Heat balanced cyclic process for manufacture of light olefins

A heat balanced cyclic process for converting a charge consisting essentially of methanol, dimethyl ether or mixtures thereof to a hydrocarbon product rich in ethylene and propylene which comprises contacting said charge with a fluidized catalyst comprising a crystalline aluminosilicate zeolite characterized by pores, the major dimension of which is less than 6 Angstroms, further characterized by pore windows of about a size such as would be provided by 8-membered rings of oxygen atoms and the capability, under the hereinafter specified conditions, of producing less than 20 weight percent methane in said hydrocarbon product, said contacting taking place in a riser reactor at an inlet temperature between about 800 and 1000.degree. F. and an increased outlet temperature between about 900.degree. and about 1150.degree. F. with a weight ratio of catalyst to charge between about 5 and about 12 and a residence time between catalyst and charge of less than 30 seconds, during which time, a minor proportion of less than about 9 percent by weight of the charge is converted to form a carbonaceous deposit on said catalyst in an amount of between about 0.4 and about 1 weight percent, thereafter separating the hydrocarbon product, rich in ethylene and propylene from the carbonaceous deposit-containing catalyst, conducting the latter to a regenerator, maintained at a temperature within the approximate range of 1200.degree. to 1400.degree. F., wherein said carbonaceous deposit is removed by combustion in air, recycling the resulting hot regenerated catalyst to further contact with a fresh stream of said charge and repeating the above cycle.