The invention describes a process for producing a catalyst useful for the epoxidation of an olefin. An electric motor generates a rotational output to be used to switch the ranges of an automatic transmission. At lower catalyst temperatures, more exhaust is metered via the bypass passage to enable catalyst temperature to be maintained above an activation level. Gas dissolution can be reduced because the dispersion liquid does not come into contact with gases at pressures higher than the atmospheric pressure and engulffing gas or deformation of solid microparticles can be avoided because no pump is used.