Influence of the acid-base character of supported vanadium catalysts on their catalytic properties for the oxidative dehydrogenation of n-butane

Journal Article · Fri Dec 01 04:00:00 EST 1995 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1995.1291· OSTI ID:223999

Blasco, T; Lopez Nieto, J M ^[1]; Dejoz, A ^[2]

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1. Instituto de Tecnologia Quimi ca, Valencia (Spain)
2. Universidade de Valencia, Burjasot (Spain); and others

The oxidative dehydrogenation of n-butane on supported vanadium catalysts has been studied. Al{sub 2}O{sub 3}, sepiolite, hydrotalcite (Mg/Al atomic ratio of 3.0), and MgO were used as supports. The vanadium content of supported catalysts was varied to obtain dispersed vanadium species. The strength and number of Lewis acid sites (determined by FTIR of adsorbed pyridine) decreases in the following trend: V/Al{sub 2}O{sub 3} > V/Sepiolite > V/ hydrotalcite > V/MgO. {sup 51}V NMR spectroscopy indicates that tetrahedral V{sup 5+}-species (with different distortion degree and/or environment) are the main vanadium species. Temperature-programmed reduction results show that the reducibility of catalysts, determined from the onset temperature of H{sub 2}-consumption, decreases in the order V/Al{sub 2}O{sub 3} > V/MgO (first peak) > V/Sepiolite > V/MgO (second peak) {approx} V/hydrotalcite. The catalytic activity for n-butane oxidation follows a trend similar to that observed in TPR, concluding that the catalytic activity is related to the reducibility of surface vanadium species in the catalysts. However, the selectivity to dehydrogenated products, as well as the distribution of C{sub 4}-olefins, can be tentatively related to the acid-base character of catalysts. Thus, the selectivities to 1-butene and butadiene decrease in the order V/MgO > V/Hydrotalcite > V/Sepiolite > V/Al{sub 2}O{sub 3}, while the selectivities to 2-butene and carbon oxides present the opposite trend. 48 refs., 10 figs., 4 tabs.

• OSTI ID: 223999
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 157; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
ALUMINIUM OXIDES
BUTANE
CATALYST SUPPORTS
CATALYTIC EFFECTS
DEHYDROGENATION
LEWIS ACIDS
MAGNESIUM OXIDES
NUCLEAR MAGNETIC RESONANCE
OXIDATION
REDUCTION
SEPIOLITE
TEMPERATURE DEPENDENCE
VANADIUM