = 1) catalysts. Thus, aluminum nitrate yielded material with higher surface area and low activity for CSI while aluminum sulfate resulted in higher surface acidity, and hence catalytic activity for CSI, although the sample is highly crystalline exhibiting low surface area. Aluminum chloride produces porous catalysts although they are less acidic.

• Research Organization: Univ. of Cordoba (Spain)
• OSTI ID: 6961624
• Journal Information: J. Catal.; (United States), Vol. 111:1
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM PHOSPHATES
CATALYTIC EFFECTS
CHEMICAL PREPARATION
SURFACE PROPERTIES
CYCLOALKENES
ISOMERIZATION
ACTIVATION ENERGY
ADSORPTION
ALUMINIUM CHLORIDES
ALUMINIUM NITRATES
ALUMINIUM SULFATES
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
HEAT TREATMENTS
INFRARED SPECTRA
NITROGEN
POROSITY
SURFACE AREA
TEXTURE
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION
ALKENES
ALUMINIUM COMPOUNDS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
ENERGY
GRAVIMETRIC ANALYSIS
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
NITRATES
NITROGEN COMPOUNDS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
SCATTERING
SORPTION
SPECTRA
SULFATES
SULFUR COMPOUNDS
SYNTHESIS
THERMAL ANALYSIS
020400* - Petroleum- Processing
400201 - Chemical & Physicochemical Properties