Patent ID: 6187227
Filing Date: 2001-02-13
Classification: B01D,C23F

Abstract:
A method for inhibiting corrosion of metals in contact with an aqueous alkanolamine solution in an acid gas removal amine unit comprising adding to the aqueous alkanolamine solution an effective corrosion inhibiting amount of at least one of thiacrown ether compound or polymeric thiacrown ether compound effective as a corrosion inhibitor wherein the at least one of thiacrown ether compound or polymeric thiacrown ether compound is selected from one or more of the following formulas: ##STR19##where Y is an integer of 1 to 7 and Z is an integer of 1 to 4 with the proviso that Y+Z cannot be greater than 8;M is a linkage group and is selected from O; COO where the carbon atom is attached to P, P.sub.1 and P.sub.2 ; C.sub.1 to C.sub.5 substituted or unsubstituted linear or branched alkylene wherein the substituent is OH, SH, F, Br, Cl, I, COOH, amine, mono- or di- C.sub.1 to C.sub.5 alkylamino, C.sub.1 to C.sub.3 lower alkanoylamino or nitro; or M is NR.sub.6 where R.sub.6 is H or C.sub.1 to C.sub.5 alkyl; or M is S with the proviso that P, P.sub.1 and P.sub.2 are not polyethyleneimine;P, P.sub.1 and P.sub.2 are polymers or oligomers in formulas 4 and 5;P.sub.1 and P.sub.2 are selected from H, polymers, or oligomers in formula 3; andX.sub.1 and X.sub.2 are independently H; SH; F; Cl; I; substituted or unsubstituted C.sub.1 to C.sub.10 linear or branched alkyl or alkenyl group; substituted or unsubstituted C.sub.6 to C.sub.10 aryl; amine; mono- or di- C.sub.1 to C.sub.10 lower alkylamino; C.sub.1 to C.sub.10 lower alkanoylamino; nitro; cyano; COOH; OCOR.sub.1 wherein R.sub.1 is C.sub.1 to C.sub.10 alkyl or alkenyl group; OR.sub.2 COOR.sub.3 wherein R.sub.2 is substituted or unsubstituted C.sub.2 to C.sub.5 linear or branched alkyl group and R.sub.3 is substituted or unsubstituted C.sub.1 to C.sub.10 linear or branched alkyl group or alkenyl group; OR.sub.4 where R.sub.4 is substituted or unsubstituted C.sub.1 to C.sub.10 linear or branched alkyl or alkenyl group; or SR.sub.5 wherein R.sub.5 is substituted or unsubstituted C.sub.1 to C.sub.10 linear or branched alkyl or alkenyl group; wherein the substituents of the X.sub.1 and X.sub.2 moieties are independently OH, SH, F, Br, Cl, I, COOH, amine, mono- or di- C.sub.1 to C.sub.10 alkylamino, alkanoylamino or nitro and with the proviso that both X.sub.1 and X.sub.2 cannot both be H.