The present invention relates to a carbon dioxide absorbent comprising a triamine, a diamine and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether. The carbon dioxide absorbent according to the present invention can improve the carbon dioxide absorption capacity, absorption rate, and regeneration performance thereof simultaneously by using the triamine as a main absorbent, the diamine as a rate enhancer, the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether as a fine disproportionation agent and a regeneration promoter.

An absorbent for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, wherein the absorbent contains an aqueous solution, comprising: a) an amine or a mixture of amines of the general formula (I) wherein R.sup.1 is C.sub.1-C.sub.5-alkyl; R.sup.2 is C.sub.1-C.sub.5-alkyl; R.sup.3 is selected from hydrogen and C.sub.1-C.sub.5-alkyl; x is an integer from 2 to 10; and b) an ether or a mixture of ethers of the general formula (II): R.sup.4—[O—CH.sub.2—CH.sub.2].sub.y—OH; wherein R.sup.4 is C.sub.1-C.sub.5-alkyl; and y is an integer from 2 to 10; wherein R.sup.1 and R.sup.4 are identical; wherein the mass ratio of b) to a) is from 0.08 to 0.5. The absorbent is suitable for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide. The absorbent has a reduced tendency for phase separation at temperatures falling within the usual range of regeneration temperatures for the aqueous amine mixtures and is easily obtainable. ##STR00001##

The present invention relates to an aqueous alkanolamine solution demonstrating low volatility comprising 2-di-methylamino-2-hydroxymethyl-1, 3-propanediol useful for removing acid gases from gaseous mixtures. Said aqueous alkanolamine solution may further comprise one or more of an acid or acid-forming compound, another amino compound, an activator, a physical solvent, or one or more other compounds used in gal-liquid treatment practices. Further, the present invention relates to a process for removing acid gases from a gaseous mixture, preferably hydrogen sulfide, comprising the step of contacting the gaseous mixture with said aqueous alkanolamine solution. Examples of the gaseous mixtures include natural gas, synthesis gas, tail gas, and refinery gas.

A carbon dioxide capture system includes: a washing unit which uses cleaning water to clean absorption unit exhaust gas or stripping unit exhaust gas; and a gas-liquid separation device which allows condensed water generated by cooling washing unit exhaust gas to be separated from the washing unit exhaust gas. The condensed water is mixed into the cleaning water by a condensed water line. If the amount of the cleaning water becomes more than a predetermined amount, the cleaning water is mixed into an absorbing liquid by a cleaning water line. A controller controls a condensed water valve.

The present invention relates to an aqueous alkanolamine solution demonstrating low volatility comprising 2-di-methylamino-2-hydroxymethyl-1, 3-propanediol useful for removing acid gases from gaseous mixtures. Said aqueous alkanolamine solution may further comprise one or more of an acid or acid-forming compound, another amino compound, an activator, a physical solvent, or one or more other compounds used in gal-liquid treatment practices. Further, the present invention relates to a process for removing acid gases from a gaseous mixture, preferably hydrogen sulfide, comprising the step of contacting the gaseous mixture with said aqueous alkanolamine solution. Examples of the gaseous mixtures include natural gas, synthesis gas, tail gas, and refinery gas.

The present invention relates to a carbon dioxide absorbent comprising an oxygen-containing diamine, a cyclodiamine and a polyalkylene glycol dialkyl ether. The carbon dioxide absorbent according to the present invention can improve the carbon dioxide absorption capacity, absorption rate and regeneration performance thereof simultaneously by using the oxygen-containing diamine as a main absorbent, the cylodiamine as a rate enhancer, and the polyalkylene glycol dialkyl ether as a fine disproportionation agent and a regeneration promoter.

An organic amine decarbonization solution includes: i) one or more organic amines serving as a carbon dioxide absorbent; and ii) an antioxidant. The antioxidant includes: a) one or more organometallic complexes of Formula [M.sub.x(L).sub.y]A.sub.n, wherein each M independently represents a central atom selected from the group consisting of transition metals, Group IVA metals and Group VA metals at a lower valence state; each L independently represents a bidentate or multidentate organic ligand with each ligating atom thereof being independently one of O, S, N and P; each A independently represents an uncoordinated counter-ion suitable for forming an outer sphere of a complex; x is 1, 2 or 3; y is 1, 2, 3, 4, 5, 6, 7 or 8; and n is 0, 1, 2, 3 or 4; and b) optionally one or more metal chelating agents.

A process for selectively removing hydrogen sulphide relative to carbon dioxide from a gaseous mixture containing at least hydrogen sulphide H.sub.2S and carbon dioxide CO.sub.2, includes a step of contacting the gaseous mixture with an absorbent solution including at least one amine, water, and at least one C.sub.2 to C.sub.4 thioalkanol. A use of the absorbent solution for selectively removing hydrogen sulphide relative to carbon dioxide from a gaseous mixture containing at least hydrogen sulphide and carbon dioxide, is disclosed. Disclosed is a use of at least one C.sub.2 to C.sub.4 thioalkanol as an additive in an absorbent solution including at least one amine, and water, for increasing the selectivity of the absorbent solution for the removal of hydrogen sulphide relative to carbon dioxide from a gaseous mixture containing at least hydrogen sulphide and carbon dioxide.

A system for absorbing and separating acid gases may include an absorbing tower in which a gas containing an acid gas is supplied, a recycling tower that is disposed close to the absorbing tower, an absorbent that absorbs an acid gas in the absorbing tower and discharges the acid gas back to the recycling tower while circulating through the absorbing tower and the recycling tower, and a condenser that is connected to the recycling tower and condenses an acid gas produced in the recycling tower, wherein a centrifugal separator that separates the absorbent, using a centrifugal force, is disposed at a lower portion in the absorbing tower.

Disclosed are a carbon dioxide absorbent composition in which an N-alkylaminoalkanol; a polyhydroxyamine-based compound; and ethylenediamine and/or diethylenetriamine are mixed, a method for preparing the same, and a method and an apparatus for carbon dioxide absorption/separation using the same. Since the carbon dioxide absorbent according to the present disclosure has superior carbon dioxide absorption capacity and remarkably lower absorbent recycling temperature as compared to the existing absorbents such as monoethanolamine, etc., total energy consumption in the capturing process can be reduced greatly. In addition, since carbon dioxide is recovered at low recycling temperature, contamination by water or absorbent vapor may be prevented.