By introduction of hydrogen peroxide into the reaction system of ZrOCl_(2)·8H_(2)O and K14[As_(2)W_(19)O_(67)(H_(2)O)],a novel polyoxometalate K_(8)Na_(19.5)H_(0.5)[Zr_(2)(O_(2))_(2)(β-AsVW_(10)O_(38))]4·68...By introduction of hydrogen peroxide into the reaction system of ZrOCl_(2)·8H_(2)O and K14[As_(2)W_(19)O_(67)(H_(2)O)],a novel polyoxometalate K_(8)Na_(19.5)H_(0.5)[Zr_(2)(O_(2))_(2)(β-AsVW_(10)O_(38))]4·68H_(2)O(1)has been successfully obtained via one-pot method and systematically characterized by IR,XPS,solid UV spectra,PXRD pattern,and TGA analysis.The analysis of X-ray crystallography exhibits that compound 1 crystallizes in the triclinic space group P-1 and presents a novel square-shaped Zr-substituted tetrameric polyoxometalate.The catalytic oxidation of sulfides by 1 are carried out,which demonstrate that 1 exhibits a good performance for the catalytic oxidation of sulfides to sulfones with high conversion(100%)and high selectivity(100%).展开更多
A novel tetra-europium(III)-containing antimonotungstate,Na_(8.2)[H_(2)N(CH_(3))_(2)]_(9)[Na_(10.8)(tar)_(4)(H_(2)O)_(20)(Eu_(2)Sb_(2)W_(21)O_(72))_(2)]·44.5H_(2)O(EuSbW,H_(4)tar=dl-tartaric acid),has been synthe...A novel tetra-europium(III)-containing antimonotungstate,Na_(8.2)[H_(2)N(CH_(3))_(2)]_(9)[Na_(10.8)(tar)_(4)(H_(2)O)_(20)(Eu_(2)Sb_(2)W_(21)O_(72))_(2)]·44.5H_(2)O(EuSbW,H_(4)tar=dl-tartaric acid),has been synthesized and characterized.The dimeric polyoxoanion of EuSbW consists of two Dawson-like{Eu_(2)Sb_(2)W_(21)}units bridged by four dl-tartaric acid ligands.The adjacent carboxyl and hydroxy groups in each tartaric acid simultaneously chelate with W and Eu atoms from different{Eu_(2)Sb_(2)W_(21)}units,thereby forming the dimeric structure.EuSbW represents an extremely rare polyoxometalate where four tartaric acid ligands function as connectors to bridge two{Eu_(2)Sb_(2)W_(21)}units.Additionally,EuSbW exhibits excellent catalytic activity and reusability in the oxidation of thioethers and alcohols,achieving 100%conversion and>99%selectivity for various thioethers,and 85–100%conversion with 90–99%selectivity for diverse alcohols under mild conditions.展开更多
Although the powder Fenton-like catalysts have exhibited high catalytic performances towards pollutant degradation,they cannot be directly used for Fenton-like industrialization considering the problems of loss and re...Although the powder Fenton-like catalysts have exhibited high catalytic performances towards pollutant degradation,they cannot be directly used for Fenton-like industrialization considering the problems of loss and recovery.Therefore,the membrane fixation of catalyst is an important step to realize the actual application of Fenton-like catalysts.In this work,an efficient catalyst was developed with Co-N_(x)configuration facilely reconstructed on the surface of Co_(3)O_(4)(Co-N_(x)/Co_(3)O_(4)),which exhibited superior catalytic activity.We further fixed the highly efficient Co-N_(x)/Co_(3)O_(4)onto three kinds of organic membranes and one kind of inorganic ceramic membrane installing with the residual PMS treatment device to investigate its catalytic stability and sustainability.Results indicated that the inorganic ceramic membrane(CM)can achieve high water flux of 710 L m-2h-1,and the similar water flux can be achieved by Co-N_(x)/Co_(3)O_(4)/CM even without the pressure extraction.We also employed the Co-N_(x)/Co_(3)O_(4)/CM system to the wastewater secondary effluent,and the pollutant in complicated secondary effluent could be highly removed by the Co-N_(x)/Co_(3)O_(4)/CM system.This paper provides a new point of view for the application of metal-based catalysts with M-N_(x)coordination in catalytic reaction device.展开更多
Herein,we fabricate an embedding structure at the interface between Pt nanoparticles(NPs)and CeO_(2)-{100}nanocubes with surface defect sites(CeO_(2)-SDS)through quenching and gas bubbling-assisted membrane reduction ...Herein,we fabricate an embedding structure at the interface between Pt nanoparticles(NPs)and CeO_(2)-{100}nanocubes with surface defect sites(CeO_(2)-SDS)through quenching and gas bubbling-assisted membrane reduction methods.The in-situ substitution of Pt NPs for atomic-layer Ce lattice significantly increases the amount of reactive oxygen species from 133.68μmol/g to 199.44μmol/g.As a result,the distinctive geometric structure of Pt/CeO_(2)-SDS catalyst substantially improves the catalytic activity and stability for soot oxidation compared with the catalyst with no quenching process,i.e.,its T_(50)and TOF values are 332°C and 2.915 h^(-1),respectively.Combined with the results of experimental investigations and density functional theory calculations,it is unveiled that the unique embedding structure of Pt/CeO_(2)-SDS catalyst can facilitate significantly electron transfer from Pt to the CeO_(2)-{100}support,and induce the formation of interfacial[Ce-O_(x)-Pt_(2)]bond chains,which plays a crucial role in enhancing the key step of soot oxidation through the dual activation of surface lattice oxygen and molecular O_(2).Such a fundamental revelation of the interfacial electronic transmission and corresponding modification strategy contributes a novel opportunity to develop high-efficient and stable noble metal catalysts at the atomic level.展开更多
Wet flue gas desulfurization(WFGD)could effectively reduce sulfur dioxide emission.However,magnesium sulfite(MgSO_(3)),a by-product of desulfurization,was easy to result in secondary pollution.In this study,the solid ...Wet flue gas desulfurization(WFGD)could effectively reduce sulfur dioxide emission.However,magnesium sulfite(MgSO_(3)),a by-product of desulfurization,was easy to result in secondary pollution.In this study,the solid catalyst Co-Bent(bentonite supported cobalt)was prepared by blending method for MgSO_(3) oxidation with bentonite as the carrier and cobalt as the active component.At the calcination temperature of 550℃ and the Co loading level of 3 wt.%,the catalyst showed excellent catalytic performance for the oxidation of high concentration MgSO_(3) slurry,and the oxidation rate of MgSO_(3) was 0.13 mol/(L·h).The research indicated that the active component was uniformly distributed within porous structure of the catalyst as Co_(3)O_(4),which facilitated the oxidation of SO_(3)^(2-) catalyzed by Co_(3)O_(4).Kinetic researches indicated the oxidation rate of MgSO_(3) was influenced by the catalyst dosage,the reaction temperature,the solution pH,the airflow rate,and the SO_(3)^(2-) concentration.Additionally,after recycling experiments,the regenerated catalyst retained its high catalytic performance for the MgSO_(3) oxidation.The reaction mechanism for the catalytic oxidation of MgSO_(3) by Co-Bent catalyst was also proposed.The generation of active free radicals(OH·,SO_(4)^(-)·,SO_(3)^(-)·,SO_(5)^(-)·)accelerated the MgSO_(3) oxidation.These results provide theoretical support for the treatment of MgSO_(3) and the development of durable catalyst.展开更多
Concurrent activation of lattice oxygen(O_L)and molecular oxygen(O_(2))is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides.Herein,we report that the introduction of ultralow...Concurrent activation of lattice oxygen(O_L)and molecular oxygen(O_(2))is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides.Herein,we report that the introduction of ultralow-loading of Ru single atoms(0.42 wt%)into Mn_(2)O_(3)matrix(0.4%Ru-Mn_(2)O_(3))greatly boosts its catalytic activity for the aerobic oxidation of 5-hydroxymethylfurfural(HMF)to 2,5-furandicarboxylic acid(FDCA).The FDCA productivity over the 0.4%Ru-Mn_(2)O_(3)(5.4 mmol_(FDCA)g_(cat)h^(-1))is 4.9 times higher than the Mn_(2)O_(3).Especially,this FDCAproductivity is also significantly higher than that of existing Ru and Mn-based catalysts.Experimental and theoretical investigations discovered that the Ru single atom facilitated the formation of oxygen vacancy(O_(v))in the catalyst,which synergistically weakened the Mn-O bond and promoted the activation of O_L.The co-presence of Ru single atoms and O_(v)also promote the adsorption and activation of both O_(2)and HMF.Consequently,the dehydrogenation reaction energy barrier of the rate-determining step was reduced via both the O_L and chemisorbed O_(2)dehydrogenation pathways,thus boosting the catalytic oxidation reactions.展开更多
Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the under...Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the underpinning mechanism remains elusive.Herein,the introduction of silanol nests enables the alloy formation on the SiO_(2)surface.The amination modification is disclosed to induce the electron transfer from RE to Pt and weaken the adsorption of CO on electron-rich Pt species.In situ/operando spectroscopic analyses in conjunction with density functional theory calculations demonstrate the electronic couple of Pt atoms and adjacent Ce atoms concurrently achieves the enhancement of CO oxidation and suppression of H_(2)oxidation.Additionally,CO_(2)is readily desorbed from the Pt_(5)Ce(111)surface to enhance intrinsic activity and longevity.These findings provide an atomic-level insight into the synergistic catalytic sites on regulating the electronic state of the Pt-RE alloy catalysts toward highly selective oxidation reactions.展开更多
Creating a new low-temperature catalyst in decreasing the emission of volatile organic compounds(VOCs)has great significance under different industrial production situations.In particular,the Zr-UiO-66 is optimized by...Creating a new low-temperature catalyst in decreasing the emission of volatile organic compounds(VOCs)has great significance under different industrial production situations.In particular,the Zr-UiO-66 is optimized by different amounts of cerium,which not only enhances the physicochemical stability but also increases the number of active sites of Ce_(x)Zr_(y)UiO-66.Furthermore,the catalysts with Co_(3)O_(4)nanoparticles supported on Ce_(x)Zr_(y)UiO-66 were successfully prepared via impregnation method.In the process of toluene degradation,the Co/Ce_(1)Zr_(2)-Ui0-66 attains a 90%conversion rate at 210℃with a space velocity of 60000 mL/(g·h)and toluene concentration at 1000×10^(-6).Meanwhile,the carbon dioxide selectivity reaches 100%at 218℃.The Co/Ce_(1)Zr_(2)-UiO-66 shows great water resistance(3 vol%H_(2)O).Multiple characterization methods were used to figure out the physicochemical properties of the catalysts.It is found that the addition of an appropriate amount of cerium can enhance stability of UiO-66 and surface lattice oxygen proportion.Additionally,the stronger electron transfer between Ce^(4+)and Co^(2+)enables the Co/Ce_(1)Zr_(2)-UiO-66 to possess more active surface oxygen species and Co_(3)+cationic species in all samples.展开更多
Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is...Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.展开更多
Formaldehyde（HCHO）is carcinogenic and teratogenic,and is therefore a serious danger to human health.It also adversely affects air quality.Catalytic oxidation is an efficient technique for removing HCHO.The developme...Formaldehyde（HCHO）is carcinogenic and teratogenic,and is therefore a serious danger to human health.It also adversely affects air quality.Catalytic oxidation is an efficient technique for removing HCHO.The development of highly efficient and stable catalysts that can completely convert HCHO at low temperatures,even room temperature,is important.Supported Pt and Pd catalysts can completely convert HCHO at room temperature,but their industrial applications are limited because they are expensive.The catalytic activities in HCHO oxidation of transition-metal oxide catalysts such as manganese and cobalt oxides with unusual morphologies are better than those of traditional MnO2,Co3O4,or other metal oxides.This is attributed to their specific structures,high specific surface areas,and other factors such as active phase,reducibility,and amount of surface active oxygens.Such catalysts with various morphologies have great potential and can also be used as catalyst supports.The loading of relatively cheap Ag or Au on transition-metal oxides with special morphologies potentially improves the catalytic activity in HCHO removal at room temperature.The preparation and development of new nanocatalysts with various morphologies and structures is important for HCHO removal.In this paper,research progress on precious-metal and transition-metal oxide catalyst systems for HCHO oxidation is reviewed; topics such as oxidation properties,structure–activity relationships,and factors influencing the catalytic activity and reaction mechanism are discussed.Future prospects and directions for the development of such catalysts are also covered.展开更多
Three-dimensional（3D）ordered mesoporous MnO2 was prepared using KIT-6 mesoporous molecular sieves as a hard template.The material was used for catalytic oxidation of HCHO.The material has high surface areas and the ...Three-dimensional（3D）ordered mesoporous MnO2 was prepared using KIT-6 mesoporous molecular sieves as a hard template.The material was used for catalytic oxidation of HCHO.The material has high surface areas and the mesoporous characteristics of the template,with cubic symmetry（ia3d）.It consists of a β-MnO2 crystalline phase corresponding to pyrolusite,with a rutile structure.Transmission electron microscopy and X-ray photoelectron spectroscopy showed that the 3D-MnO2 catalyst has a large number of exposed Mn4＋ ions on the（110）crystal plane surfaces,with a lattice spacing of 0.311 nm; this enhances oxidation of HCHO.Complete conversion of HCHO to CO2 and H2O was achieved at 130 °C on 3D-MnO2; the same conversions on α-MnO2 and β-MnO2 nanorods were obtained at 140 and 180 °C,respectively,under the same conditions.The specific mesoporous structure,high specific surface area,and large number of surface Mn4＋ ions are responsible for the catalytic activity of 3D-MnO2 in HCHO oxidation.展开更多
KIT‐6 mesoporous silica aged at 40,100,and 150°C were used as hard templates to prepare different mesoporous MnO2 catalysts,marked as Mn‐40,Mn‐100,and Mn‐150,respectively.The catalytic activities of these cat...KIT‐6 mesoporous silica aged at 40,100,and 150°C were used as hard templates to prepare different mesoporous MnO2 catalysts,marked as Mn‐40,Mn‐100,and Mn‐150,respectively.The catalytic activities of these catalysts and the effect of pore sizes on ethanol catalytic oxidation were investigated.Mn‐40,Mn‐100,and Mn‐150 have triple,double,and single pore systems,respectively.On decreasing the aging temperature of KIT‐6,the pore sizes of KIT‐6 decrease and that of mesoporous MnO2 catalysts increase.The pore sizes and catalytic activities increase in the order:Mn‐40>Mn‐100>Mn‐150.Mn‐40 catalyst has a higher TOF(0.11 s–1 at 120°C)and the best catalytic activity for ethanol oxidation because of a bigger pore size with three pore systems with maximum distribution at 1.9,3.4,and 6.6 nm,decrease in symmetry and degree of order,more surface lattice oxygen species,oxygen vacancies resulting from more Mn3+ions,and better low‐temperature reducibility.展开更多
The MoOx/AuNPs composite film modified glassy carbon electrode was fabricated by electro-depositing simultaneously gold nanoparticles and molybdenum oxides using cyclic voltammetry. The morphology and topography of th...The MoOx/AuNPs composite film modified glassy carbon electrode was fabricated by electro-depositing simultaneously gold nanoparticles and molybdenum oxides using cyclic voltammetry. The morphology and topography of the MoOx/AuNPs composite were char-acterized by scan electron microscopy and X-ray photoelectron spectroscopy respectively, and the electrocatalytic oxidation of glucose at the MoOx/AuNPs composite film was inves-tigated and analyzed in detail. It was shown that the MoOx/AuNPs composite was of strong electrocatalytic activity towards oxidation of glucose as well as other saccharides, so that an attempt was made for direct voltammetric determination of glucose. Then the positive scan polarization reverse catalytic voltammetry was proposed for the first time. Based on this method, the pure oxidation current was extracted by subtraction of the blank current in the reverse scan. The current sensitivity was enhanced tremendously and the signal to noise ra-tio was improved adequately. The electrocatalytic oxidation of glucose at the MoOx/AuNPs modified electrode was performed in alkaline medium, a wide linear range from 0.01 mmol/L to 4.0 mmol/L of glucose, a higher current sensitivity of 2.35 mA/（mmol/L·cm2）, and a lower limit of detection of 9.01 μmol/L （at signal/noise=3） were achieved. In addition, the electrocatalytic oxidation of other saccharides such as lactose, fructose and sucrose was also evaluated.展开更多
This study focuses on drawing a hydrothermal synthesis process map for Co3O4 nanoparticles with various morphologies and investigating the effects of Co3O4 nanocatalyst morphology on CO oxidation.A series of cobalt-hy...This study focuses on drawing a hydrothermal synthesis process map for Co3O4 nanoparticles with various morphologies and investigating the effects of Co3O4 nanocatalyst morphology on CO oxidation.A series of cobalt-hydroxide-carbonate nanoparticles with various morphologies（i.e.,nanorods,nanosheets,and nanocubes） were successfully synthesized,and Co3O4 nanoparticles were obtained by thermal decomposition of the cobalt-hydroxide-carbonate precursors.The results suggest that the cobalt source is a key factor for controlling the morphology of cobalt-hydroxide-carbonate at relatively low hydrothermal temperatures（≤ 140℃）.Nanorods can be synthesized in CoCl2 solution,while Co（NO3）2 solution promotes the formation of nanosheets.Further increasing the synthesis temperature（higher than 140 ℃） results in the formation of nanocubes in either Co（NO3）2 or CoCl2 solution.The reaction time only affects the size of the obtained nanoparticles.The presence of CTAB could improve the uniformity and dispersion of particles.Co3O4 nanosheets showed much higher catalytic activity for CO oxidation than nanorods and nanocubes because it has more abundant Co^（3＋） on the surface,much higher reducibility,and better oxygen desorption capacity.展开更多
The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were...The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were characterized by means of the powder X-ray diffraction and N2 adsorption-desorption, the inductively coupled plasma atomic emission spectrometry, the temperature programmed reduction, diffuse reflectance UV-Vis spectra, and the X-ray photoelectron spectroscopy. It was found that after doping little amount of Ce in copper manganese oxide, CeO2 phase was highly dispersed and could prevent sintering and aggregating of the catalyst, the size of the catalytic material was decreased, the reducibility was enhanced, the specific surface area was increased and the formation of the active sites for the oxidation of CO was improved significantly. Therefore, the activity of the rare earth promoted catalyst was enhanced remarkably.展开更多
A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microsc...A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）.The Pd micro-nanoparticles were prepared on a COOH-CNTs/PI membrane as a comparative sample.The XRD and SEM investigations for Pd electrodeposition demonstrate that the particle size of Gr/PI composite membrane is smaller than that of COOH-CNTs/PI membrane,while the uniform and dense distribution of Pd micro-nanoparticles on the Gr/PI composite membrane is greater than that on the COOH-CNTs/PI membrane.The electrocatalytic properties of Pd/Gr/PI and Pd/COOH-CNTs/PI catalysts for the oxidation of formic acid were investigated by cyclic voltammetry（CV） and chronoamperometry（CA）.It is found that the electrocatalytic activity and stability of Pd/Gr/PI are superior to those of Pd/COOH-CNTs/PI catalyst.This is because smaller metal particles and higher dense distribution desirably provide abundant catalytic sites and mean higher catalytic activity.Therefore,the Pd/Gr/PI catalyst has better catalytic performance for formic acid oxidation than the Pd/COOH-CNTs/PI catalyst.展开更多
Hierarchical layer-stacking Mn-Ce composite oxide with mesoporous structure was firstly prepared by a simple precipitation/decomposition procedure with oxalate precursor and the complete catalytic oxidation of VOCs（b...Hierarchical layer-stacking Mn-Ce composite oxide with mesoporous structure was firstly prepared by a simple precipitation/decomposition procedure with oxalate precursor and the complete catalytic oxidation of VOCs（benzene, toluene and ethyl acetate） were examined. The Mn-Ce oxalate precursor was obtained from metal salt and oxalic acid without any additives. The resulting materials were characterized by X-ray diffraction（XRD）, Brunauer-Emmett-Teller（BET）, scanning electron microscopy（SEM）, energy dispersive X-ray spectroscopy（EDX）, hydrogen temperature programmed reduction（H2-TPR） and X-ray photoelectron spectroscopy（XPS）. Compared with Mn-Ce composite oxide synthesized through a traditional method（Na2CO3 route）, the hierarchical layer-stacking Mn-Ce composite oxide exhibited higher catalytic activity in the complete oxidation of volatile organic compounds（VOCs）. By means of testing, the data revealed that the hierarchical layer-stacking Mn-Ce composite oxide possessed superior physiochemical properties such as good low-temperature reducibility, high manganese oxidation state and rich adsorbed surface oxygen species which resulted in the enhancement of catalytic abilities.展开更多
A series of manganese-cerium oxide catalysts were prepared by different methods and used for low-temperature catalytic oxidation of NO in the presence of excess O2.Their surface properties were evaluated by means of B...A series of manganese-cerium oxide catalysts were prepared by different methods and used for low-temperature catalytic oxidation of NO in the presence of excess O2.Their surface properties were evaluated by means of BET and were characterized by using scanning electron microscopy(SEM) and X-ray diffractometer(XRD).The activity test of Mn-Ce-Ox catalysts showed that addition of Ce enhanced the activities of NO oxidation.The most active catalysts with a molar Ce/(Mn+Ce) ratio of 0.3 were prepared by co-precip...展开更多
MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite str...MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.展开更多
The effect of pretreatment on Pd/Al2O3 catalysts for the catalytic oxidation of o-xylene at low temperature was studied by changing the pretreatment and testing conditions. The fresh and pretreated Pd/Al2O3 catalysts ...The effect of pretreatment on Pd/Al2O3 catalysts for the catalytic oxidation of o-xylene at low temperature was studied by changing the pretreatment and testing conditions. The fresh and pretreated Pd/Al2O3 catalysts were characterized by transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）. The results showed that the pretreatment dramatically changed the Pd/PdO ratio and then significantly affected the Pd/Al2O3 activity; while the pretreatment had not much influence on Pd particle size. The Pd/Al2O3 pre-reduced at 300~C/400~C, which has fully reduced Pd species, showed the highest activity; while the fresh Pd/Al2O3, which has fully oxidized Pd species, presented the worst performance, indicating the Pd chemical state plays an important role in the catalytic activity for the o-xylene oxidation. It is concluded that metallic Pd is the active species on the Pd/Al2O3 catalyst for the catalytic oxidation of o-xylene at low temperature.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22071043).
文摘By introduction of hydrogen peroxide into the reaction system of ZrOCl_(2)·8H_(2)O and K14[As_(2)W_(19)O_(67)(H_(2)O)],a novel polyoxometalate K_(8)Na_(19.5)H_(0.5)[Zr_(2)(O_(2))_(2)(β-AsVW_(10)O_(38))]4·68H_(2)O(1)has been successfully obtained via one-pot method and systematically characterized by IR,XPS,solid UV spectra,PXRD pattern,and TGA analysis.The analysis of X-ray crystallography exhibits that compound 1 crystallizes in the triclinic space group P-1 and presents a novel square-shaped Zr-substituted tetrameric polyoxometalate.The catalytic oxidation of sulfides by 1 are carried out,which demonstrate that 1 exhibits a good performance for the catalytic oxidation of sulfides to sulfones with high conversion(100%)and high selectivity(100%).
基金supported by the Natural Science Foundation of Jiangxi Province(20232ACB213005).
文摘A novel tetra-europium(III)-containing antimonotungstate,Na_(8.2)[H_(2)N(CH_(3))_(2)]_(9)[Na_(10.8)(tar)_(4)(H_(2)O)_(20)(Eu_(2)Sb_(2)W_(21)O_(72))_(2)]·44.5H_(2)O(EuSbW,H_(4)tar=dl-tartaric acid),has been synthesized and characterized.The dimeric polyoxoanion of EuSbW consists of two Dawson-like{Eu_(2)Sb_(2)W_(21)}units bridged by four dl-tartaric acid ligands.The adjacent carboxyl and hydroxy groups in each tartaric acid simultaneously chelate with W and Eu atoms from different{Eu_(2)Sb_(2)W_(21)}units,thereby forming the dimeric structure.EuSbW represents an extremely rare polyoxometalate where four tartaric acid ligands function as connectors to bridge two{Eu_(2)Sb_(2)W_(21)}units.Additionally,EuSbW exhibits excellent catalytic activity and reusability in the oxidation of thioethers and alcohols,achieving 100%conversion and>99%selectivity for various thioethers,and 85–100%conversion with 90–99%selectivity for diverse alcohols under mild conditions.
基金supported by National Natural Science Fundation of China(Nos.52170086,22308194,U22A20423)Natural Science Foundation of Shandong Province(No.ZR2021ME013)+1 种基金Taishan Scholars Program of Shandong Province(No.tsqn202211012)Shandong Provincial Excellent Youth(No.ZR2022YQ47)。
文摘Although the powder Fenton-like catalysts have exhibited high catalytic performances towards pollutant degradation,they cannot be directly used for Fenton-like industrialization considering the problems of loss and recovery.Therefore,the membrane fixation of catalyst is an important step to realize the actual application of Fenton-like catalysts.In this work,an efficient catalyst was developed with Co-N_(x)configuration facilely reconstructed on the surface of Co_(3)O_(4)(Co-N_(x)/Co_(3)O_(4)),which exhibited superior catalytic activity.We further fixed the highly efficient Co-N_(x)/Co_(3)O_(4)onto three kinds of organic membranes and one kind of inorganic ceramic membrane installing with the residual PMS treatment device to investigate its catalytic stability and sustainability.Results indicated that the inorganic ceramic membrane(CM)can achieve high water flux of 710 L m-2h-1,and the similar water flux can be achieved by Co-N_(x)/Co_(3)O_(4)/CM even without the pressure extraction.We also employed the Co-N_(x)/Co_(3)O_(4)/CM system to the wastewater secondary effluent,and the pollutant in complicated secondary effluent could be highly removed by the Co-N_(x)/Co_(3)O_(4)/CM system.This paper provides a new point of view for the application of metal-based catalysts with M-N_(x)coordination in catalytic reaction device.
基金supported by the Beijing Nova Program(No.20220484215)National Key Research and Development Program of China(Nos.2022YFB3504100,2022YFB3506200,2021YFA1500300 and 2022YFA1500146)National Natural Science Foundation of China(Nos.22376217,22208373,22272090 and 22272106)。
文摘Herein,we fabricate an embedding structure at the interface between Pt nanoparticles(NPs)and CeO_(2)-{100}nanocubes with surface defect sites(CeO_(2)-SDS)through quenching and gas bubbling-assisted membrane reduction methods.The in-situ substitution of Pt NPs for atomic-layer Ce lattice significantly increases the amount of reactive oxygen species from 133.68μmol/g to 199.44μmol/g.As a result,the distinctive geometric structure of Pt/CeO_(2)-SDS catalyst substantially improves the catalytic activity and stability for soot oxidation compared with the catalyst with no quenching process,i.e.,its T_(50)and TOF values are 332°C and 2.915 h^(-1),respectively.Combined with the results of experimental investigations and density functional theory calculations,it is unveiled that the unique embedding structure of Pt/CeO_(2)-SDS catalyst can facilitate significantly electron transfer from Pt to the CeO_(2)-{100}support,and induce the formation of interfacial[Ce-O_(x)-Pt_(2)]bond chains,which plays a crucial role in enhancing the key step of soot oxidation through the dual activation of surface lattice oxygen and molecular O_(2).Such a fundamental revelation of the interfacial electronic transmission and corresponding modification strategy contributes a novel opportunity to develop high-efficient and stable noble metal catalysts at the atomic level.
基金supported by the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology (No. 2022TS10)the Taishan Industrial Experts Programthe Natural Science Foundation of Shandong Province of China (No. ZR2023ME212).
文摘Wet flue gas desulfurization(WFGD)could effectively reduce sulfur dioxide emission.However,magnesium sulfite(MgSO_(3)),a by-product of desulfurization,was easy to result in secondary pollution.In this study,the solid catalyst Co-Bent(bentonite supported cobalt)was prepared by blending method for MgSO_(3) oxidation with bentonite as the carrier and cobalt as the active component.At the calcination temperature of 550℃ and the Co loading level of 3 wt.%,the catalyst showed excellent catalytic performance for the oxidation of high concentration MgSO_(3) slurry,and the oxidation rate of MgSO_(3) was 0.13 mol/(L·h).The research indicated that the active component was uniformly distributed within porous structure of the catalyst as Co_(3)O_(4),which facilitated the oxidation of SO_(3)^(2-) catalyzed by Co_(3)O_(4).Kinetic researches indicated the oxidation rate of MgSO_(3) was influenced by the catalyst dosage,the reaction temperature,the solution pH,the airflow rate,and the SO_(3)^(2-) concentration.Additionally,after recycling experiments,the regenerated catalyst retained its high catalytic performance for the MgSO_(3) oxidation.The reaction mechanism for the catalytic oxidation of MgSO_(3) by Co-Bent catalyst was also proposed.The generation of active free radicals(OH·,SO_(4)^(-)·,SO_(3)^(-)·,SO_(5)^(-)·)accelerated the MgSO_(3) oxidation.These results provide theoretical support for the treatment of MgSO_(3) and the development of durable catalyst.
基金financially supported by National Natural Science Foundation of China(22208137 and 22068022)Yunnan Fundamental Research Projects(202101BE070001-033,202401AT070825,202201BE070001007 and 202301AV070005)。
文摘Concurrent activation of lattice oxygen(O_L)and molecular oxygen(O_(2))is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides.Herein,we report that the introduction of ultralow-loading of Ru single atoms(0.42 wt%)into Mn_(2)O_(3)matrix(0.4%Ru-Mn_(2)O_(3))greatly boosts its catalytic activity for the aerobic oxidation of 5-hydroxymethylfurfural(HMF)to 2,5-furandicarboxylic acid(FDCA).The FDCA productivity over the 0.4%Ru-Mn_(2)O_(3)(5.4 mmol_(FDCA)g_(cat)h^(-1))is 4.9 times higher than the Mn_(2)O_(3).Especially,this FDCAproductivity is also significantly higher than that of existing Ru and Mn-based catalysts.Experimental and theoretical investigations discovered that the Ru single atom facilitated the formation of oxygen vacancy(O_(v))in the catalyst,which synergistically weakened the Mn-O bond and promoted the activation of O_L.The co-presence of Ru single atoms and O_(v)also promote the adsorption and activation of both O_(2)and HMF.Consequently,the dehydrogenation reaction energy barrier of the rate-determining step was reduced via both the O_L and chemisorbed O_(2)dehydrogenation pathways,thus boosting the catalytic oxidation reactions.
基金financially supported by the National Natural Science Foundation of China(22468034)the Natural Science Foundation of Inner Mongolia(2021MS02008 and 2022MS02011)the Key Research and Development Project of Ordos(YF20240062)。
文摘Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the underpinning mechanism remains elusive.Herein,the introduction of silanol nests enables the alloy formation on the SiO_(2)surface.The amination modification is disclosed to induce the electron transfer from RE to Pt and weaken the adsorption of CO on electron-rich Pt species.In situ/operando spectroscopic analyses in conjunction with density functional theory calculations demonstrate the electronic couple of Pt atoms and adjacent Ce atoms concurrently achieves the enhancement of CO oxidation and suppression of H_(2)oxidation.Additionally,CO_(2)is readily desorbed from the Pt_(5)Ce(111)surface to enhance intrinsic activity and longevity.These findings provide an atomic-level insight into the synergistic catalytic sites on regulating the electronic state of the Pt-RE alloy catalysts toward highly selective oxidation reactions.
基金Project supported by National Natural Science Foundation of China(22076180)Youth Innovation Promotion Association of CAS(2019376)Chongqing Bayu Scholar Program(Young Scholar,YS2020048)。
文摘Creating a new low-temperature catalyst in decreasing the emission of volatile organic compounds(VOCs)has great significance under different industrial production situations.In particular,the Zr-UiO-66 is optimized by different amounts of cerium,which not only enhances the physicochemical stability but also increases the number of active sites of Ce_(x)Zr_(y)UiO-66.Furthermore,the catalysts with Co_(3)O_(4)nanoparticles supported on Ce_(x)Zr_(y)UiO-66 were successfully prepared via impregnation method.In the process of toluene degradation,the Co/Ce_(1)Zr_(2)-Ui0-66 attains a 90%conversion rate at 210℃with a space velocity of 60000 mL/(g·h)and toluene concentration at 1000×10^(-6).Meanwhile,the carbon dioxide selectivity reaches 100%at 218℃.The Co/Ce_(1)Zr_(2)-UiO-66 shows great water resistance(3 vol%H_(2)O).Multiple characterization methods were used to figure out the physicochemical properties of the catalysts.It is found that the addition of an appropriate amount of cerium can enhance stability of UiO-66 and surface lattice oxygen proportion.Additionally,the stronger electron transfer between Ce^(4+)and Co^(2+)enables the Co/Ce_(1)Zr_(2)-UiO-66 to possess more active surface oxygen species and Co_(3)+cationic species in all samples.
基金supported by Beijing Natural Science Foundation(No.8244060)China Postdoctoral Science Foundation(No.2023M730143)+3 种基金the National Natural Science Foundation of China(No.22425601)the National Key R&D Program of China(No.2023YFB3810801)Beijing Nova Program(No.20240484659)the R&D Program of Beijing Municipal Education Commission(No.KZ202210005011).
文摘Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.
基金supported by the National Natural Science Foundation of China(21325731,51478241,21221004)~~
文摘Formaldehyde（HCHO）is carcinogenic and teratogenic,and is therefore a serious danger to human health.It also adversely affects air quality.Catalytic oxidation is an efficient technique for removing HCHO.The development of highly efficient and stable catalysts that can completely convert HCHO at low temperatures,even room temperature,is important.Supported Pt and Pd catalysts can completely convert HCHO at room temperature,but their industrial applications are limited because they are expensive.The catalytic activities in HCHO oxidation of transition-metal oxide catalysts such as manganese and cobalt oxides with unusual morphologies are better than those of traditional MnO2,Co3O4,or other metal oxides.This is attributed to their specific structures,high specific surface areas,and other factors such as active phase,reducibility,and amount of surface active oxygens.Such catalysts with various morphologies have great potential and can also be used as catalyst supports.The loading of relatively cheap Ag or Au on transition-metal oxides with special morphologies potentially improves the catalytic activity in HCHO removal at room temperature.The preparation and development of new nanocatalysts with various morphologies and structures is important for HCHO removal.In this paper,research progress on precious-metal and transition-metal oxide catalyst systems for HCHO oxidation is reviewed; topics such as oxidation properties,structure–activity relationships,and factors influencing the catalytic activity and reaction mechanism are discussed.Future prospects and directions for the development of such catalysts are also covered.
基金supported by the National Natural Science Foundation of China(21325731,21221004 and 51478241)~~
文摘Three-dimensional（3D）ordered mesoporous MnO2 was prepared using KIT-6 mesoporous molecular sieves as a hard template.The material was used for catalytic oxidation of HCHO.The material has high surface areas and the mesoporous characteristics of the template,with cubic symmetry（ia3d）.It consists of a β-MnO2 crystalline phase corresponding to pyrolusite,with a rutile structure.Transmission electron microscopy and X-ray photoelectron spectroscopy showed that the 3D-MnO2 catalyst has a large number of exposed Mn4＋ ions on the（110）crystal plane surfaces,with a lattice spacing of 0.311 nm; this enhances oxidation of HCHO.Complete conversion of HCHO to CO2 and H2O was achieved at 130 °C on 3D-MnO2; the same conversions on α-MnO2 and β-MnO2 nanorods were obtained at 140 and 180 °C,respectively,under the same conditions.The specific mesoporous structure,high specific surface area,and large number of surface Mn4＋ ions are responsible for the catalytic activity of 3D-MnO2 in HCHO oxidation.
基金supported by the National Key Research and Development Program Foundation of China(2016YFC0209203)the National Natural Science Foundation of China(21707130,21325731)~~
文摘KIT‐6 mesoporous silica aged at 40,100,and 150°C were used as hard templates to prepare different mesoporous MnO2 catalysts,marked as Mn‐40,Mn‐100,and Mn‐150,respectively.The catalytic activities of these catalysts and the effect of pore sizes on ethanol catalytic oxidation were investigated.Mn‐40,Mn‐100,and Mn‐150 have triple,double,and single pore systems,respectively.On decreasing the aging temperature of KIT‐6,the pore sizes of KIT‐6 decrease and that of mesoporous MnO2 catalysts increase.The pore sizes and catalytic activities increase in the order:Mn‐40>Mn‐100>Mn‐150.Mn‐40 catalyst has a higher TOF(0.11 s–1 at 120°C)and the best catalytic activity for ethanol oxidation because of a bigger pore size with three pore systems with maximum distribution at 1.9,3.4,and 6.6 nm,decrease in symmetry and degree of order,more surface lattice oxygen species,oxygen vacancies resulting from more Mn3+ions,and better low‐temperature reducibility.
文摘The MoOx/AuNPs composite film modified glassy carbon electrode was fabricated by electro-depositing simultaneously gold nanoparticles and molybdenum oxides using cyclic voltammetry. The morphology and topography of the MoOx/AuNPs composite were char-acterized by scan electron microscopy and X-ray photoelectron spectroscopy respectively, and the electrocatalytic oxidation of glucose at the MoOx/AuNPs composite film was inves-tigated and analyzed in detail. It was shown that the MoOx/AuNPs composite was of strong electrocatalytic activity towards oxidation of glucose as well as other saccharides, so that an attempt was made for direct voltammetric determination of glucose. Then the positive scan polarization reverse catalytic voltammetry was proposed for the first time. Based on this method, the pure oxidation current was extracted by subtraction of the blank current in the reverse scan. The current sensitivity was enhanced tremendously and the signal to noise ra-tio was improved adequately. The electrocatalytic oxidation of glucose at the MoOx/AuNPs modified electrode was performed in alkaline medium, a wide linear range from 0.01 mmol/L to 4.0 mmol/L of glucose, a higher current sensitivity of 2.35 mA/（mmol/L·cm2）, and a lower limit of detection of 9.01 μmol/L （at signal/noise=3） were achieved. In addition, the electrocatalytic oxidation of other saccharides such as lactose, fructose and sucrose was also evaluated.
基金supported by the National Natural Science Foundation of China (51374004,51204083)the Candidate Talents Training Fund of Yun-nan Province (2012HB009,2014HB006)+2 种基金the Applied Basic Research Program of Yunnan Province (2014FB123)a School-Enterprise Cooperation Project from Jinchuan Corporation (Jinchuan 201115)the Talents Training Program of Kunming University of Science and Technology (KKZ3201352038)~~
文摘This study focuses on drawing a hydrothermal synthesis process map for Co3O4 nanoparticles with various morphologies and investigating the effects of Co3O4 nanocatalyst morphology on CO oxidation.A series of cobalt-hydroxide-carbonate nanoparticles with various morphologies（i.e.,nanorods,nanosheets,and nanocubes） were successfully synthesized,and Co3O4 nanoparticles were obtained by thermal decomposition of the cobalt-hydroxide-carbonate precursors.The results suggest that the cobalt source is a key factor for controlling the morphology of cobalt-hydroxide-carbonate at relatively low hydrothermal temperatures（≤ 140℃）.Nanorods can be synthesized in CoCl2 solution,while Co（NO3）2 solution promotes the formation of nanosheets.Further increasing the synthesis temperature（higher than 140 ℃） results in the formation of nanocubes in either Co（NO3）2 or CoCl2 solution.The reaction time only affects the size of the obtained nanoparticles.The presence of CTAB could improve the uniformity and dispersion of particles.Co3O4 nanosheets showed much higher catalytic activity for CO oxidation than nanorods and nanocubes because it has more abundant Co^（3＋） on the surface,much higher reducibility,and better oxygen desorption capacity.
文摘The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were characterized by means of the powder X-ray diffraction and N2 adsorption-desorption, the inductively coupled plasma atomic emission spectrometry, the temperature programmed reduction, diffuse reflectance UV-Vis spectra, and the X-ray photoelectron spectroscopy. It was found that after doping little amount of Ce in copper manganese oxide, CeO2 phase was highly dispersed and could prevent sintering and aggregating of the catalyst, the size of the catalytic material was decreased, the reducibility was enhanced, the specific surface area was increased and the formation of the active sites for the oxidation of CO was improved significantly. Therefore, the activity of the rare earth promoted catalyst was enhanced remarkably.
基金Project(51372106)supported by the National Natural Science Foundation of China
文摘A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）.The Pd micro-nanoparticles were prepared on a COOH-CNTs/PI membrane as a comparative sample.The XRD and SEM investigations for Pd electrodeposition demonstrate that the particle size of Gr/PI composite membrane is smaller than that of COOH-CNTs/PI membrane,while the uniform and dense distribution of Pd micro-nanoparticles on the Gr/PI composite membrane is greater than that on the COOH-CNTs/PI membrane.The electrocatalytic properties of Pd/Gr/PI and Pd/COOH-CNTs/PI catalysts for the oxidation of formic acid were investigated by cyclic voltammetry（CV） and chronoamperometry（CA）.It is found that the electrocatalytic activity and stability of Pd/Gr/PI are superior to those of Pd/COOH-CNTs/PI catalyst.This is because smaller metal particles and higher dense distribution desirably provide abundant catalytic sites and mean higher catalytic activity.Therefore,the Pd/Gr/PI catalyst has better catalytic performance for formic acid oxidation than the Pd/COOH-CNTs/PI catalyst.
基金supported by Strategic Project of Science and Technology of Chinese Academy of Sciences(XDB05050000)the National Natural Science Foundation of China(51272253)
文摘Hierarchical layer-stacking Mn-Ce composite oxide with mesoporous structure was firstly prepared by a simple precipitation/decomposition procedure with oxalate precursor and the complete catalytic oxidation of VOCs（benzene, toluene and ethyl acetate） were examined. The Mn-Ce oxalate precursor was obtained from metal salt and oxalic acid without any additives. The resulting materials were characterized by X-ray diffraction（XRD）, Brunauer-Emmett-Teller（BET）, scanning electron microscopy（SEM）, energy dispersive X-ray spectroscopy（EDX）, hydrogen temperature programmed reduction（H2-TPR） and X-ray photoelectron spectroscopy（XPS）. Compared with Mn-Ce composite oxide synthesized through a traditional method（Na2CO3 route）, the hierarchical layer-stacking Mn-Ce composite oxide exhibited higher catalytic activity in the complete oxidation of volatile organic compounds（VOCs）. By means of testing, the data revealed that the hierarchical layer-stacking Mn-Ce composite oxide possessed superior physiochemical properties such as good low-temperature reducibility, high manganese oxidation state and rich adsorbed surface oxygen species which resulted in the enhancement of catalytic abilities.
基金supported by National Natural Science Foundation of China (20907018)Natural Science Foundation of Yunnan Province (2007E184M)+1 种基金Education Department Scientific Research Foundation of Yunnan Province (07C11400)Young and Middle-aged Academic and Technical Back-up Personnel Program of Yunnan Province (2008PY009)
文摘A series of manganese-cerium oxide catalysts were prepared by different methods and used for low-temperature catalytic oxidation of NO in the presence of excess O2.Their surface properties were evaluated by means of BET and were characterized by using scanning electron microscopy(SEM) and X-ray diffractometer(XRD).The activity test of Mn-Ce-Ox catalysts showed that addition of Ce enhanced the activities of NO oxidation.The most active catalysts with a molar Ce/(Mn+Ce) ratio of 0.3 were prepared by co-precip...
文摘MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.
基金supported by the Ministry of Science and Technology of China (No. 2012AA062702,2010AA64905)the National Natural Science Foundation of China (No. 21077117)
文摘The effect of pretreatment on Pd/Al2O3 catalysts for the catalytic oxidation of o-xylene at low temperature was studied by changing the pretreatment and testing conditions. The fresh and pretreated Pd/Al2O3 catalysts were characterized by transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）. The results showed that the pretreatment dramatically changed the Pd/PdO ratio and then significantly affected the Pd/Al2O3 activity; while the pretreatment had not much influence on Pd particle size. The Pd/Al2O3 pre-reduced at 300~C/400~C, which has fully reduced Pd species, showed the highest activity; while the fresh Pd/Al2O3, which has fully oxidized Pd species, presented the worst performance, indicating the Pd chemical state plays an important role in the catalytic activity for the o-xylene oxidation. It is concluded that metallic Pd is the active species on the Pd/Al2O3 catalyst for the catalytic oxidation of o-xylene at low temperature.
