CORROSION PROTECTIVE AGENT FOR STEEL CONTAINING AQUEOUS ALKANOLAMINE SOLUTIONS

摘要

1360836 Gas separation UNION CARBIDE CORP 12 July 1971 [13 July 1970] 32580/71 Heading C1A [Also in Division C7] In the removal of acid gases from a gas stream by absorption in an aqueous alkanolamine solution, corrosion of metal in contact therewith is inhibited by adding to the solution (1) a combination of 9 to 1 weight parts of a vanadate compound to 1 to 9 parts of an antimonyl compound, these being at least partially soluble in said solution, (2) a stannous salt, (3) an organotin compound, (4) a nitro-substituted aromatic acid or salt or (5) benzotriazole. The alkanolamine may be mono- or di-ethanolamine or monoisopropanolamine, the metal steel, and 0À01 to 1À0 wt. per cent inhibitor (based on the weight of solution) is used. In (1), the vanadate compound may be Na metavanadate, K pyrovanadate, or K orthovanadate, and the Sb compound K antimonyl tartrate or Na antimonyl gluconate, (2) may be stannous tartrate, gluconate, chloride, acetate, or fluoborate, (3) may be di-n-butyl tin dimethoxide, n-butyl stannoic acid, dimethyl tin oxide or diethyl tin dichloride and (4) may be Na-m-nitrobenzoate or Na-4-nitrophthalate. The acid gas exemplified is CO 2 ; the alkanolamine solution is heated. There is claimed a corrosion inhibiting composition comprising an alkanolamine and an inhibitor which is any of (1) to 5 as defined above.