Abstract: Light olefins such as propene and butenes are indispensable building blocks in production of large variety of polymers and valuable chemical substances. Although a major part of the C3-C4 olefins is produced in fluid catalytic cracking (FCC) and steam cracking of gaseous and liquid feedstock, on-purpose technologies for C3-C4 olefins’ manufacture such as paraffins dehydrogenation have become of great importance because of the lessening the production capacity of the former ones as a result of the shift from oil to gas based feedstock. Chromia/alumina catalysts are used for C3-C4 paraffins dehydrogenation. The catalyst formulation includes promotion with alkali metals, usually K, in order to enhance the activity and tune the selectivity. This work describes the effect of potassium loading on the physicochemical properties of supported CrOx-species in chromia/alumina catalysts (4.5-5.0 at. Ct/nm2 ) and on the kinetic parameters of isobutane dehydrogenation. It was shown that Cr2O3 in reduced catalysts was in X-ray amorphous state with approximately the same average chromia dispersion as measured by XRD and XPS. ESR spectroscopy revealed that Cr2O3 – clusters’ size increased monotonically with the K loading. At the same time very strong basic sites were created as shown by IR spectroscopy of adsorbed CDCl3. Dehydrogenation activity pattern had a maximum at K loading of 3 wt.%. The logarithm of the Arrhenius pre-exponential factor was shown to depend linearly upon the effective activation energy of dehydrogenation (so called “compensation effect”). Both parameters increased with the potassium loading.

Cite: Nazimov D.A. , Klimov O.V. , Saiko A.V. , Trukhan S.N. , Paukshtis E.A. , Prosvirin I.P. , Cherepanova S.V. , Noskov A.S.
Effect of the K Loading on the Kinetic Parameters of Isobutane Dehydrogenation over Chromia/Alumina Catalysts
The 8th Asia-Pacific Congress on Catalysis 04-07 Aug 2019