Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride （NaBH 4） for hydrogen generation.At solution temperature of 0 C,the methanolys...Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride （NaBH 4） for hydrogen generation.At solution temperature of 0 C,the methanolysis reaction can be effectively accelerated using Co/Al2O3 catalyst and provide a desirable hydrogen generation rate,which makes it suitable for applications under the circumstance of low environmental temperature.The byproduct of methanolysis reaction is analyzed by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FTIR）.The characterization results indicate that methanol can be easily recovered after methanolysis reaction by hydrolysis of the methanolysis byproduct,NaB（OCH 3） 4.The catalytic activity of Co/Al2O3 towards NaBH 4 methanolysis can be further improved by appropriate calcination treatment.The catalytic methanolysis kinetics and catalyst reusability are also studied over the Co/Al2O3 catalyst calcined at the optimized temperature.展开更多
The main objective of this paper was to characterize the voltammetric profiles of the Pt/C,Pt/C-ATO,Pd/C and Pd/CATO electrocatalysts and study their catalytic activities for methane oxidation in an acidic electrolyte...The main objective of this paper was to characterize the voltammetric profiles of the Pt/C,Pt/C-ATO,Pd/C and Pd/CATO electrocatalysts and study their catalytic activities for methane oxidation in an acidic electrolyte at 25 ℃ and in a direct methane proton exchange membrane fuel cell at 80 ℃. The electrocatalysts prepared also were characterized by X-ray diffraction( XRD) and transmission electron microscopy( TEM). The diffractograms of the Pt/C and Pt/C-ATO electrocatalysts show four peaks associated with Pt face-centered cubic( fcc) structure,and the diffractograms of Pd/C and Pd/C-ATO show four peaks associated with Pd face-centered cubic( fcc) structure. For Pt/C-ATO and Pd/C-ATO,characteristic peaks of cassiterite( SnO_2) phase are observed,which are associated with Sb-doped SnO_2( ATO) used as supports for electrocatalysts. Cyclic voltammograms( CV) of all electrocatalysts after adsorption of methane show that there is a current increase during the anodic scan. However,this effect is more pronounced for Pt/C-ATO and Pd/C-ATO. This process is related to the oxidation of the adsorbed species through the bifunctional mechanism,where ATO provides oxygenated species for the oxidation of CO or HCO intermediates adsorbed in Pt or Pd sites. From in situ ATR-FTIR( Attenuated Total Reflectance-Fourier Transform Infrared) experiments for all electrocatalysts prepared the formation of HCO or CO intermediates are observed,which indicates the production of carbon dioxide. Polarization curves at 80 ℃in a direct methane fuel cell( DMEFC) show that Pd/C and Pt/C electroacatalysts have superior performance to Pd/C-ATO and Pt/C-ATO in methane oxidation.展开更多
A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described.A variety of ali...A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described.A variety of aliphatic and aromatic aldehydes,ketones and amines when mixed with NaBH;/silica chloride at room temperature,afforded excellent yield of the corresponding amines.展开更多
We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the sol...We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt%based on all the reactants can be achieved with excellent hydrogen generation kinetics.展开更多
Reduction of d-alkoxy enal 1 and 4 by sodium borohydride in methanol with a catalytic amount of magnesium methoxide gave unexpected methoxylated poducts 3 and 6 respectively.
We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixtu...We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt% based on all the reactants can be achieved with excellent hydrogen generation kinetics.展开更多
A highly efficient and facile protocol for the selective reduction of carboxylic acid of Fenofibric acid to corresponding alcohol was developed. The selective reduction was carried out by activation of carboxylic acid...A highly efficient and facile protocol for the selective reduction of carboxylic acid of Fenofibric acid to corresponding alcohol was developed. The selective reduction was carried out by activation of carboxylic acid by mixed anhydride followed by the reaction of sodium borohydride in presence of methanol. This is the first example of chemoselective reduction of carboxylic acid to alcohol in presence of a ketone without any external catalyst or ligand in a single step. The reaction offers wide applicability for the selective carboxylic group reduction methodology. The chemoselective reduction was demonstrated by the reduction of Fenofibric acid, an active metabolite of the drug Fenofibrate, to corresponding alcohol in excellent selectivity, yield, and purity.展开更多
Two aromatic aldehydes are found to be reduced by an unusual way by sodium borohydride in the presence of water to yield the corresponding methyl substituted aryl compounds.
In the presence of catalytic amounts of tellurium,aryl chloro- acetates can be cleaved by sodium borohydride and regenerate parent phen- ols in good yields.
The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stabili...The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stability of the catalysts prepared by impregnation method is better than that prepared by chemical plating. Compared to exchange resin and activated alumina, the diatomite with high BET surface area and porosity is more suitable for as the catalyst’s support. Co is much better than Ni when used as catalytic active part.展开更多
Stability of borohydrides is determined by the localization of the negative charge on the boron atom.Ionic liquids(ILs) allow to modify the stability of the borohydrides and promote new dehydrogenation pathways with a...Stability of borohydrides is determined by the localization of the negative charge on the boron atom.Ionic liquids(ILs) allow to modify the stability of the borohydrides and promote new dehydrogenation pathways with a lower activation energy. The combination of borohydride and IL is very easy to realize and no expensive rare earth metals are required. The composite of the ILs with complex hydrides decreases the enthalpy and activation energy for the hydrogen desorption. The Coulomb interaction between borohydride and IL leads to a destabilization of the materials with a significantly lower enthalpy for hydrogen desorption. Here, we report a simple ion exchange reaction using various ILs, such as vinylbenzyltrimethylammonium chloride([VBTMA][Cl]), 1-butyl-3-methylimidazolium chloride([bmim][Cl]), and 1-ethyl-1-methylpyrrolidinium bromide([EMPY][Br]) with NaBH4 to decrease the hydrogen desorption temperature. Dehydrogenation of 1-butyl-3-methylimidazolium borohydride([bmim][BH4]) starts below 100℃. The quantity of desorbed hydrogen ranges between 2.4 wt% and 2.9 wt%, which is close to the theoretical content of hydrogen. The improvement in dehydrogenation is due to the strong amine cation that destabilizes borohydride by charge transfer.展开更多
A novel and simple synthetic way using NaBH4 in the mixure of H2O-THF was applied to prepare 1,2-bis(diphenylphosphinoborane)ethane, dppe(BH3)2, in high yield and purity. The phosphanylborohydride compound dppe(BH3)2 ...A novel and simple synthetic way using NaBH4 in the mixure of H2O-THF was applied to prepare 1,2-bis(diphenylphosphinoborane)ethane, dppe(BH3)2, in high yield and purity. The phosphanylborohydride compound dppe(BH3)2 was isolated in the form of colorless crystals and characterized by single crystal X-ray diffraction, 1H, 13C, 31P and 11B NMR spectroscopy. Prismatic colorless crystals of dppe(BH3)2 were obtained in monoclinic crystal system and space group P21 with two asymmetric units in the unit cell. Lattice parameters were: a = 11.657(2), b = 17.237(2), c = 12.764(2) ?, β = 98.735(14)°, 2535.0(7) ?展开更多
基金supported by the Key Project of Chinese Ministry of Education (No. 208076)Shandong Provincial Natural Science Foundation,China (No. ZR2010EM069)the Open Project of State Key Laboratory of Chemical Resource Engineering,Beijing University of Chemical Technology
文摘Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride （NaBH 4） for hydrogen generation.At solution temperature of 0 C,the methanolysis reaction can be effectively accelerated using Co/Al2O3 catalyst and provide a desirable hydrogen generation rate,which makes it suitable for applications under the circumstance of low environmental temperature.The byproduct of methanolysis reaction is analyzed by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FTIR）.The characterization results indicate that methanol can be easily recovered after methanolysis reaction by hydrolysis of the methanolysis byproduct,NaB（OCH 3） 4.The catalytic activity of Co/Al2O3 towards NaBH 4 methanolysis can be further improved by appropriate calcination treatment.The catalytic methanolysis kinetics and catalyst reusability are also studied over the Co/Al2O3 catalyst calcined at the optimized temperature.
基金The project was supported by the FAPESP(2014/09087-4,2014/50279-4).
文摘The main objective of this paper was to characterize the voltammetric profiles of the Pt/C,Pt/C-ATO,Pd/C and Pd/CATO electrocatalysts and study their catalytic activities for methane oxidation in an acidic electrolyte at 25 ℃ and in a direct methane proton exchange membrane fuel cell at 80 ℃. The electrocatalysts prepared also were characterized by X-ray diffraction( XRD) and transmission electron microscopy( TEM). The diffractograms of the Pt/C and Pt/C-ATO electrocatalysts show four peaks associated with Pt face-centered cubic( fcc) structure,and the diffractograms of Pd/C and Pd/C-ATO show four peaks associated with Pd face-centered cubic( fcc) structure. For Pt/C-ATO and Pd/C-ATO,characteristic peaks of cassiterite( SnO_2) phase are observed,which are associated with Sb-doped SnO_2( ATO) used as supports for electrocatalysts. Cyclic voltammograms( CV) of all electrocatalysts after adsorption of methane show that there is a current increase during the anodic scan. However,this effect is more pronounced for Pt/C-ATO and Pd/C-ATO. This process is related to the oxidation of the adsorbed species through the bifunctional mechanism,where ATO provides oxygenated species for the oxidation of CO or HCO intermediates adsorbed in Pt or Pd sites. From in situ ATR-FTIR( Attenuated Total Reflectance-Fourier Transform Infrared) experiments for all electrocatalysts prepared the formation of HCO or CO intermediates are observed,which indicates the production of carbon dioxide. Polarization curves at 80 ℃in a direct methane fuel cell( DMEFC) show that Pd/C and Pt/C electroacatalysts have superior performance to Pd/C-ATO and Pt/C-ATO in methane oxidation.
基金support of this work from the Research Council of Mazandaran University gratefully acknowledged.
文摘A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described.A variety of aliphatic and aromatic aldehydes,ketones and amines when mixed with NaBH;/silica chloride at room temperature,afforded excellent yield of the corresponding amines.
基金Funded by the Ministry of Science and Technology(MOST)of China(No.2018YFB1502104)the National Natural Science Foundation of China(No.21771006)the Equipment Development Department of People’s Republic of China Central Military Commission(Pre-research Project of the Thirteenth FiveYear Plan)(No.41421020103)。
文摘We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt%based on all the reactants can be achieved with excellent hydrogen generation kinetics.
文摘Reduction of d-alkoxy enal 1 and 4 by sodium borohydride in methanol with a catalytic amount of magnesium methoxide gave unexpected methoxylated poducts 3 and 6 respectively.
基金Funded by the Ministry of Science and Technology(MOST)of China(No.2018YFB1502104)the Natural Science Foundation of China(No.21771006)the Equipment Development Department of People’s Republic of China Central Military Commission(Preresearch Project of the Thirteenth Five-Year Plan,No.41421020103)。
文摘We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt% based on all the reactants can be achieved with excellent hydrogen generation kinetics.
文摘A highly efficient and facile protocol for the selective reduction of carboxylic acid of Fenofibric acid to corresponding alcohol was developed. The selective reduction was carried out by activation of carboxylic acid by mixed anhydride followed by the reaction of sodium borohydride in presence of methanol. This is the first example of chemoselective reduction of carboxylic acid to alcohol in presence of a ketone without any external catalyst or ligand in a single step. The reaction offers wide applicability for the selective carboxylic group reduction methodology. The chemoselective reduction was demonstrated by the reduction of Fenofibric acid, an active metabolite of the drug Fenofibrate, to corresponding alcohol in excellent selectivity, yield, and purity.
文摘Two aromatic aldehydes are found to be reduced by an unusual way by sodium borohydride in the presence of water to yield the corresponding methyl substituted aryl compounds.
文摘In the presence of catalytic amounts of tellurium,aryl chloro- acetates can be cleaved by sodium borohydride and regenerate parent phen- ols in good yields.
文摘The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stability of the catalysts prepared by impregnation method is better than that prepared by chemical plating. Compared to exchange resin and activated alumina, the diatomite with high BET surface area and porosity is more suitable for as the catalyst’s support. Co is much better than Ni when used as catalytic active part.
基金part of the activities of SCCER HeE, which is financially supported by Innosuisse – Swiss Innovation Agency
文摘Stability of borohydrides is determined by the localization of the negative charge on the boron atom.Ionic liquids(ILs) allow to modify the stability of the borohydrides and promote new dehydrogenation pathways with a lower activation energy. The combination of borohydride and IL is very easy to realize and no expensive rare earth metals are required. The composite of the ILs with complex hydrides decreases the enthalpy and activation energy for the hydrogen desorption. The Coulomb interaction between borohydride and IL leads to a destabilization of the materials with a significantly lower enthalpy for hydrogen desorption. Here, we report a simple ion exchange reaction using various ILs, such as vinylbenzyltrimethylammonium chloride([VBTMA][Cl]), 1-butyl-3-methylimidazolium chloride([bmim][Cl]), and 1-ethyl-1-methylpyrrolidinium bromide([EMPY][Br]) with NaBH4 to decrease the hydrogen desorption temperature. Dehydrogenation of 1-butyl-3-methylimidazolium borohydride([bmim][BH4]) starts below 100℃. The quantity of desorbed hydrogen ranges between 2.4 wt% and 2.9 wt%, which is close to the theoretical content of hydrogen. The improvement in dehydrogenation is due to the strong amine cation that destabilizes borohydride by charge transfer.
基金Partial support of this work by the Turkish Academy of Sciences and the Scientific and Technological Research Council of Turkey(TUBITAK,Project No:105M357)is gratefully acknowledgedL.T.Y ildirim thanks Hacettepe University Scientific Research Unit(grant,No.04 A602004)for financial support.
文摘A novel and simple synthetic way using NaBH4 in the mixure of H2O-THF was applied to prepare 1,2-bis(diphenylphosphinoborane)ethane, dppe(BH3)2, in high yield and purity. The phosphanylborohydride compound dppe(BH3)2 was isolated in the form of colorless crystals and characterized by single crystal X-ray diffraction, 1H, 13C, 31P and 11B NMR spectroscopy. Prismatic colorless crystals of dppe(BH3)2 were obtained in monoclinic crystal system and space group P21 with two asymmetric units in the unit cell. Lattice parameters were: a = 11.657(2), b = 17.237(2), c = 12.764(2) ?, β = 98.735(14)°, 2535.0(7) ?
