The Dow Chemical Company

Roscoe L Pearce

Charles W Martin

Richard A Wolcott

Charles R Pauley

John W Bozzelli

George D Shier

Michael S Dupart

David C Cringle

Leroy S Krawczyk

George W Lyon

There is disclosed a process for treating liquid (liquifiable) and gaseous hydrocarbons to remove substantially all of the acid gases including COS by contacting the hydrocarbon streams with specific aqueous treating agents in a series of sequential specific limit operations and apparatus.

Sulfur removal from hydrocarbons

Herein is described a technique for maintaining a copper ion in the plus 2 oxidation state, as it is employed as an inhibitor in an alkanolamine gas conditioning absorbent solution to provide corrosion protection of the metals in contact with the alkanolamine solution. The procedure disclosed for maintaining copper in the plus 2 state is to apply an induced or impressed voltage across a point, or several points, in the circulating copper containing solution of the gas conditioning plate for the recovery of CO.sub.2 from flue gas particularly when oxygen is present in the gas being treated.

Method for maintaining effective corrosion inhibition in gas scrubbing

There is disclosed a procedure for removing copper inhibitor from a circulating fluid which contains the same, which copper may be lost on the cool side of a gas conditioning system by plating out under certain conditions, by contacting a portion of the circulating hot fluid with an activated carbon bed to sorb the copper in excess of the solubility limits within said fluid, regenerating said carbon bed when saturated by contacting said carbon bed with cool circulating fluid, thus returning copper which may have plated out to the circulating fluid in an amount and in an ionic state which will not plate out in the system, the circulating fluid is also treated on the cool side by mechanical filtration, activated carbon sorption and/or ion exchange to remove physical and chemical impurities, contaminates and degradation products.

Process for the recovery of CO.sub.2 from flue gases

A method is disclosed for recovering carbon dioxide from gases containing the same as well as oxygen and/or sulfur compounds employing aqueous 5 to 80% alkanolamine solutions. Corrosion of the metals of construction and solvent degradation are minimized by the use of copper ion maintained in solution and continuous removal of ionic iron and solvent degradation products by treating the solvent or a portion of the solvent with a carbon bed, mechanical filter and/or a anion exchange resin.

Corrosion inhibiting compositions for use in aqueous absorbent gas-liquid contacting processes for recovering carbon dioxide (CO.sub.2) from industrial gas and oil combustion and partial combustion process flue gases, particularly employing copper carbonate, in combination with one or more of dihydroxyethylglycine, alkali metal permangenate, alkali metal thiocyanate, nickel or bismuth oxides with or without an alkali metal cartonate. The inhibitors are effective in reducing corrosion of metals in contact with the aqueous absorbent in the absorbent regeneration section of the plant as well as reduce the thermal degradation of the absorbent when high oxygen content combustion gases are treated to recover the CO.sub.2.

Process for removal of carbon dioxide from industrial gases

The corrosion of ferrous metal surfaces in gas conditioning apparatus is inhibited by using a gas conditioning solution such as aqueous alkanolamines which contain thionitrogen compounds such as metal thiocyanates or thioamides. After recycling the gas conditioning solution for a few days, the solution dissolves sufficient amounts of nickel or cobalt or other metals in the equipment to act as a synergist with the thionitrogen compounds. In the event, the equipment does not contain any soluble synergistic metals, these metals may be added to the gas conditioning solution as soluble metal salts. Examples of useful additive metals are cobalt, nickel, calcium, copper, chromium, zinc, tin, aluminum, and magnesium.

Inhibitors for acid gas conditioning solutions

Sour industrial gases containing carbon dioxide and hydrogen sulfide are treated with amines to remove the CO.sub.2 and H.sub.2 S. The amine absorbent containing or loaded with H.sub.2 S and CO.sub.2 is regenerated and the off-gas containing concentrated amounts of H.sub.2 S and CO.sub.2 is treated in a second amine absorber to produce an amine absorbent loaded with H.sub.2 S. This amine is then regenerated to provide an off-gas containing a high ratio of H.sub.2 S to CO.sub.2 which makes it suitable for use as the feed gas to a sulfur recovery unit such as a Claus plant. The process is automatically controlled so that the concentration of H.sub.2 S in the second amine absorber is built up to and controlled at a desired set point so that the off-gas has the required H.sub.2 S/CO.sub.2 ratio.

Process for removing H.sub.2 S from sour gases with generation of a

Hydrogen sulfide and lower alkyl mercaptans are selectively extracted from a gas stream by contacting the stream with piperazinone or an alkyl substituted piperazinone which may contain a substantial proportion of water. The absorbed sulfur compounds can be regenerated by heating the extraction liquid to about 85.degree.-150.degree. C.

Absorption of sulfur compounds from gas streams

A method for selectively separating sulfur oxides from carbon dioxide in an effluent gas stream by contacting the stream with solutions of alkanolamines at from 200.degree.-230.degree. F. At these temperatures the carbon dioxide is not absorbed to any degree by the alkanolamine while the sulfur oxides are quantitatively reacted. The spent alkanolamines are regenerated through the use of a weak base ion exchange resin in a cyclic process.

Selective separation of sulfur oxides from carbon dioxide in an effluent

This invention relates to the low temperature regeneration of liquid desiccants and acid gas absorbing liquid desiccants. Both classes of desiccants can be regenerated to separate water and/or water and acid gases to a satifactory degree under the pressure conditions employed at temperatures substantially below the normal boiling point of the dry desiccant or desiccant-water mixture by countercurrently contacting the desiccant to be regenerated in conventional distillation equipment with the vapors of an easily condensable hydrocarbon or hydrocarbon mixture which is substantially immiscible with the regenerated desiccant at the boiling temperature of the hydrocarbon or hydrocarbon mixture employed as a stripping agent.

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Lake Jackson, TX, United States of America

Roscoe L Pearce