Cyclohexanone oxime serves as a crucial intermediate in the synthesis of caprolactam,which is an essential precursor for manufacturing nylonfibers,high-performance engineering plastics,and specialized plasticfilms.Cat...Cyclohexanone oxime serves as a crucial intermediate in the synthesis of caprolactam,which is an essential precursor for manufacturing nylonfibers,high-performance engineering plastics,and specialized plasticfilms.Catalytic hydrogenation of nitrocyclohexane to cyclohexanone oxime has been documented to be an atom-economical,green and environmentally friendly process.In this review,wefirst introduce the current design rules of catalysts for catalytic hydrogenation of nitrocyclohexane in terms of both active metals and supports.Secondly,we discuss the influence of solvent effects on the cyclohexanone oxime from the nitrocyclohexane conversion.In addition,we concisely discuss typically proposed reaction pathways for the hydrogenation of nitrocyclohexane to produce cyclohexanone oxime.Finally,we provide our perspectives on some issues for catalytic conversion of nitrocyclohexane to cyclohexanone oxime in the future.展开更多
The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environment...The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.展开更多
An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of ...An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of cyclohexanone oxime from cyclohexanone, ammonia and hydrogen peroxide was carried out in a batch plant. Cyclohexane was used as the solvent in the three-phase reaction system. The influences of essential process parameters on ammoximation were investigated. Under the reaction conditions as catalyst content of 2.5% (by mass); H 2 O 2 /yclohexanone molar ratio of 1.10; NH 3 /cyclohexanone molar ratio of 2.20; reaction temperature of 343 K; reaction time of 5 h, high conversion of cyclohexanone and selectivity to oxime (both>99%) were obtained. Thus, the three-phase ammoximation process showed equal catalytic activity as TS-1 but much more convenient and simpler for the separation of catalyst in comparison to the industrial two-phase system with t-butanol used as solvent.展开更多
The addition of platinum over the B2O3/TiO2-ZrO2 remarkably enhanced its catalytic stability in the vapor phase Beckmann rearrangement of cyclohexanone oxime under the carder gas of H2. The content of coke deposited ...The addition of platinum over the B2O3/TiO2-ZrO2 remarkably enhanced its catalytic stability in the vapor phase Beckmann rearrangement of cyclohexanone oxime under the carder gas of H2. The content of coke deposited on catalyst surface was decreased from 1.92% over the B2O3/TiO2-ZrO2 to 1.14% over the platinum promoted B2O3/TiO2-ZrO2 after reaction of six hours. This result indicates that the platinum added on the B2O3/TiO2-ZrO2 catalyst plays an important role in reducing the coke formation on the catalyst surface.展开更多
Silicalite-1 was hydrothermally synthesized in the presence of different concentrations of Na+using tetrapropylammonium hydroxide(TPAOH)as a template.The synthesis was followed by a base treatment.The silicalite-1samp...Silicalite-1 was hydrothermally synthesized in the presence of different concentrations of Na+using tetrapropylammonium hydroxide(TPAOH)as a template.The synthesis was followed by a base treatment.The silicalite-1samples were characterized using X-ray diffrac-tion,scanning electron microscopy,N2 adsorption,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy and NH3 temperature-programmed deso-rption.The samples were used as catalysts for the vapor phase Beckmann rearrangement of cyclohexanone oxime.During the synthesis,the sodium ions were incorporated onto the silicalite-1 crystals,but were then removed by the base treatment.All the catalysts exhibited nearly complete conversion of cyclohexanone oxime toε-caprolactam with selectivities grater than 95%.Addition of less than 2.5 mol-%Na^(+)(relative to TPAOH)did not influence the catalytic properties.However,for Na+concentrations≥5 mol-%,the particle sizes of silicalite-1 increased and the catalytic activities decreased,which can be attributed to carbon deposition.The results in this work are of great importance for the polymer industry.展开更多
An intrinsic kinetics of cyclohexanone ammoximation in the liquid phase over titanium silicate molecular sieves is investigated in an isothermal slurry reactor at different initial reactant concentrations, catalyst lo...An intrinsic kinetics of cyclohexanone ammoximation in the liquid phase over titanium silicate molecular sieves is investigated in an isothermal slurry reactor at different initial reactant concentrations, catalyst loading, and reaction temperature. The rate equations are developed by analyzing data of kinetic measurements. More than 10 side reactions were found. H2O2 decomposition reaction must be considered and other side reactions can be neglected in the kinetic modeling. The predicted values of reaction rates based on the kinetic models are almost consistent with experimental ones. The models have guidance to the selection of reactor types and they are useful to the design and operation of reactor used.展开更多
A selective reaction of cyclohexanone oxime-blocked tolylene-2,4-diisocyanate（2,4-TDI）with amino siloxane was observed,in which amines were capable of discriminating two reactive groups in the 2,4-TDI molecule.Thus,...A selective reaction of cyclohexanone oxime-blocked tolylene-2,4-diisocyanate（2,4-TDI）with amino siloxane was observed,in which amines were capable of discriminating two reactive groups in the 2,4-TDI molecule.Thus,tolylene-2-tert-butyldimethylsilyloxyethyl carbamide-4-cyclohexanone oxime carbamate was synthesized and its precise structure was determined by single-crystal X-ray diffraction.Moreover,it was found that oxime-blocked isocyanate could react selectively with the–NH2group with the–OH group unprotected in ethanolamine.展开更多
Electrocatalytic reduction of nitrate(NO3−)to valuable organonitrogen compounds beyond ammonia is a promising strategy for mitigating the humancaused unbalance of the global nitrogen cycle.Herein,we present an electro...Electrocatalytic reduction of nitrate(NO3−)to valuable organonitrogen compounds beyond ammonia is a promising strategy for mitigating the humancaused unbalance of the global nitrogen cycle.Herein,we present an electrochemical strategy for synthesizing cyclohexanone oxime(CHO),an important feedstock in nylon-6 production through hydrogenative coupling of NO_(3)^(−)and cyclohexanone(CYC)using a rutile titanium dioxide(R-TiO_(2))catalyst under ambient conditions.The CHO productivity achieved 127.3μmol cm^(−2) h^(−1) with a high Faradaic efficiency(FE)of 68.2%at a current density of 30 mA cm^(−2).Moreover,the yield of CHO reached 98.2%.We demonstrated that the electrosynthesis of CHO operated through a tandem reaction mechanism involving the in situ generation of hydroxylamine(NH2OH)from NO_(3)^(−) reduction,followed by a spontaneous nucleophilic addition–elimination reaction between NH2OH and CYC.Additionally,we revealed that R-TiO_(2) exhibited a superior scaling relation with a high NH2OH generation rate and excellent CYC adsorption ability,which promoted CHO production.This electrochemical strategy was also effective for the synthesis of different oximes.Finally,we designed a coupling reaction system to realize the simultaneous production of CHO and CYC by combining cathodic NO3−reduction and anodic cyclohexane oxidation,demonstrating a greener and more economical approach.展开更多
Four different ZSM 5 zeolites are tested for the gas phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B ZSM 5 derived titanosilicalite (Ti ZSM 5) exhibits catalytic performances comparabl...Four different ZSM 5 zeolites are tested for the gas phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B ZSM 5 derived titanosilicalite (Ti ZSM 5) exhibits catalytic performances comparable to hydrothermally synthesized titanosilicalite (TS 1), much better than B ZSM 5 and Al ZSM 5. The effect of reaction conditions (solvent, feed space velocity, and water) on the catalytic performance of Ti ZSM 5 is studied. It is found that a quantitative relationship exists among the feed space velocity, the reaction time, and the CHO constant conversion. Ethanol or methanol as solvent shows higher activity, lactam selectivity, and stability than benzene and n hexanol. The addition of water to the rearrangement with a maximum amount of 1.0 mole per mole CHO results in the increase of CHO conversion while no meaningful changes in lactam selectivity and stability are observed.展开更多
Na2WO4‐acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one‐pot conversion of cyclohexanol to ε‐caprolactam. The effect of the structure of the ionic liquid ...Na2WO4‐acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one‐pot conversion of cyclohexanol to ε‐caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid‐functionalized ionic liquids with HSO4? as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase‐transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate duringthe oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rearrangement.展开更多
基金financial support from the National Natural Science Foundation of China(22125202,92461312,U24A20487,92361201)Natural Science Foundation of Jiangsu Province(BK20220033).
文摘Cyclohexanone oxime serves as a crucial intermediate in the synthesis of caprolactam,which is an essential precursor for manufacturing nylonfibers,high-performance engineering plastics,and specialized plasticfilms.Catalytic hydrogenation of nitrocyclohexane to cyclohexanone oxime has been documented to be an atom-economical,green and environmentally friendly process.In this review,wefirst introduce the current design rules of catalysts for catalytic hydrogenation of nitrocyclohexane in terms of both active metals and supports.Secondly,we discuss the influence of solvent effects on the cyclohexanone oxime from the nitrocyclohexane conversion.In addition,we concisely discuss typically proposed reaction pathways for the hydrogenation of nitrocyclohexane to produce cyclohexanone oxime.Finally,we provide our perspectives on some issues for catalytic conversion of nitrocyclohexane to cyclohexanone oxime in the future.
文摘The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.
基金Supported by the National Natural Science Foundation of China and Sinopec (20736009)
文摘An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of cyclohexanone oxime from cyclohexanone, ammonia and hydrogen peroxide was carried out in a batch plant. Cyclohexane was used as the solvent in the three-phase reaction system. The influences of essential process parameters on ammoximation were investigated. Under the reaction conditions as catalyst content of 2.5% (by mass); H 2 O 2 /yclohexanone molar ratio of 1.10; NH 3 /cyclohexanone molar ratio of 2.20; reaction temperature of 343 K; reaction time of 5 h, high conversion of cyclohexanone and selectivity to oxime (both>99%) were obtained. Thus, the three-phase ammoximation process showed equal catalytic activity as TS-1 but much more convenient and simpler for the separation of catalyst in comparison to the industrial two-phase system with t-butanol used as solvent.
文摘The addition of platinum over the B2O3/TiO2-ZrO2 remarkably enhanced its catalytic stability in the vapor phase Beckmann rearrangement of cyclohexanone oxime under the carder gas of H2. The content of coke deposited on catalyst surface was decreased from 1.92% over the B2O3/TiO2-ZrO2 to 1.14% over the platinum promoted B2O3/TiO2-ZrO2 after reaction of six hours. This result indicates that the platinum added on the B2O3/TiO2-ZrO2 catalyst plays an important role in reducing the coke formation on the catalyst surface.
文摘Silicalite-1 was hydrothermally synthesized in the presence of different concentrations of Na+using tetrapropylammonium hydroxide(TPAOH)as a template.The synthesis was followed by a base treatment.The silicalite-1samples were characterized using X-ray diffrac-tion,scanning electron microscopy,N2 adsorption,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy and NH3 temperature-programmed deso-rption.The samples were used as catalysts for the vapor phase Beckmann rearrangement of cyclohexanone oxime.During the synthesis,the sodium ions were incorporated onto the silicalite-1 crystals,but were then removed by the base treatment.All the catalysts exhibited nearly complete conversion of cyclohexanone oxime toε-caprolactam with selectivities grater than 95%.Addition of less than 2.5 mol-%Na^(+)(relative to TPAOH)did not influence the catalytic properties.However,for Na+concentrations≥5 mol-%,the particle sizes of silicalite-1 increased and the catalytic activities decreased,which can be attributed to carbon deposition.The results in this work are of great importance for the polymer industry.
文摘An intrinsic kinetics of cyclohexanone ammoximation in the liquid phase over titanium silicate molecular sieves is investigated in an isothermal slurry reactor at different initial reactant concentrations, catalyst loading, and reaction temperature. The rate equations are developed by analyzing data of kinetic measurements. More than 10 side reactions were found. H2O2 decomposition reaction must be considered and other side reactions can be neglected in the kinetic modeling. The predicted values of reaction rates based on the kinetic models are almost consistent with experimental ones. The models have guidance to the selection of reactor types and they are useful to the design and operation of reactor used.
基金financially supported by the National Natural Science Foundation of China (Nos. 21176147, 21276149 and 21204044)Program for Scientifc Research Innovation Team in Colleges and Universities of Shandong Province
文摘A selective reaction of cyclohexanone oxime-blocked tolylene-2,4-diisocyanate（2,4-TDI）with amino siloxane was observed,in which amines were capable of discriminating two reactive groups in the 2,4-TDI molecule.Thus,tolylene-2-tert-butyldimethylsilyloxyethyl carbamide-4-cyclohexanone oxime carbamate was synthesized and its precise structure was determined by single-crystal X-ray diffraction.Moreover,it was found that oxime-blocked isocyanate could react selectively with the–NH2group with the–OH group unprotected in ethanolamine.
基金supported by the National Natural Science Foundation of China(grant nos.22090031,22108008,22288102,and 22302006)the Young Elite Scientist Sponsorship Program by Chinese Association for Science and Technology(CAST,grant no.2021QNRC001)+1 种基金the Fundamental Research Funds for the Central Universities,Chongqing,China(grant no.buctrc202011)the National Funded Postdoctoral Researchers Program(grant no.GZB20230049).
文摘Electrocatalytic reduction of nitrate(NO3−)to valuable organonitrogen compounds beyond ammonia is a promising strategy for mitigating the humancaused unbalance of the global nitrogen cycle.Herein,we present an electrochemical strategy for synthesizing cyclohexanone oxime(CHO),an important feedstock in nylon-6 production through hydrogenative coupling of NO_(3)^(−)and cyclohexanone(CYC)using a rutile titanium dioxide(R-TiO_(2))catalyst under ambient conditions.The CHO productivity achieved 127.3μmol cm^(−2) h^(−1) with a high Faradaic efficiency(FE)of 68.2%at a current density of 30 mA cm^(−2).Moreover,the yield of CHO reached 98.2%.We demonstrated that the electrosynthesis of CHO operated through a tandem reaction mechanism involving the in situ generation of hydroxylamine(NH2OH)from NO_(3)^(−) reduction,followed by a spontaneous nucleophilic addition–elimination reaction between NH2OH and CYC.Additionally,we revealed that R-TiO_(2) exhibited a superior scaling relation with a high NH2OH generation rate and excellent CYC adsorption ability,which promoted CHO production.This electrochemical strategy was also effective for the synthesis of different oximes.Finally,we designed a coupling reaction system to realize the simultaneous production of CHO and CYC by combining cathodic NO3−reduction and anodic cyclohexane oxidation,demonstrating a greener and more economical approach.
基金the Foundations for Basic Research ofTsinghua U niversity and of China Petrochem icalCompany
文摘Four different ZSM 5 zeolites are tested for the gas phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B ZSM 5 derived titanosilicalite (Ti ZSM 5) exhibits catalytic performances comparable to hydrothermally synthesized titanosilicalite (TS 1), much better than B ZSM 5 and Al ZSM 5. The effect of reaction conditions (solvent, feed space velocity, and water) on the catalytic performance of Ti ZSM 5 is studied. It is found that a quantitative relationship exists among the feed space velocity, the reaction time, and the CHO constant conversion. Ethanol or methanol as solvent shows higher activity, lactam selectivity, and stability than benzene and n hexanol. The addition of water to the rearrangement with a maximum amount of 1.0 mole per mole CHO results in the increase of CHO conversion while no meaningful changes in lactam selectivity and stability are observed.
基金supported by the National Natural Science Foundation of China (20636030, 2090618, 21236001)the Natural Science Foundation of Hebei Province (B2017202226)~~
文摘Na2WO4‐acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one‐pot conversion of cyclohexanol to ε‐caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid‐functionalized ionic liquids with HSO4? as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase‐transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate duringthe oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rearrangement.
