Abstract: A process for recovering paraxylene from a substantially hydrocarbon feedstock. The recovery comprises cooling the hydrocarbon feedstock in at least one refrigerated crystallization stage that is indirectly refrigerated by evaporating at least a portion of a substantially liquid stream comprising ammonia. The crystallization stage may also be cooled by an ethylene refrigerant, which has been cooled by heat exchange with a substantially liquid stream comprising ammonia. The process further comprises a series of cooling substeps. This invention is also directed to an ammonia absorption refrigeration process powered by an enthalpy source from or near a paraxylene recovery unit.

Abstract: Improved catalysts and a method for preparing improved catalysts suitable for the selective dehydrogenation of dehydrogenatable organic compounds which method comprises contacting a composition comprising a platinum group metal component and a halide component on an alumina support material with an aqueous alkaline solution of an alkali metal salt, the amount of solution being in excess of the amount absorbed by the composition; partitioning the composition from remaining solution to form a treated composition and a filtrate containing solubilized halide removed from the composition; and drying the treated composition to form the catalysts.

Abstract: A process for selectively dehydrogenating organic compounds, and particularly for dehydrogenating dimethyltetralins to dimethylnaphthalenes, by contacting the organic compound at an elevated temperature with a catalyst prepared by treating a composition comprising an alumina support material and platinum group metal with an excess amount of an alkaline solution of an alkali metal salt.

Abstract: A catalyzed process for the isomerization of a xylene-containing stream containing a major amount of ethylbenzene under supercritical temperature and pressure which contacts the stream under supercritical conditions with a catalyst and subsequently reduces the temperature of the isomerization product at a pressure above the critical pressure.

Abstract: Gallium-containing, crystalline silicate molecular sieves in which substantially all of the gallium occupies molecular sieve lattice positions or is intimately associated with the crystal lattice of the silicate sieve when composited into a silica matrix are shown to form catalyst compositions having superior properties for the catalytic, liquid-phase isomerization of a xylene-containing stream containing a minor amount of ethylbenzene to a product mixture rich in paraxylene.

Abstract: An improved process employing a supported, platinum-containing, crystalline, silicate molecular sieve catalyst composition effective in removing ethylbenzene from unextracted xylene feeds during isomerization, primarily by hydrodeethylation, and also the primarily C.sub.9 paraffins and naphthenes. Choosing (1) a set of process conditions within narrow ranges of temperature T, total pressure P, and hydrogen to hydrocarbon mol ratio H/HC such that Z, which is defined as a function of T, P and H/HC, is less than about 0.01, and (2) a platinum-containing catalyst composition, greatly reduces the feed C.sub.9 paraffins and naphthenes content during isomerization, removes most of the ethylbenzene by hydrodeethylation to ethane and benzene, and minimizes xylene loss to hydrogenation and cracking, all without substantially changing the excellent isomerization properties of the sieve catalyst composition.

Abstract: Recovery of germanium from the effluent of optical fiber manufacturing processes depends on the realization that the germanium is to a substantial extent in gaseous form. Thus, to separate the germanium effectively appropriate measures are taken to separate not only particulate matter but also gaseous germanium compounds. This separation is done through among other steps an appropriate solvation and precipitation to remove the gaseous germanium material.