Ga[sub 13], Al[sub 13], GaAl[sub 12], and chromium-pillared montmorillonites: Acidity and reactivity for cumene conversion

Journal Article · Sat May 01 00:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1132· OSTI ID:6155009

Bradley, S M; Kydd, R A ^[1]

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1. Univ. of Calgary, Alberta (Canada)

A comparison has been made of the acidic characters of a series of metal polyoxocation pillar interlayered clay minerals (M-PILCs) by studying the infrared spectra of adsorbed pyridine. These comparisons were made for Ga[sub 13]-, Al[sub 13]- and GaAl[sub 12]-PILCs, and for Na[sup +]-exchanged montmorillonite (Na-STx-1). The Ga[sub 13]-PILC, was found to exhibit the strongest Lewis acid sites, followed by the AL[sub 13]-, and GaAl[sub 12]-PILCs and then by the Ns-STx-1. The relative number of Lewis acid sites, however, was found to be much greater for the GaAl[sub 12]-PILC, particularly after calcination at higher temperatures, indicating that the Ga[sub 13] Lewis acid sites did not have as high a thermal stability. The Broensted acidic characters for the pillared clays depend on the pillar, and follow the general decreasing order of abundance of GaAl[sub 12]-, Al[sub 13], and Ga[sub 13]-PILC when expressed as absorbance per unit mass. When the acidities per unit surface area were estimated, however, the Ga[sub 13]-PILCs were found to have the greatest number. This indicated that while the pillars contribute to the PILC acidities primarily through increasing the exposed phyllosilicate sheet surface areas, there is also a significant effect arising from the acidic characters of the pillars themselves. The dehydrogenation activities of Ga[sub 13]-, GaAl[sub 12]-, Al[sub 13]-, and Na-STx-1, in addition to a chromium polyoxocation-PILC, were compared by observing the products formed upon reaction with the model compound cumene. The Ga[sub 13]- and chromium-PILCs and the Na-Stx-1 exhibited almost exclusively dehydrogenation activities, whereas the Al[sub 13]- and GaAl[sub 12]-PILCs exhibited both cracking and dehydrogenation behaviors. These results prove that the pillars themselves can very strongly effect the catalytic activities of the PILCs. 3 refs., 6 figs., 2 tabs.

• OSTI ID: 6155009
• Journal Information: Journal of Catalysis; (United States), Vol. 141:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM COMPOUNDS
CATALYTIC EFFECTS
CHROMIUM COMPOUNDS
CUMENE
CRACKING
DEHYDROGENATION
GALLIUM COMPOUNDS
MONTMORILLONITE
ABSORPTION SPECTROSCOPY
ADSORPTION
BROENSTED ACIDS
CALCINATION
CONVERSION
HOMOGENEOUS CATALYSIS
INFRARED SPECTRA
ION EXCHANGE
LEWIS ACIDS
PYRIDINE
SORPTIVE PROPERTIES
STRUCTURAL CHEMICAL ANALYSIS
SURFACE AREA
AROMATICS
AZINES
CATALYSIS
CHEMICAL REACTIONS
CLAYS
DECOMPOSITION
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
PYROLYSIS
SORPTION
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties