Non-aqueous amine scrubbing for removal of carbon dioxide

Patent metadata

Field	Value
Publication number	US-9713788-B2
Application number	US-201514885214-A
Country	US
Kind code	B2
Filing date	Oct 16, 2015
Priority date	Sep 9, 2010
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

A method is described for separating CO 2 and/or H 2 S from a mixed gas stream by contacting the gas stream with a non-aqueous, liquid absorbent medium of a primary and/or secondary aliphatic amine, preferably in a non-aqueous, polar, aprotic solvent under conditions sufficient for sorption of at least some of the CO 2 . The solution containing the absorbed CO 2 can then be treated to desorb the acid gas. The method is usually operated as a continuous cyclic sorption-desorption process, with the sorption being carried out in a sorption zone where a circulating stream of the liquid absorbent contacts the gas stream to form a CO 2 -rich sorbed solution, which is then cycled to a regeneration zone for desorption of the CO 2 (advantageously at <100° C.). Upon CO 2 release, the regenerated lean solution can be recycled to the sorption tower. CO 2 :(primary+secondary amine) adsorption molar ratios>0.5:1 (approaching 1:1) may be achieved.

First claim

What is claimed is:

1. A CO 2 -sorbent composition comprising a reaction product of a monoepoxide and a polyalkyleneimine oligomer in a non-aqueous aprotic liquid,
wherein the monoepoxide is an aliphatic alkyleneoxide having from 4 to 12 carbon atoms,
wherein the polyalkyleneimine oligomer is linear, cyclic, and/or branched and has the following repeat unit structure: —[(CH 2 ) x —NR] y —, where x is from 2 to 6, where y is from 4 to 50, and where R is hydrogen, an alkyleneamine branch having the structure —(CH 2 ) x —NR 2 , or an alkyleneimine branch having the structure —(CH 2 ) x —NR′ 2 , wherein a first R′ is either an alkyleneamine branch or another alkyleneimine branch and a second R′ is hydrogen, another alkyleneamine branch, or yet another alkyleneimine branch,
wherein the reaction product comprises one or more secondary amines and one or more tertiary amines, as well as one or more secondary hydroxyl groups,
wherein the non-aqueous aprotic liquid is polar and has a dipole moment (D) of at least 1.7, and
wherein the composition has a viscosity at about 25° C. of about 5 cPs or less and a CO 2 adsorption efficiency of at least 0.5:1 moles CO 2 /moles of primary plus secondary amine.

2. A CO 2 -sorbent complex comprising a reversible chemisorption complex of CO 2 with a composition comprising a reaction product of a monoepoxide and a polyalkyleneimine oligomer in a non-aqueous aprotic liquid,
wherein the monoepoxide is an aliphatic alkyleneoxide having from 4 to 12 carbon atoms,
wherein the polyalkyleneimine oligomer is linear, cyclic, and/or branched and has the following repeat unit structure: —[(CH 2 ) x —NR] y —, where x is from 2 to 6, where y is from 0.4 to 50, and where R is hydrogen, an alkyleneamine branch having the structure —(CH 2 ) x —NH 2 , or an alkyleneimine branch having the structure —(CH 2 ) x —NR′ 2 , wherein a first R′ is either an alkyleneamine branch or another alkyleneimine branch and a second R′ is hydrogen, another alkyleneamine branch, or yet another alkyleneimine branch,
wherein the reaction product comprises one or more secondary amines and one or more tertiary amines, as well as one or more secondary hydroxyl groups,
wherein the non-aqueous aprotic liquid is polar and has a dipole moment (D) of at least 1.7,
wherein the composition has a viscosity at about 25° C. of about 5 cPs or less and a CO 2 adsorption efficiency of at least 0.5:1 moles CO 2 /moles of primary plus secondary amine, and
wherein the chemiosorption complex is reversible at a temperature between 25° C. and 150° C. and includes one or more carbamic acid groups and/or one or more carboxylates of carbamic acid groups formed from interaction between the CO 2 and the primary and/or secondary amines of the composition.

Assignees

• Calabro David Charles
• Baugh Lisa Saunders
• Kortunov Pavel
• Mccool Benjamin A
• Siskin Michael
• Peiffer Dennis George
• Li Quanchang
• Exxonmobil Res & Eng Co

Inventors

• Calabro David Charles
• Baugh Lisa Saunders
• Kortunov Pavel
• Mccool Benjamin A
• Siskin Michael
• Peiffer Dennis George
• Li Quanchang

Classifications

• B01D2252/2056

  Sulfur compounds, e.g. Sulfolane, thiols · CPC title

• B01D2252/30

  Ionic liquids and zwitter-ions · CPC title

• B01D2252/20421

  Primary amines · CPC title

• B01D2252/20415

  Tri- or polyamines · CPC title

• B01D2252/20426

  Secondary amines · CPC title