The present invention relates to a scavenging composition capable of scavenging a wide variety of sulfur-bearing compounds, such as hydrogen sulfide and method of use thereof. Said scavenging composition comprises an aqueous solution of a triazine compound, an anionic surfactant, and optionally an alcohol and/or glycol ether solution. The composition may be used in any kind of sulfide-scavenging operation and is particularly useful for sulfide scavenging in the context of sulfide removal from oil or gas streams and in the treatment of oil or gas transmission lines or equipment.

A method for removing carbon dioxide from a gaseous source, the method comprising: (i) contacting said gaseous source with an aqueous solution of a carbon dioxide sorbent that reacts with carbon dioxide to form an aqueous-soluble carbonate or bicarbonate salt of said carbon dioxide sorbent; (ii) contacting the aqueous solution from step (i) with a bis-iminoguanidine carbon dioxide complexing compound, which is different from the carbon dioxide sorbent, to result in precipitation of a carbonate or bicarbonate salt of said carbon dioxide complexing compound and regeneration of the carbon dioxide sorbent; and (iii) removing the precipitated carbonate or bicarbonate salt from the aqueous solution in step (ii) to result in a solid form of said carbonate or bicarbonate salt of the carbon dioxide complexing compound. The method may further include a step (iv) of regenerating the carbon dioxide complexing compound by subjecting the precipitated salt to sufficient heat and/or vacuum.

An absorbent for selective removal of hydrogen sulfide from a fluid stream comprises an aqueous solution comprising a) a tertiary amine; b) an aminic pH promoter selected from the compounds mentioned in the description; where the molar ratio of b) to a) is in the range from 0.05 to 1.0; and c) an acid having a pK.sub.A of less than 6 in such an amount that the pH of the aqueous solution measured at 120 C. is 7.9 to less than 8.8. Also described is a process for removing acidic gases from a fluid stream, in which the fluid stream is contacted with the absorbent. The absorbent is notable for a low regeneration energy.

A gas treatment device uses a gas to be treated which contains an acid compound that dissolves into water to produce acid and a treatment liquid which absorbs the acid compound to phase-separate, to separate an acid compound from the gas to be treated. The gas treatment device includes an absorber which brings the gas to be treated into contact with the treatment liquid; a regenerator 14 which heats the treatment liquid contacting the gas to be treated to separate an acid compound; and a liquid feeding portion which feeds the treatment liquid contacting the gas to be treated in the absorber to the regenerator. In the absorber, the treatment liquid contacting the gas to be treated phase-separates into a first phase portion having a high acid compound content and a second phase portion having a low acid compound content. The liquid feeding portion is configured to introduce, into the regenerator, the treatment liquid with the phase-separated first phase portion and second phase portion mixed.

An absorbent for selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide comprises a) an amine compound of the formula (I)

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in which X, R.sup.1 to R.sup.7, x, y and z are as defined in the description; and b) a nonaqueous solvent; where the absorbent comprises less than 20% by weight of water. Also described is a process for selectively removing hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, wherein the fluid stream is contacted with the absorbent. The absorbent features high load capacity, high cyclic capacity, good regeneration capacity and low viscosity.

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.

A carbon dioxide absorbent composition is disclosed. Based on 100 parts by weight of the carbon dioxide absorbent composition, the carbon dioxide absorbent composition includes 5 to 45 parts by weight of sodium 2-[(2-aminoethyl)amino]ethanesulfonate. Moreover, a method for capturing carbon dioxide using the carbon dioxide absorbent composition is disclosed.

A method of capturing a target species from a gas comprises the steps of: contacting a gas containing a target species with a first absorbent solution comprising a capture species; dissolving the target species in the first absorbent solution to form a target anion; electrochemically separating the target anion from the first absorbent solution by contacting the first absorbent solution with one or more ion-exchange membranes, and transferring the target anion through an ion-exchange membrane into a second absorbent solution; and releasing at least some of the target species from the second absorbent solution. The one or more ion-exchange membranes are not permeable to the capture species, so the capture species does not pass through the one or more ion-exchange membranes. An apparatus for capturing a target species from a gas is also provided.

A composite amine absorbent that absorbs at least one of CO.sub.2 and H.sub.2S in a gas includes: (a) a chain monoamine; (b) a diamine containing amino groups having the same number of substituents; (c) a chain diamine containing amino groups having different numbers of substituents; and (d) water.

The present disclosure provides improved systems, assemblies and methods to remove and recover CO.sub.2 from emissions. More particularly, the present disclosure provides improved membrane contactors configured to remove CO.sub.2 from flue gas by temperature swing absorption. In exemplary embodiments, the present disclosure provides a novel hollow fiber membrane contactor that integrates absorption and stripping using a nonvolatile reactive absorbent (e.g., 80% polyamidoamine (PAMAM) dendrimer generation 0, and 20% of an ionic liquid (IL)). Equilibrium CO.sub.2 absorption in the nonvolatile viscous mixed absorbent is as high as 6.37 mmolCO.sub.2/g absorbent in the presence of moisture at 50 C. A novel membrane contactor is provided for CO.sub.2 absorption and stripping via a process identified as temperature swing membrane absorption (TSMAB). The contactor integrates non-dispersive gas absorption and hot water-based CO.sub.2 stripping in one device/assembly containing two sets of commingled hollow fibers.