An acidic gas absorbent contains an amine compound of formula (1) and a cyclic amino compound of formula (2) or (3): ##STR00001## ##STR00002## ##STR00003##
where in the formulas, each R.sup.1 is independently a straight-chain hydroxyalkyl having a hydroxy at the terminal, R.sup.2 is a branched-chain secondary alkyl group, R.sup.3 and R.sup.4 are hydrogen, hydroxy, a hydroxyalkyl or aminoalkyl, provided that at least one of R.sup.3 and R.sup.4s is a hydroxyalkyl or aminoalkyl, each p is independently an integer of 2 to 4, each R.sup.5 is independently hydrogen, hydroxy, or a hydroxyalkyl or aminoalkyl, provided that at least one of R.sup.5s is a hydroxyalkyl or aminoalkyl, and q is an integer of 3 to 8.

An absorption liquid regeneration apparatus includes: a regeneration tower for regenerating a CO.sub.2 absorption liquid; a reflux water drum configured to separate released gas from the regeneration tower into CO.sub.2 gas and condensed water, and return the condensed water to the regeneration tower; and a cleaning part installed in a gas-phase part of the reflux water drum or in a CO.sub.2 flow passage through which the CO.sub.2 gas having flowed from the gas-phase part flows, and configured to remove a CO.sub.2 absorption agent contained in the CO.sub.2 gas by using a cleaning liquid. The cleaning liquid has a lower concentration of the CO.sub.2 absorption agent than the condensed water stored in a liquid-phase part of the reflux water drum.

A hybrid post-combustion carbon dioxide capture system for capturing carbon dioxide from a flue gas includes a compressor adapted to produce a compressed flue gas stream, a membrane-based carbon dioxide separation unit configured to receive a first portion of the compressed flue gas stream from the compressor, and an aqueous-based carbon dioxide capture unit configured to receive a second portion of the compressed flue gas stream from the compressor whereby the compressed flue gas stream is processed in parallel by the membrane-based carbon dioxide separation unit and the aqueous-based carbon dioxide capture unit.

A method and apparatus for processing a hydrocarbon gas stream including sulfurous components and carbon dioxide. The hydrocarbon gas stream is separated into a sweetened gas stream and an acid gas stream. The acid gas stream and an air stream, enriched with oxygen such that the air stream comprises between 22% and 100% oxygen, are combusted in a sulfur recovery unit to separate the acid gas stream into a liquid stream of elemental sulfur and a tail gas stream comprising acid gas impurities. The tail gas stream and an air flow are sub-stoichiometrically combusted to produce an outlet stream comprising hydrogen sulfide and carbon monoxide. The outlet stream is hydrogenated to convert sulfur species to a gaseous catalytic output stream comprising hydrogen sulfide. Water is removed from the gaseous catalytic output stream to produce a partially-dehydrated acid gas stream, which is pressurized and injected into a subsurface reservoir.

A solution including at least one mixed acetal compound is used to remove hydrogen sulfide and/or mercaptans from a fluid stream, preferably a fluid gas stream. A mixed acetal compound, as provided in the general structure below, includes an N-glycosidic type bond. The mixed acetal includes nitrogen and oxygen as provided below.

##STR00001##

A premixture for producing an absorbent for removing acid gases from a fluid stream containing a) at least a tertiary amine and/or a sterically hindered secondary amine; b) a dicarboxylic acid in an amount, calculated as neutralization equivalent based on the protonatable nitrogen atoms in a), of at least 30%, wherein the dicarboxylic acid has a solubility in water at a temperature of 20° C. of not more than 15 g of dicarboxylic acid per 100 g of water; and c) 20 to 80 wt % of water. Also described is a process for producing an absorbent from the premixture. The premixture is a transportable and readily handleable solution of a dicarboxylic acid having poor solubility in water for producing an absorbent for removing acid gases from a fluid stream.

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.

A scavenging composition and method for scavenging hydrogen sulfide and/or mercaptans from fluids. The scavenging composition comprises an alkali metal nitrite and a nitrogen-containing scavenger, and optionally an inorganic base, as a hydrogen sulfide and/or a mercaptan scavenger for hydrocarbon fluids, particularly for crude oil, field oil, fuel oil, straight run distillates, cracked distillates, residual fuels, natural gas, petroleum associated gas and the like.

The embodiments provide an acidic gas absorbent kept from deterioration, an acidic gas removal method using the absorbent, and an acidic gas removal apparatus using the same. The acidic gas absorbent contains an amine compound and water, and further contains superfine bubble containing inert gas wherein an average diameter of said superfine bubble is 150 nm or less. The acidic gas removal method provided here employs that absorbent. The acidic gas removal apparatus is equipped with a unit for introducing the superfine bubbles into the absorbent.

An acid gas adsorbent that reversibly adsorbs an acid gas contained in a gas to be processed includes: metal oxide porous material particles; and an acid gas adsorbing agent with which the porous material particles are impregnated. Each of the porous material particles has binary pores including: a mesopore having a pore diameter in a nanometer region of 2 nm or more and 200 nm or less; and a macropore having a pore diameter in a micrometer region of more than 0.2 μm. The macropore is an empty pore, and the mesopore is filled with the acid gas adsorbing agent.