1088results about "Amino compound preparation" patented technology

The invention relates to a preparation method of phenylmethylamine. The technical scheme adopted by the invention for mainly solving the problems of high catalyst loss, low production efficiency and high intermittent operation labor intensity is as follows: the preparation method of the phenylmethylamine comprises the following steps: mixing the raw material of cyanobenzene with a solvent material or at least one of one part of product materials in a mixing unit, introducing the mixture into a fixed bed hydrogenation reactor to be in contact with hydrogen and a catalyst and carry out multi-phase continuous hydrogenation reaction to obtain a product material containing phenylmethylamine, separating the product material to obtain a phenylmethylamine product, wherein the catalyst is a metal loaded catalyst; and the metal is selected from at least one of Pd, Pt, Cu, Ni, Mo and Fe. The preparation method can be used for preparing phenylmethylamine.

The invention relates to the technical field of scintillator materials and X-ray detection, in particular to a rare earth organic-inorganic hybrid complex scintillator and a preparation method and application thereof. The general formula of the rare earth organic-inorganic hybrid complex scintillator is [RE (L) 4] <->. [A] < + >, wherein RE is selected from Eu, Tb, Sm or Dy; l is a beta-diketone ligand; [A] < + > is selected from long-chain hydrophobic quaternary ammonium salt cations or heterocyclic quaternary ammonium cations which have the carbon atom number of C8-C20 and do not contain active functional groups. The rare earth organic-inorganic hybrid complex scintillator provided by the invention has good solubility and molecular-level dispersion capability. The scintillator film based on the rare earth organic-inorganic hybrid complex prepared by using the rare earth organic-inorganic hybrid complex has the characteristic of compatibility of high scintillator load and high light transmission, overcomes the problems of low scintillator load rate, poor transparency and limited imaging resolution of the traditional scintillator film, and has excellent practical value and popularization prospect.

The invention provides a catalyst, a preparation method and application thereof, and a method for preparing primary amine by catalyzing nitrile compound hydrogenation, and particularly relates to the technical field of catalyst synthesis. The catalyst comprises a nickel / cobalt-based catalyst and a metal salt; wherein the nickel / cobalt-based catalyst is selected from any one of a supported nickel / cobalt-based catalyst, a Raney nickel / cobalt catalyst or a nickel / cobalt nanocrystal; the metal salt comprises any one or a combination of at least two of tungsten salt, molybdenum salt, vanadium salt, aluminum salt and cerium salt. The metal salt and the nickel / cobalt main catalyst have a synergistic effect: the surface electron density is adjusted through electron transfer, the hydrogen dissociation and cyano adsorption activation capacities are enhanced, the hydrogenation activity is improved, and the mild condition reaction is assisted; the surface chemical environment is changed or steric hindrance is borrowed, the primary amine selectivity is improved, and byproducts are inhibited; aluminum salt, cerium salt and the like inhibit nickel / cobalt agglomeration, increase active sites, enhance stability, prolong the service life and reduce the dosage.

The invention relates to the field of catalysts, in particular to a preparation method of a green and efficient copper catalyst. Comprising the following steps: (1) mixing basic cupric carbonate, ammonia water and water, adding ammonium salt at the same time, and preparing a copper ammonia solution as a precursor solution at room temperature; (2) mixing the precursor solution with a carrier or a carrier precursor to realize active component loading and catalyst preparation; and (3) filtering, washing, drying and roasting the mixed system in the step (2) to prepare the copper-based catalyst. According to the preparation method of the copper ammonia complexing precursor solution, preparation of the copper ammonia complexing solution at room temperature can be achieved, heating operation in the precursor preparation process is avoided, meanwhile, the nitrogen content of the system and nitrogen emission in the subsequent roasting process can be reduced by preparing the copper-based catalyst through the basic copper carbonate precursor, and efficient and green preparation of the catalyst is achieved.

The invention discloses a low-water-solubility medicine crystal as well as a preparation method and application thereof. The compound Z pamoate crystal form I has large characteristic diffraction peaks at one or more positions with diffraction angles 2 theta of 9.9 + / -0.2 degrees, 10.7 + / -0.2 degrees, 12.1 + / -0.2 degrees, 14.9 + / -0.2 degrees, 17.3 + / -0.2 degrees, 19.4 + / -0.2 degrees, 20.7 + / -0.2 degrees and 23.1 + / -0.2 degrees. Compared with an amorphous compound Z pamoate, the crystal provided by the invention has the advantages of good stability, no crystal transformation phenomenon, no obvious increase of related substances and low solubility; the production process is simple, only water is used as a solvent in the whole process, and no organic solvent is used; when the long-acting slow-release anti-Parkinson medicine composition is prepared from the compound Z pamoate crystal form I, the medicine encapsulation efficiency is high, the burst release is low, the composition continuously releases the medicine in vivo for more than 2 weeks, the administration frequency of a patient can be reduced, and the medication compliance is improved.

The invention belongs to the technical field of catalyst preparation, and provides an M2 diatomic site catalyst for a reaction for preparing phenylenediamine through dinitrobenzene hydrogenation and a preparation method and application thereof.The catalyst is formed by anchoring transition metal M diatomic sites to the surface of a diamond-graphene carrier and is prepared by taking nano-diamond powder as a raw material through a one-step reaction. Annealing treatment is carried out at the high temperature of 750-850 DEG C, a diamond-graphene carrier of an sp3 atsp2 core-shell structure is constructed, and the surface defect density of the diamond-graphene carrier is regulated and controlled in the process; and depositing metal species on the surface of the carrier through ALD double-step deposition to obtain the M2 diatomic site catalyst with high density and stable structure. The M2 diatomic site catalyst is applied to a reaction for preparing a corresponding phenylenediamine compound through hydrogenation of a dinitrobenzene compound, and high conversion rate and high selectivity can be achieved with low metal loading capacity under mild conditions. The method can be popularized to construction of diatomic catalysts of various transition metals, and has a wide application prospect.

The invention discloses a preparation method of a nylon 66 salt crystal, which is characterized in that in the method, a nylon 66 salt aqueous solution is subjected to secondary crystallization and a rotary pressure filter process to prepare the nylon 66 salt crystal. According to the technology, the problems of low single-stage yield and large sewage discharge amount are solved by adopting secondary crystallization and evaporation condensate recycling, and the processes of centrifugation, drying, cyclone separation and the like are reduced by replacing a centrifugal machine with a rotary pressure filter, so that the energy consumption per ton of products is reduced.

The invention belongs to the field of methanol conversion and utilization, and particularly relates to a three-layer multi-core structure catalyst for high-selectivity synthesis of monomethylamine and a preparation method of the three-layer multi-core structure catalyst. The core layer of the catalyst is gamma-aluminum oxide, the middle layer of the catalyst is a mordenite (MOR) molecular sieve, and the outer layer of the catalyst is porous SiO2. The preparation of the multi-core MOR layer adopts a steam-assisted crystallization method, the preparation method is simple, no organic waste liquid is generated, the preparation method is environment-friendly, the multi-core MOR layer can be used in a reaction for preparing methylamine through continuous gas phase catalytic amination of methanol after being modified by ammonium ion exchange and chemical liquid phase deposition (CLD), the methanol conversion rate reaches 98.6% under the reaction conditions that the temperature is 340 DEG C, the methanol liquid hourly space velocity is 1.5 h <-1 >, the ammonia-alcohol ratio is 3 and the pressure is normal, and the method is suitable for industrial production. The mass ratio of monomethylamine is greater than 60%, and the method has a good application prospect.

The invention discloses clethodim diamine salt as well as a preparation method and application thereof. The stability of the clethodim diamine salt (clethodim 1, 4-butanediamine salt, clethodim 1, 5-pentanediamine salt and clethodim 1, 6-hexamethylenediamine salt) provided by the invention is superior to that of clethodim and clethodim monoamine salt (such as clethodim tert-butylamine salt); meanwhile, the herbicidal activity of the clethodim diamine salt (clethodim ethylenediamine salt, clethodim 1, 4-butanediamine salt and clethodim 1, 5-pentanediamine salt) is superior to that of clethodim tert-butylamine salt, and the herbicidal activity of the clethodim 1, 5-pentanediamine salt is superior to that of clethodim. Most clethodim diamine salt is low in degradation rate in the high-temperature heat storage process and easier to store for a long time, the clethodim diamine salt is higher in melting point than clethodim monoamine salt (such as clethodim tert-butylamine salt), granulation and smashing are more convenient, the clethodim diamine salt can be used as a herbicide to be processed into solid dosage forms such as water dispersible granules and the like, the physical performance of the preparation is better, and the preparation has good application prospects. The commercialization prospect is good.

This invention discloses a method for modifying the support medium of a Pd catalyst and its application. The preparation method of the Pd catalyst includes reacting zirconium salt, organic ligands, and acid to obtain a support UiO-66-X; then loading Pd onto the support UiO-66-X and reducing it to obtain the catalyst Pd@UiO-66-X; the organic ligands include 2-nitroterephthalic acid, 2-methoxyterephthalic acid, 2-aminoterephthalic acid, and terephthalic acid, and X is selected from NO2, OMe, NH2, and H. This invention changes the surface electron cloud density of the supported Pd nanoparticles by changing the ligands (-NO2, -H, -OMe, -NH2) of the support UiO-66, resulting in different abilities to activate hydrogen, thereby regulating the dehydrogenation and hydrogenation reactions in the racemicization process of Pd catalysis. The synergistic effect of different ligands with Pd changes the racemicization catalytic activity.

The invention relates to an alkyl tertiary amine quaternization reaction preparation process based on a micro-channel reactor, which comprises the following steps: mixing aliphatic tertiary amine and an alkylating agent, adding into a solvent, diluting into a mixed diluent, conveying to the micro-channel reactor, controlling the reaction temperature at 70-120 DEG C, and carrying out quaternization reaction to generate a reaction mixture containing target alkyl tertiary amine quaternary ammonium salt. The alkyl tertiary amine quaternary ammonium salt is synthesized by utilizing the micro-channel reactor, and compared with a traditional reaction kettle method production process, efficient mass and heat transfer and process enhancement in the reaction process can be realized, and continuity and accurate control of the reaction process can be realized, so that the reaction efficiency and the product quality of alkyl tertiary amine quaternization reaction are improved.

The present disclosure relates to the fields of chemistry and medicine, more particularly to processes for making 4-(2-chloro-4-methoxy-5-methylphenyl)-N-[(1S)-2-cyclopropyl-1-(3-fluoro-4-methylphenyl)ethyl]-5-methyl-N-prop-2-ynyl-1,3-thiazol-2-amine (Compound 1), pharmaceutically acceptable salts, and crystalline forms thereof, for the treatment of congenital adrenal hyperplasia (CAH).

The invention belongs to the field of rubber additives, and particularly relates to an anti-aging agent as well as a synthesis method and application thereof. RT base and a phenol compound are used as raw materials for synthesis under the action of a catalyst; the phenol compound is a mixture of phenol and o-methylphenol. According to the invention, RT base (p-aminodiphenylamine) is used as a precursor and reacts with phenol or o-methylphenol in the presence of a catalyst to produce the anti-aging agent. Salt-containing waste water is not generated in the precursor production process, and compared with hydroquinone serving as a precursor, the precursor has the obvious cost advantage and the environment-friendly advantage.

The invention discloses a catalytic system for preparing amine compounds through nitro reduction and application of the catalytic system. The catalytic system comprises an alkaline aqueous solution, a reducing agent and a catalyst, the alkaline aqueous solution is an alkali metal hydroxide aqueous solution; the reducing agent is alkali metal hydroboron and / or alkaline earth metal hydroboron; the catalyst is copper salt lewis acid and / or other lewis acid; the other Lewis acid is selected from one or a combination of more of cobalt salt, ferric salt, zinc salt, manganese salt and palladium salt. When the catalytic system is used for reducing the aromatic nitro-compound, the using amount of a reducing agent is small, meanwhile, the using amount of an organic solvent is reduced, the reaction yield is high, the reaction is milder, and amplified production of the process is facilitated.

This invention relates to the field of industrial wastewater treatment technology for natural gas purification, and discloses a perfluoroalkyl-substituted allyl quaternary ammonium salt and its preparation method, copolymer and its preparation method and application, and a method for treating wastewater. The quaternary ammonium salt has the structure shown in formula (1), wherein R1 and R2 are each independently selected from methyl or ethyl; n is an integer from 4 to 11. The quaternary ammonium salt is obtained through a nucleophilic substitution reaction between allyl amine or its derivative and a perfluoroalkyl haloalkane. The copolymer of this invention contains structural unit A from acrylamide and structural unit B from the quaternary ammonium salt, and is obtained through a polymerization reaction between acrylamide and the quaternary ammonium salt monomer. The copolymer of this invention has good salt resistance and strong hydrophobic association, and can be well adapted to the treatment of high-salt industrial wastewater or the removal of impurities in the field of natural gas purification.

The invention discloses a light-emitting auxiliary material, a preparation method thereof and an organic electroluminescent device, and relates to the technical field of organic photoelectric materials. According to the light-emitting auxiliary material disclosed by the invention, on the basis of a 9-phenylfluorene derivative group, triarylamine is connected to phenyl, and meanwhile, deuterium-substituted aromatic rings are connected to the triarylamine, so that the energy level can be effectively reduced, carrier migration localization can be avoided, and a hole transport energy barrier can be reduced, thereby increasing the migration rate and improving the light-emitting efficiency; triarylamine has excellent hole transport performance, a triarylamine material is used as a light-emitting auxiliary layer, a group with a high triplet state energy level is introduced, the energy range between energy levels can be reduced, and the service life of the device is greatly prolonged.

The invention discloses ternary copolymerized low-dielectric polyimide based on fluorinated cross-linked side groups as well as a preparation method and application of the ternary copolymerized low-dielectric polyimide. According to the preparation method, two diamine monomers with a fluorine-containing group and a large-volume side chain group, namely fluorine-containing triarylmethane diamine and tetrafluorostyrene side group-containing diamine, are polymerized with 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride to obtain the ternary copolymerized polyimide (Co-FPAPI-x), and the preparation method is efficient, simple, convenient and low in cost. The tetrafluorostyrene group in the ternary copolymerized polyimide structure can form a hydrophobic cross-linked network through a thermal cross-linking reaction. Besides, by changing the proportion and thermal crosslinking degree of the two diamine monomers, the accumulation state, polarization behavior and the like of a molecular chain can be adjusted, so that the performance of the material is improved.

The invention discloses a low-dielectric polyimide film based on a fluorine-containing triphenylmethane unit as well as a preparation method and application of the low-dielectric polyimide film, and the low-dielectric polyimide film is a novel polyimide material FPOPF-6FDA obtained by polymerizing a fluorine-containing triaryl methane diamine monomer and 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride. The fluorine-containing triarylmethane diamine monomer is preferably 4, 5-diphenyl-1, 3, 5-triazine. According to the invention, 4, 4 '-((4-fluoro-3-phenoxy phenyl) methylene)) bis (2-fluoroaniline) is used, specifically, 4, 4'-diaminotriphenylmethane is used as a functional core, a fluorine-containing group and a large-volume side chain group are introduced, and non-coplanar twisted conformation destroys close packing of molecular chains and increases the chain spacing, so that the effect of a charge transfer complex (CTC) is weakened, and the photoelectric conversion efficiency is improved. And the heat resistance and optical transparency of polyimide are maintained while the dielectric constant of the material is reduced.

The invention discloses preparation of a nitrogen-rich ionic organic single crystal material and application of the nitrogen-rich ionic organic single crystal material in iodine adsorption, and belongs to the technical field of functional materials and radioactive pollutant treatment. The material is formed by self-assembly at room temperature through a solution method by taking biphenyl tetracarboxylic acid tetrabutylamine as an anion ligand and tetra (4-ethyl pyridine phenyl) ethylene bromide or tetra (4-imidazole phenyl) ethylene bromide as a cation ligand. The method is simple in preparation process, mild in condition and high in yield. The skeleton of the obtained material is rich in nitrogen sites and has a large cavity, the material shows extremely high adsorption capacity and rapid adsorption kinetics for iodine in a gas phase and a liquid phase, the maximum adsorption capacity of the material for iodine steam reaches up to 5.16 g / g, the retention rate of 95% or above can still be kept within 7 days after adsorption, and the material has good recycling performance. The material provides a novel and reliable solution for efficiently capturing and fixing radioactive iodine, and has a wide application prospect in the field of nuclear waste treatment.

The invention discloses a preparation method of bis (trifluoromethylsulfonyl) imide salt, and belongs to the technical field of metal ion battery electrolyte materials, and the preparation method comprises the following steps: mixing trifluoromethylsulfonyl fluoride and organic amine alkali to obtain a mixed solution A; dropwise adding the mixed solution A into a reaction kettle filled with ammonia gas, and completely reacting to generate bis (trifluoromethanesulfonyl) imide quaternary ammonium salt; carrying out reduced pressure distillation on the reaction product to obtain pure bis (trifluoromethanesulfonyl) imide quaternary ammonium salt; the preparation method comprises the following steps: mixing bis (trifluoromethylsulfonyl) imide triethylamine salt and metal salt according to a molar ratio of 1: (1-3), and completely reacting in an organic solvent to generate bis (trifluoromethylsulfonyl) imide salt; and filtering the reaction liquid, and carrying out reduced pressure distillation to obtain the final product bis (trifluoromethylsulfonyl) imide salt. The preparation method provided by the invention has the characteristics of simple process, high yield and high product purity, and solves the problems of complex process, low yield, low product purity and the like in the existing preparation method.

The application relates to a catalyst for selectively hydrogenating nitrophenylacetylene to prepare aminophenylacetylene. The Fe2O3-CeO2 / TiO2 catalyst is used, the solvent is anhydrous ethanol, the hydrogen source is hydrazine hydrate, and the nitrophenylacetylene is catalytically hydrogenated to prepare aminophenylacetylene at 80-150 DEG C. The catalyst can realize efficient hydrogenation of the nitro group in the nitrophenylacetylene, the selectivity of the aminophenylacetylene can reach 94.8% when the nitrophenylacetylene is completely converted, the selectivity of the aminophenylacetylene is basically unchanged when the reaction time is continuously prolonged, and there is no accumulation of harmful intermediates such as phenylhydroxylamine in the reaction process.

The invention provides a modified cobalt catalyst and a preparation method and application thereof. The invention provides a modified cobalt catalyst which comprises a cobalt element, an aluminum element, a transition metal element, other metal elements of the group IIIA except the aluminum element, an alkali metal element, an alkaline earth metal element and a boron element, and the boron element exists in the form of a B-O-Al bond. The modified cobalt catalyst has the characteristics of high activity and high selectivity when used for reducing nitrile compounds.

This invention discloses a catalyst for the hydroamination of coal-based ethanol to triethylamine, its preparation method, and its application. The catalyst includes a support and an active component, cobalt, supported on the support, wherein the active component accounts for 10-30% of the catalyst mass; the support is rod-shaped alumina. The catalyst prepared by this invention fully utilizes the high-temperature complexation of lysine and cobalt nitrate. Simultaneously, the rod-shaped morphology of the alumina effectively improves the dispersion of the active metal. After hydrogen reduction, the reduced cobalt is more uniformly distributed in the rod-shaped alumina, making it less prone to agglomeration during the reaction. This facilitates the diffusion of reactants and products within the catalyst and enhances the catalyst's reactivity. When used for the amination of coal-based ethanol to ethylamine, it exhibits high selectivity for triethylamine.

The invention discloses a method for dehalogenation reduction of electron-rich aryl halide, which comprises the following step: by taking aryl halide as a raw material, carrying out heating reaction in the presence of phosphorous acid, elemental iodine and a solvent to prepare a corresponding aromatic compound. According to the method, the defect that expensive transition metal catalysts and equivalent metal reagents need to be used for participation in current mainstream methods is directly avoided, the electron-rich aryl halide is subjected to one-step dehalogenation reduction to obtain the corresponding aromatic hydrocarbon by taking low-cost, low-toxicity and relatively stable phosphorous acid as a reducing agent and taking the iodine elementary substance as a catalyst, and the method has the advantages of no metal participation, simple operation, low cost and the like. The method has the advantages of simple operation, low cost, environmental protection and the like, avoids the use of a metal reagent and the limitation that special equipment is not easy to amplify production, after the phosphorous acid reaction is finished, byproducts are generally phosphoric acid and corresponding phosphorus salts thereof and can be quickly removed by washing, the post-treatment is simple, and the method is beneficial to industrial production.

The application discloses a supported PtNi b-site adiponitrile hydrogenation catalyst and a preparation method and application thereof, and belongs to the technical field of thermal catalysis. The preparation method comprises the following steps: (1) dispersing ammonium tungsten oxide pentahydrate in water, adding an acidic solution, condensing and refluxing, heating and reacting, centrifugal filtering and drying the precipitate to prepare tungsten oxide nanorod carriers; (2) dispersing the tungsten oxide nanorod carriers in a solvent, adding a platinum salt solution, stirring, evaporating the solvent, and calcining the solid to prepare a catalyst precursor; and (3) dispersing the catalyst precursor in a solvent, adding a nickel salt solution, stirring, evaporating the solvent, and calcining the solid to prepare the catalyst. The application introduces Pt and Ni on the reducible WO3 carrier to construct a bimetallic active site catalyst, and the bimetallic active site catalyst can catalyze the reaction of adiponitrile hydrogenation to prepare primary amine under mild conditions, has the characteristics of low noble metal loading, high activity and high selectivity, and has important industrial application value.

The invention belongs to the technical field of synthesis of organic compounds, and particularly relates to a process for preparing fipronil and an intermediate thereof. Toxic 1, 2-dichloroethane is comprehensively replaced by bio-based gamma-valerolactone, low-toxicity cyclopentyl methyl ether is matched, and N, N-dimethylformamide necessary for the process is recycled, so that consumption is greatly reduced; the continuous processes of amination, diazotization and the like are realized through a tubular reactor, a micro-reactor and a static mixer, and separation technologies such as pervaporation membrane and vacuum distillation are combined, so that the reaction time is shortened, the solvent recovery rate is increased, and the production is promoted to be continuously transformed to green. The supported FeCl3 / SiO2-NH2 catalyst disclosed by the invention can be repeatedly used, and byproducts and tail gas can be recycled and reused. In addition, diazonium salt residues are controlled to be smaller than or equal to 0.5% through near infrared spectroscopy, citric acid is subjected to stable oxidation reaction, a purification process is combined, it is ensured that the finished product is high in purity, excellent in yield and small in batch fluctuation, and efficiency and safety are both considered.

A process for producing amines by reductive amination, the process includes introducing a feed stream, the feed stream comprising an amino alcohol and a reducing agent, and hydrogen in a reaction zone of a reactor, and contacting the feed stream with a catalyst in the reaction zone. A hydrogen flow rate into the reaction zone is adjusted, and a product stream comprising ethyleneamines is extracted. The catalyst includes a carrier component selected from alumina, silica, and combinations thereof; and an active component having a first metal, a second metal, and a third metal. The first metal is selected from cobalt, nickel, and copper, the second metal is selected from rhenium, ruthenium, chromium, zinc, sodium, calcium, magnesium, strontium, lithium, potassium, barium, cesium, lanthanum, tungsten, iron, silver, titanium, manganese, aluminum, rhodium, platinum, palladium, iridium, and combinations thereof, and the third metal is niobium.

The present invention relates to precursors of dibenzoylmethane compounds having an amide group on one of the rings, and corresponding photoconversion compounds, pharmaceutically or cosmetically acceptable salts thereof, or stereoisomers or mixtures thereof, for use in protecting human or animal living organisms or materials from ultraviolet light. The present invention also relates to the preparation processes thereof, as well as cosmetic compositions, pharmaceutical compositions or personal care compositions thereof.

The invention relates to a method for producing methylamine by a generally exothermic gas-phase reaction of methanol and ammonia as reactants in the presence of a heterogeneous catalyst at a pressure in the range of 15 to 35 bar. The reactants are evaporated in one or more heat exchangers and superheated prior to being fed to the reactor, wherein the heat exchangers in turn are heated with a stream of hotter product gas from the reactor. In addition to methylamine (monomethylamine, dimethylamine, and trimethylamine), the product gas stream contains unconverted reactants, water, and any other reaction by-products. To control the reactor inlet temperature and limit it to a temperature in the range of 350 DEG C to 410 DEG C, a suitable quenching liquid is introduced into the hot product gas stream prior to feeding the hot product gas stream to a heat exchanger for heating the reactants. Evaporation and overheating of the added quenching liquid removes the corresponding amount of energy extracted from the hot product gas stream, with the result of efficient and rapid cooling of the hot product gas stream. As a result, the temperature difference between the cold side and the hot side of the heat exchanger is small, which means less energy is transferred to the reactant stream, and thus its reactor inlet temperature can be adjusted or limited.

A polyurethane rigid foam containing at least one phosphorus ester flame retardant is returned to the value chain by hydrogenating the polyurethane rigid foam to obtain a hydrogenation product containing polyamines and polyols from the polyurethane rigid foam and recovering the flame retardant from the hydrogenation product. The hydrogenation is carried out in an aprotic organic solvent under a hydrogen atmosphere in the presence of at least one homogeneous transition metal catalyst complex, wherein the transition metal is selected from metals of groups 7, 8, 9 and 10 of the Periodic Table of the Elements according to IUPAC, at a reaction temperature of at least 120°C.