same time produce mtbe when there is also mtbe demand in those areas the operating conditions for forming mtbe are known see u s pat nos 5 276 212 and 5 424 458 the operating conditions for an mtbe unit can vary widely but will generally be a temperature of from about 85 u00b0 f to 210 u00b0 f a pressure of from about 140 to about 580 psig and a methanol to isobutylene weight ratio of from about 1 1 to about 2 1 using any of the known etherification catalysts such catalysts include mineral acid such as sulfuric acid boron trifluoride phosphoric acid on kieselguhr phosphorus modified zeolites heteropoly acids and sulfonated resins all as fully and completely disclosed in the above u s patents if desired the mtbe producing aspect of this invention can be coupled with a po tba plant as described in fig3 above in this case at least some of the propylene product can be used to advantage in the formation of po when there is po demand fig5 shows this embodiment wherein isobutane feed 80 oxygen feed 99 and propylene feed 81 are passed into a po tba plant 82 po stream 83 is formed as a product of the process while tba product stream 84 is passed to dehydration unit 85 unit 85 can.