Improved composition and method for removal of carbonylsulfide from acid gas containing same

A process for selective removal of COS from a gas stream containing COS and CO2, said process comprising contacting the gas stream with a solvent composition comprising

• a) at least one polyalkylene glycol alkyl ether of the formula
• R1O-(Alk-O)n—R2 (I)
• wherein R1 is an alkyl group having from 1 to 6 carbon atoms;
• R2 is hydrogen or an alkyl group having from 1 to 4 carbon atoms;
• Alk is an alkylene group, branched or unbranched, having from 2 to 4 carbon atoms;
• and n is from 1 to 10;
• and
• b) at least one alkanolamine compound of the formula
• R3NHR4OR6 (II)
• or
• at least one piperazine compound of formula
• wherein R3 is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R4OH group;
• R4 is a branched or unbranched alkylene group having from 1 to 6 carbon atoms;
• R5, independently in each occurrence, is hydrogen or an alkyl group having from 1 to 6 carbon atoms or an hydroxyalkyl group having from 1 to 4 carbon atoms.

A solvent composition for selective removal of COS from a gas stream containing same, said composition comprising

• a) 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone;
• and
• b) at least one alkanolamine compound of the formula
• R3NHR4OR6 (II)
• or
• at least one piperazine compound of formula
• R5 wherein R3 is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R4OH group;
• R4 is a branched or unbranched alkylene group having from 1 to 6 carbon atoms;
• R5, independently in each occurrence, is hydrogen or an hydroxyalkyl group having from 1 to 4 carbon atoms;
• and R6 is hydrogen, an alkyl group having from 1 to 6 carbon atoms or an hydroxyalkyl group having from 1 to 4 carbon atoms.

A process for selective removal of COS from a gas stream containing COS and CO2, said process comprising contacting the gas stream with a solvent composition comprising

• a) 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone;
• and
• b) at least one alkanolamine compound of the formula
• R3NHR4OR6 (II)
• or
• at least one piperazine compound of formula
• wherein R3 is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R4OH group;
• R4 is a branched or unbranched alkylene group having from 1 to 6 carbon atoms;
• R5, independently in each occurrence, is hydrogen or an hydroxyalkyl group having from 1 to 4 carbon atoms;
• and R6 is hydrogen, an alkyl group having from 1 to 6 carbon atoms or an hydroxyalkyl group having from 1 to 4 carbon atoms.

A solvent composition for removal of COS from a gas stream containing same, said composition comprising

• a) a mixture of N-formylmorpholine and N-acetylmorpholine;
• and
• b) at least one alkanolamine compound of the formula
• R3NHR4OR6 (II)
• or
• at least one piperazine compound of formula
• wherein R3 is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R4OH group;
• R4 is a branched or unbranched alkylene group having from 1 to 6 carbon atoms;
• R5, independently in each occurrence, is hydrogen or an hydroxyalkyl group having from 1 to 4 carbon atoms;
• and R6 is hydrogen, an alkyl group having from 1 to 6 carbon atoms or an hydroxyalkyl group having from 1 to 4 carbon atoms.

A process for selective removal of COS from a gas stream containing same, said process comprising treating the gas stream with a solvent composition comprising

• a) a mixture of N-formylmorpholine and N-acetylmorpholine;
• and
• b) at least one alkanolamine compound of the formula
• R3NHR4OR6 (II)
• or
• at least one piperazine compound of formula
• wherein R3 is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R4OH group;
• R4 is a branched or unbranched alkylene group having from 1