Infrared spectroscopic study of magnesium oxide catalysts doped with sodium ions

• Autorzy: Ignaczak W. , Jóżwiak W. , Szubiakiewicz E. , Paryjczak T.
• Języki publikacji: EN

Abstrakty

EN

Infrared results concerning the surface species in MgO catalysts doped with Na+ ions are presented. Different surface carbonate structures and hydroxyls groups have been found. It was assumed that created carbonate compounds could be involved in decreasing of MgO specific surface area. Sodium carbonate and unidentate carbonate structures may cause elimination and blockage of low coordination sites of MgO surface, being responsible both for hydrogen detachment from CH4 molecules and for oxidation of methyl radicals to carbon oxides - the undesired reactions of oxidative coupling of methane (OCM). It was observed that increasing temperature led to decomposition of surface bicarbonate and unidentate carbonate structures. Some of them are being reconverted to more stable bicarbonate structures. Carbon dioxide and water desorptions result in gradual restoration of low coordinated sites of MgO, corresponding to high selectivity to C2 hydrocarbon formation. Sodium ions may also cause structural changes in MgO lattice. The catalysts were active and selective above 950 K for C2 hydrocarbon formation, although sodium carbonate is sufficiently stable under the conditions of the OCM process.

Słowa kluczowe

EN

magnesium oxide; catalysis selectivity; IR spectroscopy; adsorption

• Wydawca: Polskie Towarzystwo Chemiczne
• Czasopismo: Polish Journal of Chemistry
• Rocznik: 1999
• Tom: vol. 73 nr 4
• Strony: 645--654

Twórcy

autor

Ignaczak W.

autor

Jóżwiak W.

autor

Szubiakiewicz E.

autor

Paryjczak T.

• Instytut Chemii Politechnika Łódź ul. Żwirki 36 90-924 Łódź