Structured NiFe catalysts derived from in-situ grown layered double hydroxides on ceramic monolith for CO_(2) methanation

Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.

Highly controlled structured catalysts for on-board methanol reforming

The on-board methanol steam reforming(MSR) has long been considered as an effective approach to insitu produce hydrogen for fuel cell vehicles(FCVs). However, the conventional MSR catalyst pellets suffer from easy breakage during the vehicle movement, leading to increased pressure drop and reduced system stability. Herein, we introduce an integrated method to prepare the highly controlled structured catalysts based on coupled processes: direct prototyping the structured substrate using digital light processing(DLP) 3D printing technology, in-situ dynamic crystallization of active components assisted by magnetic resonance imaging(MRI) and calcination. The synthesized catalyst owns a gradient layer of active component, and exhibits better MSR performance, higher mechanical strength, reduced pressure drop, higher Cu dispersion and better adhesion of active compounds when compared with the conventional powder and pellet catalysts. The demonstrated successful application proves the feasibility of developed method,which has great potential to be used for preparing precisely other monolithic catalysts with customized structures.

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.

Structured hierarchical Mn–Co mixed oxides supported on silicalite-1 foam catalyst for catalytic combustion

Silicalite-1(S1)foam was functionalized by supporting manganese-cobalt(Mn-Co)mixed oxides to develop the structured hierarchical catalyst(Mn-Co@SlF)for catalytic combustion for the first time.The self-supporting S1 foam with hierarchical porosity was prepared via hydrothermal synthesis with polyurethane(PU)foam as the template.Subsequently,Mn-Co oxide nano sheets were uniformly grown on the surface of S1 foams under hydrothermal conditions to prepare the structured hierarchical catalyst with specific surface area of 354 m^2·g^-1,micropore volume of 0.141 cm^3·g^-1 and total pore volume of 0.217 cm3·g^-1,as well as a good capacity to adsorb toluene(1.7 mmol·g^-1 at p/p0=0.99).Comparative catalytic combustion of toluene of over developed structured catalyst Mn-Co@SlF was performed against the control catalysts of bulk Mn-Co@S1(i.e.,the crushed Mn-Co@SlF)and unsupported Mn-Co oxides(i.e.,Mn-Co).Mn-Co@SlF exhibited comparatively the best catalytic performance,that is,complete and stable toluene conversion at 2480 C over 65 h due to the synergy between Mn-Co oxides and S1 foam,which provided a large number of oxygen vacancies,high redox capacity.In addition,the hierarchical porous structure also improved the accessibility of active sites and facilitated the global mass transfer across the catalyst bed,being beneficial to the catalysis and catalyst longevity.

POLYMORPH CONTROL OF ANTIMONY WHITE(Sb_2O_3)PREPARED BY HYDROMETALLURGY METHOD

The effects of reaction solvent, the properties of Sb 4O 5Cl 2 material and the ligand additives on the reaction rate and polymorph of antimony white(Sb 2O 3) in the reaction of Sb 4O 5Cl 2 transforming into Sb 2O 3 have been investigated by XRD and IR method. It is revealed that the reaction solvent and the properties of Sb 4O 5Cl 2 are the key factors affecting the reaction rate. The polymorph of antimony trioxides is determined by the reaction mechanism, i.e. the coordination state of the antimony activated complex. Adding a little ligand such as EDTA is the most economical and effective method of synthesizing cubic antimony white(Sb 2O 3)in hydrometallurgical transformation process.

Synthesis, Structure and Catalytic Activity of a Palladium(Ⅱ) Complex Based on 4-Chloro-2-[(6-methyl-pyridin-2-ylimino)-methyl]-phenol Ligand

The title complex bis{4-chloro-2-[（6-methyl-pyridin-2-ylimino）-methyl]-phenol}-palladium（Ⅱ）（C_（26）H_（20）Cl_2N_4O_2Pd） has been synthesized by the reaction of 4-chloro-2-[（6-methylpyridin- 2-ylimino）-methyl]-phenol with Pd（CH_3COO）_2, and characterized by IR spectrum and elemental analysis. Single-crystal X-ray diffraction analysis results further confirmed the molecular structures. The crystal belongs to the monoclinic system, space group P2_1/c with a = 4.1324（2）, b = 23.5432（16）, c = 11.8943（8） A, β = 91.238（5）o, V = 1156.93（12） ？~3, C_（26）H_（20）Cl_2N_4O_2Pd, M_r = 597.76, Z = 2, D_c = 1.716 g/cm^3, μ = 1.067 mm^（-1）, F（000） = 600, the final R = 0.0247 and w R = 0.0677（I 〉 2σ（I））. In the presence of methylaluminoxane（MAO）, the complex exhibits excellent catalytic activities（1.737×10~7 g of PNB（mol of Pd）^（-1）·h^（-1）） in the vinyl polymerization of norbornene.

Synthesis, Structure and Norbornene Polymerization Catalyzed by Nickel(Ⅱ) Complex Bearing N,O-bis(1-(6-ethylpyridin-2-ylimino)-methylenyl)naphthalen-2-ol Ligand

The title complex bis{1-{[（6-ethyl-2-pyridinyl）imino]methylenyl}-2-naphthale- nolato-N,O}-nickel（lI） （C36H32NnO2Ni） has been synthesized by the reaction of l-{[（6-ethyl-2- pyridinyl）imino]methylenyl}-2-naphthalenol with Ni（CH3COO）2·4H2O, and characterized by IR spectrum, elemental analysis and TG. The complicated space structure has been confirmed by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 11.410（4）, b = 14.382（4）, c = 18.121（6） ,A, β = 97.147（6）% V= 2950.5（16）A3, C36H32N4O2Ni, Mr = 611.37, Z = 4, Dc = 1.376 g/cm3, μ = 0.698 mm-1 F（000） = 1280, the final R = 0.0519 and wR = 0.1493 （1 〉2σ（I））. This title compound was used as precatalysts for the polymerisation of norbornene. When activated with MAO, the complex exhibited excellent catalytic activity up to 1.98 × 107 g ofPNB （mol of Ni）-1 h-1 with high monomer conversion.

Doping Effect of CuO on CeO_2 for CO Oxidation

Cu-Ce-O catalysts, prepared by the amorphous citrate precursor (ACP) method, wereinvestigated by ICP, XRD and ndcro-reactor techniques. At low copper content of Cu-Ce-Ocatalysts, fluorite structures formed at low calcining temperatures, and Cuo doped into the CeO2matrix; at high copper content, in addition to the fluorite structure, crystalline monoclinic phaseCuO formed as well at high calcining temperatures. There was no other phase formed even calcinedat 1000℃. The results show that only a little CuO dopes into the CeO2 matrix to form complexoxide, which promotes the catalytic activity of CO oxidation greatly. The optimum Cu-Ce-Ocatalyst is composed of 15% copper by Cu/(Ce+Cu) atomic ratio, and calcined at 700℃ for 4h. Thephase compositions include the crystalline CuO and the active complex oxide with fluoritestructure. The formulation of the active complex oxide is Cu0.06Ce0. 94O1.94.

Synthesis and Application of a Zeolite-containing Composite Material Made from Spent FCC Catalyst

Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit.

A Novel Phenoxyimine-based Schiff Base Ligand and Its Mononuclear Nickel(Ⅱ) Complex：Synthesis,Crystal Structure,Norbornene Polymerization and Catalytic Activity

A novel phenoxyimine-based Schiff base ligand and its mononuclear complex [C（58）H（52）N2NiO2]（L = 2-benzhydryl-4-dimethoxy-3,5-dimethyl-salicylaldehyde） has been synthesized and characterized by IR spectrum, elemental analysis, TG, WAXD spectra, ^1H NMR and ^（13）C NMR. In addition, the molecular structure has been measured by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 14.510（6）, b = 18.573（7）, c = 20.961（6） A, β = 123.453（19）°, V = 4713（3）A^3, Mr = 867.73, Z = 4, Dc = 1.223 g/cm^3, μ = 0.456 mm^-1, F（000） = 1832, the final R = 0.0685 and wR = 0.1758（I 〉 2σ（I））. The complex was used as homogeneous catalysis of polymerization of norbornene, and the MAO as cocatalyst. The nickel complex exhibited good catalytic activity up to 1.913 × 10^7 g of PNB（mol of Ni）^-1h^-1,and the yields of these reactions depend on the nature of the substituent in the aromatic ring.

Boosting methylcyclohexane dehydrogenation over Pt-based structured catalysts by internal electric heating

Methylcyclohexane(MCH)serves as an ideal hydrogen carrier in hydrogen storage and transportation process.In the continuous production of hydrogen from MCH dehydrogenation,the rational design of energy-efficient catalytic way with good performance remains an enormous challenge.Herein,an internal electric heating(IEH)assisted mode was designed and proposed by the directly electrical-driven catalyst using the resistive heating effect.The Pt/Al2O_(3)on Fe foam(Pt/Al2O_(3)/FF)with unique threedimensional network structure was constructed.The catalysts were studied in a comprehensive way including X-ray diffraction(XRD),scanning electron microscopy(SEM)-mapping,in situ extended X-ray absorption fine structure(EXAFS),and in situ COFourier transform infrared(FTIR)measurements.It was found that the hydrogen evolution rate in IEH mode can reach up to above 2060 mmol·gPt^(−1)·min^(−1),which is 2–5 times higher than that of reported Pt based catalysts under similar reaction conditions in conventional heating(CH)mode.In combination with measurements from high-resolution infrared thermometer,the equations of heat transfer rate,and reaction heat analysis results,the Pt/Al2O_(3)/FF not only has high mass and heat transfer ability to promote catalytic performance,but also behaves as the heating component with a low thermal resistance and heat capacity offering a fast temperature response in IEH mode.In addition,the chemical adsorption and activation of MCH molecules can be efficiently facilitated by IEH mode,proved by the operando MCH-FTIR results.Therefore,the as-developed IEH mode can efficiently reduce the heat and mass transfer limitations and prominently boost the dehydrogenation performance,which has a broad application potential in hydrogen storage and other catalytic reaction processes.

Effect of Sulfurization Temperature on Thioetherification Performance of Mo-Ni/Al_2O_3 Catalyst

The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins in the thioetherification process using fluidized catalytic cracking(FCC) naphtha as the feedstock was investigated. In order to disclose the correlation between the physicochemical characteristics of catalysts and their catalytic activity, the surface structures and properties of the catalysts sulfided at different temperatures were characterized by the high resolution transmission electronic microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and H2-temperature programmed reduction(H_2-TPR) technique. The results showed that an increase of sulfurization temperature not only could promote the sulfurization degree of active metals on the catalysts, but also could adjust the micro-morphology of active species. These changes could improve the catalytic performance of thioetherification, and hydrogenation of dienes and olefins. However, an excess sulfurization temperature was more easily to upgrade the ability of the catalyst for hydrogenation of olefins, which could lead to a decrease of the octane number of the product. It was also showed that a moderate sulfurization temperature not only could improve the catalytic performance of thioetherification and hydrogenation of dienes but also could control hydrogenation of olefins.

Synthesis, Characterization and Application of A Novel Carbon Bridged Half-metallocene Chromium Catalyst for Methyl Methacrylate Polymerization

A new carbon bridged cyclopentadienyl chromium complex of the type [（C5H4）C（CH3）2 CH2（C5H4N）]CrCl2 was prepared by treatment of CrCl3·（THF）3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis（EA）, and the crystal structure was determined by X-ray diffraction analysis. Activated by Al（i-Bu）3, the chromium complex displayed a very high activity for methyl methacrylate（MMA） polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate（PMMA） with a viscosity average molecular weight（Wη） of 416000 g·mol-1 at 60 ℃ for MMA/ Al（i-Bu）3 /chromium catalyst molar ratio of up to 2000：20：1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.

POLYMERIZATION OF ETHYLENE WITH UNSYMMETRIC 2,6-BIS(IMINO)PYRIDINE IRON(Ⅱ)COMPLEX

An unsymmetric 2,6-bis(imino)pyridine iron(II) complex 1' was synthesized. The relationship between catalyststructure and its activity in ethylene polymerization is discussed. The kinetic behavior of ethylene polymerization and theeffects of polymerization conditions such as temperature, aluminum/iron molar ratio on the activity of catalyst and thecharacteristics of polyethylene were reported. The unsymmetric catalyst 1' has a good catalytic performance of 3.47×10~6 gPE·mol^(-1)·Fe·h^(-1) at 40℃ with aluminum/iron molar ratio = 2500. A dependence of catalyst activity on themethylaluminoxane (MAO) concentration and reaction temperature was found. The molecular weight (MW) of polyethylenewith broad dispersity is about 10~4-10~5 g/mol. The melting temperature and branching of polyethylenes vary with changingreaction temperature and aluminum/iron molar ratio.

Synthesis, Structure and Norbornene Polymerization Activity of a Novel Palladium(Ⅱ) Complex with N,OBis{1-[[(3-methyl-pyridin-2-yl)amino]methyl-phenyl]-2-hydroxy-3,5-di-tert-butylphenol} Ligand

The title complex bis{1-[[（3-methyl-pyridin-2-yl） amino] methyl-phenyl]-2-hydroxy-3,5-di-tert-butylphenol} palladium（C_（42）H_（56）O_2N_4Pd） has been synthesized by the reaction of 1-[[（3-methyl-pyridin-2-yl）amino]methyl-phenyl]-2-hydroxy-3,5-di-tert-butylphenol with Pd（OAc）_2, and was characterized by IR and elemental analyses（C, H, N）. Single-crystal X-ray diffraction analysis of the complex revealed an almost parallelogram geometry of the metal center, space group P1 with a = 12.3870（13）, b = 12.9673（12）, c = 14.3998（4） ？, α = 67.53（2）, β = 75.34（2）, γ = 86.89（3）°, V = 2065.5（3） A3, M_r = 773.32, Z = 2, D_c = 1.243 g/cm^3, μ = 0.489 mm^（-1）, F（000） = 816, the final R = 0.0649 and wR = 0.1567. The compound was investigated for the catalytic behavior towards norbornene（NB） vinyl addition polymerization. And the complex exhibits high catalytic activities up to 1.668 × 10~7 g of PNB（mol of Pd）^（-1） h^（-1） with high monomer conversion using methylaluminoxane（MAO） as the cocatalyst.

Post-treatment of Ti-MWW zeolite with potassium fluoride for propylene epoxidation

Epoxidation of propylene to propylene oxide(PO)with hydrogen peroxide(HPPO)is an environmentally friendly and cost-efficient process in which titanosilicates are used as catalysts.Ti-MWW is a potential industrial catalyst for this process,which involves the addition of HPPO to PO.The silanol groups generated during secondary crystallization unavoidably result in ring-opening of PO and inefficient decomposition of HPPO,which diminish the PO selectivity and the lifespan of Ti-MWW.To address this issue,we conducted post-treatment modifications of the structured Bf-Ti-MWW catalyst with potassium fluoride aqueous solutions.By quenching the silanol groups with potassium fluoride and implanting electron-withdrawing fluoride groups into the Ti-MWW framework,both the catalytic activity and HPPO utilization efficiency were increased.Moreover,the ring opening reaction of PO was prohibited.In a continuous fixed-bed liquid-phase propylene epoxidation reaction,the KF-treated structured Ti-MWW catalyst displayed an exceptionally long lifespan of 2700 h,with a PO yield of 590 g·kg^(-1)·h^(-1).

Hydrochlorination of Acetylene Using SiC Foam Supported Structured C/Au Catalysts

AuCl3 loaded structured catalysts were prepared on SiC foam supported with pre-coated activated carbon layers. The catalytic properties of the structured catalysts towards hydrochlorination of acetylene were tested in a fixed- bed reactor with the AuCl3 loaded on activated carbon pellets as a reference. For isopyknic catalysts, the structured catalyst with only one fifth of the Au amount as that was used on the reference catalyst exhibited even a little higher acetylene conversion and much better stability than the latter no matter what the gas hourly space velocities of acetylene were used. The results indicated that the more homogeneous distribution of AuCl3 particles and better heat transfer along the fixed-bed reactor originated from the low pressure drop and high thermal conductivity of the SiC foam supported structured catalysts might be able to account for their improved efficiency and stability. It is befieved that these novel structured C/Au catalysts can be potentially applied in VCM industrialization in view of their greatly reduced cost and much prolonged life.

Advanced Transmission Electron Microscopy for Identification of Atomic-Scale Configurations of Zeolite-Supported Metal Catalysts

Zeolite-supported metal catalysts have important applications in various catalytic reactions,but unveiling their atomic-scale structures is always a grand challenge.The developed transmission electron microscopy(TEM)characterization techniques,e.g.,integrated differential-phase contrast(iDPC)scanning transmission electron microscopy(STEM)is emerging as a powerful tool for visualizing the electron beam-sensitive materials at atomic resolution,thus,providing new opportunities for imaging the exact configurations of metal species in the various channels of zeolites.This emerging topic summarizes recent progress utilizing iDPC-STEM-related technique for determination of the structures of metal species in zeolites that should offer insights into the structure-property relationships of zeolite-supported metal catalysts.A brief perspective about the new TEM technique is also presented,showing prospects in this field that will stimulate further scientific research in zeolite-supported metal catalysts.

Enhanced catalytic oxidation of dichloromethane by a surfactant-modified CeO_(2)@TiO_(2) core-shell nanostructured catalyst

Surfactant-modified CeO_(2)@TiO_(2) core-shell nanostructure catalysts were prepared by coprecipitation with the addition of sodium dodecyl sulfonate(SDS),and their catalytic oxidation of dichloromethane(DCM) was studied.A 90% DCM conversion efficiency is obtained at 300℃ with the CeO_(2)@TiO_(2)SDS catalyst,and its catalytic stability in the 55 h test period is better than that of Ce/TiO_(2) and CeO_(2)@TiO_(2).Based on the characterization of CeO_(2)@TiO_(2)SDS,the dispersion of active components is promoted due to the inhibition of crystal growth with the introduction of SDS.The improvement of surface acidity and redox capacity is beneficial to the enhancement of catalytic activity.The higher adsorbed oxygen content on the surface of the CeO_(2)@TiO_(2)SDS catalyst is responsible for the better catalytic stability.Generally,a novel method was developed to design catalytic oxidation catalysts for the treatment of chlorinated volatile organic compounds in future applications.

Effect of CeO_2 and Al_2O_3 on the activity of Pd/Co_3O_4/cordierite catalyst in the three-way catalysis reactions(CO/NO/C_nH_m)

The present article studies the effect of CeO2 and A1203 on the activity of Pd/Co304/cordierite catalyst in conversion of NO, CO, CnHm. The catalysts were characterized by temperature programmed reduction with hydrogen, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. It is shown that the effect of CeO2 on the properties of Pd/C03 O4/cordierite catalyst depends on preparation method. The catalyst obtained by co-deposition of cerium and cobalt oxides has higher activity in CO oxidation （CO ＋ 02 and CO ＋ NO） and total hexane oxidation （C6H14 ＋ 02）. Such phenomenon is probably caused by more than stoichiometric amount of formed oxygen vacancies, an increase in both mobility of surface oxygen and dispersity of components in the catalytic composition. It is demonstrated that CeO2 addition promotes the SO2 resistance of Pd/C03 O4/cordierite. The second support decreases the activity of Pd/Co3Oa/cordierite catalyst in the reactions of CO and C6H14 with oxygen because of COA1204 formation.