E.i. Dupont De Nemours and Company

John Byrne Michel

Richard E Ernst

Daniel Campos

Paul Douglas Vernooy

Paul Douglas VerNooy

Bonnie W Griffiths

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 is disclosed for producing calcium fluoride. The process comprises (a) mixing phosphate rock with aqueous H SiF at ambient temperature for at least one hour; (b) nucleating the calcium fluoride in the slurry prepared in step (a) by reacting the slurry at a temperature and for a time sufficient to initiate and sustain nucleation of calcium fluoride and SiO by-product; (c) aggregating the SiO by-product by heating the slurry produced in step (b) at a temperature of about 90&deg; C. to about 105&deg; C. for at least 0.5 hours; and (d) recovering a calcium fluoride-containing product of an average particle size of less than 1 micron.

Process for the production of calcium fluoride

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 is disclosed for producing calcium fluoride comprising: (a) mixing aqueous H,PO,with aqueous H,SiF,to form a mixture such that the concentration of H,PO,is at least about 3 moles/liter, (b) adding phosphate rock to the mixture at a rate such that the pH of the mixture is maintained at less than about 1.0 and at a temperature sufficient to form a second mixture containing calcium fluoride, and (c) separating calcium fluoride from the second mixture.

There is disclosed an improved process for preparing a superconducting composition having the formula MBa.sub.2 Cu.sub.3 O.sub.x wherein M is selected from the group consisting of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu; x is from about 6.5 to about 7.0; said composition having a superconducting transition temperature of about 90 K; said process consisting essentially of heating a precursor powder in an oxygen-containing atmosphere at a temperature from about 875.degree. C. to about 950.degree. C. for a time sufficient to form MBa.sub.2 Cu.sub.3 O.sub.y, where y is from about 6.0 to about 6.4; and maintaining the MBa.sub.2 Cu.sub.3 O.sub.y in an oxygen-containing atmosphere while cooling for a time sufficient to obtain the desired product; said precursor powder being prepared by (a) forming an aqueous solution of M(NO.sub.3).sub.3, Ba(NO.sub.3).sub.2 and Cu(NO.sub.3).sub.2 in an atomic ratio of M:Ba:Cu of about 1:2:3, (b) adding the resulting solution to sufficient oxalic acid to precipitate the metals present as salts, and spray drying the resulting slurry to obtain the precursor powder.

Process for making 90 k superconductors using a spray dried oxalate

A method for treating carbon that is deficient in alkali and/or alkaline earth metal content to improve the efficacy of the carbon as a catalyst support, particularly as a support for a noble metal hydrogenation catalyst.

Growing community of inventors

West Chester, PA, United States of America

John Byrne Michel