Abstract:
Present application discloses an industrial scale continuous process for recovery of caprolactam and crystalline ammonium sulfate. By controlling the weight ratio of the amount of aqueous ammonium sulfate solution being recycled to the amount of Beckmann rearrangement mixture charged into the neutralization section within the range of more than 0.001 and less than 1, the productivity of the crystalline ammonium sulfate is increased, however neither the color of the crystalline ammonium sulfate nor the quality of the produced pure caprolactam is unduly influenced.
Abstract:
The invention relates to a process for preparing a crystalline ammonium sulfate product, which process comprises: a) subjecting in a crystallizer a feed solution of ammonium sulfate to crystallization to form a first slurry of ammonium sulfate crystals; b) subjecting the first slurry of ammonium sulfate crystals to a first size classification to yield a first coarse ammonium sulfate crystal fraction and a first fine ammonium sulfate crystal fraction; c) recycling at least part of the first fine ammonium sulfate crystal fraction to the feed solution of ammonium sulfate; and d) recovering a crystalline ammonium sulfate product from the first coarse ammonium sulfate crystal fraction, characterized in that: e) a second size classification is carried out on a second slurry of ammonium sulfate crystals to yield a second coarse ammonium sulfate crystal fraction and a second fine ammonium sulfate crystal fraction.
Abstract:
An industrial scale continuous process for the production and recovery of cyclohexanone from phenol and hydrogen, said process comprising: hydrogenating phenol in a phenol hydrogenation reactor; separating cyclohexanone from a hydrogenated product stream in a separation and purification section [II] comprising at least 4 distillation sections; wherein at least some of the reaction heat produced in the phenol hydrogenation reaction section [I] is applied for the production of steam; and wherein the molar ratio of cyclohexanone to phenol that is charged to said phenol hydrogenation reactor is from 0.02 to 0.10; and/or wherein the molar ratio of cyclohexanol to phenol that is charged to said phenol hydrogenation reactor is from 0.001 to 0.10.
Abstract:
A continuous process for the production of purified cyclohexanone which comprises at least the following steps: oxidation of cyclohexane; decomposition of cyclohexyl hydroperoxide; separation of an organic phase and aqueous phase; removal of cyclohexane from the organic phase; removal of alkali metal salts by washing with water; distillation and recovery of cyclohexanonewherein any residue obtained after washing contains less than 10 ppm alkali metal salts.
Abstract:
The invention relates to a process for treating an aqueous solution containing ε-caprolactam, ammonium sulphate and one or more other impurities, comprising one or more organic impurities from a caprolactam production process and optionally other salts than ammonium sulphate, by means of a membrane process, thereby obtaining a retentate and a permeate, in which process the membrane used is selected from the group of polyether sulphone membranes, sulphonated polyether sulphone membranes, polyester membranes, polysulphone membranes, aromatic polyamide membranes, polyvinyl alcohol membranes, polypiperazine membranes, cellulose acetate membranes, titanium oxide membranes, zirconium oxide membranes and aluminium oxide membranes, having a molecular weight cut off in the range of 100-1000 g/mol; and wherein more than 60 wt.% of the caprolactam in the aqueous solution is passed through a membrane to the permeate side, to obtain a purified caprolactam containing permeate stream, and wherein at least 50 wt.% of the organic impurities are retained in the retentate solution.
Abstract:
The present invention provides a continuous process for producing ammonium sulfate crystals, wherein said process comprises: (a) feeding to a first group of crystallization sections, which crystallization sections are heat integrated in series, a first aqueous ammonium sulfate solution that contains one or more impurities; (b) feeding to a second group of crystallization sections, which crystallization sections are heat integrated in series, a second aqueous ammonium sulfate solution that contains one or more impurities; (c) crystallizing ammonium sulfate crystals in each crystallization section respectively from each of said solutions of ammonium sulfate that contain one or more impurities; (d) purging a fraction of the ammonium sulfate solution that contains one or more impurities from each of said crystallization sections; and (e) discharging ammonium sulfate crystals from each crystallization section, characterized in that: (i) both the first group of crystallization sections and the second group of crystallization sections are together heat integrated in one series of crystallization sections; wherein the first group of crystallization sections operates at higher temperature than the second group of crystallization sections; and (ii) the composition of the first aqueous ammonium sulfate solution that contains one or more impurities is different to the composition of the second aqueous ammonium sulfate solution that contains one or more impurities. Further provided is apparatus suitable for producing ammonium sulfate crystal.
Abstract:
The present invention provides a continuous process for the production of ammonium sulfate in combination with caprolactam, said process comprising, a) neutralizing with ammonia a mixture comprising caprolactam and sulfuric acid to form an aqueous ammonium sulfate phase and an aqueous crude caprolactam phase; b) separating the aqueous ammonium sulfate phase from the aqueous crude caprolactam phase; c) extracting into an organic solvent caprolactam present in the aqueous ammonium sulfate phase to form a caprolactam-containing organic phase and a purified aqueous ammonium sulfate phase; d) stripping organic solvent from the purified aqueous ammonium sulfate phase; and e) withdrawing organic solvent-containing gas produced in, or subsequent to, any one of steps c) and d), characterized in that f) organic solvent is recovered from said organic solvent-containing gas.
Abstract:
A method for preparing hydroxylammonium in a reaction zone in a continuous process, comprising optionally directly introducing nitric acid comprising
Abstract:
The present invention relates to a method for continuously preparing cyclohexanone from phenol making use of a catalyst comprising at least one catalytically active metal selected from platinum and palladium comprising a) hydrogenating phenol to form a product stream comprising cyclohexanone and unreacted phenol; b) separating at least part of the product stream, or at least part of the product stream from which one or more components having a lower boiling point than cyclohexanone have been removed, into a first fraction comprising cyclohexanone and a second fraction comprising phenol and cyclohexanol, using distillation; c) separating the second fraction into a third fraction, rich in cyclohexanol, and a fourth fraction, rich in phenol and, using distillation; d) subjecting at least part of the fourth fraction to a further distillation step, thereby forming a fifth fraction and a sixth fraction, wherein the fifth fraction is enriched in phenol compared to the sixth fraction, and wherein the sixth fraction comprises side-products having a higher boiling point than phenol, and phenol, wherein step d) is carried out in a vacuum distillation column equipped with trays in the lower part of the column, and wherein in the upper part of the column, i.e. in the part above the feed inlet, packing material is present instead of trays in at least part of said upper part, which packing material has a comparable or improved separating efficiency, and provides a reduction of the pressure drop by at least 30%, preferably more than 50%, as compared to the case with trays in the upper part, under otherwise similar distillation conditions.
Abstract:
A continuous process for purifying organic product solution comprising oxime dissolved in an organic medium comprising: (1) discharging the organic product solution from a oxime synthesis section [I] to a liquid-liquid mixing section [III]; (2) mixing the organic product solution with a water and/ or an aqueous solution and discharging the resulting mixture to liquid-liquidseparator [IV]; (3) separating organic top layer from aqueous bottom layer in liquid-liquidseparator [IV] and recovering oxime from the organic top layer in an oxime recovery section; (4) feeding the aqueous bottom layer of liquid-liquidseparator [IV] to the oxime synthesis section [I], optionally a fraction of which being fed back into the liquid- liquid mixing section [III].