An experimental study of the selective oxidation of ethene in a wall cooled tubular packed bed reactor

Abstract

The selective oxidation of ethene over a silver on o-alumina catalyst was studied in a wall cooled tubular reactor. Temperatures were measured inside the bed at different axial and radial positions as well as the overall conversion and selectivity. Locally measured temperatures vary after repacking the bed whereas the global properties do not vary. Angular variations in temperature cannot be described by present day models. The steady state temperature profiles in the packed bed and overall conversion and selectivity as function of different operating conditions are discussed.

Angular temperature variations in a wall‐cooled packed‐bed reactor

“…Temperature variations in the angular coordinate are considered to be secondary in importance, and consequently have been ignored. Angular variations in packed beds do exist (see, e.g., Cresswell, 1986;Borman and Westerterp, 1992;Dixon, 1993). Deviations in temperature have been observed of up to to 12°C around the average temperature for experiments with a total temperature difference over the radius of about 40°C.…”

“…Another approach to average angular variations is repacking the bed (see Borman and Westerterp, 1992;Borkink et al, 1992;and Wijngaarden and Westerterp, 1992b). Angular variations are specific for certain packing and repacking results in a different radial profile for the same operating conditions.…”

“…The temperatures were measured above the packing. Borman and Westerterp (1992) have measured in the bed itself and found variations in the radial temperature profile after repacking that they explained by angularly varying temperatures. They briefly discuss the implications of such variations.…”

A novel reactor for determination of kinetics for solid catalyzed gas reactions

“…A number of problems with this type of reactor have been identified. Whether the reactor can be assumed to behave as perfectly mixed with temperature and concentration gradients having a negligible influence on the experimental re- Table 1. action rates, depends on the recycle and the feed flow rates, the total conversion over the reactor, the reaction kinetics, and the heat of reaction (Borman, 1992). The recycle flow rate is determined by the discharge rate of the blower.…”

“…Unfortunately, this rate is hard to determine, so in practice it is difficult to prove whether perfect mixing has been achieved. The falsification of kinetic data, as well as procedures for correcting data obtained in reactors with a low recycle ratio, have been discussed (Pirjamali et al, 1973;Broucek, 1983;Georgakopoulos and Broucek, 1987;Wedel and Villadsen, 1983;Dumpelmann and Baiker, 1992;Borman, 1992). Generally, a low recycle ratio forces the experimentalist to restrict the overall conversion over the reactor.…”