The use of the combination of (a) an amino compound and (b) a compound including a soft electrophilic centre to scavenge and retain acidic sulfide species at a higher temperature and/or scavenge acidic sulfide species at an increased rate compared to that achieved using the amino compound alone.

An absorbent composition including an amino-siloxane is presented. The amino-siloxane includes structure (I): wherein R.sup.1 is independently at each occurrence a C.sub.1-C.sub.6 aliphatic or aromatic radical; R.sup.2 is independently at each occurrence a C.sub.2-C.sub.10 aliphatic or aromatic radical; and R.sup.3 is independently at each occurrence a C.sub.1-C.sub.18 aliphatic or aromatic radical or R.sup.4′ wherein R.sup.4 comprises structure (II): wherein X is independently at each occurrence an electron donating group; and n is at least 1. Methods of reducing an amount of carbon dioxide in a process stream using the absorbent composition are also presented.

##STR00001##

The invention relates to an absorbent solution and to a method using this solution for removing acid compounds contained in a gaseous effluent, comprising water and at least one diamine with general formula (I) as follows: ##STR00001## wherein: radicals R.sub.1, R.sub.2, R.sub.3 are each selected indiscriminately among a methyl radical and a hydroxyethyl radical, and at least one radical among R.sub.1, R.sub.2, R.sub.3 is a methyl radical.

The composite amine absorbing solution according to the present invention absorbs CO.sub.2 or H.sub.2S or both in a gas, and is obtained by dissolving a linear monoamine, a diamine, and an amide group-containing compound in water. By adopting this composite amine absorbing solution, the composites are interacting in a composite manner, due to an integrated effect of the components, the absorption property of CO.sub.2 or H.sub.2S or both is favorable, the desorption properties of the CO.sub.2 or H.sub.2S absorbed when regenerating the absorbing solution become favorable, and the amount of steam from a reboiler used when regenerating the absorbing solution in a CO.sub.2 recovery device can be reduced.

A sulfur dioxide absorbent that is an ionic liquid including a solvent; and a salt of a diamine compound that is substituted with a hydroxyl group and has a chemical formula 1 to 3 below dissolved in the solvent: ##STR00001## where, in Chemical Formula 1 and 2, R.sub.1-R.sub.4 are the same or different and each is independently selected from the group consisting of H, a C1-C6 alkyl, and a C1-C6 alkoxy; and where, in Chemical Formula 1 to 3, X is selected from the group consisting of Cl, Br, I, MeSO.sub.3, CF.sub.3SO.sub.3, HCO.sub.2, CF.sub.3CO.sub.2 and CH.sub.3CO.sub.2; and n is an integer of 1-10. The sulfur dioxide absorbent is constituted to selectively absorb sulfur dioxide and sulfurous acid (H.sub.2SO.sub.3) formed by combination of sulfur dioxide with water, not CO.sub.2.

Provided is a composition for removing a sulfur-containing compound contained in at least one of a liquid and gas, the sulfur-containing compound being at least one selected from the group consisting of hydrogen sulfide and an SH group-containing compound, the composition containing an aldehyde and an amine whose conjugate acid has a pKa value of 11.3 or higher in water at 25 C.

The invention relates to a process for removing hydrogen sulfide and carbon dioxide from a feed gas stream. H2S in the feed gas stream is converted to elemental sulfur in a Claus unit. At least a part of the gas stream obtained is contacted with an aqueous lean absorbing medium in an absorption zone at a pressure between 0.9 and 2 bara. The aqueous lean absorbing medium used comprises one or more amines chosen from: a polyamine in the absence of tertiary amine functionalities having a pKa sufficient to neutralize carbamic acid, the polyamine having at least one primary amine functionality having a pKa smaller than 10.0 at 25 C., a polyamine in the absence of tertiary amine functionalities having a pKa sufficient to neutralize carbamic acid, the polyamine having at least one secondary amine functionality having a pKa for each sorbing nitrogen smaller than 10.0 at 25 C. The process is improved as compared to a process involving Claus off-gas treatment with (activated) MDEA. Effective CO2 removal is achieved while at the same time a simplified line-up with less equipment can be used.

A method and apparatus for continuously treating acid gases including recovering absorbent chemicals by introducing streams leaving a regenerator and/or leaving an absorber into a static mixing zone wherein supplemental washing water is added to recover absorbent chemicals. Improvements to the prior art methods are provided where one or more absorbent chemical recovery units are included to increase the amount of recovered absorbent chemicals exiting the regenerator and/or exiting the absorber are increased and/or maximized. Absorbent chemical recovery units can include mixing units where liquid is added to the stream of sour gas and absorbent chemical to mix with and absorb the absorbent chemical from the stream.

Disclosed in the present disclosure are a low energy consumption anhydrous CO.sub.2 phase change absorption agent, and a regeneration method and an application thereof, the absorption agent using a unitary diamine with a primary amine (NH.sub.2) and a tertiary amine (N), and not containing any other organic solvent, water, and ionic liquid; two alkyl branches are linked to a nitrogen atom of the tertiary amine, forming a certain hydrophobicity; after absorbing the CO.sub.2, the diamine changes from a liquid phase to a solid phase, undergoing liquid-solid phase change to form white amino formate crystals.

A process for sweetening a syngas stream, the process comprising the steps of: providing a syngas stream to a nonselective amine absorption unit, the sour syngas stream comprising syngas, carbon dioxide, and hydrogen sulfide; separating the syngas stream in the nonselective amine absorption unit to obtain an overhead syngas stream and an acid gas stream; introducing the acid gas stream to a membrane separation unit, the acid gas stream comprising hydrogen sulfide and carbon dioxide; separating the acid gas stream in the membrane separation unit to produce a retentate stream and a permeate stream, wherein the retentate stream comprises hydrogen sulfide, wherein the permeate stream comprises carbon dioxide; introducing the retentate stream to a sulfur recovery unit; processing the retentate stream in the sulfur recovery unit to produce a sulfur stream and a tail gas stream, wherein the sulfur stream comprises liquid sulfur.