Direct synthesis of hydrogen peroxide(DSHP)was studied over Pd loaded on HZSM-5 nanosheets(Pd/ZN).Pd nanoparticles with average size of ca.4.3 nm were introduced into the adjacent nanosheet layers(thickness of ca.2.9 ...Direct synthesis of hydrogen peroxide(DSHP)was studied over Pd loaded on HZSM-5 nanosheets(Pd/ZN).Pd nanoparticles with average size of ca.4.3 nm were introduced into the adjacent nanosheet layers(thickness of ca.2.9 nm)by impregnation method.Pd/ZN with theoretical Si/Al molar ratio of 25 showed the highest selectivity for H2O2 among the prepared catalysts,together with highest formation rate of H2O2(38.0 mmol·(g cat)^-1·h^-1),1.9 times than that of Pd supported on conventional HZSM-5 zeolite(Pd/CZ-50).Better catalytic performance of nanosheet catalysts was attributed to the promoted Pd dispersion which promoted H2 dissociation,more BrΦnsted acid sites and stronger metal-support interaction which inhibited the dissociation of O-O bond in H2O2.The embedded structure sufficiently protected the Pd nanoparticles by space confinement which restrained the Pd leaching,leading to a better catalytic stability with 90%activity retained after 3 cycles,which was almost 3 times than that of Pd/CZ-50(30.4%activity retained).展开更多
The hydrogen peroxide oxidation reaction (HPOOR) on Au(111) electrode in alkaline solutions with pH values ranging from 10 to 13 was examined systematically. HPOOR activity increased and the slope of the i-E curve dec...The hydrogen peroxide oxidation reaction (HPOOR) on Au(111) electrode in alkaline solutions with pH values ranging from 10 to 13 was examined systematically. HPOOR activity increased and the slope of the i-E curve decreased with increasing pH. HO2- is suggested to be the main reactive intermediate for HPOOR in alkaline media. The fast kinetics for HPOOR in alkaline solution is facilitated by the electrostatic interaction between the positively charged electrode and the reactive anions (i.e., HO2- and HO-), which increases the concentration of these reactants and the thermodynamic driving force for HO2- oxidation at the reaction plane.展开更多
A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were...A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were characterized by nitrogen adsorption-desorption,low and wide-angle X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),elemental mapping and energy-dispersive X-ray(EDX)methods.It was found that the particle size,electronic interactions,morphology,and textural properties of these catalysts as well as their catalytic activity in the reaction of H_(2) with O_(2) were affected by Co addition and different calcination temperatures.Also,the results showed that while the H_(2)O_(2) selectivity depends on Pd^(2+) species,the H_(2) conversion is related to Pd0 active sites.Among these catalysts,CoPd/KIT-6 calcined at 350℃(CoPd/KIT-350 catalyst)showed the best catalytic activity with 50%of H_(2)O_(2) selectivity and 51%conversion of H_(2).展开更多
Direct synthesis of hydrogen peroxide from hydrogen and oxide(DSHP)is considered as a green pathway for H2O2 production because of the simple reaction route and 100%theoretical atom efficiency.Here,1.5 wt%Pd and 0.5 w...Direct synthesis of hydrogen peroxide from hydrogen and oxide(DSHP)is considered as a green pathway for H2O2 production because of the simple reaction route and 100%theoretical atom efficiency.Here,1.5 wt%Pd and 0.5 wt%Au were loaded on HZSM-5 nanosheets through sequential isovolumetric impregnation.TEM images and CO-TPD curves showed that Pd nanosheets were successfully synthesized between HZSM-5 nanosheets under zeolite confinement effect,and Au particles were loaded on the edge of Pd nanosheets and formed a structure that Pd nanosheets with edge decorated by Au nanoparticles(Au–Pd/ZN).The results showed that the selectivity for H2O2 could be reached around 60%in a 30 min reaction and the initial H2O2 productivity could reach 338.5 mmol gcat1 h1 on the Au–Pd/ZN catalyst.The enhanced selectivity and productivity could be related with high content of terrace sites and Au particles on the step sites of bimetallic nanosheets,in which both the terrace sites and the step sites replaced by Au particles showed higher dissociation activation energy for breaking the O–O bond than traditional step sites on Pd particles,inhibited the by-product reactions(2H2O2→2H2OþO2,2H2þO2→2H2O).展开更多
Addition of fluoroalkyl iodides to olefins in the presence of hydrogen peroxide(H_2O_(?)) in acetone,acetonitrile or ethanol gave the corresponding 1:1 adducts in good yields.Reaction of fluoroalkyl iodide with dially...Addition of fluoroalkyl iodides to olefins in the presence of hydrogen peroxide(H_2O_(?)) in acetone,acetonitrile or ethanol gave the corresponding 1:1 adducts in good yields.Reaction of fluoroalkyl iodide with diallyl ether(DAE)yielded tetrahydrofuran derivatives,p-Hydroquinone (p-HQ)can partly suppress the reaction.A radical initiation mechanism is proposed.展开更多
Anthraquinone(AQ)modified carbon materials could be endowed with significantly improved oxygen re-duction reaction(ORR)activity.However,the application of these materials in the generation of hydrogen peroxide(H2O2)ha...Anthraquinone(AQ)modified carbon materials could be endowed with significantly improved oxygen re-duction reaction(ORR)activity.However,the application of these materials in the generation of hydrogen peroxide(H2O2)has been rarely investigated.For this motivation,AQ covalently modified carbon nanotube(AQ-CNT)was pur-posely synthesized for H2O2 generation.It was found that the cumulative H2O2 concentration reached up to 187.18 mg(Lh)over AQ(40)-CNT catalyst,nearly 2.0 times higher than that over CNT,and being superior to those over most carbon materials reported.The enhanced activity stemmed from the improved mass transfer fficiency of oxygen and the enhanced electrocatalytic activity.Noteworthily,the AQ(40)-CNT material exhibited satisfactory stability for H2O2 generation,which was ascribed to the strong interaction force of C-N covalent bond.The present work could provide a vital idea for designing electrode material with simultancously improved activity and stability for H2O2 gencration.展开更多
基金Financial supports by the National Natural Science Foundation of China(21776210)Science and Technology Research Project of Henan Province(No.202102210048)。
文摘Direct synthesis of hydrogen peroxide(DSHP)was studied over Pd loaded on HZSM-5 nanosheets(Pd/ZN).Pd nanoparticles with average size of ca.4.3 nm were introduced into the adjacent nanosheet layers(thickness of ca.2.9 nm)by impregnation method.Pd/ZN with theoretical Si/Al molar ratio of 25 showed the highest selectivity for H2O2 among the prepared catalysts,together with highest formation rate of H2O2(38.0 mmol·(g cat)^-1·h^-1),1.9 times than that of Pd supported on conventional HZSM-5 zeolite(Pd/CZ-50).Better catalytic performance of nanosheet catalysts was attributed to the promoted Pd dispersion which promoted H2 dissociation,more BrΦnsted acid sites and stronger metal-support interaction which inhibited the dissociation of O-O bond in H2O2.The embedded structure sufficiently protected the Pd nanoparticles by space confinement which restrained the Pd leaching,leading to a better catalytic stability with 90%activity retained after 3 cycles,which was almost 3 times than that of Pd/CZ-50(30.4%activity retained).
基金supported by the National Natural Science Foundation of China(No.21473175 and No.21273215)the National Key Basic Research Program of China from the Ministry of Science andTechnology of China(No.2015CB932301)
文摘The hydrogen peroxide oxidation reaction (HPOOR) on Au(111) electrode in alkaline solutions with pH values ranging from 10 to 13 was examined systematically. HPOOR activity increased and the slope of the i-E curve decreased with increasing pH. HO2- is suggested to be the main reactive intermediate for HPOOR in alkaline media. The fast kinetics for HPOOR in alkaline solution is facilitated by the electrostatic interaction between the positively charged electrode and the reactive anions (i.e., HO2- and HO-), which increases the concentration of these reactants and the thermodynamic driving force for HO2- oxidation at the reaction plane.
基金the financial support(Research Council Grant)provided by Isfahan University of Technology(Iran).
文摘A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were characterized by nitrogen adsorption-desorption,low and wide-angle X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),elemental mapping and energy-dispersive X-ray(EDX)methods.It was found that the particle size,electronic interactions,morphology,and textural properties of these catalysts as well as their catalytic activity in the reaction of H_(2) with O_(2) were affected by Co addition and different calcination temperatures.Also,the results showed that while the H_(2)O_(2) selectivity depends on Pd^(2+) species,the H_(2) conversion is related to Pd0 active sites.Among these catalysts,CoPd/KIT-6 calcined at 350℃(CoPd/KIT-350 catalyst)showed the best catalytic activity with 50%of H_(2)O_(2) selectivity and 51%conversion of H_(2).
基金supports by the National Natural Science Foundation of China(21776210)are gratefully acknowledged.
文摘Direct synthesis of hydrogen peroxide from hydrogen and oxide(DSHP)is considered as a green pathway for H2O2 production because of the simple reaction route and 100%theoretical atom efficiency.Here,1.5 wt%Pd and 0.5 wt%Au were loaded on HZSM-5 nanosheets through sequential isovolumetric impregnation.TEM images and CO-TPD curves showed that Pd nanosheets were successfully synthesized between HZSM-5 nanosheets under zeolite confinement effect,and Au particles were loaded on the edge of Pd nanosheets and formed a structure that Pd nanosheets with edge decorated by Au nanoparticles(Au–Pd/ZN).The results showed that the selectivity for H2O2 could be reached around 60%in a 30 min reaction and the initial H2O2 productivity could reach 338.5 mmol gcat1 h1 on the Au–Pd/ZN catalyst.The enhanced selectivity and productivity could be related with high content of terrace sites and Au particles on the step sites of bimetallic nanosheets,in which both the terrace sites and the step sites replaced by Au particles showed higher dissociation activation energy for breaking the O–O bond than traditional step sites on Pd particles,inhibited the by-product reactions(2H2O2→2H2OþO2,2H2þO2→2H2O).
基金This project was supported by the National Natural Science Foundation of China.
文摘Addition of fluoroalkyl iodides to olefins in the presence of hydrogen peroxide(H_2O_(?)) in acetone,acetonitrile or ethanol gave the corresponding 1:1 adducts in good yields.Reaction of fluoroalkyl iodide with diallyl ether(DAE)yielded tetrahydrofuran derivatives,p-Hydroquinone (p-HQ)can partly suppress the reaction.A radical initiation mechanism is proposed.
基金Supported by the National Natural Science Foundation of China(Nos.21776188,2150613)the Project of the Science and Technology Department of Sichuan Province,China(Nos.2020YFG0158,2020YFH0162).
文摘Anthraquinone(AQ)modified carbon materials could be endowed with significantly improved oxygen re-duction reaction(ORR)activity.However,the application of these materials in the generation of hydrogen peroxide(H2O2)has been rarely investigated.For this motivation,AQ covalently modified carbon nanotube(AQ-CNT)was pur-posely synthesized for H2O2 generation.It was found that the cumulative H2O2 concentration reached up to 187.18 mg(Lh)over AQ(40)-CNT catalyst,nearly 2.0 times higher than that over CNT,and being superior to those over most carbon materials reported.The enhanced activity stemmed from the improved mass transfer fficiency of oxygen and the enhanced electrocatalytic activity.Noteworthily,the AQ(40)-CNT material exhibited satisfactory stability for H2O2 generation,which was ascribed to the strong interaction force of C-N covalent bond.The present work could provide a vital idea for designing electrode material with simultancously improved activity and stability for H2O2 gencration.