The use of an amine of the formula (I) ##STR00001##
in which the R.sup.1 to R.sup.5 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.

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.

The present invention is related to a method for determination of unit operations of a chemical plant for acid gas removal, the method carried out by a computer or a distributed computer system and the method comprising the steps of: providing (S1) a first set of parameters for the unit operations; providing (S2) a second set of parameters for the unit operations based on the provided first set of parameters and based on data retrieved from a database; determining (S3) a digital model of the chemical plant based on the first set of parameters and the second set of parameters, wherein the digital model comprises a system of equations defining the unit operations of the chemical plant; selecting (S4) starting points for an equation-based solution method of the system of equations, wherein the starting points are at least partially selected from the: —i) the first set of parameters; —ii) the second set of parameters; and —iii) the data retrieved from the database; determining (S5) resultant settings for the unit operations of the chemical plant using the equation-based solution method for the system of equations initialized by the selected starting points.

A method of electrochemically reducing CO.sub.2 comprises introducing a first feed stream comprising H.sub.2O to a positive electrode of an electrolysis cell comprising the positive electrode, a negative electrode, and a proton conducting membrane. A second feed stream comprising a solvent and a non polar form of a switchable polarity material is directed into a CO.sub.2 capture apparatus. A third feed stream comprising CO.sub.2 is directed into the CO.sub.2 capture apparatus to interact with the second feed stream and form a first product stream comprising the solvent and a polar form of the switchable polarity material. The first product stream is introduced to the negative electrode. A potential difference is applied between the positive electrode and the negative electrode to convert the polar form of the switchable polarity material into CO.sub.2 and the non-polar form and to form products from the CO.sub.2 and the solvent. A CO.sub.2 treatment system is also described.

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 form is (1) and a cyclic amine compound of the formula (3) or (3):

##STR00001##

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. Also disclosed herein is a method and device for removing an acid gas, in which the energy required for separating the acid gas and regenerating the absorbent is reduced, are provided.

The embodiments provide an acidic gas absorbent, an acidic gas removal method, and an acidic gas removal apparatus. The absorbent absorbs an acidic gas in a large amount and hardly diffuses in air. The acidic gas absorbent according to the embodiment comprises an amine compound having a sulfonyl group and two or more amino groups.

A method of electrochemically reducing CO.sub.2 comprises introducing a first feed stream comprising H.sub.2O to a positive electrode of an electrolysis cell comprising the positive electrode, a negative electrode, and a proton conducting membrane. A second feed stream comprising a solvent and a non polar form of a switchable polarity material is directed into a CO.sub.2 capture apparatus. A third feed stream comprising CO.sub.2 is directed into the CO.sub.2 capture apparatus to interact with the second feed stream and form a first product stream comprising the solvent and a polar form of the switchable polarity material. The first product stream is introduced to the negative electrode. A potential difference is applied between the positive electrode and the negative electrode to convert the polar form of the switchable polarity material into CO.sub.2 and the non-polar form and to form products from the CO.sub.2 and the solvent. A CO.sub.2 treatment system is also described.

Solvent absorption processes for separating components of an impure feed gas are disclosed. The processes involve two stages of gas purification. The acid gases including hydrogen sulfide, carbon dioxide and other sulfur compounds are simultaneously removed from the feed gas by contact with a physical solvent in two stages. The subject matter disclosed provides improved processes to reduce the operating costs of the system.

The embodiments provide an acidic gas absorbent, an acidic gas removal method, and an acidic gas removal apparatus. The absorbent absorbs an acidic gas in a large amount and hardly diffuses in air. The acidic gas absorbent according to the embodiment comprises an amine compound having a sulfonyl group and two or more amino groups.