E.i. Dupont De Nemours and Company

Richard E Ernst

Daniel Campos

John Byrne Michel

Harry B Copelin

Leon S Scott

Suriyanarayanan Dorai

Anne Irisa Breikss

Donald C Paul

James D Verbsky

John D Super

Peter A Bloxham

Suri Narayan Dorai

A process for the production of tetrahydrofuran, gamma butyrolactone, 1,4-butane diol and the like from a hydrogenatable precursor such as maleic acid, succinic acid, corresponding esters and their mixtures and the like in the presence of hydrogen and a noble metal catalyst, wherein oxidizing agents such as hydrogen peroxide, oxygen or air are used to regenerate spent noble metal catalyst for further use in the process.

Catalyst regeneration by treatment with an oxidizing agent

A process for producing a poly(tetramethylene ether) glycol (PTMEG) or copolymer having a narrowed molecular weight ratio of 1.9 to 2.07 and a dispersity of 1.2 to 1.65 from a starting PTMEG or copolymer with a broader molecular weight distribution having a dispersity of 1.9 to 2.3 and a molecular weight ratio of 2.3 to 2.6 is provided by feeding the PTMEG or copolymer and an effective amount of an inert solvent to a stripping apparatus and stripping at a temperature of 150 to 220 degrees C. and a pressure of 0.5 to 5 mm of mercury.

Narrowing of poly (tetramethylene ether) glycol

This invention relates to a method of improving the catalytic performance of palladium or ruthenium, rhenium-on-carbon hydrogenation catalysts operating in aqueous media where loss of soluble rhenium may result in rapid catalytic failure. A rhenium-containing hydrogenation catalyst comprised of rhenium on a support material is regenerated by first treating the catalyst with aqueous perrhenic acid or potassium perrhenate followed by treating the catalyst under reducing conditions at elevated temperature and pressure. Treatment of the catalyst as described replenishes dispersed fresh finely divided rhenium which enhances the activity of the catalyst while at the same time allowing the operations to be carried out in situ in the hydrogenation reactor or in a side stream reactor with significant savings in reducing reactor down time and precious metal expenses.

Process for regeneration of carbon-supported, rhenium-containing catalysts

A process for removing precursors, such as low boiling alkyl glycols (e.g., ethylene glycol and/or 1,2-propylene glycol), to undersirable color forming acetal impurities (e.g., 1,3 -dioxolane and 4-methyl-1,3-dioxolane) from technical grade 1,4-butanediol/2-methyl-1,4-butanediol mixtures and the like by distillative topping of the diol mixture prior to ring closing cyclization to corresponding tetrahydrofuran/3-methyl tetrahydrofuran mixture and subsequent polymerization to polytetramethylene glycol ether polymers. Such a process is useful to produce THF and PTMEG having a APHA color index of nearly zero.

Method for controlling color formation during polytetramethylene ether

A process for reducing fluoride levels in PTMEG by heating aqueous PTMEG having an undesired level of fluoride (80'600 ppm) to a temperature in the range between about 200.degree. and 300.degree. C. for a period of time sufficient to reduce the fluoride content of said PTMEG. Preferably, heating is carried out with agitation to a temperature between about 225.degree. and about 275.degree. C. for about 1 minute to about 8 hours in the presence of an aqueous base, most preferably 240.degree. to 250.degree. C. in presence of aqueous lime.

Process for reducing fluoride levels in poly(tetramethylene ether) glycol

Process for preparing 2-alkyl-1,4-butanediols and mixtures with 1,4-butanediol which comprises bringing together, at an initial alkaline pH, and at a temperature and pressure suitable for reaction, a mixture of 4-hydroxybutyraldehyde and/or its cyclic acetal, 2-hydroxytetrahydrofuran, hydrogen, an unsubstituted aliphatic aldehyde, especially formaldehyde, and a hydrogenation catalyst. Also processes for preparing mixtures of tetrahydrofuran and 3-alkyltetrahydrofuran from the diol mixtures, and copolymers from the tetrahydrofuran mixtures.

Preparation of mixtures of butanediols

Process for preparing 2-alkyl-1,4-butanediols and mixtures with 1,4-butanediol which comprises bringing together, at an initial alkaline pH, and at a temperature and pressure suitable for reaction, 2,3-dihydrofuran, hydrogen, an unsubstituted aliphatic aldehyde, especially formaldehyde, and a hydrogenation catalyst. Also processes for preparing mixtures of tetrahydrofuran and 3-alkyltetrahydrofuran from the diol mixtures, and copolymers from the tetrahydrofuran mixtures.

Synthesis of mixtures of butanediols

2-Alkyl-1,4-butanediols are prepared from 1,4-butynediol or 1,4-butenediol by catalytic hydrogenation and reaction with an aldehyde.

Process for preparing 2-alkyl-1,4-butanediols

A mixture of 1,4-butanediol and 2-alkyl-1,4-butanediol is produced by catalytic hydrogenation and reaction with an aldehyde. Such mixture is cyclized to a mixture of tetrahydrofuran and 3-alkyl tetrahydrofuran. Copolymers can then be made from such mixtures of furans.

Process for preparing a mixture of tetrahydrofuran and 3-alkyl

The hydrogenation of furan to tetrahydrofuran can be carried out simultaneously with the hydrogenation of 2-butyne-1,4-diol to 1,4-butanediol. This can be done in the same reactor, using a common catalyst, and under common reaction conditions.

Process for simultaneous hydrogenation of 2-butyne-1,4-diol and furan

The amount of methacrolein impurity in tetrahydrofuran made from acetylene and formaldehyde can be significantly reduced by treating it with hydrogen peroxide during an interval in the multi-stage distillation tetrahydrofuran refining procedure.

Purification of tetrahydrofuran

Color-forming materials or their precursors present in crude 1,4-butanediol are reduced more efficiently by subjecting the crude 1,4-butanediol to distillation under conditions wherein substantially all the water present in the crude 1,4-butanediol is first removed and then the 1,4-butanediol with reduced water content is further distilled to remove the color-forming materials.

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Kennett Square, PA, United States of America

Richard E Ernst