A ceramic membrane reactor system was developed for the continuous ammoximation of acetone to acetone oxime over titanium silicalites-1 (TS-1) catalysts. The effects of catalyst concentration and micro-sized silica particles on the performances of the membrane reactor system were examined in detail. For the membrane reactor system the optimal catalyst concentration is 17.0 g L-1, obviously higher than the one obtained from the previous experiments in a batch glass reactor, because the strong adhesion of TS-1 catalyst particles on the surface of the pipeline, the tank and the membrane leads to the decrease of effective catalyst concentration. Adding the microsized silica particles can effectively inhibit the decrease of TS-1 catalysts concentration in reaction slurry and improve the operation stability of the membrane reactor system significantly, benefiting from the scouring effect and the attachment of TS-1 particles on the surfaces of larger silica particles. According to the estimation of hydrodynamic forces acting on particles, microsized silica particles are hard to deposit on the contact surfaces at the studied conditions and therefore a longer stable operation of the membrane reactor system has been achieved. (C) 2009 Published by Elsevier B.V.