The present invention provides a process for removing mercaptans from a gas stream. A first mercaptan-comprising gas stream is contacted counter-currently with an absorption medium comprising a substituted disulphide and a nitrogen-containing base to obtain a second mercaptan-depleted gas stream. The substituted disulphinde preferably is R.sub.IISSR.sub.III wherein: R.sub.II and R.sub.III are the same and are selected from: (CH.sub.2)n-X, wherein n=2 or 3, and wherein X=OR, and wherein R=H or (CH.sub.2O).sub.nH or (CH.sub.2O)nCH.sub.3 and n=1 or 2. Absorption medium is regenerated and recycled.

An absorbent for selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide comprises a) an amine compound of the formula (I)

##STR00001##

in which X, R.sup.1 to R.sup.7, x, y and z are as defined in the description; and b) a nonaqueous solvent; where the absorbent comprises less than 20% by weight of water. Also described is a process for selectively removing hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, wherein the fluid stream is contacted with the absorbent. The absorbent features high load capacity, high cyclic capacity, good regeneration capacity and low viscosity.

The present invention is directed to a process for the removal of aromatic hydrocarbons from a lean acid gas containing less than 20 mol. % of H.sub.2S, comprising:

a) contacting the lean acid gas stream (1) with a H.sub.2S-selective liquid absorbent solution (29) in a first absorption zone (2) to produce a gas stream depleted in H.sub.2S (3) and an absorbent solution enriched in H.sub.2S (4),

b) introducing the absorbent solution (4) into a non-thermic stripping zone (8) where it is contacted with a stripping gas stream (7) to obtain an absorbent solution depleted in C.sub.4.sup.+ aliphatic and aromatic hydrocarbons (9) and a stripping gas stream enriched in aromatic and C.sub.4.sup.+ aliphatic hydrocarbons (10),

c) contacting the stripping gas stream (10) obtained in step b) with a H.sub.2S-selective liquid absorbent solution (28) in a second absorption zone (12) to obtain a stripping gas stream depleted in H.sub.2S (13), and an absorbent solution enriched in H.sub.2S (14)

d) introducing the absorbent solution (9) obtained in step b) into a desorption zone (16) wherein the H.sub.2S-selective liquid absorbent solution (17) is recovered and a lean acid gas is produced.

A compound of the general formula (I)

##STR00001##

in which R.sub.1 to R.sub.8, x, y and z are as defined in the description. Also described is an absorbent comprising a solution of the compound, and the use thereof and a process for removing acid gases from a fluid stream, wherein the fluid stream is contacted with the absorbent. The compounds of the general formula (I) are notable for thermal stability and low volatility. Absorbents based on the compounds are notable for high loading capacity, high cyclic capacity and good regeneration capacity. The solutions of the compounds in nonaqueous solvents are notable for low viscosities.

An apparatus and method for acid gas removal using an absorption liquid comprising a chemical solvent and a non-chemical solvent, each absorbing acid gas, wherein in embodiments regeneration of the absorption liquid involves separating the two components from each other in separate streams, and causing desorption from each stream using different desorption conditions.

The present invention is directed to the removal of mercury from a gas phase by injecting a scavenger solution into the gas phase.

A system for carbon dioxide capture from a gas mixture comprises an absorber that receives a lean solvent system stream (containing a chemical solvent, physical-solvent, and water) from the stripper, a stripper that receives the rich solvent stream from the absorber and produces the product carbon dioxide and the lean solvent through the use of a reboiler in fluid communication with a lower portion of the stripper, a condenser in fluid communication with a vapor outlet of the stripper, a cross-exchanger in fluid communication with a rich solvent system outlet from the absorber and a rich solvent system inlet on the stripper, and a splitter. The splitter is configured to separate the rich solvent system stream into a first portion and second portion, where the first portion directly passes to the stripper and the second portion passes through the cross-exchanger prior to passing to the stripper.

An absorbent for selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, which comprises a) 10% to 70% by weight of at least one sterically hindered secondary amine having at least one ether group and/or at least one hydroxyl group in the molecule; b) at least one nonaqueous solvent having at least two functional groups selected from ether groups and hydroxyl groups in the molecule; and c) optionally a cosolvent; where the hydroxyl group density of the absorbent .sub.abs is in the range from 8.5 to 35 mol(OH)/kg. Also described is a process for selectively removing hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, wherein the fluid stream is contacted with the absorbent. The absorbent features good regeneration capacity and high cyclic acid gas capacity.

A process is disclosed for purifying a gaseous mixture containing acidic gases, such as a natural gas, including contacting the gaseous mixture with an absorbent solution including: from 35% to 45% by weight of at least one tertiary amine relative to the total weight of the absorbent solution; from 4% to 12% by weight of at least one activator relative to the total weight of the absorbent solution selected from the primary amines and the secondary amines, the total content of tertiary amine and activator being from 38% to 50% by weight relative to the total weight of the absorbent solution, and the total concentration of tertiary amine and activator being between 3.8 and 4.2 mol/L; from 17% to 25% by weight of at least one C.sub.2 to C.sub.4 thioalkanol relative to the total weight of the absorbent solution; and the remainder being water to reach 100% by weight.

A carbon dioxide absorbent composition is disclosed. Based on 100 parts by weight of the carbon dioxide absorbent composition, the carbon dioxide absorbent composition includes 5 to 45 parts by weight of sodium 2-[(2-aminoethyl)amino]ethanesulfonate. Moreover, a method for capturing carbon dioxide using the carbon dioxide absorbent composition is disclosed.