A carbonic acid gas absorbing material on an embodiment includes a liquid carbonic acid gas absorbent and a solid carbonic acid gas absorbent. The liquid carbonic acid gas absorbent is a solution containing a first amine and a solvent. The solid carbonic acid gas absorbent is a second amine of any one among a polyamine, a base material and an amine fixed to the base material, or a polyamine, a base material, and an amine fixed to the base material.

A co-axial co-current contactor (CA-CCC) is described herein. The CA-CCC includes an outer annular support ring and an inner annular support ring configured to maintain the CA-CCC within an outer pipe and an inner pipe, respectively. The CA-CCC includes rich liquid flow channels located between the outer annular support ring and the inner annular support ring that are configured to allow a rich liquid stream to flow through the CA-CCC, and a central gas entry cone and gas flow channels configured to allow a gas stream to flow through the CA-CCC. The CA-CCC further includes radial blades configured to secure the central gas entry cone to the inner annular support ring and allow a lean liquid stream to flow into the central gas entry cone and the gas flow channels. The CA-CCC provides for efficient incorporation of liquid droplets formed from the lean liquid stream into the gas stream.

Disclosed is an adsorbent containing a metal oxide for adsorption of hydrogen sulfide in biogas, and a biogas purification system using the same.

An absorbent for selective removal of hydrogen sulfide over carbon dioxide from a fluid stream comprises an aqueous solution of a) a tertiary amine, b) a sterically hindered secondary amine of the general formula (I) ##STR00001##
in which R.sub.1 and R.sub.2 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl, with the proviso that at least one R.sub.4 and/or R.sub.5 radical on the carbon atom bonded directly to the nitrogen atom is C.sub.1-4-alkyl or C.sub.1-4-hydroxyalkyl when R.sub.3 is hydrogen; x and y are integers from 2 to 4 and z is an integer from 1 to 4; where the molar ratio of b) to a) is in the range from 0.05 to 1.0, and c) an acid in an amount, calculated as neutralization equivalent relative to the protonatable nitrogen atoms in a) and b), of 0.05 to 15.0%. One preferred amine of the formula I is 2-(2-tert-butylaminoethoxy)ethanol. The absorbent allows a defined H.sub.2S selectivity to be set at pressures of the kind typical in natural gas processing.

An absorbent for absorbing CO.sub.2 or H.sub.2S, or both of CO.sub.2 and H.sub.2S in a gas contains, as components, (a) a secondary linear monoamine, (b) a tertiary linear monoamine, and (c) a secondary cyclic diamine. When the concentration of the secondary linear monoamine (a) is more than 30% by weight and less than 45% by weight and the concentration of the tertiary linear monoamine (b) is more than 15% by weight and less than 30% by weight, absorbability of CO.sub.2 or H.sub.2S, or both of CO.sub.2 and H.sub.2S is good, and releasability of CO.sub.2 or H.sub.2S that have been absorbed during regeneration of the absorbent is good. The amount of steam of a reboiler used during regeneration of the absorbent in a CO2 recovery unit can be thus reduced.

Disclosed is an absorbent containing an amine for absorption of an acid gas in a biogas, and a biogas purification system using the same.

Disclosed herein are scavenging compounds and compositions useful in applications relating to the production, transportation, storage, and separation of crude oil and natural gas. Also disclosed herein are methods of using the compounds and compositions as scavengers, particularly in applications relating to the production, transportation, storage, and separation of crude oil and natural gas.

A gas treatment method includes an absorption step in which a gas to be treated containing an acidic compound, such as carbon dioxide, is brought into contact, in an absorber, with a treatment liquid that absorbs the acidic compound; and a regeneration step in which the treatment liquid, having the acidic compound absorbed therein, is sent to a regenerator, and the treatment liquid is then heated to separate the acidic compound from the treatment liquid. In the regeneration step, a gas almost insoluble to the treatment liquid, such as hydrogen gas, is brought into contact with the treatment liquid.

Disclosed is an adsorbent containing a metal oxide for adsorption of hydrogen sulfide in biogas, and a biogas purification system using the same.

A compound represented by Formula (1): each of L.sup.1 and L.sup.2 independently represents an alkyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, NH.sub.2, NHR.sup.3, NR.sup.3R.sup.4, an ester group, a carboxy group, an amide group, a cyano group, a nitro group, a halogen atom, an acyl group, CF.sub.3, O(CH.sub.2).sub.1OCH.sub.3, a carbamate group, or an aryl group. 1 represents 1 or 2. Each of R.sup.1 and R.sup.2 independently represents a divalent hydrocarbon group having from 1 to 10 carbon atoms, at least one hydrogen atom of the divalent hydrocarbon group is optionally substituted with an alkyl group, an aryl group, an ester group, a carboxy group, an amide group, a cyano group, a nitro group, a halogen atom, an acyl group, CF.sub.3, O(CH.sub.2).sub.1OCH.sub.3, a carbamate group, or an alkoxy group, each of R.sup.3 and R.sup.4 independently represents an alkyl group, an aryl group, an acyl group, an ester group, an alkylsulfonyl group, or an arylsulfonyl group, each of R.sup.5 and R.sup.6 independently represents a hydrogen atom, an alkyl group having from 1 to 20 carbon atoms, or an aryl group, and n+m≥1.