The selective oxidation of toluene and its derivatives is extremely important in the chemical industry.The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists becau...The selective oxidation of toluene and its derivatives is extremely important in the chemical industry.The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its ＂green＂ environmental characteristics.In this study,nanoscale Bi_2WO_6with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O_2 as the oxidant.The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi_2WO_6 was found to produce a significant enhancement in the catalytic activity.Mechanistic investigation showed that the superior performance of Pd/Bi_2WO_6 could be attributed to the improvement of both the reductive and oxidative abilities of Bi_2WO_6 by the loading of the cocatalyst.展开更多
The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1...The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1,3-PDO in polyester industry.Nevertheless,the formation of 1,3-PDO is thermodynamically less favorable than 1,2-PDO,which necessitates the development of efficient catalysts to manipulate the reaction kinetics towards the 1,3-PDO formation.Among others,Pt-W based catalysts have shown promising activities and selectivities of 1,3-PDO although the reaction mechanism is not well addressed at the molecular level.In this short review,we have compared the performances of different Pt-W based catalysts and discussed the key factors influencing the activity and selectivity.Three possible reaction mechanisms have been discussed in terms of the synergy between Pt and WO_x and the origin of acid sites.Finally,the long-term stability of the Pt-W catalysts has been discussed.We hope this review will provide useful information for the development of more efficient catalysts for this important reaction.展开更多
Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical appli...Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical application.In this work,we reported the successful preparation of a monolithic tungsten oxide(WO3)/graphene oxide(GO)aerogel photocatalyst through a cost‐effective freeze‐drying method.GO not only acts as a macroscopic support,but also increases the catalyst surface area from 46 to 57 m2/g,enhances the light absorption in the visible‐light region,and raises the separation efficiency of photogenerated electron‐hole pairs.The Obtained WO3/GO aerogel exhibited an outstanding visible‐light photocatalytic degradation rate of nitric oxide of 51%,which was 3.3 times that of pristine WO3 powder.In addition,the aerogel displayed excellent selectivity,with a generation fraction of toxic nitrogen dioxide of as low as 0.5%.This work presents a facile synthesis route to fabricate a monolithic WO3/GO aerogel photocatalyst with great promise for air purification.展开更多
Oxidative desulfurization was performed on Na2WO4 catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions （atmospheric pressure and temperature range of 293--343 K）. Different or...Oxidative desulfurization was performed on Na2WO4 catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions （atmospheric pressure and temperature range of 293--343 K）. Different organic compounds including benzothiophene （BT）, dibenzothiophene （DBT）, 4, 6-dimethyl dibenzothiophene （4, 6-DMDBT） were used to investigate the reactivity of this catalyst, and the effect of various parameters, such as temperature, solvents and the amount of oxidant reagent used in oxidative desulfurization reaction, was also examined. The results showed that the Na2WO4- H202 system was very effective for oxidative desulfurization, and the oxidation of BT, DBT and 4, 6-DMDBT was influenced by different parameters.展开更多
A homogeneous layer of Bi_2O_3-Bi_(14)WO_(24) composite(BWO/Bi_2O_3) thin film was fabricated using a combination of electrodeposition and thermal treatment. The evenly distributed Bi14 WO24 component within the Bi_2O...A homogeneous layer of Bi_2O_3-Bi_(14)WO_(24) composite(BWO/Bi_2O_3) thin film was fabricated using a combination of electrodeposition and thermal treatment. The evenly distributed Bi14 WO24 component within the Bi_2O_3 layer was found to be important in stabilising the photoelectrochemical performances of Bi_2O_3 photoanode by promoting the photoelectron transport. The unmodified Bi_2O_3 suffered from severe photocorrosion as proven by X-ray diffraction(XRD) and inductively coupled plasma(ICP) analyses while the composite thin film was active without noticeable activity decay for at least 3 h of illumination. This strategy might be applicable to other photocatalysts with stability issues.展开更多
A facile synthetic strategy was developed for insitu preparation of two-dimensional (2D)highly crystalline tungsten nitride (WN)nanosheets with controllable morphology as oxygen reduction reaction (ORR)catalysts.The d...A facile synthetic strategy was developed for insitu preparation of two-dimensional (2D)highly crystalline tungsten nitride (WN)nanosheets with controllable morphology as oxygen reduction reaction (ORR)catalysts.The dependence of the crystal structure and morphology of WN on K2SO4content,pH,and pyrolysis temperature was thoroughly examined.The electrocatalytic performance of WN toward ORR in an alkaline electrolyte indicated that K+plays an important role in the control of size and shape in the hydrothermal and nitridation process,thereby promoting the formation of plate-like WO3and 2D WN nanosheets.The WN nanosheets,with largely exposed edge sites,provide abundant catalytic active sites and allow fast charge transfer.Furthermore,they exhibit high stability for ORR and methanol tolerance.展开更多
Olefins and allylic alcohols have been epoxidized with commercially available hydrogen peroxide (30% H2O2) using a phase transfer catalyst,composed of cetyltrimethylammonium cations and a lacunary-type phosphotungstat...Olefins and allylic alcohols have been epoxidized with commercially available hydrogen peroxide (30% H2O2) using a phase transfer catalyst,composed of cetyltrimethylammonium cations and a lacunary-type phosphotungstate anion [PW11O39]7-or the complete Keggin-type heteropolyanion [PW12O40]3-,under two-phase conditions using ethyl acetate as the solvent. It was found that the lacunary-type catalyst showed higher activity and better recyclability than the complete Keggin-type catalyst under the same reaction conditions. 31P NMR spectroscopy and solubility measurements for the two catalysts revealed that the [PW11O39]7-anion had a much faster degradation rate than the [PW12O40]3-anion in an excess of H2O2,which resulted in the formation of more catalytically active species. As a result,the lacunary-type phosphotungstate anion-based catalyst gave a better catalytic performance than the complete Keggin-type anion in ethyl acetate.展开更多
The liquid-phase oxidation of ethylamine with hydrogen peroxide was studied over tungsten-doped zeolites to develop a clean and simple route for producing acetaldehyde oxime. The investigations were firstly performed ...The liquid-phase oxidation of ethylamine with hydrogen peroxide was studied over tungsten-doped zeolites to develop a clean and simple route for producing acetaldehyde oxime. The investigations were firstly performed over W/MOR, where the coordinated state as well as the acidity of the W species were characterized. The reaction parameters, including H_2O_2 amount, solvent,temperature, tungsten content as well as catalyst amount, governed the activity and oxime selectivity. Under optimized reaction conditions, W/MOR showed an ethylamine conversion and corresponding oxime selectivity of 18.3% and 88.9%. W/MOR showed a superior performance in comparison to other tungsten-containing zeolites of W/Beta, W/MWW and W/Y. Although W/MOR exhibited lower amine conversion than titanosilicates of TS-1 and Ti-MWW, it gave higher selectivity to the main product of oxime. Moreover, W/MOR proved to be a robust catalyst, exhibiting a stable catalytic performance after being reused at least for 5 times.展开更多
基金supported by the National Natural Science Foundation of China(21322202,21472187)the National Basic Research Program of China(2010CB833300)~~
文摘The selective oxidation of toluene and its derivatives is extremely important in the chemical industry.The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its ＂green＂ environmental characteristics.In this study,nanoscale Bi_2WO_6with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O_2 as the oxidant.The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi_2WO_6 was found to produce a significant enhancement in the catalytic activity.Mechanistic investigation showed that the superior performance of Pd/Bi_2WO_6 could be attributed to the improvement of both the reductive and oxidative abilities of Bi_2WO_6 by the loading of the cocatalyst.
文摘The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1,3-PDO in polyester industry.Nevertheless,the formation of 1,3-PDO is thermodynamically less favorable than 1,2-PDO,which necessitates the development of efficient catalysts to manipulate the reaction kinetics towards the 1,3-PDO formation.Among others,Pt-W based catalysts have shown promising activities and selectivities of 1,3-PDO although the reaction mechanism is not well addressed at the molecular level.In this short review,we have compared the performances of different Pt-W based catalysts and discussed the key factors influencing the activity and selectivity.Three possible reaction mechanisms have been discussed in terms of the synergy between Pt and WO_x and the origin of acid sites.Finally,the long-term stability of the Pt-W catalysts has been discussed.We hope this review will provide useful information for the development of more efficient catalysts for this important reaction.
文摘Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical application.In this work,we reported the successful preparation of a monolithic tungsten oxide(WO3)/graphene oxide(GO)aerogel photocatalyst through a cost‐effective freeze‐drying method.GO not only acts as a macroscopic support,but also increases the catalyst surface area from 46 to 57 m2/g,enhances the light absorption in the visible‐light region,and raises the separation efficiency of photogenerated electron‐hole pairs.The Obtained WO3/GO aerogel exhibited an outstanding visible‐light photocatalytic degradation rate of nitric oxide of 51%,which was 3.3 times that of pristine WO3 powder.In addition,the aerogel displayed excellent selectivity,with a generation fraction of toxic nitrogen dioxide of as low as 0.5%.This work presents a facile synthesis route to fabricate a monolithic WO3/GO aerogel photocatalyst with great promise for air purification.
文摘Oxidative desulfurization was performed on Na2WO4 catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions （atmospheric pressure and temperature range of 293--343 K）. Different organic compounds including benzothiophene （BT）, dibenzothiophene （DBT）, 4, 6-dimethyl dibenzothiophene （4, 6-DMDBT） were used to investigate the reactivity of this catalyst, and the effect of various parameters, such as temperature, solvents and the amount of oxidant reagent used in oxidative desulfurization reaction, was also examined. The results showed that the Na2WO4- H202 system was very effective for oxidative desulfurization, and the oxidation of BT, DBT and 4, 6-DMDBT was influenced by different parameters.
基金supported by the Australian Research Council under the Laureate Fellowship Scheme(FL140100081)
文摘A homogeneous layer of Bi_2O_3-Bi_(14)WO_(24) composite(BWO/Bi_2O_3) thin film was fabricated using a combination of electrodeposition and thermal treatment. The evenly distributed Bi14 WO24 component within the Bi_2O_3 layer was found to be important in stabilising the photoelectrochemical performances of Bi_2O_3 photoanode by promoting the photoelectron transport. The unmodified Bi_2O_3 suffered from severe photocorrosion as proven by X-ray diffraction(XRD) and inductively coupled plasma(ICP) analyses while the composite thin film was active without noticeable activity decay for at least 3 h of illumination. This strategy might be applicable to other photocatalysts with stability issues.
基金supported by the National Natural Science Foundation of China(21306119)the Key Research and Development Projects in Sichuan Province(2017GZ0397,2017CC0017)the Science and Technology Project of Chengdu(2015-HM01-00531-SF)
文摘A facile synthetic strategy was developed for insitu preparation of two-dimensional (2D)highly crystalline tungsten nitride (WN)nanosheets with controllable morphology as oxygen reduction reaction (ORR)catalysts.The dependence of the crystal structure and morphology of WN on K2SO4content,pH,and pyrolysis temperature was thoroughly examined.The electrocatalytic performance of WN toward ORR in an alkaline electrolyte indicated that K+plays an important role in the control of size and shape in the hydrothermal and nitridation process,thereby promoting the formation of plate-like WO3and 2D WN nanosheets.The WN nanosheets,with largely exposed edge sites,provide abundant catalytic active sites and allow fast charge transfer.Furthermore,they exhibit high stability for ORR and methanol tolerance.
基金supported by the National Natural Science Foundation of China (20773037, 21073058)
文摘Olefins and allylic alcohols have been epoxidized with commercially available hydrogen peroxide (30% H2O2) using a phase transfer catalyst,composed of cetyltrimethylammonium cations and a lacunary-type phosphotungstate anion [PW11O39]7-or the complete Keggin-type heteropolyanion [PW12O40]3-,under two-phase conditions using ethyl acetate as the solvent. It was found that the lacunary-type catalyst showed higher activity and better recyclability than the complete Keggin-type catalyst under the same reaction conditions. 31P NMR spectroscopy and solubility measurements for the two catalysts revealed that the [PW11O39]7-anion had a much faster degradation rate than the [PW12O40]3-anion in an excess of H2O2,which resulted in the formation of more catalytically active species. As a result,the lacunary-type phosphotungstate anion-based catalyst gave a better catalytic performance than the complete Keggin-type anion in ethyl acetate.
基金supported by the National Natural Science Foundation of China(21533002,21373089,21603075)the National Key Research and Development Program of China(2016YFA0202804)
文摘The liquid-phase oxidation of ethylamine with hydrogen peroxide was studied over tungsten-doped zeolites to develop a clean and simple route for producing acetaldehyde oxime. The investigations were firstly performed over W/MOR, where the coordinated state as well as the acidity of the W species were characterized. The reaction parameters, including H_2O_2 amount, solvent,temperature, tungsten content as well as catalyst amount, governed the activity and oxime selectivity. Under optimized reaction conditions, W/MOR showed an ethylamine conversion and corresponding oxime selectivity of 18.3% and 88.9%. W/MOR showed a superior performance in comparison to other tungsten-containing zeolites of W/Beta, W/MWW and W/Y. Although W/MOR exhibited lower amine conversion than titanosilicates of TS-1 and Ti-MWW, it gave higher selectivity to the main product of oxime. Moreover, W/MOR proved to be a robust catalyst, exhibiting a stable catalytic performance after being reused at least for 5 times.
