US 12,291,595 B2
Method for isocyanate and polyurethane production with improved sustainability
Andreas Bulan, Langenfeld (DE); and Rainer Weber, Odenthal (DE)
Assigned to COVESTRO INTELLECTUAL PROPERTY GMBH & CO. KG, Leverkusen (DE)
Appl. No. 17/774,163
Filed by COVESTRO INTELLECTUAL PROPERTY GMBH & CO. KG, Leverkusen (DE)
PCT Filed Nov. 5, 2020, PCT No. PCT/EP2020/081202
§ 371(c)(1), (2) Date May 4, 2022,
PCT Pub. No. WO2021/089737, PCT Pub. Date May 14, 2021.
Claims priority of application No. 19207406 (EP), filed on Nov. 6, 2019.
Prior Publication US 2022/0389150 A1, Dec. 8, 2022
Int. Cl. C07C 263/10 (2006.01); C01B 32/80 (2017.01); C08G 18/48 (2006.01); C08J 11/12 (2006.01); C25B 1/04 (2021.01); C25B 1/26 (2006.01); C25B 15/08 (2006.01)
CPC C08G 18/48 (2013.01) [C01B 32/80 (2017.08); C07C 263/10 (2013.01); C08J 11/12 (2013.01); C25B 1/04 (2013.01); C25B 1/26 (2013.01); C25B 15/081 (2021.01); C08J 2375/04 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A process for producing isocyanates and optionally polyurethanes by at least the following steps:
synthesizing phosgene from carbon monoxide and chlorine,
reacting phosgene with diamines to form diisocyanates and hydrogen chloride,
providing a CO2 gas stream,
purifying the CO2 gas stream of secondary constituents to obtain a purified carbon dioxide,
electrolyzing water to hydrogen and oxygen,
providing the hydrogen stream and feeding together with the purified CO2 gas stream as reactants into a reverse water-gas shift reaction (RWGS) reaction zone and reacting the reactants according to a principle of the RWGS reaction to form a product gas mixture consisting of water vapor, CO, and any by-products,
separating off the water of the water vapor from the product gas mixture and recycling the water to the water electrolysis,
separating off unreacted carbon dioxide from the gas mixture of the RWGS reaction obtained from the separation and recycling the unreacted carbon dioxide to the RWGS reaction,
separating off the hydrogen that has not reacted in the RWGS reaction from the gas mixture of carbon monoxide and hydrogen obtained after the separation,
feeding the remaining carbon monoxide from the separation into the phosgene synthesis,
feeding the hydrogen from the water electrolysis into the hydrogenation of nitro compounds for the production of diamines,
separating off and purifying the hydrogen chloride formed in isocyanate production and subsequent oxidative reaction of the hydrogen chloride in the form of a reaction in a thermocatalytic gas-phase oxidation with oxygen to chlorine and water and/or in the form of an electrochemical oxidation of the hydrogen chloride to chlorine and/or in the form of an electrochemical oxidation of the hydrogen chloride to chlorine and hydrogen by HCl diaphragm electrolysis,
supplying the previously formed chlorine to the phosgene synthesis.