Co(bpb) [bpbH2is N,N′-o-phenylenebis(pyridine-2-carboxamide) ,C18H12N4O2] complex has active axial sites like a porphyrin complex. We studied the coordination of azide ion(N3-) to Co(bpb) in binary methanol-water mix...Co(bpb) [bpbH2is N,N′-o-phenylenebis(pyridine-2-carboxamide) ,C18H12N4O2] complex has active axial sites like a porphyrin complex. We studied the coordination of azide ion(N3-) to Co(bpb) in binary methanol-water mixtures by spectrophotometric method at the temperature range of 283-303 K. From the temperature dependence of the rate constant,activation parameters(Ea,ΔH,ΔS,and ΔG) were obtained. An isokinetic temperature at about 302 K was observed at which the formation rate of Co(bpb) -N3-was more or less independent of the solvent composition. The resulting ΔH against TΔS plot showed a good linear correlation,indicating the existence of enthalpy-entropy compensation in azide complexation process. Under optimum conditions and based on the absorbance of Co(bpb) -N3-produced through complex formation,a spectrophotometric method for the determination of N 3-in solution was developed. A linear relationship between the absorbance and N3-concentration was obtained in the range of(0.85-5.00) × 10-4 mol·L-1(3.6-21.0 μg·mL-1) . The detection limit was 2.5×10-5 mol·L-1(1.0 μg·mL-1) . The proposed method was applied to the determination of N3-anion in real water samples.展开更多
V2O5- SiO2（VSiO） supported Cu- Ni- K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro- reactor techniques, the effect of K2O on the adso...V2O5- SiO2（VSiO） supported Cu- Ni- K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro- reactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on Cu- Ni/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15％ , K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on Cu- Ni- K2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by- products decreases.展开更多
以二苯基-1-甲基咪唑膦(dpim)为配体制备了一种新型的配合物催化剂Ni(dpim)_2Cl_2.循环伏安研究表明,Ni(dpim)2Cl2配合物在氮气气氛下表现出两步还原的电化学行为,在-0.7 V下为两电子的不可逆还原,在-1.3 V下为单电子准可逆还原.向电解...以二苯基-1-甲基咪唑膦(dpim)为配体制备了一种新型的配合物催化剂Ni(dpim)_2Cl_2.循环伏安研究表明,Ni(dpim)2Cl2配合物在氮气气氛下表现出两步还原的电化学行为,在-0.7 V下为两电子的不可逆还原,在-1.3 V下为单电子准可逆还原.向电解液中通入CO_2后,在-1.3 V下的还原峰变得不可逆,且其峰电流从0.48 m A·cm^(-2)增大到0.55 m A·cm^(-2).在质子源(CH3OH)存在的条件下,该还原峰电流可继续增大到0.72 m A·cm^(-2).该研究结果表明,Ni(dpim)_2Cl_2配合物对CO_2还原具有良好的电催化性能,且其电催化还原过程符合ECE机理.在-1.3 V下恒电位电解得到的还原产物主要为CO,催化转换频率(Turnover of Frenquency,TOF)为0.17 s^(-1).展开更多
基金supported by the National Natural Science Foundation of China(21543009,21073167,J1210060)Innovative Research Grant for Undergraduate Students of National/Zhengzhou University,China(201410459047,201510459046,2016xjxm259)~~
基金supported by the Tarbiat Modares University Research Council.
文摘Co(bpb) [bpbH2is N,N′-o-phenylenebis(pyridine-2-carboxamide) ,C18H12N4O2] complex has active axial sites like a porphyrin complex. We studied the coordination of azide ion(N3-) to Co(bpb) in binary methanol-water mixtures by spectrophotometric method at the temperature range of 283-303 K. From the temperature dependence of the rate constant,activation parameters(Ea,ΔH,ΔS,and ΔG) were obtained. An isokinetic temperature at about 302 K was observed at which the formation rate of Co(bpb) -N3-was more or less independent of the solvent composition. The resulting ΔH against TΔS plot showed a good linear correlation,indicating the existence of enthalpy-entropy compensation in azide complexation process. Under optimum conditions and based on the absorbance of Co(bpb) -N3-produced through complex formation,a spectrophotometric method for the determination of N 3-in solution was developed. A linear relationship between the absorbance and N3-concentration was obtained in the range of(0.85-5.00) × 10-4 mol·L-1(3.6-21.0 μg·mL-1) . The detection limit was 2.5×10-5 mol·L-1(1.0 μg·mL-1) . The proposed method was applied to the determination of N3-anion in real water samples.
文摘V2O5- SiO2（VSiO） supported Cu- Ni- K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro- reactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on Cu- Ni/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15％ , K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on Cu- Ni- K2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by- products decreases.
文摘以二苯基-1-甲基咪唑膦(dpim)为配体制备了一种新型的配合物催化剂Ni(dpim)_2Cl_2.循环伏安研究表明,Ni(dpim)2Cl2配合物在氮气气氛下表现出两步还原的电化学行为,在-0.7 V下为两电子的不可逆还原,在-1.3 V下为单电子准可逆还原.向电解液中通入CO_2后,在-1.3 V下的还原峰变得不可逆,且其峰电流从0.48 m A·cm^(-2)增大到0.55 m A·cm^(-2).在质子源(CH3OH)存在的条件下,该还原峰电流可继续增大到0.72 m A·cm^(-2).该研究结果表明,Ni(dpim)_2Cl_2配合物对CO_2还原具有良好的电催化性能,且其电催化还原过程符合ECE机理.在-1.3 V下恒电位电解得到的还原产物主要为CO,催化转换频率(Turnover of Frenquency,TOF)为0.17 s^(-1).
