Influence of chemical reaction rate, diffusion and pore structure on the regeneration of a coked Al2O3-catalyst

Direct detection of coke deposits on fixed bed catalysts by electrical sensors

“…a conductive path with a comparatively low internal resistance dominates the signal. This explanation bases on works of Tang et al [14] where catalyst particles with same geometry under similar reaction conditions were regenerated. This work shows diffusion-limited kinetics above 400 • C. This leads to an increasing concentration of coke in the direction to the center of the catalyst; the higher the temperatures the sharper the profile [3,15].…”

Verkokung und Koksabbrand in heterogenen Katalysatoren

“…dc O 2 =dr 0 für r = 0 (Kornmitte) (11) c O 2 c O 2;G für r = r P (Kornoberfläche) (12) Wie schon bei der Berechnung des Porennutzungsgrads (s. Abschnitt 4) taucht in der Stoffbilanz der Gasphase (Gl. (8) (6)).…”

Modelling of carbon and hydrogen oxidation kinetics of a coked ferrierite catalyst

“…If the catalyst particle is small enough, the effect of internal diffusion on observed formation rates of products can be neglected, but otherwise the diffusion must be taken into account in the modelling of any experimental set-up. The studies of Kern and Jess [6] and Tang et al [7] showed that coke Greek letters α reaction order for oxygen concentration β reaction order for hydrogen concentration oxidation rates of Al 2 O 3 -based catalysts of an industrial particle size (particle diameters 2 and 4.5 mm) are clearly diffusion limited. Tang et al [7] applied a small particle size (0.05-0.11 mm) to obtain the intrinsic kinetic parameters for combustion.…”

“…The studies of Kern and Jess [6] and Tang et al [7] showed that coke Greek letters α reaction order for oxygen concentration β reaction order for hydrogen concentration oxidation rates of Al 2 O 3 -based catalysts of an industrial particle size (particle diameters 2 and 4.5 mm) are clearly diffusion limited. Tang et al [7] applied a small particle size (0.05-0.11 mm) to obtain the intrinsic kinetic parameters for combustion. Quantitative analysis of the reactor outflow must be fast for enough measurements (successive analyses of outflow at different reactor temperatures) to be obtained from a TPO experiment.…”