Simulation and experimental studies on the polymer membrane reactor were examined for the vapor-phase MTBE (methyl tert-butyl ether) decomposition, A double pipe (shell and tube type) membrane reactor comprising 12-tungstophosphoricacid catalyst and polymer membrane was designed. The polymer membrane was coated on the porous alumina tube. Polyphenylene oxide (PPO), polysulfone (PSF) or cellulose acetate (CA) was used as a constituent membrane material. It was observed that permeabilities of methanol through each polymer membrane were higher than those of isobutene and MTBE regardless of the kind of polymer membrane used. The selective permeation of methanol through each polymer membrane shifted the chemical equilibrium toward the favorable direction in the MTBE decomposition reaction. MTBE conversions in the membrane reactors were much enhanced compared to the equilibrium conversions. The MTBE conversions were increased with the increase of reaction temperature and with the decrease of reaction pressure. Simulated results were in good agreement with the experimental results. The PPO membrane reactor showed the best performance in the experimental condition. (C) 2000 Elsevier Science B.V. All rights reserved.