(US4741745-A)      Improved CO2 sepn. from an original mixt. contg. as non-acid gas, comprises (a) contacting with an initial liq. solvent at absorption pressure to dissolve CO2 in amt. so that mol fraction CO2 remaining in the sec. gas phase remaining after absorption is less than that in original mixt., while mol. fraction CO2 in sec. solvent obtd. is more than that in initial solvent., and (b) sepg. sec. gas phase and solvent.    Process then comprises (c) exposing sec. solvent in a vessel contg. a vapour space above the solvent to desorption pressure less than absorption pressure, such that CO2 passes from sec. solvent phase into a tert. gas phase in the vapour space and a tert. solvent phase remaining liq.; (d) sepg. tert. gas phase from tert. solvent., and (e) recycling tert. solvent to extract more acid gas from a new amt. of gas mixt..    Initial solvent has formula (CH3)2CHO(C2H4O)xHC(CH3)2, where x is 2-8.    ADVANTAGE -   Lower operating costs are realised with diisopropyl ether of oligomers of ethylene glycol or absorption solvent without requiring new capital investment.    (DE3780364-G)      An acid gas (A) is separated from a non-acid gas by (a) contacting the mixed gas with a solvent (S) at an absorption pressure; (b) separating the resultant gas phase depleted in (A) from enriched (S) containing dissolved (A); (c) reducing the pressure over the enriched (S), whereby (A) passes from (S) into the gas phase; (d) separating desorbed gas from (S); and (e) recycling (S) to extract more (A) from a new quantity of the gas mixture. (S) consists of one or more diisopropyl ether of an ethylene glycol aligomer, of formula (CH3)2CHO(C2H4O)xHC(CH3)2, where x = 2-8.    In an alternative procedure, steps (a) and (c) are replaced by (a1) and (c1) respectively: (a1) contacting the mixed gas with a solvent (S) at an absorption temperature; (c1) increasing the temp. of the enriched (S), whereby (A) passes from (S) into the gas phase.    USE/ADVANTAGE -   The method is of use in separating acid gases, esp. carbon dioxide and/or hydrogen sulphide, from natural gas, synthesis gas, or coke oven gas. (S) has higher solvent capacity for (A) and lower viscosity than prior used physical solvents for the process, and can be used in equipment originally designed for use with chemical absorbents. It is also resistant to deleterious reactions, and has relatively low vapour pressure to prevent undue losses. It can be used at low temp., e.g. below 0 deg.C.    (JP94098261-B2)      An acid gas (A) is sepd. from a non-acid gas by: (a) contacting the mixed gas with a solvent (S) at an absorption pressure; (b) sepg. the resultant gas phase depleted in (A) from enriched (S) contg. dissolved (A); (c) reducing the pressure over the enriched (S), whereby (A) passes from (S) into the gas phase; (d) sepg. desorbed gas from (S); and (e) recycling (S) to extract more (A) from a new quantity of the gas mixt.. (S) consists of one or more diisopropyl ether of an ethylene glycol oligomer, of formula (CH3)2CHO(C2H4O)xHC(CH3)2, where x = 2-8.    In an alternative procedure, steps (a) and (c) are replaced by (a1) and (c1) respectively: (a1) contacting the mixed gas with a solvent (S) at an absorption temp.; (c1) increasing the temp. of the enriched (S), whereby (A) passes from (S) into the gas phase.    USE/ADVANTAGE -   The method is of use in sepg. acid gases, esp. carbon dioxide and/or hydrogen sulphide, from natural gas, synthesis gas, or coke oven gas. (S) has higher solvent capacity for (A) and lower viscosity than prior used physical solvents for the process, and can be used in equipment originally designed for use with chemical absorbents. It is also resistant to deleterious reactions, and has relatively low vapour pressure to prevent undue losses. It can be used at low temp., e.g. below 0 deg.C.