TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experimen...TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experiments show that the increase of TiB_2 content ranging from 0 to 20wt% can reduce the adiabatic temperature T_(ad) from 3100 K to 2896 K and combustion temperature T_c from 2139 K to 1621 K respectively. The particle size and half width of the particle distribution are also increased with the addition of TiB_2 increasing from 0 to 20wt%. The combustion product is a mixture of TiB_2, MgO, and other intermediate phases. The leached product contains mainly TiB_2, TiO_2 and TiN, and its oxygen content is 7.77wt%.展开更多
Combustion reaction welding, one promising method to weld ceramies and metals, was used to weld TiB2 and Mo. The results showed that the reacted products through combustion reaction were TiB2 and MoB when the Mo conte...Combustion reaction welding, one promising method to weld ceramies and metals, was used to weld TiB2 and Mo. The results showed that the reacted products through combustion reaction were TiB2 and MoB when the Mo contents in reactants were 20 wt pct and 40 wt pct while there was Mo besides MoB and TiB2 when there were 60 wt pct and 80 wt pct Mo in reactants. Diffusion of elements occurred at the interfaces of the two substrates. The interfaces between the reacted and the two substrates were indistinct after being welded. The welding temperature strongly affected properties of the samples. The value of bending strength of the sample with 80 wt pct Mo in reactant welded at 1500℃ was the highest, 368.52 MPa. The highest value of shear strength among all the samples was that of the one with 40 wt pct Mo in reactant vvelded at 1500℃, 50.97 MPa.展开更多
The reaction process of combustion synthesis for TiB2 -Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （ XRD ） analysis, SEM analysis and differential thermal analysis （ ...The reaction process of combustion synthesis for TiB2 -Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （ XRD ） analysis, SEM analysis and differential thermal analysis （ DTA ）. The XRD analysis results for the different parts of the quenched specimen show that TiCux intermetallic phase firstly forms with the propagation of combustion wave, and then Ti1.87 B50 and Ti3B4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB2 phase forms because of the continuous diffusion of B atoms. The formation of TiB2 phase is uot completed by one step, but undergoes several transient processes. The process of reaction synthesis for Ti-B-Cu ternary system can be divided into three main stages： melting of Cu and Ti , and the formation of Cu- Ti melt and few TiCux , TiBx intermetallic phases ; large numbers of TiCux intermetallic phases formation and some fine TiB2 particles precipitation ; and the TiB2 particles coarsening and the stable TiB2 and Cu two phases formation in the final product.展开更多
Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water...Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.展开更多
Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The...Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The phase transformation and pore formation of porous TiFe2intermetallics were investigated,and its corrosion behavior and hydrogen evolution reaction(HER)performance in alkali solution were studied.Porous TiFe2intermetallics with porosity in the range of 34.4%-56.4%were synthesized by the diffusion reaction of Ti and Fe elements,and the pore formation of porous TiFe2intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect.The porous TiFe2samples exhibit better corrosion resistance compared with porous 316L stainless steel,which is related to the formation of uniform nanosheets on the surface that hinder further corrosion,and porous TiFe2electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA·cm-2,suggesting a good catalytic performance.The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance,showing its potential in the field of filtration and separation.展开更多
In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave r...In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave radiation techniques.Structure and phase composition of the materials were investigated by X-ray diffraction.The electrical conductivity,Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 700 K.It is found that high purity Mg2Si powders can be obtained with excessive content of 8% Mg from the stoichiometric Mg2Si at 853 K and 2.5 kW for 30 min.A maximum dimensionless figure of merit,ZT,of about 0.13 was obtained for Mg2Si at 600 K.展开更多
Co-Ni/Al2O3catalyst was prepared by the fusion method and used in Fischer-Tropsch synthesis(FTS).The catalysts were characterized by means of nitrogen sorption and scanning electron microscopy.The effect of some react...Co-Ni/Al2O3catalyst was prepared by the fusion method and used in Fischer-Tropsch synthesis(FTS).The catalysts were characterized by means of nitrogen sorption and scanning electron microscopy.The effect of some reaction conditions such as temperature,pressure and H2/CO feed ratio on the catalytic performance of Co-Ni/Al2O3in CO hydrogenation was investigated in a fixed-bed reactor.The results indicate that the optimum reaction conditions are 250℃,0.3 MPa,H2/CO feed ratio of 2.0,and GHSV of 3 000 h-1.Kinetically,the reaction rate was correlated with the Langmuir-Hinshelwood-Hougen-Watson type models.The activation energy for the best fitted model is 88.41 kJ/mol,suggesting that the intra-particle mass transport is not significant.展开更多
Phenylurea reacted with dichlorophenylphosphine and aldehydes or ketones by Mannich-type reaction in anhydrous benzene to give five-mem- bered phosphorous heterocyclic compounds.However.derivatives of α-ureidoalkylph...Phenylurea reacted with dichlorophenylphosphine and aldehydes or ketones by Mannich-type reaction in anhydrous benzene to give five-mem- bered phosphorous heterocyclic compounds.However.derivatives of α-ureidoalkylphosphonic acids were obtained as the reaction performed in glacial acetic acid.展开更多
Six N-alkyl-4＇-methyl-1,1＇-biphenyl-2-sulfonamides were synthesized facilely and efficiently from low cost and readily available benzenesulfonyl chloride and C1-C4 fatty amines via linking DoM reaction with Suzuki r...Six N-alkyl-4＇-methyl-1,1＇-biphenyl-2-sulfonamides were synthesized facilely and efficiently from low cost and readily available benzenesulfonyl chloride and C1-C4 fatty amines via linking DoM reaction with Suzuki reaction.The structures of the new compounds synthesized were confirmed by elemental analysis,IR,1H NMR and MS.This new method makes a feature of low cost and readily available starting material,fewer steps,mild condition,easiness to operate and higher yield.展开更多
Reaction of ferrocenoyl chloride with [Et;NH] [（μ-CO）(μ-RS) Fe;=（CO）;] complexes gave bridging ferrocenoyl complexes（μ-FcCO）(μ-RS)Fe;（CO）;（Fc=ferrocenyl, R=Et, i-Pr, n-Bu, t-Bu, Ph）.The structures of all...Reaction of ferrocenoyl chloride with [Et;NH] [（μ-CO）(μ-RS) Fe;=（CO）;] complexes gave bridging ferrocenoyl complexes（μ-FcCO）(μ-RS)Fe;（CO）;（Fc=ferrocenyl, R=Et, i-Pr, n-Bu, t-Bu, Ph）.The structures of all new complexes were characterised by;HNMR, IR and MS.展开更多
The equilibrium phases and adiabatic temperature for combustion synthesis and reaction hot pressing of Al 2O 3/B 4C employing ① Al, B 2O 3 and C ② C, B, Al 2O 3 as starting reactants were analyzed by the CALP...The equilibrium phases and adiabatic temperature for combustion synthesis and reaction hot pressing of Al 2O 3/B 4C employing ① Al, B 2O 3 and C ② C, B, Al 2O 3 as starting reactants were analyzed by the CALPHAD technique. It is shown that the equilibrium phases at the adiabatic temperature in the combusion system (1) are not the intended composite Al 2O 3/B 4C but other phases. Good agreement with the experimental data was achieved for the calculated adiabatic temperature. The results were discussed with respect to the elimination of the by product in the combustion synthesis. It also revealed that the reactant mixture (2) is a weak exothermic or endothermic reaction system, which can be employed in the reaction hot pressing.展开更多
The 1.3-dipolar cycloaddition reaction of 2-trifluoromethyl- oxazolone and the activated carbon-carbon multiple bond was studied and gave a convenient way to synthesize 2-trifluoromethylpyrrole derivatives.
CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS acti...CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of NH 4 NO_(3),and the addition of alumina or silica as supports.Various techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,N 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained composites.Each specifi c perovskite-containing system(either bulk or supported)has its own optimalφand NH_(4) NO_(3) amount to achieve the highest yield and dispersion of the perovskite phase.Among all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)<Y<Ce<La(SCS).The diff erences in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide presence.In situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quantity of adsorbed H_(2) and CO_(2).This led to a signifi cant increase in CO_(2) conversion for supported CeFeO_(3) but not for the La-based system compared to bulk and SiO_(2)-supported perovskite catalysts.However,adding alumina increased the activity per mass for both Ce-and La-based perovskite systems,reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.展开更多
文摘TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experiments show that the increase of TiB_2 content ranging from 0 to 20wt% can reduce the adiabatic temperature T_(ad) from 3100 K to 2896 K and combustion temperature T_c from 2139 K to 1621 K respectively. The particle size and half width of the particle distribution are also increased with the addition of TiB_2 increasing from 0 to 20wt%. The combustion product is a mixture of TiB_2, MgO, and other intermediate phases. The leached product contains mainly TiB_2, TiO_2 and TiN, and its oxygen content is 7.77wt%.
基金The authors thank the National Natural Science Foundation of China(Contract No.59925207 and No.50272047),for the financial support.
文摘Combustion reaction welding, one promising method to weld ceramies and metals, was used to weld TiB2 and Mo. The results showed that the reacted products through combustion reaction were TiB2 and MoB when the Mo contents in reactants were 20 wt pct and 40 wt pct while there was Mo besides MoB and TiB2 when there were 60 wt pct and 80 wt pct Mo in reactants. Diffusion of elements occurred at the interfaces of the two substrates. The interfaces between the reacted and the two substrates were indistinct after being welded. The welding temperature strongly affected properties of the samples. The value of bending strength of the sample with 80 wt pct Mo in reactant welded at 1500℃ was the highest, 368.52 MPa. The highest value of shear strength among all the samples was that of the one with 40 wt pct Mo in reactant vvelded at 1500℃, 50.97 MPa.
基金Funded bythe Aerospace Innovation Fundation andthe ResearchFund by the Doctoral Program of High Education ( No.20020213037)
文摘The reaction process of combustion synthesis for TiB2 -Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （ XRD ） analysis, SEM analysis and differential thermal analysis （ DTA ）. The XRD analysis results for the different parts of the quenched specimen show that TiCux intermetallic phase firstly forms with the propagation of combustion wave, and then Ti1.87 B50 and Ti3B4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB2 phase forms because of the continuous diffusion of B atoms. The formation of TiB2 phase is uot completed by one step, but undergoes several transient processes. The process of reaction synthesis for Ti-B-Cu ternary system can be divided into three main stages： melting of Cu and Ti , and the formation of Cu- Ti melt and few TiCux , TiBx intermetallic phases ; large numbers of TiCux intermetallic phases formation and some fine TiB2 particles precipitation ; and the TiB2 particles coarsening and the stable TiB2 and Cu two phases formation in the final product.
基金the National Natural Science Foundation of China(Nos.52072151,52171211,52102253,52271218,U22A20145)the Jinan Independent Innovative Team(2020GXRC015)+1 种基金the Major Program of Shandong Province Natural Science Foundation(ZR2021ZD05)the Science and Technology Program of University of Jinan(XKY2119).
文摘Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.
基金financially supported by the National Natural Science Foundation of China(No.51971251)。
文摘Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The phase transformation and pore formation of porous TiFe2intermetallics were investigated,and its corrosion behavior and hydrogen evolution reaction(HER)performance in alkali solution were studied.Porous TiFe2intermetallics with porosity in the range of 34.4%-56.4%were synthesized by the diffusion reaction of Ti and Fe elements,and the pore formation of porous TiFe2intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect.The porous TiFe2samples exhibit better corrosion resistance compared with porous 316L stainless steel,which is related to the formation of uniform nanosheets on the surface that hinder further corrosion,and porous TiFe2electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA·cm-2,suggesting a good catalytic performance.The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance,showing its potential in the field of filtration and separation.
基金Project (2009BB4228) supported by the Natural Science Foundation Project of Chongqing Science and Technology Commission,ChinaProject (CK2010Z09) supported by the Research Foundation of Chongqing University of Science and Technology,China
文摘In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave radiation techniques.Structure and phase composition of the materials were investigated by X-ray diffraction.The electrical conductivity,Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 700 K.It is found that high purity Mg2Si powders can be obtained with excessive content of 8% Mg from the stoichiometric Mg2Si at 853 K and 2.5 kW for 30 min.A maximum dimensionless figure of merit,ZT,of about 0.13 was obtained for Mg2Si at 600 K.
文摘Co-Ni/Al2O3catalyst was prepared by the fusion method and used in Fischer-Tropsch synthesis(FTS).The catalysts were characterized by means of nitrogen sorption and scanning electron microscopy.The effect of some reaction conditions such as temperature,pressure and H2/CO feed ratio on the catalytic performance of Co-Ni/Al2O3in CO hydrogenation was investigated in a fixed-bed reactor.The results indicate that the optimum reaction conditions are 250℃,0.3 MPa,H2/CO feed ratio of 2.0,and GHSV of 3 000 h-1.Kinetically,the reaction rate was correlated with the Langmuir-Hinshelwood-Hougen-Watson type models.The activation energy for the best fitted model is 88.41 kJ/mol,suggesting that the intra-particle mass transport is not significant.
基金the National Natural Science Foundation of People's Republic of China:
文摘Phenylurea reacted with dichlorophenylphosphine and aldehydes or ketones by Mannich-type reaction in anhydrous benzene to give five-mem- bered phosphorous heterocyclic compounds.However.derivatives of α-ureidoalkylphosphonic acids were obtained as the reaction performed in glacial acetic acid.
文摘Six N-alkyl-4＇-methyl-1,1＇-biphenyl-2-sulfonamides were synthesized facilely and efficiently from low cost and readily available benzenesulfonyl chloride and C1-C4 fatty amines via linking DoM reaction with Suzuki reaction.The structures of the new compounds synthesized were confirmed by elemental analysis,IR,1H NMR and MS.This new method makes a feature of low cost and readily available starting material,fewer steps,mild condition,easiness to operate and higher yield.
基金The project was supported by Youth Science Foundation of Shandong University
文摘Reaction of ferrocenoyl chloride with [Et;NH] [（μ-CO）(μ-RS) Fe;=（CO）;] complexes gave bridging ferrocenoyl complexes（μ-FcCO）(μ-RS)Fe;（CO）;（Fc=ferrocenyl, R=Et, i-Pr, n-Bu, t-Bu, Ph）.The structures of all new complexes were characterised by;HNMR, IR and MS.
文摘The equilibrium phases and adiabatic temperature for combustion synthesis and reaction hot pressing of Al 2O 3/B 4C employing ① Al, B 2O 3 and C ② C, B, Al 2O 3 as starting reactants were analyzed by the CALPHAD technique. It is shown that the equilibrium phases at the adiabatic temperature in the combusion system (1) are not the intended composite Al 2O 3/B 4C but other phases. Good agreement with the experimental data was achieved for the calculated adiabatic temperature. The results were discussed with respect to the elimination of the by product in the combustion synthesis. It also revealed that the reactant mixture (2) is a weak exothermic or endothermic reaction system, which can be employed in the reaction hot pressing.
文摘The 1.3-dipolar cycloaddition reaction of 2-trifluoromethyl- oxazolone and the activated carbon-carbon multiple bond was studied and gave a convenient way to synthesize 2-trifluoromethylpyrrole derivatives.
基金The research was carried out within the State Assignment of the Ministry of Science and Higher Education of the Russian Federation(project No.FFUG-2024-0036)。
文摘CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of NH 4 NO_(3),and the addition of alumina or silica as supports.Various techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,N 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained composites.Each specifi c perovskite-containing system(either bulk or supported)has its own optimalφand NH_(4) NO_(3) amount to achieve the highest yield and dispersion of the perovskite phase.Among all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)<Y<Ce<La(SCS).The diff erences in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide presence.In situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quantity of adsorbed H_(2) and CO_(2).This led to a signifi cant increase in CO_(2) conversion for supported CeFeO_(3) but not for the La-based system compared to bulk and SiO_(2)-supported perovskite catalysts.However,adding alumina increased the activity per mass for both Ce-and La-based perovskite systems,reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.
