Leveraging the modularity and efficiency of click chemistry,a series of chiral diamine-triazole tetradentate nitrogen donor ligands and their corresponding nonheme iron complexes were synthesized.These iron-based cata...Leveraging the modularity and efficiency of click chemistry,a series of chiral diamine-triazole tetradentate nitrogen donor ligands and their corresponding nonheme iron complexes were synthesized.These iron-based catalysts demonstrated excellent catalytic activity and enantioselectivity in the asymmetric epoxidation of electron-deficient olefins using H_(2)O_(2) as the terminal oxidant.展开更多
Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were develop...Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were developed through Michael 1,4-addition.The precursors were synthesized from tall oil-based acetoacetates derived from epoxidized tall oil fatty acids or their methyl esters.Two different epoxidation methods were employed:enzymatic epoxidation of tall oil fatty acids and ion-exchange resin epoxidation of tall oil fatty acid methyl esters.Following oxirane opening and transesterification with trimethylolpropane,further esterification or transesterification was carried out to obtain the acetoacetates.These synthesized acetoacetates were then reacted with acrylates of various functionalities to obtain polymer resins with differing degrees of crosslinking.The developed polymer resins were characterized using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis.The results indicated that the glass transition temperature and storage modulus of the polymer resins were significantly influenced by both the functionality of the acrylates used and the epoxidation technique employed.Higher acrylate functionality resulted in increased stiffness,while enzymatic epoxidation enhanced the polymer’s mechanical properties,nearly doubling the storage modulus,achieving approximately 470 MPa,compared to the ion-exchange resin technique.Therefore,selecting the appropriate acrylate functionality and epoxidation method could tailor the mechanical properties of the polymer resins.展开更多
Selective oxidation of olefin to epoxides is an important reaction in industry,however,developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O_(2)atmosphere at room temperature ...Selective oxidation of olefin to epoxides is an important reaction in industry,however,developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O_(2)atmosphere at room temperature is challenging but highly desired.In this work,two novel 2D cobalt metal-organic complexes,namely[Co(L)(5-HIP)]·2H_(2)O(Co-MOC-1)and[Co(L)(BTEC)_(0.5)]·H_(2)O(Co-MOC-2)(L=(E)-4,4-(ethene-1,2-diyl))bis(N-(pyridin-3-yl)benzamide;5-H_(2)HIP=5-hydroxyisophthalic acid;H4BTEC=pyromellitic acid)were designed and synthesized through hydrothermal method,which exhibited different metal coordination modes(4-coordinate and 5-coordinate,respectively)and 2D layer structures directed by different carboxylates co-ligands.Two Co-MOCs can serve as heterogeneous catalysts for the selective oxidation of olefins to epoxides at room temperature using O_(2)as oxidant.Furthermore,a higher catalysis activity of Co-MOC-1 than Co-MOC-2(96.7%vs.90.2%yield of 1,2-epoxycyclooctane)was observed,which may be attributed to the coordination unsaturated Co centers,the less coordination number and larger interlayer spacing of Co-MOC-1.展开更多
Propylene oxide(PO),with its reactive three-membered epoxide functional group,exhibits remarkable functional versatility and serves as a crucial bridge connecting the gaps between fossil energy utilization and chemica...Propylene oxide(PO),with its reactive three-membered epoxide functional group,exhibits remarkable functional versatility and serves as a crucial bridge connecting the gaps between fossil energy utilization and chemical intermediate generation for new material innovation [1].For instance,PO's downstream derivatives,such as polyether polyols,carbonic esters,and polyurethanes,are widely utilized in wind power generation,battery electrolytes,solar cells,and CO_(2)-based degradable polymers,contributing to sustainable decarbonization in industry [2].展开更多
The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu（bipy）]4[Mo15O47].2H2O （1） and [Cu1（bix）][（Cu1bix） （δ-MoVl8O26）0....The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu（bipy）]4[Mo15O47].2H2O （1） and [Cu1（bix）][（Cu1bix） （δ-MoVl8O26）0.5] （2） （bipy = 4,4＇-bipyridine, bix = 1,4-bis（imidazole-1-ylmethyl）benzene）. Both compounds were catalytically active and stable for the epoxidation of cyclooctene, 1-octene, and styrene with tert-butyl hydroperoxide （t-BuOOH） as oxidant. The excellent catalytic performance was attributed to the presence of stable coordination bonds between the molybdenum oxide and copper complex, which resulted in the formation of easily accessible Mo species with high electropositivity. In addition, the copper complex also acted as an active site for the activation of t-BuOOH, thus im- proving these copper complex-modified polyoxometalates.展开更多
Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation...Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.展开更多
The epoxidation of unsaturated fatty acid methyl esters(FAMEs)by peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid was studied in the presence of SO3H-functional Brnsted acidic ionic liquid (I...The epoxidation of unsaturated fatty acid methyl esters(FAMEs)by peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid was studied in the presence of SO3H-functional Brnsted acidic ionic liquid (IL)[C3SO3HMIM][HSO4]as catalyst.The effects of hydrogen peroxide/ethylenic unsaturation ratio,acetic acid concentration,IL concentration,recycling of the IL catalyst,and temperature on the conversion to oxirane were studied.The kinetics and thermodynamics of unsaturated FAMEs epoxidation and the kinetics of oxirane cleavage of the epoxidized FAMEs by acetic acid were also studied.The conversion of ethylenic unsaturation group to oxirane, the reaction rate of the conversion to oxirane,and the rate of hydrolysis(oxirane cleavage)were higher by using the IL catalyst.展开更多
Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in i...Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in industrial processes.As the essential additives for preparing formed catalysts,binders are usually the catalytically inert components,but they would cover the surface and pore mouth of zeolite,thereby declining the accessibility of active sites.By recrystallizing the binder(silica)/Ti‐MWW extrudates with the assistance of dual organic structure‐directing agents,the silica binder was converted into MWW zeolite phase to form a structured binder‐free Ti‐MWW zeolite with Si‐rich shell,which enhanced the diffusion efficiency and maintained the mechanical strength.Meanwhile,due to the partial dissolution of Si in the Ti‐MWW matrix,abundant silanol nests formed and part of framework TiO4 species were transferred into open TiO_(6)ones,improving the accumulation and activation ability of H_(2)O_(2)inside the monolith.Successive piperidine treatment and fluoridation of the binder‐free Ti‐MWW further enhanced the H_(2)O_(2)activation and oxygen transfer ability of the active Ti sites,and stabilized the Ti‐OOH intermediate through hydrogen bond formed between the end H in Ti‐OOH and the adjacent Si‐F species,thus achieving a more efficient epoxidation process.Additionally,the side reaction of PO hydrolysis was inhibited because the modification effectively quenched numerous Si‐OH groups.The lifetime of the modified binder‐free Ti‐MWW catalyst was 2400 h with the H_(2)O_(2)conversion and PO selectivity both above 99.5%.展开更多
The epoxidation of methyl oleate(MO)was conducted in the presence of aqueous H2O2 as the oxidant and hierarchical TS-1(HTS-1)as the catalyst;the catalyst was synthesized using polyquaternium-6 as the mesopore template...The epoxidation of methyl oleate(MO)was conducted in the presence of aqueous H2O2 as the oxidant and hierarchical TS-1(HTS-1)as the catalyst;the catalyst was synthesized using polyquaternium-6 as the mesopore template.The effects of various parameters,i.e.,H2O2/C=C molar ratio,oxidant concentration,amount of the catalyst,reaction temperature,and time,were systematically studied.Furthermore,response surface methodology(RSM)was used to optimize the conditions to maximize the yield of epoxy MO and to evaluate the significance and interplay of the factors affecting the epoxy MO production.The H2O2/C=C molar ratio and catalyst amount were the determining factors for MO epoxidation,wherein the maximum yield of epoxy MO reached 94.9%over HTS-1 under the optimal conditions.展开更多
The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
A series of Mo-containing MFI zeolites with different Mo loadings(Mo-MFI-n,n represent the initial Si/Mo molar ratio)was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA co...A series of Mo-containing MFI zeolites with different Mo loadings(Mo-MFI-n,n represent the initial Si/Mo molar ratio)was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA complex as the Mo source.Various characterization results demonstrated that the use of the Mo-EDTA complex is beneficial for the incorporation of more Mo species into the MFI-type zeolites.The special complexing capability of EDTA^(2–)plays a critical role in adjusting the release rate of the Mo species to combine with the Si tetrahedron species during the zeolite growth process,thus leading to a uniform distribution of Mo in the MFI framework.In addition,a small portion of extra-framework Mo clusters may be distributed inside the channels or near the pore window of the zeolites.The catalytic properties of these Mo-containing MFI zeolites were evaluated for the epoxidation of cyclohexene with H_(2)O_(2)as the oxidant.The composition-optimized catalyst,Mo-MFI-50,efficiently converted cyclohexene to the corresponding epoxide with a relatively high conversion(93%)and epoxide selectivity(82%)at 75℃after 9 h of reaction.Moreover,the resultant Mo-containing MFI catalyst exhibited excellent structural stability and recoverability and was easily recycled by simple filtration without the need for calcination treatment.展开更多
The unsupported Cu and Ag catalysts with different oxidation states were prepared, and their catalytic performances for propylene epoxidation were investigated.The metallic Cu catalyst exhibits much higher catalytic a...The unsupported Cu and Ag catalysts with different oxidation states were prepared, and their catalytic performances for propylene epoxidation were investigated.The metallic Cu catalyst exhibits much higher catalytic activity and propylene oxide(PO) selectivity than Cu2 O and Cu O catalysts.The Cu0 species are the main active sites for propylene epoxidation, but Cu2 O and Cu O species are in favor of CO2 and acrolein production.The PO selectivity of 54.2 % and propylene conversion of 2.6 % can be achieved over the metallic Cu catalyst at 160 °C in initial stage, but metallic Cu catalyst would be oxidized to Cu2 O during propylene epoxidation, resulting in a sharp decrease in the PO selectivity and propylene conversion.Nanosize Ag Cuxbimetallic catalysts were prepared.It is found that adding Ag to the metallic Cu catalysts can prevent the oxidation of Cu and make Ag Cuxbimetallic catalysts more stable under the condition of propylene epoxidation.The Ag/Cu molar ratio can remarkably affect the catalytic performance of Ag Cuxcatalyst and the selectivity to PO and acrolein.After Ag Cuxwas supported on MOx-modified a-Al2O3, its catalytic performance can be improved and has a close relationship with the acid–base property of support.展开更多
文摘Leveraging the modularity and efficiency of click chemistry,a series of chiral diamine-triazole tetradentate nitrogen donor ligands and their corresponding nonheme iron complexes were synthesized.These iron-based catalysts demonstrated excellent catalytic activity and enantioselectivity in the asymmetric epoxidation of electron-deficient olefins using H_(2)O_(2) as the terminal oxidant.
基金funded by the Latvian State Institute of Wood Chemistry Bioeconomic grant no.04-24“Development of Composites from Polymer Resin Synthesized from Tall Oil Fatty Acids and Reinforced with Various Fillers”(FiTeCo).
文摘Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were developed through Michael 1,4-addition.The precursors were synthesized from tall oil-based acetoacetates derived from epoxidized tall oil fatty acids or their methyl esters.Two different epoxidation methods were employed:enzymatic epoxidation of tall oil fatty acids and ion-exchange resin epoxidation of tall oil fatty acid methyl esters.Following oxirane opening and transesterification with trimethylolpropane,further esterification or transesterification was carried out to obtain the acetoacetates.These synthesized acetoacetates were then reacted with acrylates of various functionalities to obtain polymer resins with differing degrees of crosslinking.The developed polymer resins were characterized using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis.The results indicated that the glass transition temperature and storage modulus of the polymer resins were significantly influenced by both the functionality of the acrylates used and the epoxidation technique employed.Higher acrylate functionality resulted in increased stiffness,while enzymatic epoxidation enhanced the polymer’s mechanical properties,nearly doubling the storage modulus,achieving approximately 470 MPa,compared to the ion-exchange resin technique.Therefore,selecting the appropriate acrylate functionality and epoxidation method could tailor the mechanical properties of the polymer resins.
基金financially supported by the National Natural Science Foundation of China(Nos.22271021,21971024,22201021)the Doctoral Scientific Research Foundation of Liaoning Province(No.2022-BS-302)。
文摘Selective oxidation of olefin to epoxides is an important reaction in industry,however,developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O_(2)atmosphere at room temperature is challenging but highly desired.In this work,two novel 2D cobalt metal-organic complexes,namely[Co(L)(5-HIP)]·2H_(2)O(Co-MOC-1)and[Co(L)(BTEC)_(0.5)]·H_(2)O(Co-MOC-2)(L=(E)-4,4-(ethene-1,2-diyl))bis(N-(pyridin-3-yl)benzamide;5-H_(2)HIP=5-hydroxyisophthalic acid;H4BTEC=pyromellitic acid)were designed and synthesized through hydrothermal method,which exhibited different metal coordination modes(4-coordinate and 5-coordinate,respectively)and 2D layer structures directed by different carboxylates co-ligands.Two Co-MOCs can serve as heterogeneous catalysts for the selective oxidation of olefins to epoxides at room temperature using O_(2)as oxidant.Furthermore,a higher catalysis activity of Co-MOC-1 than Co-MOC-2(96.7%vs.90.2%yield of 1,2-epoxycyclooctane)was observed,which may be attributed to the coordination unsaturated Co centers,the less coordination number and larger interlayer spacing of Co-MOC-1.
基金supported by the National Natural Science Foundation of China (29792072, 22278441, 22478452)National Key Research and Development Program of China (937) (2006CB202508)the SINOPEC Project (419019-2, 413108)。
文摘Propylene oxide(PO),with its reactive three-membered epoxide functional group,exhibits remarkable functional versatility and serves as a crucial bridge connecting the gaps between fossil energy utilization and chemical intermediate generation for new material innovation [1].For instance,PO's downstream derivatives,such as polyether polyols,carbonic esters,and polyurethanes,are widely utilized in wind power generation,battery electrolytes,solar cells,and CO_(2)-based degradable polymers,contributing to sustainable decarbonization in industry [2].
基金supported by the National Natural Science Foundation of China(21173100 and 21320102001)~~
文摘The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu（bipy）]4[Mo15O47].2H2O （1） and [Cu1（bix）][（Cu1bix） （δ-MoVl8O26）0.5] （2） （bipy = 4,4＇-bipyridine, bix = 1,4-bis（imidazole-1-ylmethyl）benzene）. Both compounds were catalytically active and stable for the epoxidation of cyclooctene, 1-octene, and styrene with tert-butyl hydroperoxide （t-BuOOH） as oxidant. The excellent catalytic performance was attributed to the presence of stable coordination bonds between the molybdenum oxide and copper complex, which resulted in the formation of easily accessible Mo species with high electropositivity. In addition, the copper complex also acted as an active site for the activation of t-BuOOH, thus im- proving these copper complex-modified polyoxometalates.
文摘Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.
文摘The epoxidation of unsaturated fatty acid methyl esters(FAMEs)by peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid was studied in the presence of SO3H-functional Brnsted acidic ionic liquid (IL)[C3SO3HMIM][HSO4]as catalyst.The effects of hydrogen peroxide/ethylenic unsaturation ratio,acetic acid concentration,IL concentration,recycling of the IL catalyst,and temperature on the conversion to oxirane were studied.The kinetics and thermodynamics of unsaturated FAMEs epoxidation and the kinetics of oxirane cleavage of the epoxidized FAMEs by acetic acid were also studied.The conversion of ethylenic unsaturation group to oxirane, the reaction rate of the conversion to oxirane,and the rate of hydrolysis(oxirane cleavage)were higher by using the IL catalyst.
文摘Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in industrial processes.As the essential additives for preparing formed catalysts,binders are usually the catalytically inert components,but they would cover the surface and pore mouth of zeolite,thereby declining the accessibility of active sites.By recrystallizing the binder(silica)/Ti‐MWW extrudates with the assistance of dual organic structure‐directing agents,the silica binder was converted into MWW zeolite phase to form a structured binder‐free Ti‐MWW zeolite with Si‐rich shell,which enhanced the diffusion efficiency and maintained the mechanical strength.Meanwhile,due to the partial dissolution of Si in the Ti‐MWW matrix,abundant silanol nests formed and part of framework TiO4 species were transferred into open TiO_(6)ones,improving the accumulation and activation ability of H_(2)O_(2)inside the monolith.Successive piperidine treatment and fluoridation of the binder‐free Ti‐MWW further enhanced the H_(2)O_(2)activation and oxygen transfer ability of the active Ti sites,and stabilized the Ti‐OOH intermediate through hydrogen bond formed between the end H in Ti‐OOH and the adjacent Si‐F species,thus achieving a more efficient epoxidation process.Additionally,the side reaction of PO hydrolysis was inhibited because the modification effectively quenched numerous Si‐OH groups.The lifetime of the modified binder‐free Ti‐MWW catalyst was 2400 h with the H_(2)O_(2)conversion and PO selectivity both above 99.5%.
基金supported by the Evonik Industries AGthe Program for New Century Excellent Talents in University(NCET-04-0270)~~
文摘The epoxidation of methyl oleate(MO)was conducted in the presence of aqueous H2O2 as the oxidant and hierarchical TS-1(HTS-1)as the catalyst;the catalyst was synthesized using polyquaternium-6 as the mesopore template.The effects of various parameters,i.e.,H2O2/C=C molar ratio,oxidant concentration,amount of the catalyst,reaction temperature,and time,were systematically studied.Furthermore,response surface methodology(RSM)was used to optimize the conditions to maximize the yield of epoxy MO and to evaluate the significance and interplay of the factors affecting the epoxy MO production.The H2O2/C=C molar ratio and catalyst amount were the determining factors for MO epoxidation,wherein the maximum yield of epoxy MO reached 94.9%over HTS-1 under the optimal conditions.
文摘The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
文摘A series of Mo-containing MFI zeolites with different Mo loadings(Mo-MFI-n,n represent the initial Si/Mo molar ratio)was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA complex as the Mo source.Various characterization results demonstrated that the use of the Mo-EDTA complex is beneficial for the incorporation of more Mo species into the MFI-type zeolites.The special complexing capability of EDTA^(2–)plays a critical role in adjusting the release rate of the Mo species to combine with the Si tetrahedron species during the zeolite growth process,thus leading to a uniform distribution of Mo in the MFI framework.In addition,a small portion of extra-framework Mo clusters may be distributed inside the channels or near the pore window of the zeolites.The catalytic properties of these Mo-containing MFI zeolites were evaluated for the epoxidation of cyclohexene with H_(2)O_(2)as the oxidant.The composition-optimized catalyst,Mo-MFI-50,efficiently converted cyclohexene to the corresponding epoxide with a relatively high conversion(93%)and epoxide selectivity(82%)at 75℃after 9 h of reaction.Moreover,the resultant Mo-containing MFI catalyst exhibited excellent structural stability and recoverability and was easily recycled by simple filtration without the need for calcination treatment.
基金financially supported by the National Basic Research Program of China (No. 2010CB732300)
文摘The unsupported Cu and Ag catalysts with different oxidation states were prepared, and their catalytic performances for propylene epoxidation were investigated.The metallic Cu catalyst exhibits much higher catalytic activity and propylene oxide(PO) selectivity than Cu2 O and Cu O catalysts.The Cu0 species are the main active sites for propylene epoxidation, but Cu2 O and Cu O species are in favor of CO2 and acrolein production.The PO selectivity of 54.2 % and propylene conversion of 2.6 % can be achieved over the metallic Cu catalyst at 160 °C in initial stage, but metallic Cu catalyst would be oxidized to Cu2 O during propylene epoxidation, resulting in a sharp decrease in the PO selectivity and propylene conversion.Nanosize Ag Cuxbimetallic catalysts were prepared.It is found that adding Ag to the metallic Cu catalysts can prevent the oxidation of Cu and make Ag Cuxbimetallic catalysts more stable under the condition of propylene epoxidation.The Ag/Cu molar ratio can remarkably affect the catalytic performance of Ag Cuxcatalyst and the selectivity to PO and acrolein.After Ag Cuxwas supported on MOx-modified a-Al2O3, its catalytic performance can be improved and has a close relationship with the acid–base property of support.
