It is known from e.g. U.S. Pat. No. 4,025,575 that light oxygenates can be converted to the lower olefins ethylene and propylene using H-ZSM-5 zeolite as a catalyst.
U.S. Pat. No. 3,911,041 describes that methanol and DME can be converted to a reaction product containing olefins using a zeolite catalyst containing at least 0.78 wt-% phosphorus incorporated with the crystal structure of the zeolite. The zeolite used in the process of U.S. Pat. No. 3,911,041 may be ZSM-5. U.S. Pat. No. 3,911,041 further teaches that the activity of the phosphorus-containing zeolite catalyst can be increased by depositing zinc (Zn) on the zeolite.
U.S. Pat. No. 5,367,100 describes a method for the conversion of methanol or dimethyl ether to light olefins using a zeolite ZSM-5 based catalyst containing at least 0.7 wt-% phosphorus and at least 0.97 wt-% rare earth elements which are incorporated within the structure of the catalyst. The rare earth elements are preferably rich in lanthanum so that the content of lanthanum in the catalyst preferably is between 2.5 and 3.5 wt-%.
U.S. Pat. No. 4,049,573 describes a number of different boron or magnesium-comprising catalyst compositions useful for converting monohydric alcohols and their ethers to a hydrocarbon mixture ring in C2-C3 olefins and mononuclear aromatics.
The oxygenate-to-olefin catalysts of the prior art have the disadvantage that they have a relatively low selectivity for C2-C3 olefins and/or become quickly deactivated by coke deposition on the catalyst surface.