Method for producing 1,3-butadiene by dehydrogenating n-butenes, a material flow containing butanes and 2-butenes being provided

A process for preparing 1,3-butadiene from n-butenes, the process comprising the steps of:

• A) providing an input gas stream that includes butanes, 1-butene, 2-butene and isobutene, with or without 1,3-butadiene, the input gas stream being from a fluid catalytic cracking plant;
• B) removing the isobutene from the input gas stream to provide a stream b that includes the butanes, the 1-butene and the 2-butene, with or without 1,3-butadiene;
• C) feeding the stream b and optionally an oxygenous gas and optionally water vapor into at least one dehydrogenating zone to dehydrogenate the 1-butene and the 2-butene to 1,3-butadiene, giving a product gas stream that includes the 1,3-butadiene, the butanes, the 2-butene and water vapor, with or without oxygen, with low-boiling hydrocarbons, with high-boiling secondary components, with or without carbon oxides and with or without inert gases, wherein at least 99% of the 1-butene present in stream b is converted in step C);
• D) cooling and compressing the product gas stream to provide at least one aqueous condensate stream d1 and a gas stream d2 comprising the 1,3-butadiene, the butanes, the 2-butene and the water vapor, with or without oxygen, with low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases;
• Ea) removing uncondensable and low-boiling gas constituents comprising low-boiling hydrocarbons, with or without oxygen, with or without carbon oxides and with or without inert gases, as gas stream e2 from the gas stream d2 by absorbing the C4 hydrocarbons comprising the 1,3-butadiene, the butanes and the 2-butene, in an absorbent to provide an absorbent stream laden with the C4 hydrocarbons and the gas stream e2, and
• Eb) desorbing the C4 hydrocarbons from the laden absorbent stream to provide a C4 hydrocarbon stream e1;
• F) separating the C4 hydrocarbon stream e1 by extractive distillation with a 1,3-butadiene-selective solvent to provide a stream f1 that includes the 1,3-butadiene and the selective solvent and a stream f2 that includes the butanes and the 2-butene;
• wherein the stream f2 obtained in step F) is directly fed to and converted further in one or more of steps G1), G2) or G3) by
• G1) alkylating 2-butene with butanes to give isooctanes;
• G2) subjecting 2-butene to olefin metathesis with ethene to give propene;
• or
• G3) oligomerizing 2-butene.