Production of hydrocarbons from methanol in the presence of zeolite catalysts

Claim 1

Method of producing light olefinic hydrocarbons having 2-5 carbons from methanol, in particular unsaturated hydrocarbons, in the presence of a zeolitic mordenite catalyst, wherein gasified methanol introduced into a carrier gas, the concentration of the methanol in an entering mixture being between 5 and 60% by volume, is passed through a catalytic bed based on dealuminised synthetic mordenite whose Si/Al ratio (atomic) is higher than 80, the methanol flow rate being between 1 and 5 liters of liquid methanol per liter of catalyst and per hour, the reaction being carried out at a temperature between 350° and 550° C., under a pressure which can reach 20 bars; said synthetic mordenite having been de-aluminised by subjecting the mordenite to a series of alternate acid and hydrothermic treatments; during the acid treatment phase, subjecting the mordenite to treatment in a concentrated acid medium, at a temperature between 60° and 90° C., with stirring for some hours; in the hydrothermic treatment phase, bringing the mordenite to a temperature between 550° and 680° C. for some hours, at atmospheric pressure, in an air-steam mixture of which the air-steam flow rate under normal conditions of temperature and pressure is between 500 and 1250 l/h for a weight of catalyst of 1 kg, the steam concentration by volume being between 2.5 and 60%; the series of treatments commencing with an acid treatment and terminating with an acid treatment.