ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The Oxidative Dehydrogenation of Alkanes C₃—C₄ by Carbon Dioxide

M. Králik, V. Macho, E. Jurečková, and L. Jureček

Department of Organic Technology, Faculty of Chemical Technology, Slovak University of Technology, SK-812 37 Bratislava

E-mail: kralik@chelin.chtf.stuba.sk

Abstract: The oxidative dehydrogenation of propane, butane, isobutane, and their mixtures, by carbon dioxide over manganese-, chromium-, copper-, and silver-based catalysts at temperatures from 700 up to 850 °C at the atmospheric pressure was studied using a continuous reactor. All the tested catalysts have exhibited a low activity for this type of process, which was demonstrated by comparison with the results obtained over the catalyst which did not contain dehydrogenation- and cracking-active sites. The yield of alkenes has been controlled mainly by temperature and the residence time. The highest yield of alkenes was approximately 55 % at the mole ratio of alkanes to CO₂ equal to 1:1.35, the temperature 840°C, and the space velocity GHSV = 650 dm³ h^-1 dm^-3 (with a gas flow-rate measured at 25°C). On the basis of a simple equilibrium model, the behaviour of the studied system is discussed. From both the experimental data and theoretical calculations, the potential usefulness of carbon dioxide for improving the yield of alkenes in the dehydrogenation processes and a mild-temperature pyrolysis process is demonstrated. Carbon dioxide seems to be important: as a reactant; to enhance the production of alkenes, especially ethylene; to prevent from coking; as a dilutant of the reaction mixture; and as a heat supporter.

Full paper in Portable Document Format: 525a682.pdf

Chemical Papers 52 (5) 682–691 (1998)