Multi-stage adiabatic process for methanol conversion to light olefins

Claim 1

In a process for converting lower aliphatic alcohols into a predominantly olefinic hydrocarbon product by (a) contacting a feed comprising said aliphatic alcohol with a dehydration catalyst at elevated temperatures and exothermic reaction conditions effective to convert said alcohol to an ether-rich product, and (b) contacting the ether-rich product with at least a plurality of fixed beds of crystalline aluminosilicate zeolite in a sequential manner at elevated temperatures at substantially the same temperature increases across each of said fixed beds and under exothermic reaction conditions effective to convert said ether-rich product, at a predetermined conversion, to olefinic hydrocarbons, and cooling the reaction mixture effluent from each of said fixed beds, except the last, to reduce the temperature of said effluent by an amount substantially equal to the temperature increase across each fixed bed, the improvement comprising cofeeding with said ether-rich product about 0.5-3 percent by weight of a light olefin to the first of said fixed beds to stabilize the operation of said fixed beds whereby the shapes of the temperature profiles of the individual fixed beds are closer to each other allowing increased stable temperature rise in each stage.