PROCESS FOR PREPARING 1,3-BUTADIENE FROM N-BUTENES BY OXIDATIVE DEHYDROGENATION

摘要

The invention relates to a process for preparing butadiene from n-butenes, comprising the steps of: A) providing a feedstock gas stream a containing n-butenes; B) feeding feedstock gas stream a containing n-butenes and a gas containing oxygen into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, resulting in a product gas stream b containing butadiene, unconverted n-butenes, steam, oxygen, low-boiling hydrocarbons, and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling product gas stream b by bringing same in contact with a coolant, and condensing at least some of the high-boiling secondary components; Cb) compressing the remaining product gas stream b in at least one compression stage, resulting in at least one aqueous condensate stream c1 and one gas stream c2 containing butadiene, n-butenes, steam, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases; Da) removing uncondensable and low-boiling gas constituents comprising oxygen, low-boiling hydrocarbons, any carbon oxides and any inert gases as a gas stream d2 from gas stream c2 by absorbing the C4 hydrocarbons comprising butadiene and n-butenes in an absorbent, resulting in an absorbent stream laden with C4 hydrocarbons and gas stream d2, and Db) then desorbing the C4 hydrocarbons from the laden absorbent stream in a desorption column, resulting in a C4 product gas stream d1. The disclosed method is characterized in that a lateral discharge stream containing methacrolein is withdrawn from the desorption column.