A novel perfectly mixed laboratory reactor for determining kinetics of
heterogeneously catalyzed gas-phase reactions has been developed. Per
fect mixing is achieved by circulating the gas in the reactor using an
axial flow impeller in a well streamlined enclosure. Pellets are fixe
d in a rectangular opening in the blades of the impeller. They rotate
with the impeller, thus realizing high particle velocities in the reac
tor. Interparticle mass transfer was studied experimentally by vaporiz
ation of naphthalene pellets. The mass-transfer coefficient in the nov
el reactor was found to depend on the velocity of a particle in the re
actor. Mass-transfer coefficients in an internal recycle reactor at eq
ual impeller tip speeds are 4-6 times lower than those in the novel re
actor, and conditions can be chosen easily where at higher rotational
speeds the mass- and heat-transfer rates are 8-10 times higher than in
classical recycle reactors. The recycle flow rate in a recycle reacto
r was found to depend strongly on the resistance to flow caused by the
catalyst bed itself. The novel reactor was tested under reacting cond
itions using the hydrogenation of ethene.