Abstract: 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) in which R1 and R2 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; R3, R4, R5 and R6 are each independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl, with the proviso that at least one R4 and/or R5 radical on the carbon atom bonded directly to the nitrogen atom is C1-4-alkyl or C1-4-hydroxyalkyl when R3 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.

Abstract: In a process for removal of acid gases from a fluid stream the fluid stream is contacted with an absorbent to obtain a treated fluid stream and a laden absorbent.

Abstract: The use of an amine of the formula (I) in which the R1 to R5 radicals are each as defined in the description, and an absorbent and a process for removing acidic gases from a fluid stream, especially for selectively removing hydrogen sulfide over carbon dioxide. The invention also relates to particular amines suitable for selective removal of hydrogen sulfide. Absorbents based on amines of the formula (I) have high selectivity, high loading capacity and good regeneration capacity.

Abstract: An absorbent for selective removal of hydrogen sulfide from a fluid stream comprises an aqueous solution of a) a tertiary amine, b) a sterically hindered secondary amine of the general formula (I) in which R1 and R2 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; R3, R4, R5 and R6 are each independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl, with the proviso that at least one R4 and/or R5 radical on the carbon atom bonded directly to the nitrogen atom is C1-4-alkyl or C1-4-hydroxyalkyl when R3 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.

Abstract: 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) in which R1, R2 and R3 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; each R4 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; each R5 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; X is OH or NH(CR1R2R3); 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.

Abstract: An absorbent for removing carbon dioxide from a fluid stream, comprising an aqueous solution a) of an amine of the general formula (I) in which R1, R2 and R3 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; each R4 is independently selected from hydrogen, C1-4alkyl and C1-4-hydroxyalkyl; each R5 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; X is OH or NH(CR1R2R3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and b) at least one activator selected from b1) a sterically unhindered primary amine and/or a sterically unhindered secondary amine; and a carboanhydrase. The absorbent allows rapid absorption of carbon dioxide from fluid streams.

Abstract: 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.

Abstract: 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) in which R1, R2 and R3 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; each R4 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; each R5 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; X is OH or NH(CR1R2R3); 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.

Abstract: 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 pKA 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.

Abstract: The use of an amine of the formula (I) in which the R1 to R5 radicals are each as defined in the description, and an absorbent and a process for removing acidic gases from a fluid stream, especially for selectively removing hydrogen sulfide over carbon dioxide. The invention also relates to particular amines suitable for selective removal of hydrogen sulfide. Absorbents based on amines of the formula (I) have high selectivity, high loading capacity and good regeneration capacity.

Abstract: A process for selectively separating H2S from a gas mixture which also comprises CO2 is disclosed. A stream of the gas mixture is contacted with an absorbent solution comprising one or more amines, alkanolamines, hindered alkanolamines, capped alkanolamines, or mixtures thereof. The H2S/CO2 selectivity of the absorbent solution is preferably greater than about 4.0 for an acid gas loading [mol(CO2+H2S)/mol(amine)] between about 0.2 and about 0.6, and is achieved by reducing pH of the absorbent solution.

Abstract: An absorbent for selective removal of hydrogen sulfide from a fluid stream comprises an aqueous solution of a) a tertiary amine, b) a sterically hindered secondary amine of the general formula (I) in which R1 and R2 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; R3, R4, R5 and R6 are each independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl, with the proviso that at least one R4 and/or R5 radical on the carbon atom bonded directly to the nitrogen atom is C1-4-alkyl or C1-4-hydroxyalkyl when R3 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.

Abstract: A process for selectively separating H2S from a gas mixture which also comprises CO2 is disclosed. A stream of the gas mixture is contacted with an absorbent solution comprising one or more amines, alkanolamines, hindered alkanolamines, capped alkanolamines, or mixtures thereof. The H2S/CO2 selectivity of the absorbent solution is preferably greater than about 4.0 for an acid gas loading [mol(CO2+H2S)/mol(amine)] between about 0.2 and about 0.6, and is achieved by reducing pH of the absorbent solution.

Abstract: An absorbent for removing carbon dioxide from a fluid stream, comprising an aqueous solution a) of an amine of the general formula (I) in which R1, R2 and R3 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; each R4 is independently selected from hydrogen, C1-4alkyl and C1-4-hydroxyalkyl; each R5 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; X is OH or NH(CR1R2R3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and b) at least one activator selected from b1) a sterically unhindered primary amine and/or a sterically unhindered secondary amine; and a carboanhydrase. The absorbent allows rapid absorption of carbon dioxide from fluid streams.

Abstract: 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) in which R1, R2 and R3 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; each R4 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; each R5 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; X is OH or NH(CR1R2R3); 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.

Abstract: A process for selectively separating H2S from a gas mixture which also comprises CO2 is disclosed. A stream of the gas mixture is contacted with an absorbent solution comprising one or more amines, alkanolamines, hindered alkanolamines, capped alkanolamines, or mixtures thereof. The H2S/CO2 selectivity of the absorbent solution is preferably greater than about 4.0 for an acid gas loading [mol(CO2+H2S)/mol(amine)] between about 0.2 and about 0.6, and is achieved by reducing pH of the absorbent solution.

Abstract: An absorption medium for removing acid gases from a fluid stream comprises an aqueous solution (A) of an alkali metal salt of an N,N-di-C1-C4-alkylaminocarboxylic acid and (B) N-hydroxyethylpiperazine. The absorption medium has a low vapor pressure and an increased resistance to oxygen. Preferred fluid streams are combustion exhaust gases or biogas.

Abstract: An absorption medium for removing acid gases from a fluid stream comprises an aqueous solution of a) of at least one metal salt of an aminocarboxylic acid, and b) of at least one acid promoter, wherein the molar ratio of b) to a) is in the range from 0.0005 to 1.0. The acid promoter is selected from mineral acids, carboxylic acids, sulfonic acids, organic phosphonic acids and partial esters thereof. The absorption medium, compared with absorption media based on amino acid salts, has a reduced regeneration energy requirement without significantly reducing the absorption capacity of the solution for acid gases. In a process for removing acid gases from the fluid stream, the fluid stream is brought into contact with the absorption medium.

Abstract: An absorption medium for the removal of acid gases from a fluid stream comprises an aqueous solution a) of at least one amine and b) at least one phosphonic acid, wherein the molar ratio of b) to a) is in the range from 0.0005 to 1.0. The phosphonic acid is, e.g., 1-hydroxyethane-1,1-diphosphonic acid. The absorption medium exhibits a reduced regeneration energy requirement compared with absorption media based on amines or amine/promoter combinations, without significantly decreasing the absorption capacity of the solution for acid gases.

Abstract: Catalysts comprising: a ground, spent (de)hydrogenation catalyst material present in an amount of 10 to 70% by weight based on the catalyst, the ground, spent catalyst material comprising iron oxide; and a fresh catalyst material present in an amount of 30 to 90% by weight based on the catalyst, the fresh catalyst material comprising iron oxide, wherein at least a portion of the iron oxide in the fresh catalyst material comprises a phase selected from the group consisting of hematite, potassium ferrite, and mixtures thereof are described along with processes for preparing and using the same.