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

摘要

The invention relates to a method for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream (a) comprising n-butenes; B) feeding the input gas stream (a) comprising n-butenes and an oxygenous gas into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream (b) comprising butadiene, unconverted n-butenes, steam, oxygen, low-boiling hydrocarbons and high-boiling secondary components and inert gases; Ca) cooling the thinned product gas stream (b') by bringing it into 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 step, resulting in at least one aqueous condensate stream (c1) and one gas stream (c2) containing butadiene, n-butenes, steam, oxygen and low-boiling hydrocarbons and inert gases; Da) removing uncondensable and low-boiling gas constituents comprising oxygen, low-boiling hydrocarbons and 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 the gas stream (d2), and Db) then desorbing the C4 hydrocarbons from the laden absorbent stream, resulting in a C4 product gas stream (d1). The disclosed method is characterized in that between step B) and step Ca), a gas stream (x) containing a non-oxidizing gas, said non-oxidizing gas being selected from the group consisting of nitrogen and carbon dioxide, is fed in such amounts into the product gas stream (c) such that in the following steps Ca), Cb) and Da), no explosive mixture is formed.