Combustion catalyst La_(0.8)Sr_(0.2)CoO_3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al_2O_3 is used as its support, cobalt ions can easily ...Combustion catalyst La_(0.8)Sr_(0.2)CoO_3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al_2O_3 is used as its support, cobalt ions can easily react with γ-Al_2O_3 at not very high temperature to form spinel CoAl_2O_4 or spinel-like, which decreases the activity of the combustion catalyst. In this paper, MgAl_2O_4 and CaAl_2O_4 were pre-coated on γ-Al_2O_3 by impregnation respectively, which formed compound support for LSC. It is shown that, when MgAl_2O_4 layer is covered on the surface of MgAl_2O_4 by impregnation, the entering of cobalt ions into γ-Al_2O_3 lattice is restrained, then LSC formed on the surface of MgAl_2O_4, which leads to a good catalytic activity of xylene complete oxidation. But the layer of MgAl_2O_4 should be thick enough to reach 30% (mass fraction) MgO in the support due to large size particle of MgAl_2O_4 crystalline. If polyvinyl alcohol (PVA) is added into the impregnation solution adequately, MgAl_2O_4 particles formed on the surface of γ-Al_2O_3 are getting smaller, and less amount of MgAl_2O_4 is needed to cover up the surface of γ-Al_2O_3. If CaAl_2O_4 layer substituted for MgAl_2O_4, more closed cover is obtained in virtue of fine particles of CaAl_2O_4. The activity examination shows that smaller particles of MgAl_2O_4 or CaAl_2O_4 can be more effective to hinder cobalt ions entering the lattice of γ-Al_2O_3, and better activities will be obtained.展开更多
Stable and high‐efficiency bifunctional catalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desired for the practical application of Li‐O_(2)batteries with excellent rate performanc...Stable and high‐efficiency bifunctional catalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desired for the practical application of Li‐O_(2)batteries with excellent rate performance and cycle stability.Herein,a novel hybrid bifunctional catalyst with carbon nanofibers inlaid with hollow Co_(3)O_(4)nanoparticles and separate active sites for ORR and OER were prepared and applied in Li‐O_(2)batteries.Benefiting from the synergistic effect of unique porous structural features and high electrocatalytic activity of hollow Co3O4 intimately bound to N‐doped carbon nanofibers,the assembled Li‐O_(2)batteries with novel catalyst exhibited high specific capacity,excellent rate capability,and cycle stability up to 150 cycles under a capacity limitation of 500 mAh g^(–1)at a current density of 100 mA g^(–1).The facile synthesis and preliminary results in this work show the as‐prepared catalyst as a promising bifunctional electrocatalyst for applications in metal‐air batteries,fuel cells,and electrocatalysis.展开更多
Highly active solid superacid catalysts for n-butane isomerization, SZ/A1_2O_3-P, were prepared by supporting SO-(4-2)/ZrO2, (SZ) on y-A1_2O_3 carrier using a precipitation method. The activities of some catalysts wer...Highly active solid superacid catalysts for n-butane isomerization, SZ/A1_2O_3-P, were prepared by supporting SO-(4-2)/ZrO2, (SZ) on y-A1_2O_3 carrier using a precipitation method. The activities of some catalysts were enhanced significantly j The activity of the most active sample. 60%SZ/Al_2O3-P, was even about 2 times more active than that of the SZ catalyst.展开更多
文摘Combustion catalyst La_(0.8)Sr_(0.2)CoO_3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al_2O_3 is used as its support, cobalt ions can easily react with γ-Al_2O_3 at not very high temperature to form spinel CoAl_2O_4 or spinel-like, which decreases the activity of the combustion catalyst. In this paper, MgAl_2O_4 and CaAl_2O_4 were pre-coated on γ-Al_2O_3 by impregnation respectively, which formed compound support for LSC. It is shown that, when MgAl_2O_4 layer is covered on the surface of MgAl_2O_4 by impregnation, the entering of cobalt ions into γ-Al_2O_3 lattice is restrained, then LSC formed on the surface of MgAl_2O_4, which leads to a good catalytic activity of xylene complete oxidation. But the layer of MgAl_2O_4 should be thick enough to reach 30% (mass fraction) MgO in the support due to large size particle of MgAl_2O_4 crystalline. If polyvinyl alcohol (PVA) is added into the impregnation solution adequately, MgAl_2O_4 particles formed on the surface of γ-Al_2O_3 are getting smaller, and less amount of MgAl_2O_4 is needed to cover up the surface of γ-Al_2O_3. If CaAl_2O_4 layer substituted for MgAl_2O_4, more closed cover is obtained in virtue of fine particles of CaAl_2O_4. The activity examination shows that smaller particles of MgAl_2O_4 or CaAl_2O_4 can be more effective to hinder cobalt ions entering the lattice of γ-Al_2O_3, and better activities will be obtained.
文摘Stable and high‐efficiency bifunctional catalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desired for the practical application of Li‐O_(2)batteries with excellent rate performance and cycle stability.Herein,a novel hybrid bifunctional catalyst with carbon nanofibers inlaid with hollow Co_(3)O_(4)nanoparticles and separate active sites for ORR and OER were prepared and applied in Li‐O_(2)batteries.Benefiting from the synergistic effect of unique porous structural features and high electrocatalytic activity of hollow Co3O4 intimately bound to N‐doped carbon nanofibers,the assembled Li‐O_(2)batteries with novel catalyst exhibited high specific capacity,excellent rate capability,and cycle stability up to 150 cycles under a capacity limitation of 500 mAh g^(–1)at a current density of 100 mA g^(–1).The facile synthesis and preliminary results in this work show the as‐prepared catalyst as a promising bifunctional electrocatalyst for applications in metal‐air batteries,fuel cells,and electrocatalysis.
文摘Highly active solid superacid catalysts for n-butane isomerization, SZ/A1_2O_3-P, were prepared by supporting SO-(4-2)/ZrO2, (SZ) on y-A1_2O_3 carrier using a precipitation method. The activities of some catalysts were enhanced significantly j The activity of the most active sample. 60%SZ/Al_2O3-P, was even about 2 times more active than that of the SZ catalyst.
