Acrylonitrile from propane on (VO)[sub 2]P[sub 2]O[sub 7] with preadsorbed ammonia 2. Study of the mechanism of ammonia adsorption and reaction with C[sub 3] hydrocarbons

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1191· OSTI ID:5713917

Centi, G; Perathoner, S ^[1]

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1. Universita di Bologna (Italy)

Infrared data on the time-on-stream changes of the adsorbed species on vanadyl pyrophosphate with preadsorbed ammonia during interaction with propane and oxygen are reported, together with an infrared and thermogravimetric analysis of the ammonia interaction with this catalyst and of the adsorbed species formed in ammonia and propylene coadsorption. Results indicate that (i) ammonia forms mainly ammonium ions at room temperature, but increasing the temperature of interaction up to 400[degrees]C results in a progressive increase in the amount of ammonia coordinated to surface Lewis acid sites; (ii) the amount of adsorbed ammonia at 400[degrees]C corresponds to about a 1:1 NH[sub 3]-to-P surface ratio, but is lower for higher reaction temperatures; (iii) in the presence of gaseous oxygen, the amount of coordinated ammonia decreases, with the probable formation of an amido (NH[sub 2]) species; (iv) propylene is coordinated as a [pi]-bonded complex with vanadium Lewis acid sites and, in the absence of gaseous oxygen, is slowly transformed to acrylonitrile through the intermediate formation of propylamine; and (v) propane does not form adsorbed intermediates in the absence of gaseous oxygen, but in the presence of gaseous oxygen, acrylate species are detected. It is suggested that two pathways of formation of acrylonitrile from propane are present on vanadyl pyrophosphate, the first in anaerobic conditions involving the intermediate formation of propylamine and the second, when O[sub 2] is present, involving the reaction between surface acrylate species and chemisorbed ammonia species. The second pathway is much more rapid than the first. 23 refs., 7 figs.

• OSTI ID: 5713917
• Journal Information: Journal of Catalysis; (United States), Vol. 142:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
ACRYLONITRILE
CHEMICAL PREPARATION
AMMONIA
ADSORPTION
PYROPHOSPHATES
CATALYTIC EFFECTS
VANADIUM OXIDES
ABSORPTION SPECTROSCOPY
ANAEROBIC CONDITIONS
CARBON OXIDES
CATALYSTS
DEHYDROGENATION
HETEROGENEOUS CATALYSIS
LEWIS ACIDS
PROPANE
REACTION INTERMEDIATES
SORPTIVE PROPERTIES
THERMAL GRAVIMETRIC ANALYSIS
ALKANES
CARBON COMPOUNDS
CATALYSIS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
GRAVIMETRIC ANALYSIS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
NITRILES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
SORPTION
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing