E.i. Dupont De Nemours and Company

Other

Robert E Michel

Roger George Rudolph

Richard Redfearn Hepner

George Malcolm Williamson

Robert E Trotter

Matthew Roland Kegelman

Frederick J Sebelist

Donald Richard Wheatcraft, Jr

Mark S Katzenberger

Stephen Dana Hall

Polyester is depolymerized by methanolysis and methanol is recovered in a process that uses methyl benzoate and/or p-methyltoluate as an azeotropic agent while the methanol is present.

Process for depolymerizing polyester

Dimethyl terephthalate is recovered from polymer mixtures containing polymers of terephthalic acid and glycol and a chloride polymer, by adding base to neutralize the hydrochloric acid formed by the degradation of the chloride polymer.

Recovery of dimethyl terephthalate from polymer mixtures

Separation of ethylene glycol and diethylene glycol from dimethyl terephthalate is accomplished by distillation using methyl benzoate or the methyl ester of p-toluic acid as an azeotropic agent.

Process for the separation of glycols from dimethyl terephthalate

Acetic acid is recovered from the mother liquor used to oxidize para-xylene to terephthalic acid by adding at least one organic compound having a melting point below 140.degree. C. and an atmospheric boiling point above 230.degree. C.

Recovery and recycle of acetic acid in an oxidation process

A process for the removal of manganese catalyst from the bis glycol ester of terephthalic acid, by adding terephthalic acid and/or isophthalic acid, and separating the precipitate.

Process for the production of polyethyleneterephthalate from

Recovery of cobalt and manganese catalyst from oxidation process, by precipitation with oxalic acid and alkali metal hydroxide, followed by oxidation of the precipitate in acetic acid to form cobalt and manganese acetate.

Catalyst recovery

A block of dimethylterephthalate having a needle-like crystal structure. The block is easily cleavable, and has a reduced tendency to fuse to other blocks when subjected to bag-stacking pressure.

Form of solid dimethylterephthalate

A continuous process for recovery of metals, especially precious metals, from various ores, involves pulverizing the ore to a particle size less than five microns, forming a colloidal suspension of the particles in a liquid, extracting metal from the slurry with a solvent, and separating the solvent from the particles centrifugally. Metals are recovered from the liquid solvent, which is recycled. Contacting of the slurry with fresh solvent is preferably effected in a staged counter-current centrifugal extraction unit.

Method of extraction of metals from low grade ores

A method is disclosed for the manufacture of phosphoric acid directly from phosphate rock wherein the crushed phosphate rock is mixed with dilute phosphoric acid to form a slurry and the slurry is then heated to produce calcium monophosphate. Thereafter, oxalic acid is added to the slurry to precipitate the calcium therein as calcium oxalate which is separated. The liquid resulting therefrom which contains the phosphoric acid from the rock is then treated conventionally to recover the phosphoric acid therein.

Growing community of inventors

Wilmington, NC, United States of America

Robert E Michel