Method for preparing 1,3-butadiene from N-butenes by oxidative dehydrogeneation

Patent metadata

Field	Value
Publication number	US-10647639-B2
Application number	US-201716074454-A
Country	US
Kind code	B2
Filing date	Jan 30, 2017
Priority date	Feb 4, 2016
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

The invention relates to a method for producing butadiene from n-butenes having the steps:
A) providing an n-butene-comprising feed gas stream a; B) feeding the n-butene-comprising feed gas stream a and an oxygen-comprising gas into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, wherein a product gas stream b comprising butadiene, unreacted n-butenes, steam, oxygen, low-boiling hydrocarbons, high-boiling minor components, optionally carbon oxides and optionally inert gases is obtained; Ca) cooling the product gas stream b by contacting it with a refrigerant and condensing at least a part of the high-boiling minor components; Cb) compressing the remaining product gas stream b in at least one compression step, wherein at least one aqueous condensate stream c1 and a gas stream c2 comprising butadiene, n-butenes, steam, oxygen, low-boiling hydrocarbons, optionally carbon oxides and optionally inert gases is obtained; Da) separating off non-condensable and low-boiling gas components comprising oxygen, low-boiling hydrocarbons, optionally carbon oxides and optionally inert gases as gas stream d2 from the gas stream c2 by absorbing the C 4 hydrocarbons comprising butadiene and n-butenes in an absorption medium, wherein an absorption medium stream loaded with C 4 hydrocarbons and the gas stream d2 are obtained, and Db) subsequently desorbing the C 4 hydrocarbons from the loaded absorption medium stream in a desorption column, wherein a C 4 product gas stream d1 is obtained, Dc) separating off the steam condensate from the absorption medium in a phase separator and vaporizing it in a steam generator and providing it again as stripping gas in the desorption column,

wherein, the steam condensate before the vaporization in a steam generator, is subjected to a pretreatment in a further method step.

First claim

The invention claimed is:

1. A method for producing butadiene from n-butenes having the steps:
A) providing a feed gas stream a comprising the n-butenes;
B) feeding the feed gas stream a and an oxygen-comprising gas into an oxidative dehydrogenation zone to oxidatively dehydrogenating n-butenes to butadiene and obtaining a product gas stream b comprising butadiene, unreacted n-butenes, steam, oxygen, low-boiling hydrocarbons, high-boiling minor components, optionally carbon oxides and optionally inert gases;
Ca) cooling the product gas stream b by contacting it with a refrigerant and condensing at least a part of the high-boiling minor components;
Cb) compressing the cooled product gas stream b in at least one compression step and obtaining at least one aqueous condensate stream c1 and a gas stream c2 comprising butadiene, n-butenes, steam, oxygen, low-boiling hydrocarbons, optionally carbon oxides and optionally inert gases;
Da) absorbing the C 4 hydrocarbons butadiene and n-butenes in an absorption medium to produce an absorption medium stream loaded with C 4 hydrocarbons and a gas stream d2 comprising oxygen, low-boiling hydrocarbons, optionally carbon oxides and optionally inert gases;
Db) desorbing the C 4 hydrocarbons from the loaded absorption medium stream in a desorption column by stripping with stream and obtaining a C 4 product gas stream d1 and a liquid mixture comprising absorption medium and steam condensate;
Dc1) separating off the steam condensate from the absorption medium in a phase separator;
Dc2) pretreating the steam condensate by stripping with a stripping gas, by heating, or by stripping and heating to remove low-boiling minor components from the steam condensate; and
Dc3) vaporizing the pretreated steam condensate in a steam generator, and providing the steam as stripping gas in the desorption column.

2. The method according to claim 1 having the additional steps:
E) separating the C 4 product stream d1 by extractive distillation using a solvent selective for butadiene into a material stream e1 comprising butadiene and the selective solvent and a material stream e2 comprising n-butenes;
F) distilling the butadiene and the material stream f2 comprising the selective solvent into a material stream g1 substantially comprising the selective solvent and a material stream g2 comprising butadiene.

3. The method according to claim 1 , wherein the low-boiling minor components are separated off from the steam condensate by stripping with nitrogen.

4. The method according to claim 3 , wherein the stripping with nitrogen is performed at a temperature from 0 to 150° C. and a pressure from 1 to 10 000 mbar.

5. The method according to claim 1 , wherein the low-boiling minor components are selected from the group consisting of acrolein, methacrolein and 3-hydroxypropanal.

6. The method according to claim 1 , wherein the oxygen-comprising gas fed in step B) comprises at least 90% by volume of oxygen.

7. The method according to claim 1 , wherein the gas stream d2 that is separated off in step Da) is recycled at least in part in step B).

8. The method according to claim 1 , wherein:
the absorption medium stream loaded with C 4 hydrocarbons from step Da) is stripped with a non-condensable gas to remove oxygen from the absorption medium stream loaded with C 4 hydrocarbons, and the C 4 product gas stream d1 obtained from step Db) comprises less than 100 ppm of oxygen.

9. The method according to claim 1 , wherein the absorption medium used in step Da) is an aromatic hydrocarbon solvent.

Assignees

• Basf Se
• Linde Ag

Inventors

• Josch Jan Pablo
• Balegedde Ramachandran Ragavendra Prasad
• Wenning Ulrike
• Wellenhofer Anton
• Toegel Christine
• Reyneke Hendrik
• Boelt Heinz

Classifications

• B01J2523/68

  Molybdenum · CPC title

• B01J2523/48

  Zirconium · CPC title

• C07C7/08

  by extractive distillation · CPC title

• C07C11/167

  1, 3-Butadiene · CPC title

• C07C7/11

  by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids · CPC title