Enhanced bifunctional oxygen electrochemical catalytic performance using La-doped CoFe_(2)O_(4)spinel supported by 3D-G for Zn-air batteries

The preparation of bifunctional catalysts for oxygen reduction(ORR)and oxygen evolution(OER)is crucial for Zn-air batteries.Here,we report a La doped CoFe_(2)O_(4) spinel catalyst supported on threedimensional graphene(3D-G),where La can facilitate electron transfer from Co to Fe,leading to increased electron cloud density in Fe and improved catalytic performance.The redshift of the G peak in the Raman spectra indicates the interaction between theπbond of 3D-G and d orbitals in La_(0.2)CoFe_(1.8)O_(4).La_(0.2)CoFe_(1.8)/3D-G exhibits superior ORR performance(E_(1/2)=0.86 V vs.RHE)and OER performance(E_(j=10)=1.55 V vs.RHE)to CoFe_(2)O_(4)/3D-G(E_(1/2)=0.831 V vs.RHE,E_(j=10)=1.603 V vs.RHE).Furthermore,it demonstrates excellent bifunctional oxygen catalytic performance while maintaining high power density and stability in liquid zinc-air batteries(ZABs)and flexible ZABs(F-ZABs).This work presents a viable strategy for utilizing rare earth element doped spinels to enhance oxygen catalyst and ZABs performance.

Impacts of support properties on the vacuum residue slurry-phase hydrocracking performance of Mo catalysts

To deeply understand the effects of support properties on the performance of Mo-based slurry-phase hydrocracking catalysts,four Mo-based catalysts supported on amorphous silica alumina(ASA),γ-Al_(2)O_(3),ultra-stable Y(USY)zeolite and SiO_(2) were prepared by the incipient wetness impregnation method,respectively,and their catalytic performances were compared in the vacuum residue(VR)hydrocracking process.It is found that the Mo/ASA catalyst exhibits the highest VR conversion among the different catalysts,indicating that both the appropriate amount of acid sites,especially B acid sites and larger mesoporous volume of ASA can enhance the VR hydrocracking into light distillates.Furthermore,Mo catalysts supported on the different supports show quite different product distributions in VR hydrocracking.The Mo/ASA catalyst provides higher yields of naphtha and middle distillates and lower yields of gas and coke compared with other catalysts,it is attributed to the highest MoS_(2) slab dispersion,the highest sulfuration degree of Mo species,and the most Mo atoms located at the edge sites for the Mo/ASA catalyst,as observed by HRTEM and XPS analyses.These features of Mo/ASA are beneficial for the hydrogenation of intermediate products and polycyclic aromatic hydrocarbons to restrict the gas and coke formation.

Preparation of Zn-modified nano-ZSM-5 zeolite and its catalytic performance in aromatization of 1-hexene

The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity（WHSV） of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.

Boosting the catalytic activity toward oxygen reduction via a heterostructure of porous iron oxide-decorated 2D NiO/NG nanosheets

As a noble metal substitute,two-dimensional(2D)hierarchical nano-frame structures have attracted great interest as candidate catalysts due to their remarkable advantages-high intrinsic activity,high electron mobility,and straightforward surface functionalization.Therefore,they may replace Pt-based catalysts in oxygen reduction reaction(ORR)applications.Herein,a simple method is developed to design hierarchical nano-frame structures assembled via 2D NiO and N-doped graphene(NG)nanosheets.This procedure can yield nanostructures that satisfy the criteria correlated with improved electrocatalytic performance,such as large surface area,numerous undercoordinated atoms,and high defect densities.Further,porous NG nanosheet architectures,featuring NiO nanosheets densely coordinated with accessible holey Fe_(2)O_(3) moieties,can enhance mesoporosity and balance hydrophilicity.Such improvements can facilitate charge transport and expose formerly inaccessible reaction sites,maximizing active site density utilization.Density functional theory(DFT)calculations reveal favored O_(2) adsorption and dissociation on Fe_(2)O_(3) hybrid structures when supported by 2D NiO and NG nanomaterials,given 2D materials donated charge to Fe_(2)O_(3) active sites.Our systematic studies reveal that synergistic contributions are responsible for enriching the catalytic activity of Fe_(2)O_(3)@NiO/NG in alkaline media-encompassing internal voids and pores,unique hierarchical support structures,and concentrated N-dopant and bimetallic atomic interactions.Ultimately,this work expands the toolbox for designing and synthesizing highly efficient 2D/2D shelled functional nanomaterials with transition metals,endeavoring to benefit energy conversion and related ORR applications.

Effects of sol-gel method and lanthanum addition on catalytic performances of nickel-based catalysts for methane reforming with carbon dioxide

The nickel-based catalysts were prepared by the sol-gel method and used for the CH4 reforming with CO2. The effects of the sol-gel method on the specific surface area, catalytic activity, desorption, and reduction performances of catalysts were investigated with BET, TPR, and TPD. Compared with the catalyst prepared by the impregnation method, the results indicated that the catalysts prepared by the sol-gel method had larger specific surface area, showing higher catalytic activities and exhibiting perfect desorption and reduction performances. In addition, the modification effects of adding La were studied, and it was found that the 0.75NLBT catalyst constituted of 5wt.%Ni-0.75wt.%La was optimal.

Performance and characterization of iron-nickel catalysts for light olefin production

A series of x （Fe,Ni）/Al2O3 catalysts （x = 2-12 wt%） were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%（Fe,Ni）/Al2O3 catalyst was found to be the optimal catalyst for the production of C2-C4 olefins.The effects of calcination behaviors and operational conditions on the catalytic performance of the optimal catalyst were investigated.The best operational conditions were molar feed ratio H2/CO = 2/1,T = 260 ℃,gas hourly space velocity （GHSV） = 2600 h^-1 and the pressure of 3 bar.Character-izations of both precursors and catalysts were carried out using X-ray diffraction （XRD）,temperature-programmed reduction （TPR）,scanning electron microscopy （SEM）,N2-adsorption-desorption measurement,thermal gravimetric analysis （TGA） and differential scanning calorimetry （DSC）.

Improving the performance of metal-organic frameworks for thermo-catalytic CO_(2)conversion:Strategies and perspectives

Climate change caused by the increasing emission of CO_(2)to the atmosphere has become a global concern.To ameliorate this issue,converting CO_(2)into valuable chemicals is highly desirable,enabling a sustainable low-carbon future.To this end,developing efficient catalytic systems for CO_(2)conversion has sparked intense interests from both academia and industry.Taking advantage of their highly porous structures and unique properties,metal−organic frameworks(MOFs)have shown great potential as heterogeneous catalysts for CO_(2)conversion.Various transformations involving CO_(2)have been accomplished over MOFs-based materials.Here we provide a comprehensive and up-to-date review on recent advances of heterogeneous CO_(2)thermocatalysis using MOFs,highlighting relationships between structures and properties.Special attention is given to the design strategies for improving the catalytic performance of MOFs.Avenues available to enrich the catalytic active sites in MOF structures are stressed and their respective impacts on CO_(2)conversion efficiency are presented.The synergistic effects between each active site within the structure of MOFs and derivatives are discussed.In the end,future perspectives and challenges in CO_(2)conversion by heterogeneous catalysis with MOFs are described.

Catalytic Performance of MnO_x-WO_3/TiO_2 Catalyst for Selective Catalytic Reduction of NO_x with NH_3 and Its Tolerance Towards SO_2

The performance of Mn-W/TiO2 for selective catalytic reduction（SCR） of NOx with NH3 and its resistance to different concentrations of SO2 at various temperatures were investigated. The results show that WO3 increased the active sites and enhanced the strength of acid, so it was an effective promoter of MnOJTiO2. The NOx conversion on Mn-W/TiO2 ranges from 80.3% to 99.6% between 100 ℃to 350℃ at GHSV=18900 h 1, while N2 product selectivity changes from 100% to 98.7%. In the presence of 0.01% SO2 and 6% H20, NOx conversion maintained 98.5% at 120℃. The influence of more than 0.01% SO2 on the activity of MnOx-WO3/TiO2 will disappear if the temperature rises above 250℃. By means of heating and sweeping with He, the activity of the catalysts can be recovered. At 300℃, NOx conversion yielded 99% with 0.07% SO2 and reached the level of commercial V-W/TiO2 catalysts. The Mn-W/TiO2 catalyst showed excellent performance for SCR of NOx with NH3 in a wider range of temperature with strong tolerance to SO2.

Ru effect on the catalytic performance of Pd@Ru/C catalysts for methanol electro-oxidation

Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation （MEO）. The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry （CV） techniques. The results showed that the introduction of Ru element （2-10 wt%） into Pd 20 wt%/C （hereafter, denoted as Pd/C） produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C （hereafter, denoted as Pd@Rus/C） catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E = -0.038 V （vs. Hg/HgO） was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of dbp/dfp （the ratio of MEO peak current density in the negative scan and positive scan） were also investigated. The result demonstrated that Pd@Rus/C offering the smallest value of Jbp/Jfp displayed the best stable catalytic performance.

Distribution of nitrogen and oxygen compounds in shale oil distillates and their catalytic cracking performance

The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds in four distillates of Fushun shale oil,and their catalytic cracking performance was investigated.There are nine classes of basic nitrogen compounds(BNCs)and eleven classes of non-basic heteroatomic compounds(NBHCs)in the different distillates.The dominant BNCs are mainly basic N1 class species.The dominant NBHCs are mainly acidic O2 and O1 class species in the300-350℃,350-400℃,and 400-450℃distillates,while the neutral N1,N1 O1 and N2 compounds become relatively abundant in the>450℃fraction.The basic N1 compounds and acidic O1 and O2 compounds are separated into different distillates by the degree of alkylation(different carbon number)but not by aromaticity(different double-bond equivalent values).The basic N1 O1 and N2 class species and neutral N1 and N2 class species are separated into different distillates by the degrees of both alkylation and aromaticity.After the catalytic cracking of Fushun shale oil,the classes of BNCs in the liquid products remain unchanged,while the classes and relative abundances of NBHCs vary significantly.

Synthesis,characterization and catalytic performance of nanosized iron-cobalt catalysts for light olefins production

Nanosized Fe-Co catalysts were prepared by co-precipitation method and studied for the conversion of synthesis gas to light olefins.In particular,the effects of a range of preparation variables such as Co/Fe molar ratios of the precipitation solution,pH value of precipitate,temperature of precipitation,promoters and loading of optimum promoter on the structure and catalytic performance are investigated.The optimal nano catalyst for light olefins （C2-C4） production was obtained over the catalyst with Co/Fe molar ratio of 3/1 which promoted with 2 wt% K.The results show that the best operational conditions were GHSV=2200 h^-1 （H2/CO=2/1） at 260℃ under atmospheric pressure.Characterization of catalysts were carried out using X-ray diffraction （XRD）,thermal gravimetric analysis （TGA）,differential scanning calorimetry （DSC）,scanning electron microscopy （SEM）,transmission electron microscopy （TEM） and N2 physisorption measurements such as Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods.

Effects of Operating Conditions on the Catalytic Performance of HZSM-5 Zeolites in n-Pentane Cracking

In this work,n-pentane catalytic cracking over HZSM-5 zeolites was studied at 650°C under atmosphere pressure.A particular attention was paid to the measurement of n-pentane conversion,light olefins production,product distribution,coke deposit,etc.Several indexes were defined to evaluate the effects of operating conditions on the catalytic performance of HZSM-5 zeolites.It was found that decreasing the weight hourly space velocity,increasing the reactant partial pressure,and increasing the carrier gas flow rate could inhibit C-H bond breaking and enhance the C-C bond breaking and hydride transfer reactions,leading to reduced alkenes selectivity,which suppressed the formation of external coke and alleviated the deactivation of HZSM-5 zeolites.It was deduced that the catalytic stability of HZSM-5 zeolites was improved at the cost of alkenes selectivity.Compared with decreasing the weight hourly space velocity and increasing the reactant partial pressure,increasing the carrier gas flow rate could enhance the diffusion process and protect alkenes from being consumed in coke formation in order to improve the catalytic stability of HZSM-5 zeolites with less reduction of alkenes selectivity.

Hydrogen Production Performances via Steam Reforming over Hydrotalcite Derived Catalyst: A Sustainable Energy Production Review

The review outcome represents the optimum catalytic conditions for the production of hydrogen using hydrotalcite derived catalysts. It covers dry and steam reforming of methane, steam reforming of methanol and ethanol to hydrogen. The review also revealed the specific properties of hydrotalcite derived catalysts for the reactions. Among catalyst investigated, Ni & Fe promoted Al-Mg containing hydrotalcite catalyst perform best (99%) for dry reforming of methane at 250°C. For steam methane reforming, Ni containing ca-aluminates hydrotalcite catalyst act as the best (99%) at 550°C. Cu-supported Zn-Al-containing catalyst performs the best (99.98%) for steam reforming of methanol at 300°C whereas Cu impregnated Mg-Al containing hydrotalcite is the best (99%) for steam reforming of ethanol at 200°C - 600°C. It’s (HT) tunable and versatile textural and morphological properties showed excellent catalytic performances for different industrial processes and in sustainable hydrogen production.

CATALYTIC PERFORMANCE OF ETHYLENE HYDROFORMYLATION OVER[H_XRu_3(CO)_9(CCO)]^(2-X)/SiO_2-Al_2O_3,SiO_2 AND MgO(X=0-2)CATALYSTS

The various surface species[H_XRu_3(CO)_9(CCO)]^(2-X)(X=0-2)prepared from impregnation of[PPN]_2[Ru_3(CO)_9(CCO)]on SiO_2-Al_2O_3,SiO_2 and MgO show quite different activities and selectivities for oxygenates and ethane in ethylene hydroformylation.

Direct Synthesis,Characterization and Catalytic Performance of Iron-Containing SBA-15 for Phenol Degradation

An iron-containing SBA-15（Fe-SBA-15） has been synthesized via one-pot hydrothermal method under weak acidic conditions. A series of characterizations show nanocomposite materials of iron particles supported over mesostructured materials. The catalytic activity of these iron-containing SBA-15 materials has been tested for the heterogeneous Fenton degradation of phenolic aqueous solutions. The catalytic performance has beta monitored in terms of phenol conversion, whereas the catalytic stability was evaluated by catalyst recycle. The influence of concentration of hydrogen peroxide, catalyst loading, catalyst prepared with different Fe/Si molar ratios in the gel and pH values of the solution on phenol conversion has been studied. Achieving a good catalytic performance accompanied with a noteworthy stability, Fe-SBA-15 materials prepared by this method are shown as the successful catalyst for degradation of phenolic aqueous solutions by Fenton process.

The regulating effect of doping Cu on the catalytic performance of CO oxidative coupling to DMO on Pd_(x)Cu_(y)/GDY:A DFT study

Rely on the density functional theory(DFT)calculation,the catalytic performance of Pd_(x)Cu_(y)/GDY(x=1,2,3,4;x+y≤4)for CO oxidative coupling reaction was obtained.The Pdx/GDY(x=1,2,3,4)are not ideal catalyst for dimethyl oxalate(DMO)formation because byproduct dimethyl carbonate(DMC)is easily formed on Pd_(1)/GDY and Pd_(2)/GDY,and high activation energies are needed on Pd_(3)/GDY and Pd_(4)/GDY.Therefore the second metal Cu is doped to regulate the performance of Pdx/GDY(x=1,2,3,4).Doping Cu not only improve the activity of DMO formation,but more importantly,controlling the ratio of Cu:Pd can effectively regulate the selectivity of DMO.Thus taking into account the activity and selectivity of the reaction for the preparation of DMO by CO oxidative coupling,the Pd_(1)Cu_(1)/GDY and Pd_(1)Cu_(2)/GDY with the activation energies of 105.2 and 99.2 kJ mol^(-1)to generate DMO show excellent catalytic activity and high DMO selectivity,which are considered as good catalysts for CO oxidative coupling.The differential charge density analysis shows the decrease in the charge density of metal clusters is an important reason for improving the selectivity of the catalyst.

Pore Structure and Catalytic Performance of Steam-Dealuminated ZSM-5/Y Composite Zeolites

For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD (X-ray diffraction) characterization indicates that the relative crystallinity of the composite zeolites decreases with the increase in Si/Al ratio after steaming. N2 adsorption-desorption suggests that more mesopores are formed while the BET (Brunauer, Emmett and Teller) specific surface area and the micropore specific surface area decrease as the temperature of steaming rises. Daqing heavy oil was used as feedstock to test the catalytic cracking activity of ZSM-5/Y composite zeolites. The experimental results of the catalytic cracking performance reveal that the distribution of products differs due to the different conditions of hydrothermal treatment. Further hydrothermal treatment leads to an increase in the yield of light oil, and a decrease in the yield of gas products and coke.

Preparation and Catalytic Performance of Microporous Polymer/Au Nanoparticles Composite Microspheres

Polystyrene crosslinked microspheres were prepared by soap-free emulsion polymerization using styrene (St) and divinylbenzene (DVB) as monomers;then,the microporous structure was knitted by the Friedel-Crafts alkylation reaction,and the Au nanoparticles (AuNPs) were loaded into the pores through thermal reduction,to obtain AuNPs/ hyper-crosslinked microporous polymer composite microspheres.SEM and particle-size test results show that the microspheres show good monodispersity.The micropore analysis indicates that the specific surface area and the pore volume of the microporous polymer microspheres decrease with increasing DVB content,and when the DVB content is 0.1%,the specific surface area reaches a maximum of 1 174.6 m2/g.After loading AuNPs,the specific surface area and the amount of micropores of the composite microspheres decrease obviously.The results of XRD and XPS analyses suggest that HAuCl4 is reduced to AuNPs.The composite microspheres show a good catalytic performance for the reduction catalyst of 4-nitrophenol.

CATALYTIC PERFORMANCE OF MIXED-BIMETALLIC RUTHENIUM CARBONYL CLUSTERDERIVED CATALYSTS IN CO HYDROGENATION

The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru- Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivities towards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalysts prepared from homometallic and bimetallic Ru,Ru-Ni,Ru-Rh,Ru-Mn,and Ru- Cr carbonyl clusters.The FTIR investigation revealed that the 1584 cm^(-1) species plays an important role in the formation of oxygenates in CO hydrogenation,which is possibly assigned to surface formyl species.

THE RELATIONSHIPS BETWEEN THE POLARIZING FORCE OF CATIONS AND THE ELECTROPHILIC CHARACTER AND CATALYTIC PERFORMANCES OF PROMOTED Pt-Al_2O_3 CATALYST

The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.