CFD simulation of the ethylbenzene dehydrogenation reaction in the fixed bed reactor with a cylindrical catalyst of various sizes

In this paper, the Discrete Element Method of simulation was used to study the catalytic granule size effect on the efficiency of a bed reactor for the ethylbenzene dehydrogenation reaction. The model constructed for the laboratory experiment was made of catalyst granules of lengths 3, 6 and 9 mm, and diameters 2.8, 3, and 3.2 mm. A detailed evaluation of the catalyst total surface area and porosity effect was conducted owing to the analysis of particles size effect on the packing. Different results were observed for a wide feed gas mixture rate. Calculations performed allowed to deduce dependences of the reaction product concentration, the pressure drops, and the reactor productivity for all the particle sizes investigated.

Catalytic properties and chemical stability of potassium polyferrites with the addition of four-charged cations

In order to elucidate the effect exerted by the addition of four-charged cations on the composition, chemical stability and catalytic properties, samples of potassium polyferrites with the β′′-alumina type structure of the composition K2FeII1+qFeIII10–2q MeqIVO17, where Me is Ce, Ti, Zr, and q = 0÷1.0, were synthesized. The mechanism of the effect of four-charged cations on the activity, selectivity of action and corrosion resistance of β′′-potassium polyferrite has been determined. Polyferrites doped with four-charged cations are characterized by a decrease in the specific rate of styrene formation and an increase in the selectivity of action in the ethylbenzene dehydrogenation reaction. The destabilizing effect of titanium additives is revealed, which is expressed in facilitating the emission of an alkali metal from the crystal lattice of polyferrite. Cerium additives lead to the destruction of the polyferrite structure due to the reduction of Ce4+ → Се3+ at the q parameter values above 0.6. Zirconium additives do not reduce the corrosion resistance of ferrite systems under the conditions of the dehydrogenation reaction.