A method for separating carbon dioxide from a gas stream, comprising: contacting a gas stream containing CO 2 in a sorption zone with an aqueous sorption solution comprising a promoter amine and at least one of a sterically hindered amine and a tertiary amine, the aqueous sorption solution having a total amine concentration of at least 3.0 M, at a temperature of at least 10°C to sorb at least a portion of the CO 2 into the aqueous sorption solution and form a rich stream of the sorbed CO 2 in the aqueous sorption solution comprising one or more amine-CO 2 reaction products dissolved in the aqueous sorption solution; passing the rich stream from the sorption zone to a second zone and precipitating at least a portion of the amine-CO 2 reaction products to form a precipitate slurry; separating the precipitate slurry to form a portion enriched in precipitate solids and a first recycle stream, the first recycle stream comprising a majority of the solvent from the precipitate slurry; and passing the portion enriched in precipitate solids to at least one regeneration zone and desorbing the sorbed carbon dioxide as gas to form a second recycle stream, the second recycle stream containing a lower concentration of carbon dioxide than the rich stream and containing an increased concentration of total amine relative to the rich stream, wherein the aqueous sorption solution comprises at least a portion of the first recycle stream and at least a portion of the second recycle stream, and wherein the promoter amine comprises piperazine, piperidine, bridged derivatives of piperidine and piperazine, 4-dimethylamino pyridine, N-methyl imidazolineor a derivative of piperazine or piperidine that includes at least one tertiary amine. contacting a gas stream containing CO 2 in a sorption zone with an aqueous sorption solution comprising a promoter amine and at least one of a sterically hindered amine and a tertiary amine, the aqueous sorption solution having a total amine concentration of at least 3.0 M, at a temperature of at least 10°C to sorb at least a portion of the CO 2 into the aqueous sorption solution and form a rich stream of the sorbed CO 2 in the aqueous sorption solution comprising one or more amine-CO 2 reaction products dissolved in the aqueous sorption solution; passing the rich stream from the sorption zone to a second zone and precipitating at least a portion of the amine-CO 2 reaction products to form a precipitate slurry; separating the precipitate slurry to form a portion enriched in precipitate solids and a first recycle stream, the first recycle stream comprising a majority of the solvent from the precipitate slurry; and passing the portion enriched in precipitate solids to at least one regeneration zone and desorbing the sorbed carbon dioxide as gas to form a second recycle stream, the second recycle stream containing a lower concentration of carbon dioxide than the rich stream and containing an increased concentration of total amine relative to the rich stream, wherein the aqueous sorption solution comprises at least a portion of the first recycle stream and at least a portion of the second recycle stream, and wherein the promoter amine comprises piperazine, piperidine, bridged derivatives of piperidine and piperazine, 4-dimethylamino pyridine, N-methyl imidazolineor a derivative of piperazine or piperidine that includes at least one tertiary amine.