A system for processing a gas stream can include a physical solvent unit, an acid gas removal unit upstream or downstream of the physical solvent unit, and an LNG liquefaction unit downstream of the acid gas removal unit. The physical solvent unit is configured to receive a feed gas, remove at least a portion of any C.sub.5+ hydrocarbons in the feed gas stream using a physical solvent, and produce a cleaned gas stream comprising the feed gas stream with the portion of the C.sub.5+ hydrocarbons removed. The acid gas removal unit is configured to receive the cleaned gas stream, remove at least a portion of any acid gases present in the cleaned gas stream, and produce a treated gas stream. The LNG liquefaction unit is configured to receive the treated gas stream and liquefy at least a portion of the hydrocarbons in the treated gas stream.

An efficient and selective catalyst for the condensed phase hydrogenation of captured CO.sub.2 in the presence of an advanced water-lean post combustion capture solvent, EEMPA. Selected heterogenous catalysts for suppress N-methylation of the capture solvent; especially a noble metal on a reducible metal oxide support is highly selective for CN cleavage to produce methanol.

In a method of absorbing CO.sub.2 from a gas mixture the use of an absorption medium comprising water and at least one amine of formula (I) ##STR00001## where R.sup.1 is a (CH.sub.2).sub.n(XCH.sub.2CH.sub.2).sub.mYR.sup.3 radical where R.sup.3=hydrogen or an alkyl radical having from 1 to 6 carbon atoms, X and Y are each, independently of one another, NR.sup.3, oxygen, SO or SO.sub.2, where in the case of YSO and in the case of YSO.sub.2, R.sup.3 is not hydrogen, and YR.sup.3 can be an N-morpholinyl radical or an N-piperazyl radical, n=2 to 4, m=0 to 4 and R.sup.2 is hydrogen, an alkyl radical having from 1 to 6 carbon atoms or a radical R.sup.1, where m is not 0 when R.sup.2 is not a radical R.sup.1, YNR.sup.3 and YR.sup.3 is not an N-morpholinyl radical and not an N-piperazyl radical, makes it possible to avoid precipitation of a solid during the absorption of CO.sub.2 and a separation into two liquid phases during the regeneration of the absorption medium.

A novel blend of piperazine (PZ) and a second amine compound is provided as a superior solvent for CO2 capture from coal-fired flue gas. Blending PZ with various second amine compounds can remediate the precipitation issue of concentrated PZ while maintaining its high CO2 absorption capacity and rate, and high resistance to oxidative degradation.

Provided are a carbon dioxide absorbing composition including an ionic material containing a spiro ammonium cation and a method of separating carbon dioxide using the same, and the carbon dioxide absorbing composition of the present disclosure has high thermal and chemical stability and excellent carbon dioxide absorption effect. In addition, the method of separating carbon dioxide using the carbon dioxide absorbing composition is very effective for desorption of carbon dioxide, and is a very economical method since it allows repeated use of the carbon dioxide absorbing composition.

Provided are a carbon dioxide absorbing composition comprising an ionic material comprising a cyclic ammonium cation and a method of separating carbon dioxide using the same, and the carbon dioxide absorbing composition of the present disclosure has high thermal and chemical stability and excellent carbon dioxide absorption effect. In addition, the method of separating carbon dioxide using the carbon dioxide absorbing composition is very effective for desorption of carbon dioxide, and is a very economical method since it allows repeated use of the carbon dioxide absorbing composition.

In one aspect, the invention provides a method for the capture of at least one acid gas in a composition, the release of said gas from said composition, and the subsequent regeneration of said composition for re-use, said method comprising performing, in order, the steps of: (a) capturing the at least one acid gas by contacting said at least one gas with a capture composition comprising at least one salt of a carboxylic acid and at least one water-miscible non-aqueous solvent; (b) releasing said at least one acid gas by adding at least one protic solvent or agent to said composition; and (c) regenerating the capture composition by partial or complete removal of said added protic solvent or agent from said composition. Optionally, said capture composition comprising at least one salt of a carboxylic acid and at least one water-miscible non-aqueous solvent additionally comprises water or another protic solvent. In another aspect, the invention envisages a composition which additionally comprises at least one protic solvent or agent and release of the at least one acid gas is achieved solely by subjecting the composition to the application of heat or stripping with a stream of air. The method is typically applied to the capture and subsequent release of carbon dioxide, and offers a convenient and simple process which uses inexpensive consumables and offers significant advantages over the methods of the prior art.

Disclosed herein is a method and system for CO.sub.2 removal from a gas stream using a diamine solvent having a Formula I
R.sup.1(R.sup.2)N-L.sup.1-NHR.sup.3 Formula I.
With respect to Formula I, each of R.sup.1 and R.sup.2 independently is aliphatic, cycloaliphatic, or R.sup.1 and R.sup.2 together with the nitrogen to which they are attached, form a heterocyclyl ring; L.sup.1 is aliphatic, cycloaliphatic, or L.sup.1 and R.sup.1 together with the nitrogen to which they are attached form a heterocyclyl ring; and R.sup.3 is aliphatic, cycloaliphatic, cycloalkylalkyl, or alkoxyalkyl. And/or the compound may have a viscosity of less than 75 cP at a CO.sub.2-loading of 40 mol % and at a temperature of 40 C.

Capture of hydrogen sulfide from a gas mixture may be accomplished using an aqueous solution comprising an amine. Certain sterically hindered amines may selectively form a reaction product with hydrogen sulfide under kinetically controlled contacting conditions and afford a light phase and a heavy phase above a critical solution temperature, wherein the hydrogen sulfide may be present in either phase. Upon separation of the light phase from the heavy phase, processing of one of the phases may take place to remove hydrogen sulfide therefrom. Recycling of the amine to an absorber tower may then take place to promote capture of additional hydrogen sulfide.

Capture of hydrogen sulfide from a gas mixture may be accomplished using an aqueous solution comprising an amine. Certain sterically hindered amines may selectively form a reaction product with hydrogen sulfide under kinetically controlled contacting conditions and afford a light phase and a heavy phase above a critical solution temperature, wherein the hydrogen sulfide may be present in either phase. Upon separation of the light phase from the heavy phase, processing of one of the phases may take place to remove hydrogen sulfide therefrom. Recycling of the amine to an absorber tower may then take place to promote capture of additional hydrogen sulfide.