Developing the alternative supported noble metal catalysts with low cost,high catalytic efficiency,and good resistance toward carbon dioxide and water vapor is critically demanded for the oxidative removal of volatile...Developing the alternative supported noble metal catalysts with low cost,high catalytic efficiency,and good resistance toward carbon dioxide and water vapor is critically demanded for the oxidative removal of volatile organic compounds(VOCs).In this work,we prepared the mesoporous chromia-supported bimetallic Co and Ni single-atom(Co_(1)Ni_(1)/meso-Cr_(2)O_(3))and bimetallic Co and Ni nanoparticle(Co_(NP)Ni_(NP)/mesoCr_(2)O_(3))catalysts adopting the one-pot polyvinyl pyrrolidone(PVP)-and polyvinyl alcohol(PVA)-protecting approaches,respectively.The results indicate that the Co_(1)Ni_(1)/meso-Cr_(2)O_(3)catalyst exhibited the best catalytic activity for n-hexane(C_(6)H_(14))combustion(T_(50%)and T_(90%)were 239 and 263℃ at a space velocity of 40,000 mL g^(-1)h^(-1);apparent activation energy and specific reaction rate at 260℃ were 54.7 kJ mol^(-1)and 4.3×10^(-7)mol g^(-1)_(cat)s^(-1),respectively),which was associated with its higher(Cr^(5+)+Cr^(6+))amount,large n-hexane adsorption capacity,and good lattice oxygen mobility that could enhance the deep oxidation of n-hexane,in which Ni_(1) was beneficial for the enhancements in surface lattice oxygen mobility and low-temperature reducibility,while Co_(1) preferred to generate higher contents of the high-valence states of chromium and surface oxygen species as well as adsorption and activation of n-hexane.n-Hexane combustion takes place via the Mars van Krevelen(MvK)mechanism,and its reaction pathways are as follows:n-hexane→olefins or 3-hexyl hydroperoxide→3-hexanone,2-hexanone or 2,5-dimethyltetrahydrofuran→2-methyloxirane or 2-ethyl-oxetane→acrylic acid→CO_x→CO_(2)and H_(2)O.展开更多
Ordered mesoporous Mn2O3 (meso‐Mn2O3) and meso‐Mn2O3‐supported Pd, Pt, and Pd‐Pt alloy x(PdyPt)/meso‐Mn2O3; x = (0.10?1.50) wt%; Pd/Pt molar ratio (y) = 4.9?5.1 nanocatalysts were prepared using KIT‐6‐templated...Ordered mesoporous Mn2O3 (meso‐Mn2O3) and meso‐Mn2O3‐supported Pd, Pt, and Pd‐Pt alloy x(PdyPt)/meso‐Mn2O3; x = (0.10?1.50) wt%; Pd/Pt molar ratio (y) = 4.9?5.1 nanocatalysts were prepared using KIT‐6‐templated and poly(vinyl alcohol)‐protected reduction methods, respectively.The meso‐Mn2O3 had a high surface area, i.e., 106 m2/g, and a cubic crystal structure. Noble‐metalnanoparticles (NPs) of size 2.1?2.8 nm were uniformly dispersed on the meso‐Mn2O3 surfaces. AlloyingPd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso‐Mn2O3gave the best performance; T10%, T50%, and T90% (the temperatures required for achieving methaneconversions of 10%, 50%, and 90%) were 265, 345, and 425 °C, respectively, at a space velocity of20000 mL/(g?h). The effects of SO2, CO2, H2O, and NO on methane combustion over1.41(Pd5.1Pt)/meso‐Mn2O3 were also examined. We conclude that the good catalytic performance of1.41(Pd5.1Pt)/meso‐Mn2O3 is associated with its high‐quality porous structure, high adsorbed oxygen species concentration, good low‐temperature reducibility, and strong interactions between Pd‐Pt alloy NPs and the meso‐Mn2O3 support.展开更多
Sodium-treated sepiolite(Na Sep)-supported transition metal catalysts(TM/Na Sep;TM = Cu, Fe, Ni, Mn, and Co) were synthesized via a rotary evaporation method. Physicochemical properties of the as-synthesized samples w...Sodium-treated sepiolite(Na Sep)-supported transition metal catalysts(TM/Na Sep;TM = Cu, Fe, Ni, Mn, and Co) were synthesized via a rotary evaporation method. Physicochemical properties of the as-synthesized samples were characterized by means of various techniques, and their catalytic activities for HCHO(0.2%) oxidation were evaluated. Among the samples, Cu/Na Sep exhibited superior performance, and complete HCHO conversion was achieved at 100 ℃(GHSV = 240000 m L/(g·h)). Additionally, the sample retained good catalytic activity during a 42 h stability test. A number of factors, including elevated acidity, the abundance of oxygen species, and favorable low-temperature reducibility, were responsible for the excellent catalytic activity of Cu/Na Sep. According to the results of the in-situ DRIFTS characterization, the HCHO oxidation mechanism was as follows:(i) HCHO was rapidly decomposed into dioxymethylene(DOM) species on the Cu/Na Sep surface;(ii) DOM was then immediately converted to formate species;(iii) the resultant formate species were further oxidized to carbonates;(iv) the carbonate species were eventually converted to CO2 and H2O.展开更多
Perovskite-like oxide La2-xSrxCuO4 （x = 0, 1） single crystallites with microrod-like morphologies and tetragonal crystal structures were prepared hydrothermally at 240 ℃ with poly（ethylene glycol） （PEG） or hexa...Perovskite-like oxide La2-xSrxCuO4 （x = 0, 1） single crystallites with microrod-like morphologies and tetragonal crystal structures were prepared hydrothermally at 240 ℃ with poly（ethylene glycol） （PEG） or hexadecyltrimethyl ammonium bromide （CTAB） as a surfactant and after calcination at 850 ℃. The physicochemical properties of the materials were characterized by means of XRD, BET, SEM, TEM/SAED （selected-area electron diffraction）, XPS and H2-TPR techniques. It is found that doping Sr2＋ to La2CuO4 lattice enhanced the catalytic activity for methane combustion and the LaSrCuO4 catalyst derived from PEG is the best among the tested ones. It is concluded that factors, such as adsorbed oxygen species concentration, reducibility and surface area, determined the catalytic performance of such single-crystalline materials.展开更多
The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H...The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.展开更多
The meso-Co3O4 and AgxAuyPd/meso-Co3O4 catalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods,respectively.Various techniques were used to characterize physicochemic...The meso-Co3O4 and AgxAuyPd/meso-Co3O4 catalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods,respectively.Various techniques were used to characterize physicochemical properties of these materials.Catalytic performance of the samples was evaluated for methanol combustion.The cubically crystallized Co3O4 support displayed a three-dimensionally ordered mesoporous structure.The supported noble metal nanoparticles(NPs)possessed a surface area of 115.125 m^2/g,with the noble NPs(average size=2.8.4.5 nm)being uniformly dispersed on the surface of meso-Co3O4.Among all of the samples,0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 showed the highest catalytic activity(T50%=100℃and T90%=112℃at a space velocity of 80000 mL(g^–1 h^–1).The partial deactivation of the 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 sample due to water vapor or carbon dioxide introduction was reversible.It is concluded that the good catalytic performance of 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 was associated with its highly dispersed Ag0.75Au1.14Pd alloy NPs,high adsorbed oxygen species concentration,good low-temperature reducibility,and strong interaction between Ag0.75Au1.14Pd alloy NPs and meso-Co3O4.展开更多
The PdPtVO_(x)/CeO_(2)-ZrO_(2)(PdPtVO_(x)/CZO)catalysts were obtained by using different approaches,and their physical and chemical properties were determined by various techniques.Catalytic activities of these materi...The PdPtVO_(x)/CeO_(2)-ZrO_(2)(PdPtVO_(x)/CZO)catalysts were obtained by using different approaches,and their physical and chemical properties were determined by various techniques.Catalytic activities of these materials in the presence of H_(2)O or SO_(2)were evaluated for the oxidation of ethylbenzene(EB).The PdPtVO_(x)/CZO sample exhibited high catalytic activity,good hydrothermal stability,and reversible sulfur dioxide-poisoning performance,over which the specific reaction rate at 160℃,turnover frequency at 160℃(TOF_(Pd or Pt)),and apparent activation energy were 72.6 mmol/(g_(Pt)·sec)or 124.2 mmol/(g_(Pd)·sec),14.2 sec^(-1)(TOF_(Pt))or 13.1 sec^(-1)(TOF_(Pd)),and 58 k J/mol,respectively.The large EB adsorption capacity,good reducibility,and strong acidity contributed to the good catalytic performance of PdPtVO_(x)/CZO.Catalytic activity of PdPtVO_(x)/CZO decreased when 50 ppm SO_(2)or(1.0 vol.%H_(2)O+50 ppm SO_(2))was added to the feedstock,but was gradually restored to its initial level after the SO_(2)was cut off.The good reversible sulfur dioxide-resistant performance of PdPtVO_(x)/CZO was associated with the facts:(i)the introduction of SO_(2)leads to an increase in surface acidity;(ii)V can adsorb and activate SO_(2),thus accelerating formation of the SO_(x)^(2-)(x=3 or 4)species at the V and CZO sites,weakening the adsorption of sulfur species at the PdPt active sites,and hence protecting the PdPt active sites to be not poisoned by SO_(2).EB oxidation over PdPtVO_(x)/CZO might take place via the route of EB→styrene→phenyl methyl ketone→benzaldehyde→benzoic acid→maleic anhydride→CO_(2)and H_(2)O.展开更多
Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution problems.The key issue is the development o...Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution problems.The key issue is the development of high-efficiency photocatalysts.Various strategies in the state-of-the-art advancements,such as heterostructure construction,heteroatom doping,metal/single atom loading,and defect engineering,have been presented for the graphitic carbon nitride(g-C3N4)-based nanocomposite catalysts to design their surface chemical environments and internal electronic structures to make them more suitable for different photocatalytic applications.In this review,nanoarchitecture design,synthesis methods,photochemical properties,potential photocatalytic applications,and related reaction mechanisms of the modified high-efficiency carbon nitride-based photocatalysts were briefly summarized.The superior photocatalytic performance was identified to be associated with the enhanced visible-light response,fast photoinduced electron-hole separation,efficient charge migration,and increased unsaturated active sites.Moreover,the further advance of the visible-light harvesting and solar-to-energy conversions are proposed.展开更多
The cryptomelane-type manganese oxide (OMS-2)-supported Co (x Co/OMS-2;x=5,10,and15 wt.%) catalysts were prepared via a pre-incorporation route.The as-prepared materials were used as catalysts for catalytic oxidation ...The cryptomelane-type manganese oxide (OMS-2)-supported Co (x Co/OMS-2;x=5,10,and15 wt.%) catalysts were prepared via a pre-incorporation route.The as-prepared materials were used as catalysts for catalytic oxidation of toluene (2000 ppmV).Physical and chemical properties of the catalysts were measured using the X-ray diffraction (XRD),Fourier transform infrared spectroscopic (FT-IR),scanning electron microscopic (SEM),X-ray photoelectron spectroscopy (XPS),and hydrogen temperature-programmed reduction (H_(2)-TPR)techniques.Among all of the catalysts,10Co/OMS-2 performed the best,with the T90%,specific reaction rate at 245℃,and turnover frequency at 245℃ (TOFCo) being 245℃,1.23×10^(-3)moltoluene/(gcat·sec),and 11.58×10^(-3)sec-1for toluene oxidation at a space velocity of 60,000mL/(g·hr),respectively.The excellent catalytic performance of 10Co/OMS-2 were due to more oxygen vacancies,enhanced redox ability and oxygen mobility,and strong synergistic effect between Co species and OMS-2 support.Moreover,in the presence of poisoning gases CO_(2),SO_(2)or NH_(3),the activity of 10Co/OMS-2 decreased for the carbonate,sulfate and ammonia species covered the active sites and oxygen vacancies,respectively.After the activation treatment,the catalytic activity was partly recovered.The good low-temperature reducibility of 10Co/OMS-2 could also facilitate the redox process accompanied by the consecutive electron transfer between the adsorbed O_(2)and the cobalt or manganese ions.In the oxidation process of toluene,the benzoic and aldehydic intermediates werefirst generated,which were further oxidized to the benzoate intermediate that were eventually converted into H_(2)O and CO_(2).展开更多
Herein,a series of three-dimensionally ordered macroporous(3DOM)Bi_(4)O_(5)Br_(2)photocatalysts with different macropore sizes were successfully fabricated via a polymethyl methacrylate(PMMA)template method.The photoc...Herein,a series of three-dimensionally ordered macroporous(3DOM)Bi_(4)O_(5)Br_(2)photocatalysts with different macropore sizes were successfully fabricated via a polymethyl methacrylate(PMMA)template method.The photocatalytic activity for phenol degradation over 3DOM Bi_(4)O_(5)Br_(2)first increased and then decreased with the rise in macropore size.Specifically,3DOM Bi_(4)O_(5)Br_(2)-255(macropore diameter ca.170 nm)exhibits the best photocatalytic activity in the static system,which is about 4.5,7.3,and 11.9 times higher than those of bulk Bi_(4)O_(5)Br_(2),Bi_(2)WO_(6),and g-C_(3)N_(4),respectively.Meanwhile,high phenol conversion(75%)is also obtained over 3DOM Bi_(4)O_(5)Br_(2)-255 in the flow system under full spectrum irradiation.Furthermore,3DOM Bi_(4)O_(5)Br_(2)-255 also shows strong mineralization capacity owing to the downward shift of valance band position(0.15 V)as compared with Bi_(4)O_(5)Br_(2).Total organic carbon(TOC)removal rate over 3DOM Bi_(4)O_(5)Br_(2)-255(62%)is much higher than that of Bi_(4)O_(5)Br_(2)(17%).The enhancement in photocatalytic performance of 3DOM Bi_(4)O_(5)Br_(2)-255 is attributable to its better phenol adsorption,O_(2)activation,and charge separation and transfer abilities.This work combines the advantages of 3D structure and surface dangling bonds,providing new possibilities for designing highly efficient photocatalysts for pollutants removal.展开更多
Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous cataly...Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous catalysis is an effective pathway for the removal of these pollutants,and the critical issue is the development of novel and high-performance catalysts.In this review,we briefly summarize the preparation methods,physicochemical properties,catalytic activities,and related reaction mechanisms for the above pollutants removal of the rare earth oxides,mixed rare earth oxide,rare earth oxidesupported noble metal,and mixed rare earth oxide-supported noble metal catalysts that have been investigated by our group and other researchers.It was found that catalytic performance was associated with the factors,such as specific surface area,pore structure,particle size and dispersion,adsorbed oxygen species concentration,reducibility,reactant activation ability or interaction between metal nanoparticles and support.Furthermore,we also envision the development trend of such a topic in future work.展开更多
α-MnO2 nanotubes and their supported Au-Pd alloy nanocatalysts were prepared using hydrothermal and polyvinyl alcohol-protected reduction methods, respectively. Their catalytic activity for the oxidation of toluene/m...α-MnO2 nanotubes and their supported Au-Pd alloy nanocatalysts were prepared using hydrothermal and polyvinyl alcohol-protected reduction methods, respectively. Their catalytic activity for the oxidation of toluene/m-xylene, acetone/ethyl acetate, acetone/m-xylene and ethyl acetate/m-xylene mixtures was evaluated. It was found that the interaction between Au-Pd alloy nanoparticles and α-MnO2 nanotubes significantly improved the reactivity of lattice oxygen, and the 0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst outperformed the α-MnO2 nanotube catalyst in the oxidation of toluene, m-xylene, ethyl acetate and acetone. Over the0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst,（i） toluene oxidation was greatly inhibited in the toluene/m-xylene mixture, while m-xylene oxidation was not influenced;（ii） acetone and ethyl acetate oxidation suffered a minor impact in the acetone/ethyl acetate mixture; and（iii） m-xylene oxidation was enhanced whereas the oxidation of the oxygenated VOCs（volatile organic compounds） was suppressed in the acetone/m-xylene or ethyl acetate/m-xylene mixtures. The competitive adsorption of these typical VOCs on the catalyst surface induced an inhibitive effect on their oxidation, and increasing the temperature favored the oxidation of the VOCs. The mixed VOCs could be completely oxidized into CO2 and H2 O below 320°C at a space velocity of 40,000 m L/（g·hr）. The 0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst exhibited high catalytic stability as well as good tolerance to water vapor and CO2 in the oxidation of the VOC mixtures. Thus, the α-MnO2 nanotube-supported noble metal alloy catalysts hold promise for the efficient elimination of VOC mixtures.展开更多
Atmospheric pollutants such as nitrogen oxides(NO x),carbon monoxide,and volatile organic compounds(VOCs),chiefly emanating from industrial activities and transportation vehicles,are harmful to human health.Catalysis ...Atmospheric pollutants such as nitrogen oxides(NO x),carbon monoxide,and volatile organic compounds(VOCs),chiefly emanating from industrial activities and transportation vehicles,are harmful to human health.Catalysis is one of the most effective and economic technologies to control serious air pollution problems;however,the key issue is the availability of high-performance catalysts.Great efforts have been made to develop展开更多
Monoclinic BiVO4 with multiple morphologies and/or porous structures were fabricated using the hydrothermal strategy. The materials were characterized by means of the XRD, Raman, TGA/DSC, SEM, XPS, and UV-Vis techniqu...Monoclinic BiVO4 with multiple morphologies and/or porous structures were fabricated using the hydrothermal strategy. The materials were characterized by means of the XRD, Raman, TGA/DSC, SEM, XPS, and UV-Vis techniques. The photocatalytic activities of the BiVO4 materials were evaluated for the degradation of Methyl Orange under visible-light irradiation. It is observed that pH value and surfactant exerted a great effect on the morphology and pore structure of the BiVO4 product. Spherical BiVO4 with porous structures, flower-cluster-like BiVO4, and flower-bundle-like BiVO4 were generated hydrothermally at 100°C with poly（vinyl pyrrolidone） （PVP） and urea （pH = 2） and at 160°C with NaHCO3 （pH = 7 and 8）, respectively. The PVP-derived BiVO4 showed much higher surface areas （5.0-8.4 m2/g） and narrower bandgap energies （2.45-2.49 eV）. The best photocatalytic performance of the spherical BiVO4 material with a surface area of 8.4 m2/g was associated with its higher surface area, narrower bandgap energy, higher surface oxygen vacancy density, and unique porous architecture.展开更多
High-surface-area and well-ordered mesoporous Fe-incorporated SBA-15(xFe-SBA-15)and SBA-15-supported FeOx(yFeOx/SBA-15)with the Fe surface density between 0.09 to 1.11 Fe-atom/nm2have been prepared using the one-step ...High-surface-area and well-ordered mesoporous Fe-incorporated SBA-15(xFe-SBA-15)and SBA-15-supported FeOx(yFeOx/SBA-15)with the Fe surface density between 0.09 to 1.11 Fe-atom/nm2have been prepared using the one-step synthesis and incipient wetness impregnation methods,respectively.Physicochemical properties of these materials were characterized by means of numerous techniques,and their catalytic activities for the combustion of toluene were evaluated.It is found that the xFe-SBA-15 and yFeOx/SBA-15 samples possessed rod-or chain-like morphologies.The Fe species were of high dispersion when the Fe surface density was lower than0.76 Fe-atom/nm2in xFe-SBA-15 and 0.64 Fe-atom/nm2in yFeOx/SBA-15.At a similar Fe surface density and space velocity,the xFe-SBA-15 catalysts showed better activity than the yFeOx/SBA-15 catalysts,in which the xFe-SBA-15 catalyst with Fe surface density 0.59 Fe-atom/nm2performed the best.It is concluded that the good performance of the xFe-SBA-15 sample with Fe surface density0.59 Fe-atom/nm2was associated with its large surface area,high Fe species dispersion,and good low-temperature reducibility.展开更多
Porous S-doped bismuth vanadate with an olive-like morphology and its supported iron oxide （y wt.% FeOx/BiVO4-δS0.08, y = 0.06, 0.76, and 1.40） photocatalysts were fabricated using the dodecylamine-assisted alcohol...Porous S-doped bismuth vanadate with an olive-like morphology and its supported iron oxide （y wt.% FeOx/BiVO4-δS0.08, y = 0.06, 0.76, and 1.40） photocatalysts were fabricated using the dodecylamine-assisted alcohol-hydrothermal and incipient wetness impregnation methods, respectively. It is shown that the y wt.% FeOx/BiVO4-δS0.08 photocatalysts contained a monoclinic scheetlite BiVO4 phase with a porous olive-like morphology, a surface area of 8.8-9.2 m^2/g, and a bandgap energy of 2.38-2.42 eV. There was co-presence of surface Bi^5＋, Bi^3＋, V^5＋, V^3＋, Fe^3＋, and Fe^2＋ species in y wt.% FeOx/BiVO4-δS0.08. The 1.40 wt.% FeOx/BiVO4-δS0.08 sample performed the best for Methylene Blue degradation under visible-light illumination. The photocatalytic mechanism was also discussed. We believe that the sulfur and FeOx co-doping, higher oxygen adspecies concentration, and lower baudgap energy were responsible for the excellent visible-light-driven catalytic activity of 1.40 wt.% FeOx/BiVO4-δS0.08.展开更多
Nanorod-like Ce0.7Zr0.3O2 solid solutions were synthesized by a sodium dodecyl sulfate-assisted precipitation method. The samples were characterized by means of scanning electron microscopy, transmission electron micr...Nanorod-like Ce0.7Zr0.3O2 solid solutions were synthesized by a sodium dodecyl sulfate-assisted precipitation method. The samples were characterized by means of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and specific surface area measurement. Typical Ce0.7Zr0.3O2 nanorods were 40 nm in average diameter and 450 nm in length, with specific surface area and oxygen storage capacity of 194 m2/g and 374 μmol/g, respectively.展开更多
The Pd catalyst supported on cryptomelanetype manganese oxide octahedral molecular sieve （OMS- 2） were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate ove...The Pd catalyst supported on cryptomelanetype manganese oxide octahedral molecular sieve （OMS- 2） were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over xPd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the xPd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/ OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 ℃, and the temperature for 90% conversion was 55,285 and 200 ℃ for oxidation of CO, toluene, and ethyl acetate, respectively. The low- temperature reducibility and high oxygen mobility ofxPd/ OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.展开更多
A new method called ultrasonic-assisted membrane reaction(UAMR)was reported for the fabrication of ceria-zirconia solid solution.A series of ceria-zirconia solid solutions with different Ce/Zr molar ratios were prepar...A new method called ultrasonic-assisted membrane reaction(UAMR)was reported for the fabrication of ceria-zirconia solid solution.A series of ceria-zirconia solid solutions with different Ce/Zr molar ratios were prepared by the UAMR method and characterized by Xray diffraction(XRD),N2 adsorption,hydrogen temperature-programmed reduction(H2-TPR),scanning electron microscope(SEM),and transmission electron microscopy(TEM)techniques.The UAMR method proved to be superior,especially when the Ce/Zr molar ratio was lower than 1,in fabricating ceria-zirconia solid solutions with large BET surface area,high oxygen storage capacity(OSC),and low reduction temperature.展开更多
基金supported by the National Natural Science Committee of China-Liaoning Provincial People's Government Joint Fund(U1908204)National Natural Science Foundation of China(21876006,21976009,and 21961160743)+2 种基金Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal Institutions(IDHT20190503)Natural Science Foundation of Beijing Municipal Commission of Education(KM201710005004)Development Program for the Youth Outstanding-Notch Talent of Beijing Municipal Commission of Education(CIT&TCD201904019)。
文摘Developing the alternative supported noble metal catalysts with low cost,high catalytic efficiency,and good resistance toward carbon dioxide and water vapor is critically demanded for the oxidative removal of volatile organic compounds(VOCs).In this work,we prepared the mesoporous chromia-supported bimetallic Co and Ni single-atom(Co_(1)Ni_(1)/meso-Cr_(2)O_(3))and bimetallic Co and Ni nanoparticle(Co_(NP)Ni_(NP)/mesoCr_(2)O_(3))catalysts adopting the one-pot polyvinyl pyrrolidone(PVP)-and polyvinyl alcohol(PVA)-protecting approaches,respectively.The results indicate that the Co_(1)Ni_(1)/meso-Cr_(2)O_(3)catalyst exhibited the best catalytic activity for n-hexane(C_(6)H_(14))combustion(T_(50%)and T_(90%)were 239 and 263℃ at a space velocity of 40,000 mL g^(-1)h^(-1);apparent activation energy and specific reaction rate at 260℃ were 54.7 kJ mol^(-1)and 4.3×10^(-7)mol g^(-1)_(cat)s^(-1),respectively),which was associated with its higher(Cr^(5+)+Cr^(6+))amount,large n-hexane adsorption capacity,and good lattice oxygen mobility that could enhance the deep oxidation of n-hexane,in which Ni_(1) was beneficial for the enhancements in surface lattice oxygen mobility and low-temperature reducibility,while Co_(1) preferred to generate higher contents of the high-valence states of chromium and surface oxygen species as well as adsorption and activation of n-hexane.n-Hexane combustion takes place via the Mars van Krevelen(MvK)mechanism,and its reaction pathways are as follows:n-hexane→olefins or 3-hexyl hydroperoxide→3-hexanone,2-hexanone or 2,5-dimethyltetrahydrofuran→2-methyloxirane or 2-ethyl-oxetane→acrylic acid→CO_x→CO_(2)and H_(2)O.
基金supported by the Ph.D.Program Foundation of Ministry of Education of China(20131103110002)the NNSF of China(21377008)+2 种基金National High Technology Research and Development Program(863 Program,2015AA034603)Foundation on the Creative Research Team Con-struction Promotion Project of Beijing Municipal InstitutionsScientific Research Base Construction-Science and Technology Creation Plat-form-National Materials Research Base Construction~~
文摘Ordered mesoporous Mn2O3 (meso‐Mn2O3) and meso‐Mn2O3‐supported Pd, Pt, and Pd‐Pt alloy x(PdyPt)/meso‐Mn2O3; x = (0.10?1.50) wt%; Pd/Pt molar ratio (y) = 4.9?5.1 nanocatalysts were prepared using KIT‐6‐templated and poly(vinyl alcohol)‐protected reduction methods, respectively.The meso‐Mn2O3 had a high surface area, i.e., 106 m2/g, and a cubic crystal structure. Noble‐metalnanoparticles (NPs) of size 2.1?2.8 nm were uniformly dispersed on the meso‐Mn2O3 surfaces. AlloyingPd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso‐Mn2O3gave the best performance; T10%, T50%, and T90% (the temperatures required for achieving methaneconversions of 10%, 50%, and 90%) were 265, 345, and 425 °C, respectively, at a space velocity of20000 mL/(g?h). The effects of SO2, CO2, H2O, and NO on methane combustion over1.41(Pd5.1Pt)/meso‐Mn2O3 were also examined. We conclude that the good catalytic performance of1.41(Pd5.1Pt)/meso‐Mn2O3 is associated with its high‐quality porous structure, high adsorbed oxygen species concentration, good low‐temperature reducibility, and strong interactions between Pd‐Pt alloy NPs and the meso‐Mn2O3 support.
文摘Sodium-treated sepiolite(Na Sep)-supported transition metal catalysts(TM/Na Sep;TM = Cu, Fe, Ni, Mn, and Co) were synthesized via a rotary evaporation method. Physicochemical properties of the as-synthesized samples were characterized by means of various techniques, and their catalytic activities for HCHO(0.2%) oxidation were evaluated. Among the samples, Cu/Na Sep exhibited superior performance, and complete HCHO conversion was achieved at 100 ℃(GHSV = 240000 m L/(g·h)). Additionally, the sample retained good catalytic activity during a 42 h stability test. A number of factors, including elevated acidity, the abundance of oxygen species, and favorable low-temperature reducibility, were responsible for the excellent catalytic activity of Cu/Na Sep. According to the results of the in-situ DRIFTS characterization, the HCHO oxidation mechanism was as follows:(i) HCHO was rapidly decomposed into dioxymethylene(DOM) species on the Cu/Na Sep surface;(ii) DOM was then immediately converted to formate species;(iii) the resultant formate species were further oxidized to carbonates;(iv) the carbonate species were eventually converted to CO2 and H2O.
基金supported by the National Natural Science Foundation of China (No. 20973017 and 21077007)the Creative Research Foundation of Beijing University Technology (No. 00500054R4003)the Creative Research Team of Beijing Municipality (No. PHR201007105)
文摘Perovskite-like oxide La2-xSrxCuO4 （x = 0, 1） single crystallites with microrod-like morphologies and tetragonal crystal structures were prepared hydrothermally at 240 ℃ with poly（ethylene glycol） （PEG） or hexadecyltrimethyl ammonium bromide （CTAB） as a surfactant and after calcination at 850 ℃. The physicochemical properties of the materials were characterized by means of XRD, BET, SEM, TEM/SAED （selected-area electron diffraction）, XPS and H2-TPR techniques. It is found that doping Sr2＋ to La2CuO4 lattice enhanced the catalytic activity for methane combustion and the LaSrCuO4 catalyst derived from PEG is the best among the tested ones. It is concluded that factors, such as adsorbed oxygen species concentration, reducibility and surface area, determined the catalytic performance of such single-crystalline materials.
基金Supported by the National Natural Science Foundation of China(21277008,20777005)the Natural Science Foundation of Beijing(8082008)
文摘The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.
基金supported by the National Natural Science Foundation of China(21677004,21876006,and 21622701)the National High Technology Research and Development Program of China(863 Program,2015AA034603)~~
文摘The meso-Co3O4 and AgxAuyPd/meso-Co3O4 catalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods,respectively.Various techniques were used to characterize physicochemical properties of these materials.Catalytic performance of the samples was evaluated for methanol combustion.The cubically crystallized Co3O4 support displayed a three-dimensionally ordered mesoporous structure.The supported noble metal nanoparticles(NPs)possessed a surface area of 115.125 m^2/g,with the noble NPs(average size=2.8.4.5 nm)being uniformly dispersed on the surface of meso-Co3O4.Among all of the samples,0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 showed the highest catalytic activity(T50%=100℃and T90%=112℃at a space velocity of 80000 mL(g^–1 h^–1).The partial deactivation of the 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 sample due to water vapor or carbon dioxide introduction was reversible.It is concluded that the good catalytic performance of 0.68 wt%Ag0.75Au1.14Pd/meso-Co3O4 was associated with its highly dispersed Ag0.75Au1.14Pd alloy NPs,high adsorbed oxygen species concentration,good low-temperature reducibility,and strong interaction between Ag0.75Au1.14Pd alloy NPs and meso-Co3O4.
基金supported by the National Natural Science Foundation Committee of China-Liaoning Provincial People’s Government Joint Fund(No.U1908204)the National Natural Science Foundation of China(21976009)+2 种基金the National Key R&D Program of China(Nos.2022YFB3506200 and 2022YFB3504100)the Beijing Natural Science Foundation(J210006)the R&D Program of Beijing Municipal Education Commisson(No.KZ202210005011)。
文摘The PdPtVO_(x)/CeO_(2)-ZrO_(2)(PdPtVO_(x)/CZO)catalysts were obtained by using different approaches,and their physical and chemical properties were determined by various techniques.Catalytic activities of these materials in the presence of H_(2)O or SO_(2)were evaluated for the oxidation of ethylbenzene(EB).The PdPtVO_(x)/CZO sample exhibited high catalytic activity,good hydrothermal stability,and reversible sulfur dioxide-poisoning performance,over which the specific reaction rate at 160℃,turnover frequency at 160℃(TOF_(Pd or Pt)),and apparent activation energy were 72.6 mmol/(g_(Pt)·sec)or 124.2 mmol/(g_(Pd)·sec),14.2 sec^(-1)(TOF_(Pt))or 13.1 sec^(-1)(TOF_(Pd)),and 58 k J/mol,respectively.The large EB adsorption capacity,good reducibility,and strong acidity contributed to the good catalytic performance of PdPtVO_(x)/CZO.Catalytic activity of PdPtVO_(x)/CZO decreased when 50 ppm SO_(2)or(1.0 vol.%H_(2)O+50 ppm SO_(2))was added to the feedstock,but was gradually restored to its initial level after the SO_(2)was cut off.The good reversible sulfur dioxide-resistant performance of PdPtVO_(x)/CZO was associated with the facts:(i)the introduction of SO_(2)leads to an increase in surface acidity;(ii)V can adsorb and activate SO_(2),thus accelerating formation of the SO_(x)^(2-)(x=3 or 4)species at the V and CZO sites,weakening the adsorption of sulfur species at the PdPt active sites,and hence protecting the PdPt active sites to be not poisoned by SO_(2).EB oxidation over PdPtVO_(x)/CZO might take place via the route of EB→styrene→phenyl methyl ketone→benzaldehyde→benzoic acid→maleic anhydride→CO_(2)and H_(2)O.
基金supported by the Natural Science Foundation of Anhui Province (No. 1908085ME165)the Anhui Provincial Natural Science Key Foundation (No. 2008085UD07)the Special Funds for the Development of Local Science and Technology from the Central Government in Anhui Province (No. 803214271050)
文摘Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution problems.The key issue is the development of high-efficiency photocatalysts.Various strategies in the state-of-the-art advancements,such as heterostructure construction,heteroatom doping,metal/single atom loading,and defect engineering,have been presented for the graphitic carbon nitride(g-C3N4)-based nanocomposite catalysts to design their surface chemical environments and internal electronic structures to make them more suitable for different photocatalytic applications.In this review,nanoarchitecture design,synthesis methods,photochemical properties,potential photocatalytic applications,and related reaction mechanisms of the modified high-efficiency carbon nitride-based photocatalysts were briefly summarized.The superior photocatalytic performance was identified to be associated with the enhanced visible-light response,fast photoinduced electron-hole separation,efficient charge migration,and increased unsaturated active sites.Moreover,the further advance of the visible-light harvesting and solar-to-energy conversions are proposed.
基金supported by the National Natural Science Foundation of China (Nos. 21277008 and 20777005)National Key Research and Development Program of China (No. 2017YFC0209905)。
文摘The cryptomelane-type manganese oxide (OMS-2)-supported Co (x Co/OMS-2;x=5,10,and15 wt.%) catalysts were prepared via a pre-incorporation route.The as-prepared materials were used as catalysts for catalytic oxidation of toluene (2000 ppmV).Physical and chemical properties of the catalysts were measured using the X-ray diffraction (XRD),Fourier transform infrared spectroscopic (FT-IR),scanning electron microscopic (SEM),X-ray photoelectron spectroscopy (XPS),and hydrogen temperature-programmed reduction (H_(2)-TPR)techniques.Among all of the catalysts,10Co/OMS-2 performed the best,with the T90%,specific reaction rate at 245℃,and turnover frequency at 245℃ (TOFCo) being 245℃,1.23×10^(-3)moltoluene/(gcat·sec),and 11.58×10^(-3)sec-1for toluene oxidation at a space velocity of 60,000mL/(g·hr),respectively.The excellent catalytic performance of 10Co/OMS-2 were due to more oxygen vacancies,enhanced redox ability and oxygen mobility,and strong synergistic effect between Co species and OMS-2 support.Moreover,in the presence of poisoning gases CO_(2),SO_(2)or NH_(3),the activity of 10Co/OMS-2 decreased for the carbonate,sulfate and ammonia species covered the active sites and oxygen vacancies,respectively.After the activation treatment,the catalytic activity was partly recovered.The good low-temperature reducibility of 10Co/OMS-2 could also facilitate the redox process accompanied by the consecutive electron transfer between the adsorbed O_(2)and the cobalt or manganese ions.In the oxidation process of toluene,the benzoic and aldehydic intermediates werefirst generated,which were further oxidized to the benzoate intermediate that were eventually converted into H_(2)O and CO_(2).
基金This work was supported by the National Natural Science Foundation of China(Nos.22206102,21872077,and 21621003)the National Key Research and Development Program of China(No.2020YFA0710304)the China Postdoctoral Science Foundation(No.2021M700078).
文摘Herein,a series of three-dimensionally ordered macroporous(3DOM)Bi_(4)O_(5)Br_(2)photocatalysts with different macropore sizes were successfully fabricated via a polymethyl methacrylate(PMMA)template method.The photocatalytic activity for phenol degradation over 3DOM Bi_(4)O_(5)Br_(2)first increased and then decreased with the rise in macropore size.Specifically,3DOM Bi_(4)O_(5)Br_(2)-255(macropore diameter ca.170 nm)exhibits the best photocatalytic activity in the static system,which is about 4.5,7.3,and 11.9 times higher than those of bulk Bi_(4)O_(5)Br_(2),Bi_(2)WO_(6),and g-C_(3)N_(4),respectively.Meanwhile,high phenol conversion(75%)is also obtained over 3DOM Bi_(4)O_(5)Br_(2)-255 in the flow system under full spectrum irradiation.Furthermore,3DOM Bi_(4)O_(5)Br_(2)-255 also shows strong mineralization capacity owing to the downward shift of valance band position(0.15 V)as compared with Bi_(4)O_(5)Br_(2).Total organic carbon(TOC)removal rate over 3DOM Bi_(4)O_(5)Br_(2)-255(62%)is much higher than that of Bi_(4)O_(5)Br_(2)(17%).The enhancement in photocatalytic performance of 3DOM Bi_(4)O_(5)Br_(2)-255 is attributable to its better phenol adsorption,O_(2)activation,and charge separation and transfer abilities.This work combines the advantages of 3D structure and surface dangling bonds,providing new possibilities for designing highly efficient photocatalysts for pollutants removal.
基金Project supported by National Natural Science Foundation of China(21677004,21876006,21622701)National Natural Science Committee of China-Liaoning Provincial People’s Government Joint Fund(U1908204)Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal Institutions(IDHT20190503)。
文摘Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous catalysis is an effective pathway for the removal of these pollutants,and the critical issue is the development of novel and high-performance catalysts.In this review,we briefly summarize the preparation methods,physicochemical properties,catalytic activities,and related reaction mechanisms for the above pollutants removal of the rare earth oxides,mixed rare earth oxide,rare earth oxidesupported noble metal,and mixed rare earth oxide-supported noble metal catalysts that have been investigated by our group and other researchers.It was found that catalytic performance was associated with the factors,such as specific surface area,pore structure,particle size and dispersion,adsorbed oxygen species concentration,reducibility,reactant activation ability or interaction between metal nanoparticles and support.Furthermore,we also envision the development trend of such a topic in future work.
基金supported by the Natural Science Foundation of China(Nos.21622701,21477005,U1507108,and 21676028)National Key R&D Program of China(No.2016YFC0204800)+3 种基金Foundation for the Author of National Excellent Doctoral Dissertation of China(No.201462)Beijing Nova Program(No.Z141109001814106)Beijing Municipal Natural Science Foundation(No.2132015)Natural Science Foundation of Beijing Municipal Commission of Education(No.KM201410005008)
文摘α-MnO2 nanotubes and their supported Au-Pd alloy nanocatalysts were prepared using hydrothermal and polyvinyl alcohol-protected reduction methods, respectively. Their catalytic activity for the oxidation of toluene/m-xylene, acetone/ethyl acetate, acetone/m-xylene and ethyl acetate/m-xylene mixtures was evaluated. It was found that the interaction between Au-Pd alloy nanoparticles and α-MnO2 nanotubes significantly improved the reactivity of lattice oxygen, and the 0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst outperformed the α-MnO2 nanotube catalyst in the oxidation of toluene, m-xylene, ethyl acetate and acetone. Over the0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst,（i） toluene oxidation was greatly inhibited in the toluene/m-xylene mixture, while m-xylene oxidation was not influenced;（ii） acetone and ethyl acetate oxidation suffered a minor impact in the acetone/ethyl acetate mixture; and（iii） m-xylene oxidation was enhanced whereas the oxidation of the oxygenated VOCs（volatile organic compounds） was suppressed in the acetone/m-xylene or ethyl acetate/m-xylene mixtures. The competitive adsorption of these typical VOCs on the catalyst surface induced an inhibitive effect on their oxidation, and increasing the temperature favored the oxidation of the VOCs. The mixed VOCs could be completely oxidized into CO2 and H2 O below 320°C at a space velocity of 40,000 m L/（g·hr）. The 0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst exhibited high catalytic stability as well as good tolerance to water vapor and CO2 in the oxidation of the VOC mixtures. Thus, the α-MnO2 nanotube-supported noble metal alloy catalysts hold promise for the efficient elimination of VOC mixtures.
文摘Atmospheric pollutants such as nitrogen oxides(NO x),carbon monoxide,and volatile organic compounds(VOCs),chiefly emanating from industrial activities and transportation vehicles,are harmful to human health.Catalysis is one of the most effective and economic technologies to control serious air pollution problems;however,the key issue is the availability of high-performance catalysts.Great efforts have been made to develop
基金supported by the National Natural Science Foundation of China (No. 20973017, 21077007)the Creative Research Foundation of Beijing University of Technology (No. 00500054R4003, 005000543111501)+2 种基金the HiTech Research and Development Program (863)of China (No. 2009AA063201)the Funding Projectfor Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (No. PHR200907105, PHR201007105,PHR201107104)the Hong Kong Baptist University (FRG2/09-10/023)
文摘Monoclinic BiVO4 with multiple morphologies and/or porous structures were fabricated using the hydrothermal strategy. The materials were characterized by means of the XRD, Raman, TGA/DSC, SEM, XPS, and UV-Vis techniques. The photocatalytic activities of the BiVO4 materials were evaluated for the degradation of Methyl Orange under visible-light irradiation. It is observed that pH value and surfactant exerted a great effect on the morphology and pore structure of the BiVO4 product. Spherical BiVO4 with porous structures, flower-cluster-like BiVO4, and flower-bundle-like BiVO4 were generated hydrothermally at 100°C with poly（vinyl pyrrolidone） （PVP） and urea （pH = 2） and at 160°C with NaHCO3 （pH = 7 and 8）, respectively. The PVP-derived BiVO4 showed much higher surface areas （5.0-8.4 m2/g） and narrower bandgap energies （2.45-2.49 eV）. The best photocatalytic performance of the spherical BiVO4 material with a surface area of 8.4 m2/g was associated with its higher surface area, narrower bandgap energy, higher surface oxygen vacancy density, and unique porous architecture.
基金supported by the National Natural Science Foundation of China (21103005)the Natural Science Foundation of Beijing Municipality (2132015)the Discipline and Postgraduate Education Foundation (20111000501,005000542513551)
文摘High-surface-area and well-ordered mesoporous Fe-incorporated SBA-15(xFe-SBA-15)and SBA-15-supported FeOx(yFeOx/SBA-15)with the Fe surface density between 0.09 to 1.11 Fe-atom/nm2have been prepared using the one-step synthesis and incipient wetness impregnation methods,respectively.Physicochemical properties of these materials were characterized by means of numerous techniques,and their catalytic activities for the combustion of toluene were evaluated.It is found that the xFe-SBA-15 and yFeOx/SBA-15 samples possessed rod-or chain-like morphologies.The Fe species were of high dispersion when the Fe surface density was lower than0.76 Fe-atom/nm2in xFe-SBA-15 and 0.64 Fe-atom/nm2in yFeOx/SBA-15.At a similar Fe surface density and space velocity,the xFe-SBA-15 catalysts showed better activity than the yFeOx/SBA-15 catalysts,in which the xFe-SBA-15 catalyst with Fe surface density 0.59 Fe-atom/nm2performed the best.It is concluded that the good performance of the xFe-SBA-15 sample with Fe surface density0.59 Fe-atom/nm2was associated with its large surface area,high Fe species dispersion,and good low-temperature reducibility.
基金supported by the National Natural Science Foundation of China(No.21077007)the Natural Science Foundation of Beijing Municipality(No.2102008)+3 种基金the Discipline and Postgraduate Education Foundation(No.PXM2013 014204 07 000261,005000542513551)the Creative Research Foundation of Beijing University of Technology(No.00500054R4003,005000543111501)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality(No.PHR201007105,PHR201107104)the Hong Kong Baptist University for financial support(No.FRG2/09-10/023)
文摘Porous S-doped bismuth vanadate with an olive-like morphology and its supported iron oxide （y wt.% FeOx/BiVO4-δS0.08, y = 0.06, 0.76, and 1.40） photocatalysts were fabricated using the dodecylamine-assisted alcohol-hydrothermal and incipient wetness impregnation methods, respectively. It is shown that the y wt.% FeOx/BiVO4-δS0.08 photocatalysts contained a monoclinic scheetlite BiVO4 phase with a porous olive-like morphology, a surface area of 8.8-9.2 m^2/g, and a bandgap energy of 2.38-2.42 eV. There was co-presence of surface Bi^5＋, Bi^3＋, V^5＋, V^3＋, Fe^3＋, and Fe^2＋ species in y wt.% FeOx/BiVO4-δS0.08. The 1.40 wt.% FeOx/BiVO4-δS0.08 sample performed the best for Methylene Blue degradation under visible-light illumination. The photocatalytic mechanism was also discussed. We believe that the sulfur and FeOx co-doping, higher oxygen adspecies concentration, and lower baudgap energy were responsible for the excellent visible-light-driven catalytic activity of 1.40 wt.% FeOx/BiVO4-δS0.08.
文摘Nanorod-like Ce0.7Zr0.3O2 solid solutions were synthesized by a sodium dodecyl sulfate-assisted precipitation method. The samples were characterized by means of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and specific surface area measurement. Typical Ce0.7Zr0.3O2 nanorods were 40 nm in average diameter and 450 nm in length, with specific surface area and oxygen storage capacity of 194 m2/g and 374 μmol/g, respectively.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 21277008 and 20777005） and Natural Science Foundation of Beijing （Grant No. 8082008）.
文摘The Pd catalyst supported on cryptomelanetype manganese oxide octahedral molecular sieve （OMS- 2） were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over xPd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the xPd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/ OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 ℃, and the temperature for 90% conversion was 55,285 and 200 ℃ for oxidation of CO, toluene, and ethyl acetate, respectively. The low- temperature reducibility and high oxygen mobility ofxPd/ OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.
基金the National High-Tech Research and Development Program of China(Grant No.2006AA06Z347)the National Natural Science Foundation of China(Grant Nos.20877006 and 20833011).
文摘A new method called ultrasonic-assisted membrane reaction(UAMR)was reported for the fabrication of ceria-zirconia solid solution.A series of ceria-zirconia solid solutions with different Ce/Zr molar ratios were prepared by the UAMR method and characterized by Xray diffraction(XRD),N2 adsorption,hydrogen temperature-programmed reduction(H2-TPR),scanning electron microscope(SEM),and transmission electron microscopy(TEM)techniques.The UAMR method proved to be superior,especially when the Ce/Zr molar ratio was lower than 1,in fabricating ceria-zirconia solid solutions with large BET surface area,high oxygen storage capacity(OSC),and low reduction temperature.
