Abstract: A process for producing ammonium thiosulfate by contacting a feed gas containing hydrogen sulfide and ammonia with an aqueous absorbing stream containing ammonium sulfite and ammonium bisulfite to form an ammonium thiosulfate-containing solution; the absorption being controlled by monitoring the oxidation reduction potential of the absorbing stream and varying the feed rates in response to the oxidation reduction potential measurements. An ammonium bisulfide-containing aqueous stream is contacted with and absorbs sulfur dioxide to form an aqueous stream containing the ammonium sulfite and ammonium bisulfite reagents. This sulfite/bisulfite-containing stream is combined with the ammonium thiosulfate-containing solution in a vessel to produce a combined solution. A portion of the combined solution is recycled back to contact the feed gas and ammonium thiosulfate is recovered from the remaining portion of the combined solution.

Abstract: A process for producing ammonium thiosulfate wherein in a first reaction zone a feed gas mixture containing hydrogen sulfide and ammonia is contacted with an aqueous absorbing stream containing ammonium thiosulfite, ammonium bisulfite, and ammonium sulfite under conditions to limit conversion of sulfite to thiosulfate and produce an ammonia-rich absorbing stream, the unreacted hydrogen sulfide being rejected from the ammonia-rich absorbing stream, sulfur dioxide from a sulfur dioxide-containing gas stream being absorbed in the ammonia-rich absorbing stream in the absence of any substantial quantity of hydrogen sulfide, the ammonia-rich absorbing stream containing the sulfur dioxide being at least partially transferred to the first reaction zone, an aqueous product stream of ammonium thiosulfate being recovered.

Abstract: A method for producing urea having a low biuret content comprising providing solid crystals of urea and forming the solid crystals into discrete masses of urea by mechanical compacting.

Abstract: A vapor-solids contacting apparatus useful as a catalytic reactor in the processing of hydrocarbonaceous reactants. A plurality of preferably rectangular cross-section elongated catalyst compartments are formed by box-like structures having two opposing parallel perforate planar sides and sealed ends. The perforate sides of adjacent catalyst compartments form two of the sides of reactant flow chambers having the same length. Alternating ends of the reactant flow chambers are sealed to direct the reactants flowing from one end of the vessel to the other through the catalyst compartments.

Abstract: A hydrocarbon separation process which includes a novel method of fractionating the extract and raffinate streams removed from a simulated moving bed of a selective adsorbent. The extract and raffinate streams are passed into separate fractionation columns, each having a sidecut removed above the feed point. Each sidecut is stripped, with the stripper overhead vapor passing directly into the extract or raffinate column. The bottoms streams of the two sidecut strippers are combined and passed into the adsorbent bed.

Abstract: A process, apparatus and control system for the fractionation of a hydrocarbon feed stream containing relatively nonvolatile impurities. A sidecut liquid stream which is substantially free of the impurities is withdrawn below the feed point. The liquid derived from the feed stream is confined to a first lateral half of the fractionation column to prevent the transfer of the nonvolatile impurities to the second lateral half from which the sidecut is removed. Liquid descending from above the feed point is collected and distributed between the two lateral halves of the column in response to temperature measurements taken in the two halves to thereby equalize liquid flow rates in the two halves. The flow of vapor between the two halves is not obstructed.

Abstract: Normal paraffinic hydrocarbons, having from three to about twenty carbon atoms per molecule, are dehydrogenated to produce corresponding linear mono-olefins.These are separated from unreacted paraffins, preferably via an adsorption-separation technique. Raffinate, containing the unreacted normal paraffins, is subjected to mild hydrotreating, as is the hydrogen-rich vaporous phase recovered from the dehydrogenation zone product effluent,to saturate the olefins therein. Hydrotreated effluent is introduced, generally in admixture with fresh feed paraffins, into the dehydrogenation reaction zone.This technique avoids by-product dehydrogenation reactions otherwise resulting in non-linear mono-olefins, di-olefinic hydrocarbons and aromatics.

Abstract: A mixture of cymene isomers, containing paracymene is subjected to adsorption-separation in contact with a crystalline aluminosilicate adsorbent which selectively retains para-cymene. Raffinate therefrom, being a para-cymene deficient mixture of cymene isomers, is isomerized to form additional para-cymene. Isomerization conditions employed to produce para-cymene, also effect formation of olefinic material. To prevent the adverse effect which olefins exhibit toward the efficiency and capacity of the zeolitic adsorbent, the isomerization effluent is subjected to hydrotreating at conditions which provide a liquid-phase operation and saturate olefins without saturation of the cymene isomers.

Abstract: A C.sub.8 -aromatic hydrocarbon mixture containing para-xylene is subjected to adsorption-separation in contact with a crystalline aluminosilicate adsorbent which selectively retains para-xylene. Raffinate therefrom, being a para-xylene deficient C.sub.8 -aromatic concentrate, is isomerized in contact with a catalytic composite containing a Group VIII noble metal component to form additional para-xylene. Isomerization conditions employed to produce the para-xylene, also effect the formation of olefinic material. To prevent the adverse effect which olefins exhibit toward the efficiency and capacity of the zeolitic adsorbent, the isomerization effluent is subjected to hydrotreating at conditions which provide a liquid-phase operation and saturate olefins without saturation of the C.sub.8 -aromatics. The hydrotreating is effected in contact with a substantially non-acidic catalytic composite comprising a Group VIII noble metal component.