Preparation and properties of zirconia nanotube-supported 12-tungstophosphoric acid catalyst

Zirconia nanotube-supported H₃PW₁₂O₄0 (HPW) catalysts exhibit high catalytic activities in the synthesis of fatty acid ethyl ester.     

氧化铝负载的银纳米颗粒高选择性催化合成亚胺(英)

The oxidative dehydrogenation of alcohols to aldehydes catalyzed by Ag nanoparticles supported on Al₂O₃ was studied.The catalyst promoted the direct formation of imines by tandem oxidative dehydrogenation and condensation of alcohols and amines.The reactions were performed under mild conditions and afforded the imines in high yield（up to 99%） without any byproducts other than H₂O.The highest activity was obtained over 5 wt%Ag/Al₂O₃ in toluene with air as oxidant.The reactions were also performed under oxidant-free conditions where the reaction was driven to the product side by the production of H₂ in the gas phase.The use of an efficient and selective Ag catalyst for the oxidative dehydrogenation of alcohol in the presence of amines gives a new green reaction protocol for imine synthesis.     

Magnetic graphene nanocomposite as an efficient catalyst for hydrogenation of nitroarenes

Graphene-Fe₃O₄ nanocomposite（G-Fe₃O₄） was synthesized by a chemical co-precipitation method which was used as an efficient catalyst for the reduction of nitroarenes with hydrazine hydrate.The method has been applied to a broad range of compounds with different properties and the yields were in the range of 75%-92%.The G-Fe₃O₄ catalyst can be readily recovered and reused 5 times without significant loss of the catalytic activity.     

The efficient synthesis of 14-alkyl or aryl 14H-dibenzo[a,j]xanthenes catalyzed by bismuth(Ⅲ)chloride under solvent-free conditions

An efficient method for the synthesis of 14-alkyl or aryl 14H-dibenzo[a,j]xanthene derivatives by the reaction of β-naphthol,and aldehydes in the presence of a catalytic amount of bismuth（Ⅲ） chloride（BiCl₃） under solvent-free conditions at 110℃is described.Aliphatic and aromatic aldehydes were used in the reaction and in all cases the desired products were synthesized successfully.This reaction was studied under different temperatures;the maximum yield was obtained in a short reaction period at 110℃.The method offers the advantages of high yields,short reaction times,simplicity and easy workup compared to the conventional method of syntheses.     

Oxidation of alcohols to aldehydes and ketones using selenium ionic liquid

A new type of ionic liquid supported selenium reagents were synthesized and found to be an excellent catalyst in the oxidation of alcohols to aldehydes and ketones in the presence of 30%H₂O₂.The predictable solubility of ionic liquids allows an easy separation of the oxidation products from the reaction mixture.Furthermore,the oxidation reaction can be carried out using an ionic liquid as the solvent,and the ionic liquid-supported selenium reagents can be recycled and used for four times with a little decrease in catalytic performance.     

A novel magnetic silica supported spinel ferrites NiFe2O4 catalyst for heterogeneous Fenton-like oxidation of rhodamine B

As the heterogeneous Fenton-like catalyst, a series of spinel ferrites magnetic nanoparticles NiFe₂O₄ and NiFe₂O₄@SiO₂ catalysts were synthesized and were applied into the oxidation of rhodamine B, which exhibited the good catalytic performance and strong magnetic separation after reaction.     

Catalytic effect of lucunary heteropolyanion containing molybdenum and tungsten atoms on decolorization of direct blue 71

In this research,a lucunary Keggin structure,[PMo₂W₉O₃₉]^7- was selected as an efficient homogenous catalyst for degradation of an azo dye（direct blue 71） and a simple method was developed for degradation of DB71.The method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates,K₇[PMo₂W₉O₃₉]? 19H₂O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H₂O₂,pH and reaction time were investigated and optimized. Results show that K₇[PMo₂W₉O₃₉]? 19H₂O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H₂O₂ could lead to the disappearance approximately 65%of dye after 60 min.But degradation for the same experiment performed in the absence of catalyst or in the absence of H₂O₂ was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H₂O₂ and optimize conditions(0.6 g/L of K₇[PMo_2- W₉O₃₉H₉H₂O,0.08 mol/L hydrogen peroxide and room temperature).     

Transition-Metal-Free Catalyzed Dehydrative Coupling of Quinoline and Isoquinoline N-Oxides with Propargylic Alcohols

A novel,green,and transition-metal-free protocol for the facile modification of quinoline and isoquinoline derivatives is introduced,starting from readily available and environmentally benign quinoline and isoquinoline N-oxides with propargylic alcohols in the presence of Na₂S₂O₈ or K₂S₂O₈ at 100℃.The one-pot transformation features the advantages of good functional group compatibility,short reaction time,operational simplicity,and highly efficient reaction system.This protocol,which produces water as the only byproduct,provides efficient and atom-economical access to a class of fascinating quinoline and isoquinoline products in satisfactory yields.The method is effective on the gram scale,thus highlighting the inherent practicality of this methodology.     

Tetrabutylammonium salts of tritransition-metal-substituted A-α-tungstogermanate:Halogen-free and single-component catalysts for the coupling reaction of carbon dioxide and epichlorohydrin

The green synthesis of chloropropylene carbonate via the coupling reaction of carbon dioxide and epichlorohydrin had been achieved using halogen-free and single-component catalysts tetrabutylammonium salts of tritransition-metal-substituted A-α-tungstogermanate [（n-C₄H₉）₄N]₃H₇GeW₉M₃（H₂O）₃O₃₇（M = Cu^Ⅱ,Ni^Ⅱ,Co^Ⅱand Mn^Ⅱ） without any solvent.The catalytic activity was significantly depended on the transition metal introduced in polyoxometalates.[（n-C₄H₉）₄N]₃H₇GeW₉Mn₃（H₂O）₃O₃₇ exhibited the highest catalytic activity with 94.9%conversion for epichlorohydrin and 98%selectivity for chloropropylene carbonate in 3 h.Plausible mechanism was proposed based on the results.     

Epoxy ether cleaving reactions catalyzed by supporting Lewis acidic ionic liquid

Lewis acidic ionic liquids were used to catalyze the reaction of epoxypropane with POCl₃.Considering the lower cost and catalytic activities,we concluded that[Et₃NH]Cl/AlCl₃ was the most attractive ionic liquid from an economical point of view.But it would be easily inactivated because of sensitive to water and air.Moreover,it could not be reused easily because of difficulty recovery in the reaction.However,supporting[Et₃NH]Cl/AlCl₃ catalyst could resolve above problems.Supporting[Et₃NH]Cl/ AlCl₃ catalyst could be separated by filter easily and reused 5 times in 98%yield.Furthermore,the catalyst was applicable to other epoxy ether cleaving reactions.     

H4SiW12O40: An efficient catalyst for the synthesis of new spiro- [dibenzo[a, i]xanthene-14, 3'-indoline]-2', 8, 13-triones

Novel spiro[dibenzo[a,i]xanthene-14,3’-indoline]-2’,8,13-triones were prepared by the three-component reaction ofβ-naphthol, isatins,and 2-hydroxy-1,4-naphoquinone in the presence of a catalytic amount of H₄SiW₁₂O₄₀.This protocol provides a simple one-step procedure with the advantages of easy work-up,mild reaction conditions and environmentally benign.     

负载型钌催化剂催化山梨醇氢解制乙二醇(英)

Supported Ru catalysts were prepared by wet impregnation to evaluate the role of different oxide supports（Al₂O₃,SiO₂,TiO₂,ZrO₂） in sorbitol hydrogenolysis to glycols.X-ray diffraction,transmission electron microscopy,hydrogen chemisorption,X-ray photoelectron spectroscopy,and NH3temperature-programmed desorption were used to characterize the catalysts,which were active in the hydrogenolysis of sorbitol.The support affected both the physicochemical properties and catalytic behavior of the supported Ru particles.The characterization results revealed that the Ru/Al₂O₃catalyst has a high surface acidity,partially oxidized Ru species on the surface,and a higher surface Ru/Al atomic ratio,which gave it the highest selectivity and yield to glycols.     

Regeneration of C4H10 dry reforming catalyst by nonthermal plasma

Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons.An effort was made to regenerate the catalyst（Ni/7-alumina） by oxidation methods.Two approaches were carried out for the regeneration of the deactivated catalyst.The first one involves the plasma treatment of the deactivated catalyst in the presence of dry air over a temperature range of 300～500℃,while the second one only the thermal treatment in the same temperature range.The performance of the regenerated catalyst was evaluated in terms of C₄H₁₀ and CO₂ conversions and the physicochemical characteristics were examined using a surface area analyzer,an elemental analyzer,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.It was observed that the carbon deposit （coke） on the catalyst was about 9.89 wt%after reforming C₄H₁₀ for 5 h at 540℃.The simple thermal treatment at 400℃reduced carbon content to 6.59 wt%whereas it was decreased to 3.25 wt%by the plasma and heat combination.The specific surface area was fully restored to the original state by the plasma-assisted regeneration at 500℃.As far as the catalytic activity is concerned,the fresh and regenerated catalysts exhibited similar C₄H₁₀ and CO₂ conversion efficiencies.     

Study on the Different Photocatalytic Performances for Tetracycline Hydrochloride Degradation of p-block Metal Composite Oxides Sr_(1.36)Sb_2O_6 and Sr_2Sb_2O_7

p-block metal composite oxides Sr_1.36Sb₂O₆ and Sr₂Sb₂O₇ synthesized by a hydrothermal method as photocatalysts in the degradation of tetracycline hydrochloride under UV light irradiation have been extensively studied.The effects of synthesis conditions on the photocatalytic activity were discussed.The Sr_1.36Sb₂O₆-100°C-24 h-5 and Sr₂Sb₂O₇-150℃-24 h^-2 samples prepared under optimal conditions exhibited remarkably different photocatalytic activities.The essential factors influencing the difference of photocatalytic performance were revealed.The results showed that the different photocatalytic activities observed for Sr_1.36Sb₂O₆and Sr₂Sb₂O₇ could be attributed to their different electronic and crystal structures.Our work will provide a new perspective for the screening and design of p-block metal composite oxide photocatalysts to enhance the removal of organic pollutants in the environment.     

Supramolecular assembly of Keggin polyoxomolybdate and 2,2’-bipyridine generated in situ from a decarboxylation coupling reaction

An assembly of Keggin polyoxomolybdate and organic substrate（Hbipy）₃[PMo₁₂O₄₀]（1,bipy=2,2’-bipyridine） was synthesized and characterized by elemental analysis,infrared spectrum,and single-crystal X-ray analysis.The ligand bipy of compound 1 was generated by a decarboxylation coupling reaction of H₂pdc（H₂pdc=pyridine-2,6-dicarboxylic acid） in situ under hydrothermal reaction conditions and the control experiments illustrate that La（NO₃）₃ or Ce（NO₃）₃,which does not appear in the final structure,is necessary for the decarboxylation coupling reaction.Moreover,compound 1 displays strong photoluminescence property in the solid state at room temperature.     

Methane conversion under cold plasma over Pd-containing ionic liquids immobilized on γ-Al2O3

Pd-containing ionic liquid（IL） 1-hexyl-3-methylimidazolium tetrafluoroborate（C₆MIMBF₄） immobilized on 7-Al₂O₃（Pd-IL/γ-Al₂O₃） was prepared and characterized by Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM） and Brunauer-Emmett-Teller （BET） analysis.The influences of C₆MIMBF₄ loading and Pd on methane conversion to C₂ hydrocarbons under cold plasma were investigated.FTIR and SEM analyses indicated that C₆MIMBF₄ had been successfully immobilized on 7-Al₂O₃ and the C₆MIMBF₄ showed excellent stability under cold plasma.The results of BET and methane conversion showed that with the increase in immobilization amount of C₆MIMBF₄ ontoγ-Al₂O₃,the specific surface area and pore volume of IL/γ-Al₂O₃ decreased,while the selectivity and yield of C₂ hydrocarbons increased.The selectivity of C₂ hydrocarbons was 94.6%when the loading of C₆MIMBF₄ was 40%,and the percentage of C₂H₄ in C₂ hydrocarbons was as high as 64%when using Pd-IL/γ-Al₂O₃ as a catalyst with no conventional thermal reduction treatment. Optical emission spectra（OES） from the cold plasma reactor during methane conversion were also studied.The results indicated that the intensity of the C₂,CH,H,and C active species from methane and hydrogen decomposition increased when IL/γ-Al₂O₃ or Pd-IL/γ-Al₂O₃ was introduced into the plasma system.Based on the analyses of the gas product and OES spectra,it can be concluded that the surface catalyzed reactions between plasma and ionic liquid were very important for the reduction of Pd²⁺ and the formation of C₂H₄.     

Rational design of hollow oxygen deficiency-enriched NiFe2O4@N/rGO as bifunctional electrocatalysts for overall water splitting

Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Herein,hollow oxygen deficiency-enriched NiFe₂O₄ is synthesized by pyrolytic FeNi bimetallic MOF.The defects of rGO during carbonization can act as nucleation sites for FeNi particles.After nucleation and N doping,the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/rGO.These deposited carbon,like a bridge,connect N/rGO and hollow oxygen deficiency-enriched NiFe₂O₄ together,which giving full play to the advantages of N/rGO in fast electron transfer,thereby improving its catalytic activity.The resultant NiFe₂O₄@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm^-2 for OER and 157 mV at 10 mA cm^-2 for HER in 1 M KOH,respectively.When used as bifunctional electrodes for overall water splitting,it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm^-2,respectively.     

Operando HERFD-XANES and surface sensitive Δμ analyses identify the structural evolution of copper(Ⅱ) phthalocyanine for electroreduction of CO2

The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO₂reduction reaction is challenging.Due to the complexity of catalytic systems,conventional in situ X-ray spectroscopy plays a limited role in tracing the underlying dynamic structural changes in catalysts active sites.Herein,operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy was used to precisely identify the dynamic structural transformation of well-defined active sites of a representative model copper(Ⅱ)phthalocyanine catalyst which is of guiding significance in studying single-atom catalysis system.Comprehensive X-ray spectroscopy analyses,including surface sensitive△μspectra which isolates the surface changes by subtracting the disturb of bulk base and X-ray absorption near-edge structure spectroscopy simulation,were used to discover that Cu species aggregated with increasing applied potential,which is responsible for the observed evolution of C₂H₄.The approach developed in this work,characterizing the active-site geometry and dynamic structural change,is a novel and powerful technique to elucidate complex catalytic mechanisms and is expected to con tribute to the rational design of highly effective catalysts.     

Optimizing the electronic structure of Fe-doped Co3O4 supported Ru catalyst via metal-support interaction boosting oxygen evolution reaction and hydrogen evolution reaction

Metal-support interaction(MSI) is an efficient way in heterogeneous catalysis and electrocatalysis to modulate the electronic structure of metal for enhanced catalytic activity. However, there are still great challenges in promoting the hydrogen evolution reaction(HER) and oxygen evolution reaction(OER) simultaneously by this way. Herein, Fe-doped Co₃O₄ supported Ru(Ru/FeCo) catalysts are synthesized by MSI strategies to further improve the electrocatalytic activity and sta...     

NiSe2-CoSe2 with a Hybrid Nanorods and Nanoparticles Structure for Efficient Oxygen Evolution Reaction

Hetero-structure induced high performance catalyst for oxygen evolution reaction(OER)in the water splitting reaction has received increased attention.Herein,we demonstrated a novel catalyst system of NiSe₂-CoSe₂ consisting of nanorods and nanoparticles for the efficient OER in the alkaline electrolyte.This catalyst system can be easily fabricated via a low-temperature selenization of the solvothermal synthesized NiCo(OH)x precursor and the unique morphology of hybrid nanorods and nanoparticles was found by the electron microscopy analysis.The high valence state of the metal species was indicated by X-ray photoelectron spectroscopy study and a strong electronic effect was found in the NiSe₂-CoSe₂ catalyst system compared to their counterparts.As a result,NiSe₂-CoSe₂ exhibited high catalytic performance with a low overpotential of 250 mV to reach 10 mA·cm^-2 for OER in the alkaline solution.Furthermore,high catalytic stability and catalytic kinetics were also observed.The superior performance can be attributed to the high valence states of Ni and Co and their strong synergetic coupling effect between the nanorods and nanoparticles,which could accelerate the charge transfer and offer abundant electrocatalytic active sites.The current work offers an efficient hetero-structure catalyst system for OER,and the results are helpful for the catalysis understanding.