The Dow Chemical Company

Van A Kent

Larry H Kirby

Raymond A Plepys

Johnny Chavez, Jr

William R Behr

Duane S Treybig

Hans R Friedli

Shenghong A Dai

Vaughn M Nace

Steven B Lowenkron

Paul D Bettge

Rory D Daussin

Roberto A Abib

Craig A McClure

Kathryn Hock

Richard N Gerstle

Andrew S Farnum

Randall K Whitmire

Residues from the distillation of a toluene diamine phosgenation mixture are hydrolyzed by mixing them with water and subjecting the mixture to a temperature of 200-350 &deg; C. The hydrolysis is performed in the presence of a sufficient amount of a base to maintain the pressure in the reactor to no more than a predetermined operating level. The product mixture is then extracted to recover TDA, which can be recycled. This provides an efficient process whereby nearly quantitative conversion of the residues to TDA can be achieved.

Process for recovering toluene diamine from toluene diisocyanate distillation residues

The concentration of propenyl ethers in a hydroxy-functional polyether having oxypropylene units is reduced by a process including the step of contacting the polyether with an acid ion exchange resin for a time and at a temperature sufficient for the conversion of at least some of the propenyl ethers to propionaldehyde and in the presence of sufficient water for the conversion. Optionally, the polyether is treated with an epoxy compound in an amount sufficient to reduce the acidity of the polyol.

Purified hydroxy-functional polyether compounds

Disclosed is a method for reducing hydrolyzable chloride in toluene diisocyanate (TDI) and, particularly, in TDI distillation bottoms, and polymers produced using the reduced hydrolyzable chloride bottoms. Crude TDI is heated, optionally in the presence of a solvent, to cause: (a) partial reflux, (b) partial reflux and fractionation, or (c) complete reflux and fractionation; under conditions sufficient to reduce hydrolyzable chloride. After distilling the crude TDI to form TDI monomer, the bottoms produced are thereby desirably reactive and viscosity-stable over a significant period of time. The treated bottoms can be reacted with compounds containing active hydrogen containing groups to form polyurethane, polyurea, and polyisocyanurate polymers, particularly foams.

Method for reducing hydrolyzable chloride in toluene diisocyanate

A process for reducing the amount of propenyl polyethers in hydroxy-functional polyethers comprising (1) contacting a neutral hydroxy-functional polyether, containing a propenyl polyether and water, and an acid catalyst soluble in the hydroxy-functional polyether under reaction conditions sufficient to convert at least a portion of the propenyl polyether to propionaldehyde; (2) contacting the product of step (1) and an epoxy compound to substantially scavenge the acid catalyst; and (3) stripping the product of step (2) to substantially remove the epoxy compound the the propionaldehyde. The resulting hydroxy-functional polyethers contain reduced amounts of propenyl polyethers and can therefore be used to prepare polyurethane foams having a reduced tendency to discoloration.

Process to reduce propenyl polyethers in hydroxyfunctional polyethers

Gas feed streams containing sulfur dioxide such as flue gas streams are first contacted with an aqueous solution of inorganic sulfites and bisulfites having a pH range from about 2 to about 6.5 to remove a minor amount of sulfur dioxide. The same gas stream is then contact with a second aqueous solution of sulfites and bisulfites having a pH range from about 7.0 to about 12.5. Alkali metal hydroxide or ammonium hydroxide solution is added to the liquid inlet of the second contactor and the solution of the second contactor is pumped to the liquid inlet of the first contactor.

Process for selectively removing sulfur dioxide

Fluid streams containing hydrogen sulfide from a steam tubine or from a sour gas stream are contacted with an aqueous solution of a polyvalent metal chelate and a bisulfite whereby the hydrogen sulfide is converted to free sulfur and then to soluble sulfur compounds. The metal chelate is reduced to a lower oxidation state metal chelate and reduced metal chelate is subsequently oxidized with air back to the higher oxidation state and reused. The bisulfite is formed by combustion of a portion of the fluid stream and subsequent absorption of the sulfur dioxide formed thereby in a two-stage countercurrent scrubber operating at conditions favorable for high bisulfite and low sulfite formation and selective away from carbon dioxide absorption.

Removal of hydrogen sulfide from fluid streams with minimum production

Hydrogen sulfide is removed from gas streams containing it with or without carbon dioxide by contacting the gas feed stream with an aqueous liquid containing sulfide and bisulfide ions and having a pH in the range from 9 to 12 to remove a minor portion of the hydrogen sulfide and then removing the remainder with an aqueous liquid containing sulfide and bisulfide ions having a higher pH in the range from 11 to 13.5.

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Lake Jackson, TX, United States of America

Van A Kent