Abstract: Process for preparing an alkali metal from a salt of the alkali metal which is soluble in a solvent, including a first electrolysis, a concentration, and a second electrolysis. The first electrolysis produces a product mixture. This product mixture is then concentrated to give a largely solvent-free alkali metal (poly)sulfide melt. A second electrolysis at a temperature above the melting point of the alkali metal is then performed in a second electrolysis cell comprising an anode space and a cathode space, separated by a solid electrolyte which conducts alkali metal cations. The alkali metal (poly)sulfide melt from the concentration step is fed to the anode space. Sulfur is removed from the anode space and liquid alkali metal is removed from the cathode space.

Abstract: Absorption medium for acid gases comprising an oligoamine (A) of the general formula (I) and a piperazine derivative (B) of the general formula (II) in which the weight ratio of oligoamine (A) to the piperazine derivative (B) is 0.2 to 25, and also process for removing acid gases from a gas stream by contacting the gas stream at a pressure of 0.05 to 10 MPa abs with an aqueous solution of said absorption medium which is brought to and maintained at a temperature of 20 to 80° C.

Abstract: Absorption medium for acid gases comprising an oligoamine (A) of the general formula (I) and a primary or secondary alkanolamine (B) of the general formula (II) in which the weight ratio of oligoamine (A) to the primary or secondary alkanolamine (B) is 0.2 to 4, and also the process for removing acid gases from a gas stream by contacting the gas stream at a pressure of 0.05 to 10 MPa abs with an aqueous solution brought to and maintained at a temperature of 20 to 80° C. of said absorption medium.

Abstract: Absorption medium for acid gases comprising an oligoamine (A) of the general formula (I) and a primary or secondary alkanolamine (B) of the general formula (II) in which the weight ratio of oligoamine (A) to the primary or secondary alkanolamine (B) is 0.2 to 4, and also the process for removing acid gases from a gas stream by contacting the gas stream at a pressure of 0.05 to 10 MPa abs with an aqueous solution brought to and maintained at a temperature of 20 to 80° C. of said absorption medium.

Abstract: Absorption medium for acid gases comprising an oligoamine (A) of the general formula (I) and a piperazine derivative (B) of the general formula (II) in which the weight ratio of oligoamine (A) to the piperazine derivative (B) is 0.2 to 25, and also process for removing acid gases from a gas stream by contacting the gas stream at a pressure of 0.05 to 10 MPa abs with an aqueous solution of said absorption medium which is brought to and maintained at a temperature of 20 to 80° C.

Abstract: The present invention relates to a process for separating off carbon dioxide from gas mixtures by absorption using aqueous alkaline solutions, which comprises carrying out the absorption in a countercurrent flow apparatus in which the gas mixture which is to be worked up and the aqueous alkaline solution used are passed in countercurrent flow and wherein a discontinuous liquid phase forms in the interior of the countercurrent flow apparatus and the separation is carried out in the interior of the countercurrent flow apparatus in the presence of activated carbon, wherein the activated carbon is present in the interior of the countercurrent flow apparatus in an amount of 1 g to 2 kg of activated carbon per m3 of volume of the countercurrent flow apparatus.