Compounds for the capture of carbon dioxide from gaseous mixtures and subsequent release, related process and plant

A process for the separation of carbon dioxide from a gaseous mixture, the process comprising the step of contacting said gaseous mixture containing carbon dioxide with at least one absorbent liquid comprising a compound,

• wherein said compound is an ionic liquid of the following general formula (I) or (II):
• wherein R3, R4, R5 are each independently H, a C1-C6 alkyl group or an aromatic group, R2 is a C1-C6 alkyl group, R1 is a C5-C19 alkyl group, and X31 0 is a carboxylate anion of a natural or artificial amino acid, and/or
• at least one glycerol ester having the general formula (III):
• wherein the groups R6, R7 and R8 are selected from H, an acyl group of formula R9—C(═OR)— where R9 is a C5-C19 alkyl group, an amino-acyl group deriving from a natural or artificial amino acid or an acyl residue of ectoin of formula (IV),
• and wherein at least one of the groups R6, R7, R8 is an acyl group of formula R9—C(═OR)— and at least one of the groups R6, R7, R8 is an amino-acyl group deriving from a natural or artificial amino acid or an acyl residue of ectoin of formula (IV),
• or in the form of an ester, having the general formula (V):
• R10—OR—R11 (V)
• wherein R10 is a C5-C19 alkyl group and R11 is an amino-acyl group deriving from a natural or artificial amino acid or an acyl residue of ectoin of formula (IV)
• under conditions such as to absorb CO2 in said absorbent liquid.

A plant for the separation of CO2 from a gaseous mixture and subsequent release of CO2, comprising a column having:

• an absorption section (2) comprising means (5) for feeding a gaseous stream containing CO2, means (6) for feeding a stream of absorbent liquid, and means (8) for the exit of a gaseous stream deprived of CO2,
• a desorption (release of CO2) and regeneration section (3) in fluid communication with said absorption section (2), said desorption and regeneration section comprising output means (11) for a gaseous stream containing CO2 and output means (10) for a liquid stream of regenerated absorbent liquid,
• wherein said absorption section (2) and said desorption and regeneration section (3) each comprise a sequence of first areas (51) of liquid/gas exchange, alternated with a sequence of second areas (52) for the collection of absorbent liquid and a plurality of interspaces (55) arranged externally and adjacent to corresponding first liquid/gas exchange areas (51), each of said interspaces (55) putting in fluid communication a second collection area (52) with a successive first exchange area (51) so as to transfer said absorbent liquid from a second collection area (52) to a first exchange area (51) subsequent thereto,
• a jacket (56) outside said absorption section (2) and a jacket (56) outside said desorption and regeneration section (3), each run through by a thermal exchange fluid to carry out a thermal exchange between the absorbent liquid running through said interspaces (55) and said thermal exchange fluid,
• wherein each interspace (55) has an outer length (55a) with a descending path, followed by an inner length (55b) with an ascending path.