Abstract: 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.

Abstract: A process is disclosed for producing calcium fluoride. The process comprises (a) mixing phosphate rock with aqueous H2SiF6 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 SiO2 by-product; (c) aggregating the SiO2 by-product by heating the slurry produced in step (b) at a temperature of about 90° C. to about 105° 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.

Abstract: 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.

Abstract: A process is disclosed for producing calcium fluoride comprising: (a) mixing aqueous H3PO4 with aqueous H2SiF6 to form a mixture such that the concentration of H3PO4 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.