Acrylonitrile from propane on (VO)[sub 2]P[sub 2]O[sub 7] with preadsorbed ammonia. 1. Role of competitive adsorption phenomena in determining selectivity

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

DOI:https://doi.org/10.1006/jcat.1993.1190· OSTI ID:5846023

Centi, G; Tosarelli, T; Trifiro, F ^[1]

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1. Universita di Bologna (Italy)

The dependence on time-on-stream of the catalytic behavior of (VO)[sub 2]P[sub 2]O[sub 7] and [alpha][sub 1]-VPO[sub 5] with preadsorbed ammonia in the aerobic and anaerobic interaction with propane is reported. The rate of propane conversion and the selectivity to acrylonitrile depends on the surface coverage with ammonia. Three different limiting surface situations for vanadyl pyrophosphate as a function of the amount of adsorbed ammonia were found: (a) for high surface coverage with adsorbed ammonia, propane is oxidatively dehydrogenated to propylene, but is not further oxidized to acrylonitrile or to carbon oxides; (b) for an intermediate surface coverage with adsorbed ammonia, the selectivity to acrylonitrile is maximum; and (c) for a very low surface coverage with adsorbed ammonia, the rate of propane depletion is higher, but mainly carbon oxides are formed. the dependence of the activity on the surface coverage with ammonia was attributed to a competitive adsorption between ammonia and oxygen on coordinatively unsaturated vanadyl sites. In addition, the comparison of the evolution of the catalytic behavior of both (VO)[sub 2]P[sub 2]O[sub 7] and [alpha][sub 1]-VPO[sub 5] in propane conversion in the presence and absence of gaseous oxygen suggests a possible role of adsorbed oxygen species in the mechanism of propane activation and selective transformation to acrylonitrile. 23 refs., 9 figs.

• OSTI ID: 5846023
• 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
PYROPHOSPHATES
CATALYTIC EFFECTS
VANADIUM OXIDES
ADSORPTION
AMMONIA
ANAEROBIC CONDITIONS
CARBON OXIDES
DEHYDROGENATION
HETEROGENEOUS CATALYSIS
PROPANE
SORPTIVE PROPERTIES
ALKANES
CARBON COMPOUNDS
CATALYSIS
CHALCOGENIDES
CHEMICAL REACTIONS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
NITRILES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
SORPTION
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing