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.

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.

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.

Promoted catalytic performance of Ag-Mn bimetal catalysts synthesized through reduction route

VOCs can exert great harm to both human and environment,and catalytic oxidation is believed to be an effective technique to eliminate these pollutants.In this paper,Ag-Mn bimetal catalysts with 10 wt.%of silver were synthesized using doping,impregnation,and reduction methods respectively,and then they were applied to the catalytic oxidation of benzene.Through series of characterizations it showed that the loading of silver using reduction method significantly resulted in improved physico-chemical properties of manganese oxides,such as larger surface area and pore volume,higher proportion of surface Mn~(3+)and Mn~(4+),stronger reducibility and more active of surface oxygen species,which were all beneficial to its catalytic activity.As a result,the Ag-Mn catalysts synthesized by reduction method showed a lower T_(90)value(equals to the temperature at which 90%of initial benzene was removed)of 203℃.Besides,both the used and fresh Ag-Mn catalysts synthesized by reduction method showed preferable stability in this research.

Mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes synthesized in deep eutectic solvent and their catalytic performances

To develop high-performance metal-organic frameworks(MOFs)for catalysis is of great importance.Here,we synthesized the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)(BTC=benzene-1,3,5-tricarboxylate)nanocubes in a deep eutectic solvent of ZnCl_(2)/ethylene glycol solution.The route can proceed at room temperature and the reaction time needed is shortened to be 30 min,which is superior to the conventional solvothermal route that usually needs high temperature and long reaction time.The formation mechanism of the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes in deep eutectic solvent(DES)was investigated by in situ synchrotron X-ray diffraction/small angle X-ray scattering/X-ray absorption fine structure conjunction technique.The mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes exhibit high catalytic activity and reusability for cyanosilylation reaction of benzaldehyde and aerobic oxidation reaction of benzylic alcohol.

Modulating the local coordination environment of single-atom catalysts for enhanced catalytic performance

The local coordination environment of catalysts has been investigated ftor an extended period to obtain enhanced catalytic performance.Especially with the advancement of single-atom catalysts(SACs),research on the coordination environment has been advanced to the atomic level.The surrounding coordination atoms of central metal atoms play important roles in their catalytic activity,selectivity and stability.In recent years,remarkable improvements of the catalytic performance of SACs have been achieved by the tailoring of coordination atoms,coordination numbers and second-or higher-coordination shells,which provided new opportunities for the further development of SACs.In this review,the characterization of coordination environment,tailoring of the local coordination environment,and their related adjustable catalytic performance will be discussed.We hope this review will provide new insights on further research of SACs.

Highly crystalline core dominated the catalytic performance of carbon dot for cyclohexane to adipic acid reaction

Carbon dots(CDs)have uniquely structural,physicochemical and photochemical properties,suggesting a promising platform for catalysis applications.The in-depth understanding of the structure-activity relationship in the CDs-based catalyst system needs to know the effect of the crystalline core on their catalytic performance.The efficient catalytic oxidation of cyclohexane is an urgent challenge in current chemical industry,in which,adipic acid(AA)plays an important role in industry for synthesis of nylon6 and nylon-66.Here,we fabricated the pristine CDs by electrochemical etching graphite rod method and derived CDs with high crystalline core(CD-600,CD-800,and CD-1100)through a thermal treatment method in tube furnace.Furthermore,these CDs performed an outstanding catalytic performance for one-step synthesis of AA from cyclohexane.With the help of machine learning(ML),the deep correlations between features(structures of CDs,catalytic conditions)and catalytic performances were investigated by XGBoost(XGB)model.Then under the optimization and prediction of XGB,it was found that high crystalline core preceded the other features and CD-1100 could get the best conversion of 30.696%and selectivity to AA of 92.52%at reaction conditions of 130℃,1.5 MPa,and 10 h.This work pioneered the application of ML in industrial issues and demonstrated a comprehensive understanding on CDs as catalyst to realize one-step synthesis of AA.

Effect of WOx promoter on Pt/ZrO2-HMS catalysts for n-heptane isomerization： Catalytic performance and kinetics study

Platinated W/Zr mixed oxides supported on mesoporous silica with various amounts of Si/Zr, namely PtWO_3/ZrO_2([76_TD$IF]x)-HMS, were prepared and studied for n-heptane isomerization reaction at 200–350 C. The various methods such as XRD, XRF, FT-IR, UV–vis DRS, NH_3-TPD, H_2 chemisorption, nitrogen adsorption–desorption, Py-IR, SEM and TGA techniques were used for characterization of these materials. Kinetics of n-heptane isomerization was also investigated under various hydrogen. n-Heptane pressures and the influence of reaction conditions on catalytic performance were studied. The ideal catalytic performance was observed on HMS with 0.6%Pt/12%WO_3/ZrO_2 and Si/Zr = 10.

Influence of the Substituents on Imino-aryl Ring of Mono(imino)pyrrole-NiⅡ Complexes to Their Ethylene Polymerization Catalytic Performance

In order to study the influence of substituents on imino-aryl rings of mono(imino)pyrrole-transition metal complexes to their ethylene polymerization performance,a series of mono(imine)pyrroles(L1-L3)were synthesized by microwave irradiation from 2-acetylpyrrole and a series of 2,6-position disubstituted anilines(substituent:H,Me,Et).A simplified synthetic method was introduced to prepare the corresponding nickel complexes NiL2(1~3)with direct condensation of mono(imine)pyrrole ligands and nickel dichloride.All the compounds were fully characterized by 1 H NMR,IR,EA,MS,and X-ray crystal diffraction.Ligand L3(C16H20N2,Mr=240.34)belongs to the triclinic system,space group P1,with a=7.9606(19),b=9.028(2),c=11.205(3)?,the final R=0.0606 and wR=0.1875.Complex 3(C32H38N4Ni,Mr=537.37)belongs to the monoclinic system,space group C2/c with a=19.811(3),b=11.262(2),c=26.004(4)?,the final R=0.0388 and wR=0.1020.The crystal structures indicated that all the NiⅡcomplexes have similar tetra-coordinated geometries,in which the ligand chelated to the center nickel with a 2:1 molar ratio.Catalytic properties of the NiⅡcomplexes for ethylene polymerization were systematically investigated,and the results showed a regular increase of catalytic activities with steric hindrance of the substituents on the imino-aryl ring of NiⅡcomplexes.

Spectroscopic analysis of acetamide-AlCl_(3)-based ionic liquid analog and their catalytic performance in isobutene oligomerization

The spectral structures of acetamide-AlCl_(3)-based ionic liquid(IL)analogs were determined in detail through IR,NMR,and Raman spectroscopy.IR spectroscopy showed that 0.65AA-1.0AlCl_(3) was the coordination structure of Al and O atoms because of the resonance structure of acetamide.The mutual verification of the results of ^(27)Al NMR and ^(1)H NMR indicated that acetamide coexisted mainly in the form of cationic Al species and molecular Al species in xAA-1.0AlCl_(3),and AA/AlCl_(3) molar ratio affected the transformation of cationic Al species to molecular Al species.xAA-1.0AlCl_(3) was used as a green acidic catalyst for isobutene oligomerization,and the effects of AA/AlCl_(3) molar ratio,reaction temperature,reaction time,and volumetric ratio between IL analog and isobutene on product distribution were investigated.Optimal reaction conditions were AA/AlCl_(3) molar ratio of 0.75,reaction temperature of 60 C,reaction time of 30 min,and catalyst/i-C4¼volumetric ratio of 1.4 v/v.Under optimal conditions,isobutene conversion,(C8^(-)+C12^(-))selectivity,(C16^(-)+C20^(-))selectivity,and by-product selectivity were 85.26,80.20,6.80,and 13.00 wt%,respectively。

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.

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.

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.

Perovskite Oxides in Catalytic Combustion of Volatile Organic Compounds:Recent Advances and Future Prospects

Volatile organic compounds are a kind of important indoor and outdoor air pollutants.In recent years,more and more attention has been paid to the ways of volatile organic compound elimination because of its potential long-term effects on human health.Among the various available methods for volatile organic compound elimination,the catalytic combustion is the most attractive method due to its high efficiency,low cost,simple operation,and easy scale-up.Perovskite oxides,as a large family of metal oxides with their A-site mainly of lanthanide element and/or alkaline earth metal element and B-site of transition metal element,have been extensively investigated as active and stable catalysts for volatile organic compound removal reactions due to their abundant compositional elements,high thermal/chemical stability,and compositional/structural flexibility.The catalytic performance of perovskite oxides is strongly depended on its material composition,morphology,and surface/bulk properties,while the doping,tailored synthesis route,and composite construction may have a significant effect on the bulk(oxygen vacancy concentration,lattice structure),surface(oxygen species,defect)properties,and particulate morphology,consequently the catalytic activity and stability for volatile organic compound removal.Herein,a comprehensive review about the recent advances in perovskite oxides for volatile organic compound elimination reactions based on catalytic combustion is presented from different aspects with a special emphasis on the material design strategies,such as compositional tuning,morphology control,nanostructure building,hybrid construction,and surface modification.At last,some perspectives are presented on the development and design of perovskite oxide-based catalysts for volatile organic compound removal applications by highlighgting the critical issues and challenges.

Performance of mesoporous CeO_(2)-Cr_(2)O_(3) mixed metal oxides applied to benzene catalytic combustion

In this paper,a hydrothermal method was used to prepare(Ce,Cr)-MOF with different Ce/Cr molar ratios and then a series of CeO_(2)-Cr_(2)O_(3) mixed metal oxides(CeCr-MMO)with mesoporous structure were prepared by thermal decomposition of these MOFs at different temperatures.After a series of characterization techniques were applied to test the physicochemical properties of the materials,it is found that thermal decomposition temperature(TDT)and Ce/Cr molar ratios have important effects on the structure and performance of CeCr-MMO.As the TDT reaches 400℃ and above,(Ce,Cr)-MOF can be completely decomposed to form CeCr-MMO.The catalyst with Ce/Cr molar ratio of 4:1 has the highest catalytic activity,which can completely degrade benzene at 230℃.It is concluded that the interaction between CeO_(2) and Cr_(2)O_(3) is helpful for increasing the concentration of Ce^(3+),Cr^(6+) and lattice oxygen species(OLatt)on the catalyst surface,thus improving the catalytic performance.Moreover,CeCr(4:1)-MMO-400 shows excellent durability against the presence of chlorobenzene and H2O during 100 h continuous reaction.

Thermal decomposition effect of MgCo_(2)O_(4)nanosheets on ammonium perchlorate-based energetic molecular perovskites

Energetic molecular perovskites have attracted widespread attention in the fields of energy materials due to their high detonation performance.In this work,we reported the effect of MgCo_(2)O_(4) nanosheets on the thermal decomposition of ammonium perchlorate(NH_(4)ClO_(4),AP)-based energetic molecular perovskites(AP-based energetic molecular perovskites).The morphology and structure of the MgCo_(2)O_(4) nanosheets were characterized.And their catalytic effect on the thermal decomposition of AP-based energetic molecular perovskites(H_2pz)[NH_(4)(ClO_(4))_(3)](PAP-4),(H_2dabco)[NH_(4)(ClO_(4))_(3)](DAP-4),(H_2mpz)[NH_(4)(ClO_(4))_(3)](PAP-M_(4)),and (H_2hpz)[NH_(4)(ClO_(4))_(3)](PAP-H_(4)) was analyzed.The results showed that MgCo_(2)O_(4) nanosheets had excellent intrinsically catalytic performance towards enhancing the thermal decomposition of AP-based energetic molecular perovskites.After adding MgCo_(2)O_(4) nanosheets,the thermal decomposition peak temperatures of PAP-4,DAP-4,PAP-M_(4),and PAP-H_(4) had been reduced by35.7℃,48.4℃,37.9℃,and 43.6℃,respectively.And the activation energy(Ea)of the thermal decomposition of AP-based energetic molecular perovskites had been reduced,the Eaof PAP-H_(4) decreased by 46.4 kJ/mol at most among them.The catalytic mechanism of MgCo_(2)O_(4) nanosheets for AP-based energetic molecular perovskites is analyzed.This work provides a reference for the future application of AP-based energetic molecular perovskites.

Design of Support Effect in the Catalytic Application of Ligand-Protect Gold Clusters

Ligand-protected gold(Au_(n))clusters sometimes need the removal of organic ligands to expose more active sites and reduce steric hindrance in catalytic reactions,and large amount of organic and inorganic materials usually need to be employed as supports to anchor Aun clusters through different interaction mechanisms.Whereas,less comprehensive summaries have been provided about the crucial contribution of various supports to the catalytic performance of the supported Aun clusters.Herein,this review firstly summarizes synthesis methods(e.g.,impregnation and encapsulation processes)for the supported Aun cluster catalysts,and then mainly points out specific contributions of support effect in a great diversity of catalytic reactions,as well as deep interaction mechanisms.Besides,opportunities and challenging issues will be stated towards supported Aun clusters,in terms of improving catalytic performance and structural stability of Aun clusters inthedemand of catalysis.

Study on iron-manganese catalysts for Fischer-Tropsch synthesis

铁锰催化剂被一起沉淀方法准备。催化剂的描述被使用 X 光衍射(XRD ) 执行，扫描电子显微镜学(SEM ) ，温度程序减小(TPR ) ， N2 吸附解吸附作用大小。从 Fischer-Tropsch 合成的催化表演测试的结果证明铁锰催化剂对催化剂作文和材料来源敏感过度。当 CH4 和 CO2 由使用从铁(II ) 准备的铁锰催化剂减少了时， C24 轻石蜡增加了，这被发现当 CH4 和 CO2 由使用从铁(II ) 准备的铁锰催化剂减少了时硫酸盐(催化剂) 。催化剂的活动和选择处于不同运作的条件被学习。结果证明为 C24 轻石蜡生产的最好的运作的条件在 260 点是 H2/CO=1/1 (GHSV=2400 h1 )

Recent advances on the construction of encapsulated catalyst for catalytic applications

In heterogeneous catalytic reactions,supported metal catalysts have attracted increasing attention for the environmental remediation and industrial manufacture due to their inherent catalytic capacity.However,leaching,agglomeration,and poisoning of active metal particles lead to catalyst deactivation,thereby limiting their applications.To avoid this,strategies to protect the active metals from such inactivating processes are major areas of research.Emerging encapsulation strategies,in which active species are coated by protective shells,have proven to be a powerful technology to enhance catalytic performance by creating a well-developed structure about the active catalytic sites.This review highlights the recent advances on preparation method and application of encapsulated catalysts since 2016.Building upon the traditional confinement effect,new categories and extended concepts of encapsulation are introduced.In parallel,effects of encapsulation structure on performance and key factors controlling the structure of encapsulated catalyst are discussed definitely in this review.Finally,future perspectives on opportunities and challenges for further research in the field are given at the end of this paper.

Preparation of porous polyamide 6(PA6)membrane with copper oxide(CuO)nanoparticles selectively localized at the wall of the pores via reactive extrusion

In this study,CuO nanoparticles are pre-modified with styrene-maleic anhydride copolymers(SMAs)of different molecular weights and MAH contents.Then the pre-modified CuO nanoparticles(CuO-SMAs)are added to the PA6/SEBS(Styrene Ethylene Butylene Styrene copolymer)(40/60 wt/wt)polymer blends with a co-continuous morphology.When SMA3(MAH=8 wt%,M_(n)=250000 g/mol)is used to modify CuO nanoparticles,and the grafting degree of SMA3 on the surface of CuO reaches 2.74 wt%,90.71%of the added mCuO-SMA3 nanoparticles can be located at the interface of PA6 and SEBS.A porous PA6 membrane with CuO nanoparticles located at the pore walls can be obtained after the SEBS phase is etched with xylene.The catalytic reaction velocity constant(k)for the reduction of p-nitrophenol in NaBH_(4)solutions with the PA6/mCuO-SMA3 porous membrane can reach 1.0040 min^(-1).This work provides a feasible and straightforward method for the preparation of porous polymer membranes with functional nanoparticles located at the wall of the pores.