Abstract: The present invention comprises a process for the recovery from a reaction mixture of cellulose carbamate produced by conversion of cellulose with excess urea in an inert organic liquid reaction carrier, wherein the reaction mixture is treated with added water under heat, then the liquid phase is separated as much as possible on a filter, the cellulose carbamate remaining on the filter is washed with water, optionally pre-dried and, if desired, dried and recovered, and the organic reaction carrier is recovered by phase separation from the combined liquids.

Abstract: The invention is an apparatus for spinning solutions of cellulose carbamate by extruding the solution through a spinneret into a precipitation bath, coagulating the cellulose carbamate fibers thus formed and drawing off the fibers by mechanical means, where the fibers are enveloped from the outlet of the spinneret to the outlet of the precipitation bath in a stream of precipitating medium flowing in the same direction, where the velocity of flow of the precipitation medium where the fibers exit the spinneret (plane X1) amounts to 0.1 to 0.8 times the draw-off speed of the fibers, and the velocity of flow of the precipitation medium where the fibers exit the precipitation bath (plane X3) amounts to 0.96 to 1.1 times the draw-off speed of the fibers.

Abstract: The invention is a process for spinning solutions of cellulose carbamate by extruding the solution through a spinneret into a precipitation bath, coagulating the cellulose carbamate fibers thus formed and drawing off the fibers by mechanical means, where the fibers are enveloped from the outlet from the spinneret to the outlet from the precipitation bath in a stream of precipitating medium flowing in the same direction, where the velocity of flow of the precipitation medium where the fibers exit the spinneret (plane X1) amounts to 0.1 to 0.8 times the draw-off speed of the fibers, and the velocity of flow of the precipitation medium where the fibers exit the precipitation bath (plane X3) amounts to 0.96 to 1.1 times the draw-off speed of the fibers.

Abstract: A method for the manufacture of cellulose carbamate, whereby cellulose pulp is preliminarily activated by alkaline, hydrothermal and/or enzymatic treatment, then the activated cellulose pulp is mixed with aqueous urea solution, the water in the solution replaced with an organic reaction carrier, and thereafter the cellulose is reacted with urea in the liquid phase to yield cellulose carbamate, which is separated from the liquid medium and washed. The method results in uniform substitution and distribution of carbamate groups and in cellulose chain, which leads to good solubility of the cellulose carbamate in aqueous alkali solution as well as excellent spinnability for producing fibers, films, and other products.

Abstract: The invention comprises a process for producing cellulose carbamate with improved solubility properties comprising converting cellulose with urea in an inert, liquid, organic reaction carrier, at reaction temperature in the range of 80.degree. to 180.degree. C. where the reaction temperature is increased as the reaction time increases.

Abstract: A process for the production of cellulose carbamate from cellulose and urea through the conversion of the cellulose with excess urea in an inert liquid organic reaction carrier at a temperature in the range of 130 .degree. to 160.degree. C., separation of the reaction carrier from the reaction mixture and washing of the reaction mixture with water. The cellulose is intimately mixed with an aqueous urea solution. Then the water in the solution is replaced with the organic reaction carrier, and the reaction of urea and cellulose is carried out in the presence of an inert gaseous carrier to remove the by-product ammonia. Thereafter, the organic reaction carrier remaining in the reaction product is replaced with an aqueous urea solution and the resulting suspension of cellulose carbamate in the urea solution is filtered and washed free of urea with water. No liquid ammonia is required in this process.

Abstract: A process is provided for the continuous separation of slightly volatile components from a crude phthalic acid anhydride wherein a portion of the crude phthalic acid anhydride is compressed and heated before being reintroduced into a flash evaporator.

Abstract: A process is provided for the production of hydrogen and sulphur from a gas containing hydrogen sulphide. Such a process comprises passing the gas through a cracking zone at a temperature of from about 850.degree. C. to 1600.degree. C., cooling the cracked gas to a temperature of from about 110.degree. C. to 150.degree. C., and separating the condensed elemental sulphur. The uncracked hydrogen sulphide is separated and returned to the cracking zone; the remaining gas is withdrawn as hydrogen-rich gas.

Abstract: Phthalic anhydride is continuously separated from the reaction gas mixture formed by the catalytic oxidation of o-xylene and/or naphthalene, by treating said rection gas mixture in at least two absorption stages with organic absorbents. The absorbent employed in the first absorption stage is a mixture of phthalic anhydride and benzoic acid. The absorbent employed in the subsequent absorption stage(s) contains maleic anhydride and may also contain phthalic anhydride.

Abstract: Phthalic anhydride is continuously separated from the reaction gas mixture formed by the catalytic oxidation of o-xylene and/or naphthalene, by treating said reaction gas mixture with a maleic anhydride absorbent.

Abstract: In a process for the production of phthalic anhydride comprising a stage of catalytic oxidation of a mixture of o-xylene or naphthalene and air, a stage of separation of the crude phthalic anhydride from the reaction gas by cooling, and a stage of purification of the crude phthalic anhydride by rectification under vacuum, said vacuum being maintained by at least one jet pump, the improvement which comprises employing compressed air as the operating medium for said jet pump, and recycling resultant compressed air loaded with the exhaust gas to a process gas upstream of the phthalic anhydride separation stage, said process gas being any gas leading to the separation stage, preferably the gas between the oxidation stage and the separation stage.

Abstract: An improved process is provided for the recovery and storage of maleic anhydride from maleic anhydride-containing gases. Such gases are scrubbed with a water or maleic acid scrubbing solution in a scrubbing zone to form a maleic acid-containing solution. This maleic acid-containing solution is then concentrated and dehydrated in an evaporation zone and a dehydration zone, respectively, to form maleic anhydride. The maleic anhydride so formed is then purified by distillation in a distillation zone. The evaporation, dehydration, and distillation steps are all carried out under a vacuum maintained by withdrawing gases containing organic and water vapor from said evaporation, dehydration and distillation zones using jet pumps propelled by pressurized air. The vapor-containing gases so removed are admixed with the pressurized air pump propellant streams, and this mixture is then introduced into the scrubbing zone for the maleic anhydride-containing gases.

Abstract: A process for utilization of the reaction heat generated by the catalytic oxidation of o-xylene with air to phthalic anhydride in a tubular reactor, which heat is partially carried away from the reactor by the reaction gas and partially by fused salt used as a cooling medium. Water is heated by heat exchange with the hot reaction gas, evaporated by heat exchange with the fused salt and the steam is superheated and expanded in a condensation turbine coupled with the feed air compressor. The hot reaction gas is used successively to heat, or evaporate, a heat carrier liquid serving for the heating of the phthalic anhydride distillation, and the pressurized water. Low pressure steam can be generated by heat exchange of pressurized water with the reaction gas and used for heating the feed air and/or o-xylene.

Abstract: In a process for the separation of phthalic anhydride from reaction gas oined from the catalytic air oxidation of o-xylene which comprises cooling the gas in a separator in indirect heat exchange relationship with cooling surfaces inside the separator maintained at 45.degree.-65.degree. C, withdrawing residual reaction gas through a gas outlet and melting off resultant desublimated phthalic anhydride from the cooling surfaces by heating the latter to a temperature in the range of 150.degree.-250.degree. C, the improvement wherein heat is applied to an external surface of the separator adjacent said gas outlet during the cooling of the gas inside the separator, said heat being sufficient to prevent a buildup of non-meltable impurities on the cooling surface inside said separator and adjacent to said gas outlet.