Amorphous Cu0 on Carbon Nanofiber as Recyclable Heterogeneous Catalyst for N-Arylation Reactions

A novel heterogeneous catalyst,amorphous Cu^0 on the carbon nanofibers was developed and characte-rized by means of several characterization techniques.The prepared Cu^0 was investigated as a heterogeneous catalyst for N-arylation reaction.The results show it is an excellent catalyst with recyclability,high consistency and catalytic activity.After the catalyst was used for 5 cycles in the N-arylation reaction,amorphous Cu^0 reunited into crystalline copper nanoparticles with different particle sizes and its good heterogeneity in the catalytic system was confirmed after the catalyst recovery.     

Influence of Aging Time on the Properties of Precursors of CuO／ZnO Catalysts for Methanol Synthesis

The aging process of pure copper precursors and copper-zinc binary precursors were studied by XRD, TG-DTG and TPR techniques. The catalytic activity and stability of CuO/ZnO were tested using fixed-bed flow reactor, and the physical properties of the catalysts and Cu species were characterized with N2 adsorption and N2O passivation method, respectively. For the Cu-Zn binary system prepared at the precipitating condition of pH=8.0 and temperature=80℃, the initial phase was a mixture of copper nitrate hydroxide Cu2(NO3)(OH)3, georgeite and hydrozincite Zn5(CO3)2(OH)6. By increasing the duration of its aging time, the phase of Cu2(NO3)(OH)2 first transited to georgeite, and then interdiffused into Zns(CO3)2(OH)6 and resulted in two new phases: rosasite (Cu,Zn)2CO3(OH)2 and aurichalcite (Zn,Cu)5(CO3)2(OH)6. The former phase was much easier to be formed than the latter one, while the latter phase was more responsible for the activity of methanol synthesis than the former one. It is found that the composition and structure of the precursors altered obviously after the colour transition point. The experimental results showed that methanol synthesis is a structure-sensitive catalytic reaction.     

Morphology Control and Catalytic Dehydrogenation Performance of Zeolitic Imidazolate Frameworks-8北大核心CSCD

Zeolitic imidazolate frameworks-8（ZIF-8）is a kind of porous material with large specific surface area and strong stability,which is widely used in gas storage,separation,catalysis and other fields. In this work,the effect of different reaction conditions,such as the molar ratio of Zn2+ to 2-methylimidazole,the amount of surfactant and the reaction solvents,on the size and morphology of ZIF-8 were reported. Among these conditions,the molar ratio of Zn2+ to 2-methylimidazole is the key factor affecting the size and morphology of ZIF-8. The synthesized ZIF-8 nanoparticles were characterized by SEM,BET and XRD. The size of ZIF-8 decreases gradually from 1500 nm to 850 nm then to 250 nm,and the morphology changes from truncated hexahedron to truncated dodecahedron and finally to dodecahedron. The specific surface area of ZIF-8 nanoparticles with a particle size of 250 nm is 1730 m2/g,and the pore size and pore volume are 1. 5 nm and 0. 6 cm3/g,respectively. Therefore,it can be seen that ZIF-8 nanoparticles with a particle size of 250 nm have excellent carrier characteristics. The impregnation method was further adopted to synthesize the supported catalyst,and boron ammonia was used as the reducing agent. The ZIF-8（250 nm）nanoparticles were loaded with metals/precious metal nanoparticles in situ,the component optimization and catalytic performance were further studied. The obtained catalyst ZIF-8/Pt0. 002@Ni0. 2 shows excellent performance in hydrogen generation from aminoborane. © 2022, Science Press (China). All rights reserved.     

Effect of Solvents on Oxidation of 1,1′-Bi-2-naphthol

A novel biomimetic catalyst of complex Cu(p-OTs)2/ethanolamine(1∶1) was used to oxidize 1,1′-bi-2-naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide(DMSO) and CH3OH. The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H2O in the mixed solvents of H2O and DMSO. No product can be obtained when the content of H2O is up to 70%. The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)2/ethanolamine(1∶1) is reduced via a two-step one-electron reduction process from Cu(Ⅱ) to Cu in the mixture of DMSO and H2O. Water as a poor solvent in respect to the reactants probably hampered the coordination of 1,1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs)2/ethanolamine(1∶1).     

Effect of Solvents on Oxidation of 1, 1′-Bi-2-naphthol

A novel biomimetic catalyst of complex Cu (p-OTs)2/ethanolamine (1 : 1 ) was used to oxidize 1, 1′-bi-2naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide (DMSO) and CH3OH. The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H2O in the mixed solvents of H2O and DMSO. No product can be obtained when the content of H2O is up to 70%. The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)2/ethanolamine(1:1) is reduced via a twostep one-electron reduction process from Cu (Ⅱ) to Cu in the mixture of DMSO and H2O. Water as a poor solvent in respect to the reactants probably hampered the coordination of 1, 1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs),/ethanolamine(1:1).     

纳米晶PbTiO3负载CuO催化NO分解

A large specific surface area perovskite-type mixed oxide PbTiO₃ supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H₂-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO₃ was inactive for the reactions, but 1wt % Cu/PbTiO₃ catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO₃. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO₃ support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.     

EFFECT OF La AND Zr ON THE CATALYTIC PERFORMANCE OF SUPPORTED COPPER CATALYST FOR DEHYDROGENATION OF METHANOL TO METHYL FORMATE

The catalytic dehydrogenation of methanol over supported Cu/SiO_2and Cu/Al_2O_3 prepared by impregnation and by ion-exchange (Cu/SiO_2(im),Cu/Al_2_3(im) and Cu/SiO_2(ex)), La_2O_3 and ZrO_2 promoted Cu/SiO_2 or Cu/Al_2O_3 catalyst has been studied in a fixed bed microreactor at 250℃ and atmo-spheric pressure. The Cu/SiO_2 (ex) catalyst was found to be very active and se-lective toward methyl formate (MF). However, Cu/SiO_2(im) catalyst wasless active and selective among the studied catalysts. The catalytic activity, MFselectivity and MF yield over Cu/SiO_2 And Cu/Al_2O_3 are greatly improved byLa and Zr. XPS and XRD results suggest that the crystallite size of copper wasreduced by coating La and Zr, the surface Cu/Si or Cu/Al atomic ratio in-creased. TPR results show when the support was coated with La and Zr thepeak temperatures of catalysts significantly decreased.     

Transformation of Structure and Properties of Vesicles Induced by Transition Metal Ions

This paper proved that octodecyl propylenediamine could form vesicles in pure water and aqueous solution of CuCl2 or Cu（NO3）2. The structure and morphology of vesicles were different when the copper （Ⅱ） salt was added to the solution. The results showed that both the counterions and the ligands had strong influence on the configuration of coordinated structures and packing model in bilayer membrane of vesicles.     

Copper-cobalt Bimetallic Oxides-doped Alumina Hollow Spheres:a Highly Efficient Catalyst for Epoxidation of Styrene

Copper-cobalt bimetallic oxides-doped alumina hollow spheres(CuCo/AHS)were labricatcd through the sacrificial carbonaceous template strategy.The dependence of the physicochemical properties and morphologies of CuCo/AHS on the composition of copper and cobalt in CuxCoy/AHS(x/y=9/1,7/3,5/5,and 3/7)was characterized bv means of X-ray powder diffraction,nitrogen physisorption,atomic adsorption spectroscopy,scanning electron microscopy,transmission electron microscopy and X-ray photoelectron spectroscopy.Among these catalysts, Cu7-Co3/AHS catalyst exhibited perfect hollow sphere structure,thin wall,and big pore size.The calcined catalysts were examined for the epoxidation of styrene with tert-butyl hydroperoxide as oxidant.Compared with the monometallic counterparts(Cu/AHS and Co/AHS)and other CuxCoy/AHS catalysts,Cu7Co3/AHS catalyst showed higher performance,yielding a styrene conversion of 64.6% with 93.0% selectivity toward styrene oxide.In addition,the strong interaction of Cu^2+or Co^2+ with AHS ensured good stability after four consecutive reactions.     

手性铜(Ⅱ)-席夫碱配合物催化苯乙烯不对称环丙烷化反应

Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl diazoacetate. It was found that the substituents at 3 and 5 positions of salicylaldehyde in the ligands had great effects on catalytic activity and enantioselectivity of the catalyst. The complex with strong electron withdrawing group (NO 2) at 5 position and the smallest stereo hinder (H) at 3 position of salicylaldehyde showed highly catalytic activity and enantioselectivity, up to ee =87 4% for trans and ee =82 8% for cis isomers respectively, and the ratio 39/61 of cis to trans isomers was obtained at 40 ℃ with 1,2 dichloroethane as solvent.     

Trihydrated Complex of Tetrabenzimidazole Copper(Ⅱ) Sulfate

A Trihydrated complex of benzimidazole copper(Ⅱ) sulfate [(C7H6N2)4CuSO4]·3H2O was synthesized and structurally characterized. The crystal structure of this compound is built up of six solvated water molecules and two dissimilar copper ions identified as Cu1 and Cu2. The coordination geometry of copper(Ⅱ) is a slightly distorted square pyramid. The four equivalent tertiary nitrogen atoms of the benzimidazole ligand form an equatorial plane, while the oxygen atoms of sulfato occupy the axial site. In the solid state, the title compound forms a three dimensional network structure via hydrogen bonds. The benzimidazole, sulfato ion and H2O moieties are connected by the intermolecular hydrogen bonds. The (EPR) spectrum shows axial symmetry with g⊥=2.039 and g∥=2.285. Variable temperature magnetic susceptibility shows that there is a weak antiferromagnetic interaction between the neighboring copper(Ⅱ) ions.     

Copolymerization of Ethylene/1-Butene with Heterogeneous TiCl4/(α-Diimine)nickel(Ⅱ) Complex Combined Catalyst

The new type heterogeneous combined catalyst system TiCl4-(α-diimine)nickel(Ⅱ) complexes/MgCl2-SiO2/AlR3 was prepared. Ethylene and 1-butene were copolymerized with the catalysts in slurry phase. It was found that with combined catalyst, the copolymers with lower density and higher branched degree were obtained. 13CNMR results showed that in the obtained copolymers existed not only ethyl but also some other kinds of branches due to the fact that ethylene exhibits the behavior of oligomerization and copolymerization in-situ with combined catalysts.     

高效可回收多相催化剂SiO_2-Cu_2O催化伯胺和仲胺苄基化反应(英文)

A mild,effective,and selective procedure is reported for the mono N-benzylation and N,N-dibenzylation of primary amines as well as mono N-benzylation of secondary amines using silicasupported copper(I) oxide in water.The silica-supported Cu2O was generated in situ by the reaction of Fehling solution and glucose at 100 °C onto activated silica.The catalyst was filtered,washed with water,and oven-dried,and was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy,transmission electron microscopy,and atomic absorption spectroscopy.The prepared Cu2O-SiO2 was found to be thermally stable up to 325 °C.The copper was uniformly distributed onto the surface of the silica,and the mean particle diameter was 7 nm.The catalyst served as a selective heterogenous catalyst for the N-benzylation of primary and secondary amines.The catalyst is recyclable and was used effectively upto fifth run without a significant loss of catalytic activity.Various reaction solvents including water,acetonitrile,and toluene were screened for N-benzylation of amines,and the success of the aqueous system highlights the low environmental impact of the procedure.     

Catalytic transfer hydrogenation of levulinate ester intoγ-valerolactone over ternary Cu/ZnO/Al_2O_3 catalyst

An effective catalytic transfer hydrogenation(CTH) process of bio-based levulinate esters into γ-valerolactone(GVL) was explored over ternary Cu/ZnO/Al_2O_3 catalyst which was prepared by coprecipitation method and could be sustainably used. As a result, quantitative conversion of ethyl levulinate(EL) and 99.0% yield of GVL were obtained in the CTH process using i-PrOH as hydrogen donor.The Cu/ZnO/Al_2O_3 catalyst with high-surface-area could be reused at least four times without the loss of catalytic activity. Furthermore, the structure and properties of Cu/ZnO/Al_2O_3 catalyst was characterized through XRD, BET, SEM, TEM and H_2-TPR. Also, the influence of different support oxides and calcination temperatures was investigated.     

Preparation, Characterization and Catalytic Properties of S2O8^2-／ZrO2 Supported by Tungsten Carbide

A WC-supported S2O8^2-/ZrO2(PSZ) catalyst was prepared and characterized by means of XRD, BET, FTIR and XPS. The isomerization of n-pentane over the catalyst was investigated as well. The results show that the skeletal isomerization and the crack of n-pentane proceed simultaneously on WC-supported S2O8^2-/ZrO2 catalyst. The addition of tungsten carbide showed a significant enhancement in the activity and stability of the catalyst for n-pentane isomerization. The catalyst showed evidently a better activity than S2O8^2-/ZrO2 supported by Pt and WO3. The results can be interpreted by the existence of the tungsten oxycarbide compound(WCxOy) with carbidic, oxide and acidic sites.     

An IR Study on Adsorption of CO and NO on Copper Ion-exchanged Zeolite Beta

Thee adsorption of CO and NO on copper ion-exchanged zeolite Beta was investigated using IR method.It was found that the thermalvacuum pretreatment procedure could result in the reduction of Cu2 ions in zeolite Beta.The adsorption of CO on Cu sites in zeolite Beta closely follows Langmuir isotherm.Another Cu species may form during the reaction between water and CO.The catalytic decomposition of NO on the zeolite was observed at room temperature,indicating that the decomposition reaction may occur between two coordinated NO ligands of the same dinitrosyhc complex.Furthermore,the appearance of two series of NO adsorption bands reveals that copper ions existing at different cation sites may have different effect on the adsorption and decomposition of NO molecules.     

Selective catalytic oxidation of NO with O2 over Ce-doped MnOx/TiO2 catalysts

A series of Ce-doped MnOx/TiO2 catalysts were prepared by impregnation method and used for catalytic oxidation of NO in the presence of excess O2. The sample with the Ce doping concentration of Ce/Mn=1/3 and calcined at 300°C shows a superior activity for NO oxidation to NO2. On Ce(1)Mn(3)Ti catalyst, 58% NO conversion was obtained at 200°C and 85% NO conversion at 250°C with a GHSV of 41000 h-1, which was much higher than that over MnOx/TiO2 catalyst (48% at 250°C). Characterization results implied that the higher activity of Ce(1)Mn(3)Ti could be attributed to the enrichment of well-dispersed MnOx on the surface and the abundance of Mn3+ and Ti3+ species. The addition of Ce into MnOx/TiO2 could improve oxygen storage capacity and facilitate oxygen mobility of the catalyst as shown by PL and ESR, so that its activity for NO oxidation could be enhanced. The effect of H2O and SO2 on the catalyst activity was also investigated.     

Vapor phase synthesis of N-butylaniline over copper-based catalysts

Cu-based catalysts, such as Cu/SiO2, Cu/γ-Al2O3 and Cu/SiO2-Al2O3, for the vapor phase synthesis of N-butylaniline from aniline and 1-butanol were investigated and the catalysts were characterized by BET, H2-TPR, XRD and NH3-TPD techniques. The results indicated that the dispersion of copper on support was greatly influenced by the interaction between Cu and the support. Copper-based catalyst with larger amounts of acidic sites did not favor the synthesis of N-butylaniline because more by-products were prod...     

POLYKETONE FROM ETHYLENE WITH CARBON MONOXIDE CATALYZED BY NOVEL CATALYST SYSTEMS BASED ON COPPER WITH BIDENTATE PHOSPHORUS CHELATING LIGANDS

Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH_3COO)_2/ligand/acid) were firstly reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand. The experimental results showed that this kindof Cu catalyst system exhibited high activity. When DPPP (1, 3-bis(diphenylphosphine)propane) and CH_3COOH were usedas ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer/(gCu·h). The novel Cu catalyst system had the advantages of high stability and low cost.     

Effect of copper loading on texture,structure and catalytic performance of Cu/SiO2 catalyst for hydrogenation of dimethyl oxalate to ethylene glycol

Cu/SiO2 catalysts prepared by a convenient and efficient method using the urea hydrolysis deposition-precipitation (UHDP) technique have been proposed focusing on the effect of copper loading.The texture,structure and composition are systematically characterized by ICP,FTIR,N 2-physisorption,N2O chemisorption,TPR,XRD and XPS.The formation of copper phyllosilicate is observed in Cu/SiO2 catalyst by adopting UHDP method,and the amount of copper phyllosilicate is related to copper loading.It is found the structure properties and catalytic performance is profoundly affected by the amount of copper phyllosilicate.The excellent catalytic activity is attributed to the synergetic effect between Cu0 and Cu +.DMO conversion and EG selectivity are determined by the amount of Cu0 and Cu+,respectively.The proper copper loading (30 wt%) provides with the highest ratio of Cu + /Cu0,giving rise to the highest EG yield of 95% under the reaction conditions of p=2.0 MPa,T=473 K,H2/DMO=80 and LHSV=1.0h-1.