The effect of oxygen on the conversion of light paraffins on ZSM-5 zeolites

Journal Article · Wed Feb 01 04:00:00 EST 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90049-3· OSTI ID:6911379

Centi, G; Golinelli, G ^[1]

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1. Universita di Bologna (Italy)

The oxygen effect in the conversion of ethane, propane, and n-butane to aromatics using two H-ZSM-5 zeolites with different Si/Al ratios is studied. The presence of small amounts of gas-phase oxygen increases benzene-toluene-xylene formation, in particular at the lower reaction temperatures (below 773 K). The enhancement factor compared to anaerobic activity is higher for the less reactive alkane (ethane) and for the less active zeolite (Si/Al = 164) which also shows the lower total oxidation activity. The formation of carbon oxides decreases considerably when the surface acidity is inhibited by potassium exchange, and the K zeolite is active only in the oxidative dehydrogenation of the alkane. However, it was found that the aerobic activity of the zeolite is also correlated to surface acidity. It is suggested that the main oxygen effect is in the first stage of alkane activation, enhancing the formation of the corresponding olefin. The creation of new active sites was attributed to the interaction of oxygen with solid-state defects forming very reactive oxygen free radical species. Their activity, however, is inhibited during reaction due the formation of carbonaceous residues.

• OSTI ID: 6911379
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 115:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ALKALI METALS
ALKANES
ALKYLATED AROMATICS
ALUMINIUM
AROMATICS
BENZENE
BUTANE
CARBON
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHEMICAL REACTIONS
DEACTIVATION
DEHYDROGENATION
DEPOSITION
ELEMENTS
ETHANE
HYDROCARBONS
INHIBITION
INORGANIC ION EXCHANGERS
ION EXCHANGE
ION EXCHANGE MATERIALS
MATERIALS
METALS
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN
PH VALUE
POTASSIUM
PROPANE
QUANTITY RATIO
RADICALS
REFORMER PROCESSES
SEMIMETALS
SILICON
SURFACE PROPERTIES
SYNTHESIS
TOLUENE
XYLENES
ZEOLITES