Intensification techniques are described for enhancing biocatalytic CO.sub.2 absorption operations, and may include the use of a rotating packed bed, a rotating disc reactor, a zig-zag reactor or other reactors that utilize process intensification. Carbonic anhydrase can be deployed in the high intensity reactor free in solution, immobilized with respect to particles that flow with the liquid, and/or immobilized to internals, such as packing, that are fixed within the high intensity reactor.

An absorbent for the selective removal of hydrogen sulfide over carbon dioxide from a fluid stream, wherein the absorbent contains an aqueous solution, comprising an amine of formula (I) and/or an amine of formula (II) wherein U—V—W is CH—O—CHR.sup.5, N—CO—CHR.sup.5 or N—CO—NR.sup.5; U′—V′—W is C—O—CR.sup.5; R.sup.1 is independently C.sub.1-C.sub.5-alkyl; R.sup.2 is selected from hydrogen and C.sub.1-C.sub.5-alkyl; R.sup.3 is independently selected from hydrogen and C.sub.1-C.sub.5-alkyl; R.sup.4 is independently selected from hydrogen and C.sub.1-C.sub.5-alkyl; R.sup.5 is selected from hydrogen, C.sub.1-C.sub.5-alkyl, (C.sub.1-C.sub.5-alkoxy)-C.sub.1-C.sub.5-alkyl, and hydroxy-C.sub.1-C.sub.5-alkyl; and x is an integer from 1 to 10. The absorbent has a reduced tendency for phase separation at temperatures falling within the usual range of regeneration temperatures for the aqueous amine mixtures and a low volatility in aqueous solvents. ##STR00001##

The invention concerns a plant and a method for treating gas by chemical, physical or hybrid absorption of compounds for removal, comprising at least: a) a step of absorption by contacting a gas for treatment with a depleted solvent to give a treated gas and a rich solvent; b) a step of optional separation by medium-pressure flashing c) a step of heat exchange between a fraction of the cold rich solvent and the hot depleted solvent in a first heat exchanger d) a step of heat exchange between the complementary fraction of the cold rich solvent and a hot gaseous effluent in a second exchanger e) a step of optional separation by low-pressure flashing f) a step of regeneration of the rich solvent by heating in a reboiler g) a step of separation by low-pressure flashing h) a cooling of the depleted solvent.

The acid gas removal system for removing acidic gases from gaseous hydrocarbons (10) removes sour gases, such as hydrogen sulfide (H.sub.2S) and carbon dioxide (CO.sub.2), from an input gaseous stream. The system (10) includes a contactor (12) for contacting the input gaseous stream with an absorption liquid solvent (ALS), and a stripper (24) for recycling the absorption liquid solvent (ALS) and removing acidic gases (AG) therefrom, but with the addition of a pair of plate-plate heat exchangers (22, 26). The first heat exchanger (22) heats the used absorption liquid solvent (UALS) output from the contactor (12) prior to injection into the stripper (24). The used absorption liquid solvent (UALS) is heated via heat exchange with the acidic gases (AG) output from the stripper (24). The second heat exchanger (26) cools the recycled absorption liquid solvent (RALS) before injection back into the contactor (12).

An absorbent composition includes an amino-siloxane having 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; R.sup.3 is independently at each occurrence a hydrogen atom or a C.sub.1-C.sub.6 aliphatic or aromatic radical; R.sup.4 is independently at each occurrence a C.sub.1-C.sub.18 aliphatic or aromatic radical or R.sup.5, wherein R.sup.5 comprises structure (II): wherein X is independently at each occurrence an oxygen atom or a sulfur atom; w is between 0 and 5; y is between 0 and 10; and z is between 0 and 10; wherein, when R.sup.4 is R.sup.5 comprising the structure (II), a sum of w, y, and z is greater than or equal to 0, and, when R.sup.4 is not R.sup.5, a sum of w, y, and z is greater than or equal to 1. ##STR00001##

An aqueous solvent composition is provided, comprising a nucleophilic component having one or more sterically unhindered primary or secondary amine moieties, a Brønsted base component having one or more basic nitrogen moieties, a water-soluble organic solvent, and water. A biphasic composition is provided, comprising one or more carbamate compounds, one or more conjugate acids of Brønsted base, a water-soluble organic solvent, and water. A biphasic CO.sub.2 absorption process is also provided, utilizing the biphasic solvent composition.

The present invention relates to a novel phase transfer solvent composition for enhanced CO.sub.2 and/or H.sub.2S capture from flue gas and biogas having various gaseous compositions. Further, the present invention provides a process of preparing the phase transfer solvent composition of the present invention.

A process for removing hydrogen sulfide and carbon dioxide from a fluid stream comprises a) an absorption step in which the fluid stream is contacted with an absorbent comprising an aqueous solution (i) of an amine of the general formula (I) ##STR00001##
in which R.sub.1, R.sub.2 and R.sub.3 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.4 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.5 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; X is OH or NH(CR.sub.1R.sub.2R.sub.3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and optionally (ii) at least one tertiary amine, where the molar ratio of (i) to (ii) is greater than 0.05; wherein at least 90% of the hydrogen sulfide is removed from the fluid stream and selectivity for hydrogen sulfide over carbon dioxide is not greater than 8, wherein a CO.sub.2— and H.sub.2S-laden absorbent is obtained; b) a regeneration step in which at least a substream of the CO.sub.2— and H.sub.2S-laden absorbent is regenerated and a regenerated absorbent is obtained; and c) a recycling step in which at least a substream of the regenerated absorbent is recycled into the absorption step a). The process allows a high level of hydrogen sulfide removal with a simultaneously high coabsorption of carbon dioxide.

Disclosed herein are acid gas absorbents that afford high acid gas (CO2) absorption amount per unit volume and high absorption speed and can prevent the absorbent components from diffusing. The acid gas absorbent contains an amine compound of the formula (1) and a cyclic amine compound of the formula (3) or (3′): ##STR00001##

A process is proposed for producing pure hydrogen by steam reforming of a feed gas comprising hydrocarbons, preferably natural gas or naphtha, with a simultaneously low and preferably adjustable export steam flow rate. The process includes the steam reforming of the feed gas, for which the heat of reaction required is provided by combustion of one or more fuel gases with combustion air in a multitude of burners arranged within the reformer furnace. According to the invention, the combustion air, before being introduced into the burners, is heated by means of at least one heat exchanger in indirect heat exchange with the hot flue gas to temperatures of at least 530° C.