The Ru-based catalysts with different preparation methods or supports were achieved and applied in efficientlycatalytic elimination of 1,2-dichloroethane(1,2-DCE).It wasfirstly found that the redox ability and chlorine...The Ru-based catalysts with different preparation methods or supports were achieved and applied in efficientlycatalytic elimination of 1,2-dichloroethane(1,2-DCE).It wasfirstly found that the redox ability and chlorine re-sistance of the catalyst could be improved by regulating the interaction between Ru and supports.Compared withother supports and conventionally impregnated methods,the Ru@ZSM-5 catalyst synthesized by the in-situ en-capsulation strategy exhibited an excellent low-temperature catalytic performance(T50=262°C,T90=327℃),superior stability in long-term test as well as ideal target products.The acidity,specific surface area,and in-teraction with precious metals of the supports have significant influences on the catalytic activity,and the Ruclusters inside the pore structures are more closely bound to the framework Al species,which promotes theoxidation behavior.The encapsulation strategy also significantly improves the Ru dispersion thereby facilitatesoxygen activation as well as Cl-containing volatile organic compounds(CVOCs)deep oxidation,and preserveslarge amounts of Brønsted acid sites to optimize the hydrolysis mechanism for purification of CVOCs.Subse-quently,the synergistic effect between metal redox and acidity is greatly optimized,thus extremely promotingthe catalytic efficiency of 1,2-DCE oxidation.展开更多
Owing to the complexity of multicomponent gases,developing multifunctional catalysts for synergistic removal of benzene and toluene remains challenging.The spinel MMn_(2)O_(4)(M=Co,Ni,or Cu)catalysts were successfully...Owing to the complexity of multicomponent gases,developing multifunctional catalysts for synergistic removal of benzene and toluene remains challenging.The spinel MMn_(2)O_(4)(M=Co,Ni,or Cu)catalysts were successfully synthesized via the sol–gel method and tested for their catalytic performance for simultaneous degradation of benzene and toluene.The CuMn_(2)O_(4)sample exhibited the best catalytic performance,the conversion of benzene reached 100%at 350℃,and toluene conversion reached 100%at 250℃.XRD,N_(2)adsorption-desorption,HRTEM-EDS,ED-XRF,Raman spectroscopy,H_(2)-TPR,NH_(3)-TPD,O_(2)-TPD and XPS were used to characterize the physical and chemical properties of MMn_(2)O_(4)catalysts.The excellent redox properties,high concentration of surface Mn4+,and adsorption of oxygen species over the CuMn_(2)O_(4)sample facilitated the simultaneous and efficient removal of benzene and toluene.Additionally,in situ DRIFTS illustrated the intermediate species and reaction mechanism for the synergetic catalytic oxidation of benzene and toluene.Notably,as an effective catalytic material,spinel oxide exhibited excellent synergistic degradation performance for benzene and toluene,providing some insight for the development of efficient multicomponent VOC catalysts.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
Perovskite oxides have been widely applied as an effective catalyst in heterogeneous catalysis.However,the rational design of active catalysts has been restricted by the lack of understanding of the electronic structu...Perovskite oxides have been widely applied as an effective catalyst in heterogeneous catalysis.However,the rational design of active catalysts has been restricted by the lack of understanding of the electronic structure.The correlations between surface properties and bulk electronic structure have been ignored.Herein,a simple handler of LaFeO_(3)with diluted HNO3 was employed to tune the electronic structure and catalytic properties.Experimental analysis and theoretical calculations elucidate that acid etching could raise the Fe valence and enhance Fe-O covalency in the octahedral structure,thereby lessening charge transfer energy.Enhanced Fe-O covalency could lower oxygen vacancy formation energy and enhance oxygen mobility.In-situ DRIFTS results indicated the inherent adsorption capability of Toluene and CO molecules has been greatly improved owing to higher Fe-O covalency.As compared,the catalysts after acid etching exhibited higher catalytic activity,and the T_(90)had a great reduction of 45 and 58℃ for toluene and CO oxidation,respectively.A deeper understanding of electronic structure in perovskite oxides may inspire the design of high-performance catalysts.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
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
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
Sulfur dioxide(SO_(2))frequently coexist with volatile organic compounds(VOCs)in exhaust gas.The competitive adsorption of SO_(2) and VOCs can adversely affect the efficiency of catalytic combustion,leading to catalys...Sulfur dioxide(SO_(2))frequently coexist with volatile organic compounds(VOCs)in exhaust gas.The competitive adsorption of SO_(2) and VOCs can adversely affect the efficiency of catalytic combustion,leading to catalyst poisoning and irreversible loss of activity.To investigate the impact of sulfur poisoning on the catalysts,we prepared the MnO_(2)/Beta zeolite,and a corresponding series of sulfur-poisoned catalysts through in-situ thermal decomposition of(NH_(4))_(2)SO_(4).The decrease in toluene catalytic activity of poisoned MnO_(2)/Beta zeolite primarily results from the conversion of the active species MnO_(2) to MnSO_(4).However,the crystal structure and the porous structure of MnO_(2)/Beta zeolite were stable,and original structure was still maintained when 1.6%(mass)sulfur species were introduced.Furthermore,the extra-framework Al of Beta zeolite could capture sulfur species to generate Al2(SO_(4))_(3),thereby reducing sulfur species from reacting with Mn^(4+) active sites.The combination of sulfur and Beta zeolite was found to directly produce new strong-acid sites,thus effectively compensating for the effect of reduced Mn4+active species on the catalytic activity.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
An efficient and novel approach is proposed for oxidative arylation of bio-based furfuryl alcohol(FA)to aryl furans(AFs),a versatile monomer of photoelectric materials,in the presence of UiO-67-Pd(F)with phenanthrolin...An efficient and novel approach is proposed for oxidative arylation of bio-based furfuryl alcohol(FA)to aryl furans(AFs),a versatile monomer of photoelectric materials,in the presence of UiO-67-Pd(F)with phenanthroline/bipyridine,and poly-F substituted phenyl ligands as the mixture linkers.The results of control experiments and theoretical calculations reveal that the–F on the phenyl linkers efficiently tunes the electron-deficient nature of Pd through the Zr_(6) clusters bridges,which favors the adsorption and activation of the furan ring.Furthermore,the conjugation of different nitrogen-containing ligands facilitates Pd coordination for the Heck-type insertion and subsequent electrophilic palladation,respectively.As a result,the oxidative arylation of FA derivatives is substantially enhanced because of these electronic and steric synergistic effects.Under the optimized conditions,72.2%FA conversion and 74.8%mono aryl furan(MAF)selectivity are shown in the Heck-type insertion.Meanwhile,85.3%of MAF is converted,affording 74.8%selectivity of final product(AFs)in the subsequent electrophilic palladation reaction.This process efficiency is remarkably higher than that with homogeneous catalysts.In addition,furan-benzene polymer obtained from the halogen-free synthesis catalyzed by UiO-67-Pd(F)show significantly better properties than that from conventional Suzuki coupling method.Therefore,the present work provides a new insight for useful AFs synthesis by oxidative arylation of bio-furan via rational tunning the metal center micro-environment of heterogeneous catalyst.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
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
Using the molten salt and polyvinyl alcohol-protected reduction method,we fabricated Co3O4 octahedron-supported Au-Pd（x（AuPdy）/Co3O4;x =（0.18,0.47,and 0.96） wt%;y（Pd/Au molar ratio） =1.85-1.97） nanocatalysts.T...Using the molten salt and polyvinyl alcohol-protected reduction method,we fabricated Co3O4 octahedron-supported Au-Pd（x（AuPdy）/Co3O4;x =（0.18,0.47,and 0.96） wt%;y（Pd/Au molar ratio） =1.85-1.97） nanocatalysts.The molten salt-derived Co3O4 sample possessed well-defined octahedral morphology,with an edge length of 300 nm.The Au-Pd nanoparticles,with sizes of 2.7-3.2 nm,were uniformly dispersed on the surface of Co3O4.The 0.96（AuPd1.92）/Co3O4 sample showed the highest catalytic activity for toluene and o-xylene oxidation,and the temperature required for achieving 90%conversion of toluene and o-xylene was 180 and 187 ℃,respectively,at a space velocity of 40000 mL/（g·h）.The high catalytic performance of Co3O4 octahedron-supported Au-Pd nanocatalysts was associated with the interaction between Au-Pd nanoparticles and Co3O4 and high concentration of adsorbed oxygen species.展开更多
Ruthenium （Ru）‐based catalysts are widely employed in several types of gas‐solid reactions because of their high catalytic activities. This review provides theoretical research on Ru‐based catalysts and an analys...Ruthenium （Ru）‐based catalysts are widely employed in several types of gas‐solid reactions because of their high catalytic activities. This review provides theoretical research on Ru‐based catalysts and an analysis of their basic properties and oxidation behavior. There is particular emphasis on Ru‐catalyzed gas‐solid catalytic reactions, including the catalytic oxidation of VOCs, preferential oxidation of CO, synthesis of ammonia, oxidation of HCl and partial oxidation of CH4. Recent litera‐ture on catalysis is summarized and compared. Finally, we describe current challenges in the field and propose approaches for future development of Ru‐based catalysts.展开更多
CeO_(2),La_(2)O_(3),and CeO_(2)-Y_(2)O_(3) oxides were coated on the surface of spherical granular AI_(2)O_(3)(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of ...CeO_(2),La_(2)O_(3),and CeO_(2)-Y_(2)O_(3) oxides were coated on the surface of spherical granular AI_(2)O_(3)(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of rare earth metal doping on the adsorption rates of Pd and Pt ions,as well as the catalytic performance,were investigated.Results show that the H_(2)PtCl_(6)·6H_(2)O adsorption rates of the Al_(2)O_(3) carriers modified by Ce,La,and CeY increase significantly.These rare earth coatings can adsorb almost all H2PtCl_(6)·6H_(2)O in the solution.Compared with Pt/Al_(2)O_(3) catalyst,Pt/Ce-AI_(2)O_(3) and Pt/CeY-AI_(2)O_(3) catalysts have better degradation performance for toluene,and the T_(90) temperatures are both about 147℃.According to X-ray photoelectron spectroscopy(XPS)characterization,Pt^(0)is an important active species for catalytic oxidation reaction of toluene.After CeO_(2)modification to the conventional Pt/Al_(2)O_(3)catalyst,the proportion of Pt^(0)increases from 74.5%to 82.1%.When the Pt^(0)content in the metal state is improved,the redox activity of the catalyst is promoted correspondingly.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
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supported by the National Key Research and Development Program of China(No.2023YFC3905400)the National Natural Science Foundation of China(No.22176010).
文摘The Ru-based catalysts with different preparation methods or supports were achieved and applied in efficientlycatalytic elimination of 1,2-dichloroethane(1,2-DCE).It wasfirstly found that the redox ability and chlorine re-sistance of the catalyst could be improved by regulating the interaction between Ru and supports.Compared withother supports and conventionally impregnated methods,the Ru@ZSM-5 catalyst synthesized by the in-situ en-capsulation strategy exhibited an excellent low-temperature catalytic performance(T50=262°C,T90=327℃),superior stability in long-term test as well as ideal target products.The acidity,specific surface area,and in-teraction with precious metals of the supports have significant influences on the catalytic activity,and the Ruclusters inside the pore structures are more closely bound to the framework Al species,which promotes theoxidation behavior.The encapsulation strategy also significantly improves the Ru dispersion thereby facilitatesoxygen activation as well as Cl-containing volatile organic compounds(CVOCs)deep oxidation,and preserveslarge amounts of Brønsted acid sites to optimize the hydrolysis mechanism for purification of CVOCs.Subse-quently,the synergistic effect between metal redox and acidity is greatly optimized,thus extremely promotingthe catalytic efficiency of 1,2-DCE oxidation.
基金supported by the National Natural Science Foundation of China(Nos.22206146,22006079,and U21A20524)the Fundamental Research Funds for the Central Universities,the Youth Innovation Promotion Association of Chinese Academy of Sciences,the Fundamental Research Program of Shanxi Province(No.202103021223280)+1 种基金the Special Fund for Science and Technology Innovation Teams of Shanxi Province(No.202204051002026)the Natural Science Foundation of Shandong Province(No.ZR2021QB133).
文摘Owing to the complexity of multicomponent gases,developing multifunctional catalysts for synergistic removal of benzene and toluene remains challenging.The spinel MMn_(2)O_(4)(M=Co,Ni,or Cu)catalysts were successfully synthesized via the sol–gel method and tested for their catalytic performance for simultaneous degradation of benzene and toluene.The CuMn_(2)O_(4)sample exhibited the best catalytic performance,the conversion of benzene reached 100%at 350℃,and toluene conversion reached 100%at 250℃.XRD,N_(2)adsorption-desorption,HRTEM-EDS,ED-XRF,Raman spectroscopy,H_(2)-TPR,NH_(3)-TPD,O_(2)-TPD and XPS were used to characterize the physical and chemical properties of MMn_(2)O_(4)catalysts.The excellent redox properties,high concentration of surface Mn4+,and adsorption of oxygen species over the CuMn_(2)O_(4)sample facilitated the simultaneous and efficient removal of benzene and toluene.Additionally,in situ DRIFTS illustrated the intermediate species and reaction mechanism for the synergetic catalytic oxidation of benzene and toluene.Notably,as an effective catalytic material,spinel oxide exhibited excellent synergistic degradation performance for benzene and toluene,providing some insight for the development of efficient multicomponent VOC catalysts.
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the National Natural Science Foundation of China(Nos.22376178,22322606,22276105)the National Key Research and Development Program of China(No.2022YFC3704300)the Beijing Natural Science Foundation(No.8222054).
文摘Perovskite oxides have been widely applied as an effective catalyst in heterogeneous catalysis.However,the rational design of active catalysts has been restricted by the lack of understanding of the electronic structure.The correlations between surface properties and bulk electronic structure have been ignored.Herein,a simple handler of LaFeO_(3)with diluted HNO3 was employed to tune the electronic structure and catalytic properties.Experimental analysis and theoretical calculations elucidate that acid etching could raise the Fe valence and enhance Fe-O covalency in the octahedral structure,thereby lessening charge transfer energy.Enhanced Fe-O covalency could lower oxygen vacancy formation energy and enhance oxygen mobility.In-situ DRIFTS results indicated the inherent adsorption capability of Toluene and CO molecules has been greatly improved owing to higher Fe-O covalency.As compared,the catalysts after acid etching exhibited higher catalytic activity,and the T_(90)had a great reduction of 45 and 58℃ for toluene and CO oxidation,respectively.A deeper understanding of electronic structure in perovskite oxides may inspire the design of high-performance catalysts.
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 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(21577094)the Zhejiang Public Welfare Technology Research Project(LGG19B070003).
文摘Sulfur dioxide(SO_(2))frequently coexist with volatile organic compounds(VOCs)in exhaust gas.The competitive adsorption of SO_(2) and VOCs can adversely affect the efficiency of catalytic combustion,leading to catalyst poisoning and irreversible loss of activity.To investigate the impact of sulfur poisoning on the catalysts,we prepared the MnO_(2)/Beta zeolite,and a corresponding series of sulfur-poisoned catalysts through in-situ thermal decomposition of(NH_(4))_(2)SO_(4).The decrease in toluene catalytic activity of poisoned MnO_(2)/Beta zeolite primarily results from the conversion of the active species MnO_(2) to MnSO_(4).However,the crystal structure and the porous structure of MnO_(2)/Beta zeolite were stable,and original structure was still maintained when 1.6%(mass)sulfur species were introduced.Furthermore,the extra-framework Al of Beta zeolite could capture sulfur species to generate Al2(SO_(4))_(3),thereby reducing sulfur species from reacting with Mn^(4+) active sites.The combination of sulfur and Beta zeolite was found to directly produce new strong-acid sites,thus effectively compensating for the effect of reduced Mn4+active species on the catalytic activity.
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.
文摘An efficient and novel approach is proposed for oxidative arylation of bio-based furfuryl alcohol(FA)to aryl furans(AFs),a versatile monomer of photoelectric materials,in the presence of UiO-67-Pd(F)with phenanthroline/bipyridine,and poly-F substituted phenyl ligands as the mixture linkers.The results of control experiments and theoretical calculations reveal that the–F on the phenyl linkers efficiently tunes the electron-deficient nature of Pd through the Zr_(6) clusters bridges,which favors the adsorption and activation of the furan ring.Furthermore,the conjugation of different nitrogen-containing ligands facilitates Pd coordination for the Heck-type insertion and subsequent electrophilic palladation,respectively.As a result,the oxidative arylation of FA derivatives is substantially enhanced because of these electronic and steric synergistic effects.Under the optimized conditions,72.2%FA conversion and 74.8%mono aryl furan(MAF)selectivity are shown in the Heck-type insertion.Meanwhile,85.3%of MAF is converted,affording 74.8%selectivity of final product(AFs)in the subsequent electrophilic palladation reaction.This process efficiency is remarkably higher than that with homogeneous catalysts.In addition,furan-benzene polymer obtained from the halogen-free synthesis catalyzed by UiO-67-Pd(F)show significantly better properties than that from conventional Suzuki coupling method.Therefore,the present work provides a new insight for useful AFs synthesis by oxidative arylation of bio-furan via rational tunning the metal center micro-environment of heterogeneous catalyst.
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 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 Natural Science Foundation of China (21377008, 21477005, U1507108)National High Technology Re-search and Development Program of China (2015AA034603)+1 种基金Beijing Nova Program (Z141109001814106)Natural Science Foundation of Bei-jing Municipal Commission of Education (KM201410005008)~~
文摘Using the molten salt and polyvinyl alcohol-protected reduction method,we fabricated Co3O4 octahedron-supported Au-Pd（x（AuPdy）/Co3O4;x =（0.18,0.47,and 0.96） wt%;y（Pd/Au molar ratio） =1.85-1.97） nanocatalysts.The molten salt-derived Co3O4 sample possessed well-defined octahedral morphology,with an edge length of 300 nm.The Au-Pd nanoparticles,with sizes of 2.7-3.2 nm,were uniformly dispersed on the surface of Co3O4.The 0.96（AuPd1.92）/Co3O4 sample showed the highest catalytic activity for toluene and o-xylene oxidation,and the temperature required for achieving 90%conversion of toluene and o-xylene was 180 and 187 ℃,respectively,at a space velocity of 40000 mL/（g·h）.The high catalytic performance of Co3O4 octahedron-supported Au-Pd nanocatalysts was associated with the interaction between Au-Pd nanoparticles and Co3O4 and high concentration of adsorbed oxygen species.
基金supported by Beijing Natural Science Foundation (8164063)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB05050100)~~
文摘Ruthenium （Ru）‐based catalysts are widely employed in several types of gas‐solid reactions because of their high catalytic activities. This review provides theoretical research on Ru‐based catalysts and an analysis of their basic properties and oxidation behavior. There is particular emphasis on Ru‐catalyzed gas‐solid catalytic reactions, including the catalytic oxidation of VOCs, preferential oxidation of CO, synthesis of ammonia, oxidation of HCl and partial oxidation of CH4. Recent litera‐ture on catalysis is summarized and compared. Finally, we describe current challenges in the field and propose approaches for future development of Ru‐based catalysts.
基金supported by the Scientific Research Fund of Zhejiang Provincial Education Department(Y202043197)the National Natural Science Foundation of China(22078294)+1 种基金the Natural Science Foundation of Zhejiang Province(LZ21E080001,LGF20E080018)the Key Laboratory of Environmental Pollution Control Technology Research of Zhejiang Province(2021ZEKL04)。
文摘CeO_(2),La_(2)O_(3),and CeO_(2)-Y_(2)O_(3) oxides were coated on the surface of spherical granular AI_(2)O_(3)(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of rare earth metal doping on the adsorption rates of Pd and Pt ions,as well as the catalytic performance,were investigated.Results show that the H_(2)PtCl_(6)·6H_(2)O adsorption rates of the Al_(2)O_(3) carriers modified by Ce,La,and CeY increase significantly.These rare earth coatings can adsorb almost all H2PtCl_(6)·6H_(2)O in the solution.Compared with Pt/Al_(2)O_(3) catalyst,Pt/Ce-AI_(2)O_(3) and Pt/CeY-AI_(2)O_(3) catalysts have better degradation performance for toluene,and the T_(90) temperatures are both about 147℃.According to X-ray photoelectron spectroscopy(XPS)characterization,Pt^(0)is an important active species for catalytic oxidation reaction of toluene.After CeO_(2)modification to the conventional Pt/Al_(2)O_(3)catalyst,the proportion of Pt^(0)increases from 74.5%to 82.1%.When the Pt^(0)content in the metal state is improved,the redox activity of the catalyst is promoted correspondingly.
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 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.
