Methanol‐to‐Olefins in a Membrane Reactor with in situ Steam Removal – The Decisive Role of Coking

The reaction of methanol to light olefins and water (MTO) was studied in a fixed bed tubular membrane reactor using commercial SAPO‐34 catalyst. In the fixed bed reactor without membrane support, the MTO reaction collapsed after 3 h time on stream. However, if the reaction by‐product steam is in situ extracted from the reactor through a hydrophilic tubular LTA membrane, the reactor produces long‐term stable about 60 % ethene and 10 % propene. It is shown that the reason for the superior performance of the membrane‐assisted reactor is not the prevention of catalyst damage caused by steam but the influence of the water removal on the formation of different carbonaceous residues inside the SAPO‐34 cages. Catalytically beneficial methylated 1 or 2 ring aromatics have been found in a higher percentage in the MTO reaction with a water removal membrane compared to the MTO reaction without membrane support.