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
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
Propylene oxide plays a pivotal role as an organic synthesis intermediate,boasting extensive downstream applications and promising market prospects.Propene epoxidation via molecular oxygen has garnered considerable at...Propylene oxide plays a pivotal role as an organic synthesis intermediate,boasting extensive downstream applications and promising market prospects.Propene epoxidation via molecular oxygen has garnered considerable attention due to its cost-effectiveness,environmental friendliness,ease of operation,and straightforward product separation.This paper provides an in-depth exploration of recent advance-ments,ranging from nanoparticle to Single-atom catalysts(SACs),in the context of propene epoxidation using molecular oxygen.Conventional nanoparticle catalysts,including those based on Ag,Cu,and other metals,are examined with regard to their contributions to support effects,electron effects,or crystal-plane effects within the mechanistic investigation.Furthermore,emerging SACs(specifically Mo,Cu,and Co)are discussed in terms of synthesis strategies,characterization methods,and mechanism studies.This comprehensive review sheds new light on design strategies,relevant characterizations,and thorough mechanism investigations aimed at fostering the development of efficient catalysts,thereby expediting progress in the industrial implementation of propene epoxidation.展开更多
Au sites supported on Ti-containing materials(Au/Ti-containing catalyst)are currently considered as a promising catalyst for the propylene epoxidation owing to the synergistic effect that hydrogen peroxide species for...Au sites supported on Ti-containing materials(Au/Ti-containing catalyst)are currently considered as a promising catalyst for the propylene epoxidation owing to the synergistic effect that hydrogen peroxide species formed on Au sites diffuses to the Ti sites to form the Ti-hydroperoxo intermedi-ates and contributes to the formation of propylene oxide(PO).In principle,thermal treatment will significantly affect the chemical and physical structures of Ti-containing materials.Consequently,the synergy between tailored Ti sites with different surface properties and Au sites is highly expected to enhance the catalytic performance for the reaction.Herein,we systematically studied the intrinsic effects of different microenvironments around Ti sites on the PO adsorption/desorption and conversion,and then effectively improved the catalytic performance by tailoring the number of surface hydroxyl groups.The Ti^(Ⅵ) material with fewer hydroxyls stimulates a remarkable enhancement in PO selectivity and H_(2) efficiency compared to the Ti^(Ⅵ) material that possessed more hydroxyls,offering a 7-fold and 4-fold increase,respectively.As expected,the Ti^(Ⅵ+Ⅳ) and Ti^(Ⅳ) materials also exhibit a similar phenomenon to the Ti^(Ⅵ) materials through the same thermal treatment,which strongly supports that the Ti sites microenvironment is an important factor in suppressing PO con-version and enhancing catalytic performance.These insights could provide guidance for the rational preparation and optimization of Ti-containing materials synergizing with Au catalysts for propylene epoxidation.展开更多
The heterogeneously copper-catalyzed oxidative cleavage of styrene was studied using copper-doped mesoporous KIT-6（CU-KIT-6_x） prepared via pH adjustment（where x is the pH：1.43,2.27,3.78,3.97,4.24 or 6.62）.Variat...The heterogeneously copper-catalyzed oxidative cleavage of styrene was studied using copper-doped mesoporous KIT-6（CU-KIT-6_x） prepared via pH adjustment（where x is the pH：1.43,2.27,3.78,3.97,4.24 or 6.62）.Variations in the catalyst structure and morphology with pH values were characterized by X-ray power diffraction,nitrogen adsorption-desorption analysis,transmission electron microscopy and X-ray photoelectron spectroscopy.As the pH value applied during the initial synthesis,the resulting Cu-KIT-6_x exhibited different structural,textural and surface characteristics,especially in terms of specific copper species and copper content At a pH value of 3.78,approximately 4.6 wt%copper（Ⅱ） was successfully incorporated into the framework of the initial KIT-6,in the form of-Cu-O-Si- groups.The catalytic performance of each catalyst was evaluated by following the epoxidation of styrene,employing tert-butyl hydroperoxide as the oxidant and CH_3CN as the solvent.A significant styrene conversion of 43.5%with 86.6%selectivity for the desired styrene epoxide was obtained over the Cu-KIT-63.78.A higher Cu content,an ordered cubic laid mesoporous architecture and various specific textural characteristics all combined to endow the Cu-KIT-63.78 with high catalytic activity and good stability.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
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.
Hybrid composites of phosphomolybdic acid@UiO-66(PMo12@UiO-66)and Co-substituted phosphomolybdic acid@UiO-66(PMo11Co@UiO-66)were synthesized using the direct solvothermal method.A variety of characterization results d...Hybrid composites of phosphomolybdic acid@UiO-66(PMo12@UiO-66)and Co-substituted phosphomolybdic acid@UiO-66(PMo11Co@UiO-66)were synthesized using the direct solvothermal method.A variety of characterization results demonstrated that phosphomolybdic acid(PMo12)or Co-substituted phosphomolybdate acid(PMo11Co)clusters are uniformly dispersed in the cages of Zr-based metal-organic UiO-66 frameworks.The catalytic properties of these hybrid composites were investigated by applying the epoxidation of olefins with tert-butyl hydroperoxide as the oxidant.Compared to PMo12@UiO-66,PMo11Co@UiO-66 showed a much higher catalytic activity and was simply recovered by filtration and reused for at least ten runs without significant loss of catalytic activity.Particularly,PMo11Co@UiO-66 can efficiently convert cyclic olefins like limonenes to epoxides,and its selectivity to 1,2-limonene oxide reached 91%in the presence of a radical inhibitor such as hydroquinone.The excellent catalytic activity and stability of the hybrid composite PMo11Co@UiO-66 are mainly attributed to the uniform distribution of highly active PMo11Co units within the smaller cages of UiO-66,to the suitable surface polarity of the hybrid composite for facilitating the access of reagents and solvent,and to the strong interface-interactions between the polyoxometalate and the UiO-66 framework.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
Epoxidation of cyclohexene to cyclohexene oxide was studied in a new type reactor—the ultrasound airlift loop reactor. The influences of ultrasound intensity, molar ratio of isobutyraldehyde to cyclohexene and oxy-ge...Epoxidation of cyclohexene to cyclohexene oxide was studied in a new type reactor—the ultrasound airlift loop reactor. The influences of ultrasound intensity, molar ratio of isobutyraldehyde to cyclohexene and oxy-gen gas flow rate on the conversion of cyclohexene and selectivity of cyclohexene oxide were investigated and dis-cussed, and the optimal operation condition was found, under which 95.2% conversion of cyclohexene and 90.7% selectivity of cyclohexene oxide were achieved. The ultrasonic airlift loop reactor utilizes the synergistic effect of sonochemsitry and higher oxygen transfer rate. Possible reaction mechanisms were outlined and the reason of ul-trasound promotion of epoxidation reactionwas analyzed.展开更多
Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts f...Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene.The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide.The optimal formation rate(68.3μmol/g·h)and selectivity(52.3%)toward propylene oxide were achieved with an Au:Ag mass ratio of4:1.Notably,the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems.A probable reaction mechanism was proposed based on the theoretical and experimental results.展开更多
Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized b...Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.展开更多
Titanium silicalite-1(TS-1) was synthesized by a hydrothermal synthesis method with different amounts of tetrapropyl ammonium hydroxide(TPAOH) as template.The as-prepared TS-1 was characterized by scanning electron mi...Titanium silicalite-1(TS-1) was synthesized by a hydrothermal synthesis method with different amounts of tetrapropyl ammonium hydroxide(TPAOH) as template.The as-prepared TS-1 was characterized by scanning electron microscopy,X-ray powder diffraction,Fourier-transform infrared resonance spectroscopy,ultravioletvisible diffuse reflectance spectroscopy and nitrogen physical adsorption and desorption,and studied in the propylene epoxidation with hydrogen peroxide in a fixed bed reactor.The results showed that the amount of TPAOH had a strong influence on the grain morphology,the amount of framework Ti,and the average particle sizes of TS-1.With the increase of TPAOH amount in the synthesis(the molar ratio of TPAOH/SiO_2 increasing from 0.25 to 0.45),the morphology changed gradually from ellipsoids to cubes,the particle sizes of TS-1 decreased slightly,the amount of the framework Ti increased appreciably,and the catalytic stability in the propylene epoxidation increased markedly.Moreover,all the catalysts had the same selectivity to propylene epoxide.However,when the molar ratio of TPAOH/SiO_2 was further increased to 0.55,the particles became large hexagons with the size distribution in a wide range,and the catalytic stability decreased sharply although the amount of the framework Ti increased further,which can be attributed to the long diffusion paths of the reactants in the zeolite.展开更多
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
Gold catalysts supported on SiO2, TiO2, TiO2-SiO2, and ZrO2-SiO2 supports were prepared by impregnating each support with a basic solution of tetrachloroauric acid. X-ray diffraction （XRD）, transmission electron mic...Gold catalysts supported on SiO2, TiO2, TiO2-SiO2, and ZrO2-SiO2 supports were prepared by impregnating each support with a basic solution of tetrachloroauric acid. X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and X-ray photoelectron spectroscopy （XPS） techniques were used to characterize their structure and surface composition. The results indicated that the size of gold particles could be controlled to below 10 nm by this method of preparation. Washing gold catalysts with water could markedly enhance the dispersion of metallic gold particles on the surface, but it could not completely remove the chloride ions left on the surface. The catalytic performance of direct vapor-phase epoxidation of propylene using air as an oxidant over these catalysts was evaluated at atmospheric pressure. The selectivity to propylene oxide （PO） was found to vary with reaction time on the stream. At the reaction conditions of atmosphere pressure, temperature 325 ℃, feed gas ratio V（C3H6）/V（O2）= 1/2, and GHSV =6000h^-1, 17.9% PO selectivity with 0.9% propylene conversion were obtained at initial 10 min for Au/SiO2 catalyst. After reacting 60 min only 8.9% PO selectivity were detected, but the propylene conversion rises to 1.4% and the main product is transferred to acrolein （72% selectivity）. Washing Au/TiO2-SiO2 and Aa/ZrO2-SiO2 samples with magnesium citrate solution could markedly enhance the activity and PO selectivity because smaller gold particles were obtained.展开更多
Engineering unique electronic structure of catalyst to boost catalytic performance is of prime scientific and industrial importance.Herein,the identification of intrinsic electronic sensitivity for direct propene epox...Engineering unique electronic structure of catalyst to boost catalytic performance is of prime scientific and industrial importance.Herein,the identification of intrinsic electronic sensitivity for direct propene epoxidation was first achieved over highly stable Au/wormhole-like TS-1 catalyst.Results show that the electron transfer of Au species can be regulated by manipulating the dynamic evolutions and contents of Au valence states,thus resulting in different catalytic performance in 100 h time-on-stream.By DFT calculations,kinetic analysis and multicharacterizations,it is found that the Au^(0) species with higher electronic population can easily transfer more electrons to activate surface O_(2) compared with Au^(1+) and Au^(3+) species.Moreover,there is a positive correlation between Au^(0) content and activity.Based on this correlation,a facile strategy is further proposed to boost Au^(0) percentage,resulting in the reported highest PO formation rate without adding promoters.This work harbors tremendous guiding significance to the design of highly efficient Au/Ti-containing catalyst for propene epoxidation with H_(2) and O_(2).展开更多
The advocacy of green chemical industry has led to the development of highly efficient catalysts for direct gas-phase propene epoxidation with green,sustainable and simple essence.The S-1/TS-1@dendritic-SiO_(2) materi...The advocacy of green chemical industry has led to the development of highly efficient catalysts for direct gas-phase propene epoxidation with green,sustainable and simple essence.The S-1/TS-1@dendritic-SiO_(2) material with three-layer core–shell structure was developed and used as the support for Au catalysts,which showed simultaneously fantastic PO formation rate,PO selectivity and stability(over 100 h)for propene epoxidation with H_(2) and O_(2).It is found that silicalite-1(S-1)core and the middle thin layer of TS-1 offer great mass transfer ability,which could be responsible for the excellent stability.The designed dendritic SiO_(2) shell covers part of the acid sites on the external surface of TS-1,inhibiting the side reactions and improving the PO selectivity.Furthermore,three kinds of SiO_(2) shell morphologies(i.e.,dendritic,net,mesoporous shell)were designed,and relationship between shell morphology and catalytic performance was elucidated.The results in this paper harbour tremendous guiding significance for the design of highly efficient epoxidation catalysts.展开更多
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-Outstanding Youth foundation(No.22322814)National Natural Science Foundation of China(No.22108307,No.22108305)+1 种基金the National Natural Foundation of Shandong Province(ZR2021QB076,ZR2020YQ17,ZR2020KB006,ZR2023YQ009 and ZR2022MB015)the Fundamental Research Funds for the Central Universities(23CX04029 A).
文摘Propylene oxide plays a pivotal role as an organic synthesis intermediate,boasting extensive downstream applications and promising market prospects.Propene epoxidation via molecular oxygen has garnered considerable attention due to its cost-effectiveness,environmental friendliness,ease of operation,and straightforward product separation.This paper provides an in-depth exploration of recent advance-ments,ranging from nanoparticle to Single-atom catalysts(SACs),in the context of propene epoxidation using molecular oxygen.Conventional nanoparticle catalysts,including those based on Ag,Cu,and other metals,are examined with regard to their contributions to support effects,electron effects,or crystal-plane effects within the mechanistic investigation.Furthermore,emerging SACs(specifically Mo,Cu,and Co)are discussed in terms of synthesis strategies,characterization methods,and mechanism studies.This comprehensive review sheds new light on design strategies,relevant characterizations,and thorough mechanism investigations aimed at fostering the development of efficient catalysts,thereby expediting progress in the industrial implementation of propene epoxidation.
文摘Au sites supported on Ti-containing materials(Au/Ti-containing catalyst)are currently considered as a promising catalyst for the propylene epoxidation owing to the synergistic effect that hydrogen peroxide species formed on Au sites diffuses to the Ti sites to form the Ti-hydroperoxo intermedi-ates and contributes to the formation of propylene oxide(PO).In principle,thermal treatment will significantly affect the chemical and physical structures of Ti-containing materials.Consequently,the synergy between tailored Ti sites with different surface properties and Au sites is highly expected to enhance the catalytic performance for the reaction.Herein,we systematically studied the intrinsic effects of different microenvironments around Ti sites on the PO adsorption/desorption and conversion,and then effectively improved the catalytic performance by tailoring the number of surface hydroxyl groups.The Ti^(Ⅵ) material with fewer hydroxyls stimulates a remarkable enhancement in PO selectivity and H_(2) efficiency compared to the Ti^(Ⅵ) material that possessed more hydroxyls,offering a 7-fold and 4-fold increase,respectively.As expected,the Ti^(Ⅵ+Ⅳ) and Ti^(Ⅳ) materials also exhibit a similar phenomenon to the Ti^(Ⅵ) materials through the same thermal treatment,which strongly supports that the Ti sites microenvironment is an important factor in suppressing PO con-version and enhancing catalytic performance.These insights could provide guidance for the rational preparation and optimization of Ti-containing materials synergizing with Au catalysts for propylene epoxidation.
基金supported by Guangdong Science and Technology Planning Project(2015A020216002)Guangdong Natural Science Foundation(2014A030313259)the National Natural Science Foundation of China(21543014,21173086,U1301245)~~
文摘The heterogeneously copper-catalyzed oxidative cleavage of styrene was studied using copper-doped mesoporous KIT-6（CU-KIT-6_x） prepared via pH adjustment（where x is the pH：1.43,2.27,3.78,3.97,4.24 or 6.62）.Variations in the catalyst structure and morphology with pH values were characterized by X-ray power diffraction,nitrogen adsorption-desorption analysis,transmission electron microscopy and X-ray photoelectron spectroscopy.As the pH value applied during the initial synthesis,the resulting Cu-KIT-6_x exhibited different structural,textural and surface characteristics,especially in terms of specific copper species and copper content At a pH value of 3.78,approximately 4.6 wt%copper（Ⅱ） was successfully incorporated into the framework of the initial KIT-6,in the form of-Cu-O-Si- groups.The catalytic performance of each catalyst was evaluated by following the epoxidation of styrene,employing tert-butyl hydroperoxide as the oxidant and CH_3CN as the solvent.A significant styrene conversion of 43.5%with 86.6%selectivity for the desired styrene epoxide was obtained over the Cu-KIT-63.78.A higher Cu content,an ordered cubic laid mesoporous architecture and various specific textural characteristics all combined to endow the Cu-KIT-63.78 with high catalytic activity and good stability.
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Hybrid composites of phosphomolybdic acid@UiO-66(PMo12@UiO-66)and Co-substituted phosphomolybdic acid@UiO-66(PMo11Co@UiO-66)were synthesized using the direct solvothermal method.A variety of characterization results demonstrated that phosphomolybdic acid(PMo12)or Co-substituted phosphomolybdate acid(PMo11Co)clusters are uniformly dispersed in the cages of Zr-based metal-organic UiO-66 frameworks.The catalytic properties of these hybrid composites were investigated by applying the epoxidation of olefins with tert-butyl hydroperoxide as the oxidant.Compared to PMo12@UiO-66,PMo11Co@UiO-66 showed a much higher catalytic activity and was simply recovered by filtration and reused for at least ten runs without significant loss of catalytic activity.Particularly,PMo11Co@UiO-66 can efficiently convert cyclic olefins like limonenes to epoxides,and its selectivity to 1,2-limonene oxide reached 91%in the presence of a radical inhibitor such as hydroquinone.The excellent catalytic activity and stability of the hybrid composite PMo11Co@UiO-66 are mainly attributed to the uniform distribution of highly active PMo11Co units within the smaller cages of UiO-66,to the suitable surface polarity of the hybrid composite for facilitating the access of reagents and solvent,and to the strong interface-interactions between the polyoxometalate and the UiO-66 framework.
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.
基金Supported by Qinglan Project Foundation of Jiangsu Province and Doctoral Dissertation Innovate Foundation of Nanjing Uni-versity of Technology (No.BSCS200508).
文摘Epoxidation of cyclohexene to cyclohexene oxide was studied in a new type reactor—the ultrasound airlift loop reactor. The influences of ultrasound intensity, molar ratio of isobutyraldehyde to cyclohexene and oxy-gen gas flow rate on the conversion of cyclohexene and selectivity of cyclohexene oxide were investigated and dis-cussed, and the optimal operation condition was found, under which 95.2% conversion of cyclohexene and 90.7% selectivity of cyclohexene oxide were achieved. The ultrasonic airlift loop reactor utilizes the synergistic effect of sonochemsitry and higher oxygen transfer rate. Possible reaction mechanisms were outlined and the reason of ul-trasound promotion of epoxidation reactionwas analyzed.
基金supported by the National Natural Science Foundation of China(21576050)the Natural Science Foundation of Jiangsu Province(BK20150604)~~
文摘Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene.The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide.The optimal formation rate(68.3μmol/g·h)and selectivity(52.3%)toward propylene oxide were achieved with an Au:Ag mass ratio of4:1.Notably,the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems.A probable reaction mechanism was proposed based on the theoretical and experimental results.
基金supported by National Basic Research Program of China (2013CB933200)Commission of Science and Technology of Shanghai Municipality (15DZ1205305)~~
文摘Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.
基金Supported by the National Natural Science Foundation of China(No.21276183)
文摘Titanium silicalite-1(TS-1) was synthesized by a hydrothermal synthesis method with different amounts of tetrapropyl ammonium hydroxide(TPAOH) as template.The as-prepared TS-1 was characterized by scanning electron microscopy,X-ray powder diffraction,Fourier-transform infrared resonance spectroscopy,ultravioletvisible diffuse reflectance spectroscopy and nitrogen physical adsorption and desorption,and studied in the propylene epoxidation with hydrogen peroxide in a fixed bed reactor.The results showed that the amount of TPAOH had a strong influence on the grain morphology,the amount of framework Ti,and the average particle sizes of TS-1.With the increase of TPAOH amount in the synthesis(the molar ratio of TPAOH/SiO_2 increasing from 0.25 to 0.45),the morphology changed gradually from ellipsoids to cubes,the particle sizes of TS-1 decreased slightly,the amount of the framework Ti increased appreciably,and the catalytic stability in the propylene epoxidation increased markedly.Moreover,all the catalysts had the same selectivity to propylene epoxide.However,when the molar ratio of TPAOH/SiO_2 was further increased to 0.55,the particles became large hexagons with the size distribution in a wide range,and the catalytic stability decreased sharply although the amount of the framework Ti increased further,which can be attributed to the long diffusion paths of the reactants in the zeolite.
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The Natural Science Foundation of China (No.20273057,20473070).
文摘Gold catalysts supported on SiO2, TiO2, TiO2-SiO2, and ZrO2-SiO2 supports were prepared by impregnating each support with a basic solution of tetrachloroauric acid. X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and X-ray photoelectron spectroscopy （XPS） techniques were used to characterize their structure and surface composition. The results indicated that the size of gold particles could be controlled to below 10 nm by this method of preparation. Washing gold catalysts with water could markedly enhance the dispersion of metallic gold particles on the surface, but it could not completely remove the chloride ions left on the surface. The catalytic performance of direct vapor-phase epoxidation of propylene using air as an oxidant over these catalysts was evaluated at atmospheric pressure. The selectivity to propylene oxide （PO） was found to vary with reaction time on the stream. At the reaction conditions of atmosphere pressure, temperature 325 ℃, feed gas ratio V（C3H6）/V（O2）= 1/2, and GHSV =6000h^-1, 17.9% PO selectivity with 0.9% propylene conversion were obtained at initial 10 min for Au/SiO2 catalyst. After reacting 60 min only 8.9% PO selectivity were detected, but the propylene conversion rises to 1.4% and the main product is transferred to acrolein （72% selectivity）. Washing Au/TiO2-SiO2 and Aa/ZrO2-SiO2 samples with magnesium citrate solution could markedly enhance the activity and PO selectivity because smaller gold particles were obtained.
基金supported by the Natural Science Foundation of China(21978325,21776312,22078364)Key research and development plan of Shandong Province(2019RKE28003,2018GGX107005)Fundamental Research Funds for the Central Universities(18CX02014A).
文摘Engineering unique electronic structure of catalyst to boost catalytic performance is of prime scientific and industrial importance.Herein,the identification of intrinsic electronic sensitivity for direct propene epoxidation was first achieved over highly stable Au/wormhole-like TS-1 catalyst.Results show that the electron transfer of Au species can be regulated by manipulating the dynamic evolutions and contents of Au valence states,thus resulting in different catalytic performance in 100 h time-on-stream.By DFT calculations,kinetic analysis and multicharacterizations,it is found that the Au^(0) species with higher electronic population can easily transfer more electrons to activate surface O_(2) compared with Au^(1+) and Au^(3+) species.Moreover,there is a positive correlation between Au^(0) content and activity.Based on this correlation,a facile strategy is further proposed to boost Au^(0) percentage,resulting in the reported highest PO formation rate without adding promoters.This work harbors tremendous guiding significance to the design of highly efficient Au/Ti-containing catalyst for propene epoxidation with H_(2) and O_(2).
基金supported by the Natural Science Foundation of China(21978325,21776312,22078364)Postgraduate Innovation Engineering(YCX2020044).
文摘The advocacy of green chemical industry has led to the development of highly efficient catalysts for direct gas-phase propene epoxidation with green,sustainable and simple essence.The S-1/TS-1@dendritic-SiO_(2) material with three-layer core–shell structure was developed and used as the support for Au catalysts,which showed simultaneously fantastic PO formation rate,PO selectivity and stability(over 100 h)for propene epoxidation with H_(2) and O_(2).It is found that silicalite-1(S-1)core and the middle thin layer of TS-1 offer great mass transfer ability,which could be responsible for the excellent stability.The designed dendritic SiO_(2) shell covers part of the acid sites on the external surface of TS-1,inhibiting the side reactions and improving the PO selectivity.Furthermore,three kinds of SiO_(2) shell morphologies(i.e.,dendritic,net,mesoporous shell)were designed,and relationship between shell morphology and catalytic performance was elucidated.The results in this paper harbour tremendous guiding significance for the design of highly efficient epoxidation catalysts.
