A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic re...A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic reduction（SCR） performance and SO2-resistant ability of TiO2-SiO2-WO3 were greatly enhanced by the introduction of cerium. The catalyst containing 10% CeO2 showed the highest NO conversion in a wide temperature range and good N2 selectivity with broad operation temperature window at the gas hourly space velocity（GHSV） of 30000 h–1, which was a very promising catalyst for NOx abatement from diesel engine exhaust. The catalysts were characterized by X-ray diffraction（XRD）, scanning electron microscopy with energy dispersive X-ray spectroscopy（SEM-EDS）, N2 adsorption-desorption（BET） and X-ray photoelectron spectroscopy（XPS）. The characterization results showed that the bigger pore radius, higher surface atomic concentration and dispersion of Ce and the abundant adsorbed oxygen on the surface of catalyst contributed to the best NH3-SCR performance of CeO2/TiO2-SiO2-WO3 catalyst containing 10% CeO2.展开更多
A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(...A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...展开更多
Metal isolated single atomic sites catalysts have attracted intensive attention in recent years owing to their maximized atom utilization and unique structure.Despite the success of single atom catalyst synthesis,dire...Metal isolated single atomic sites catalysts have attracted intensive attention in recent years owing to their maximized atom utilization and unique structure.Despite the success of single atom catalyst synthesis,directly anchoring metal single atoms on three-dimensional(3D)macro support,which is promising to achieve the heterogenization of homogeneous catalysis,remains a challenge and a blank in this field.Herein,we successfully fabricate metal single atoms(Pd,Pt,Ru,Au)on porous carbon nitride/reduced graphene oxide(C3N4/rGO)foam as highly efficient catalysts with convenient recyclability.C3N4/rGO foam features two-dimensional microstructures with abundant N chelating sites for the stabilization of metal single atoms and vertically-aligned hierarchical mesostructure that benefits the mass diffusion.The obtained Pdi/C3N4/rGO monolith catalyst exhibits much enhanced activity over its nanoparticle counterpart for Suzuki-Miyaura reaction.Moreover,the Pdi/C3N4/rGO monolith catalyst can be readily assembled in a flow reactor to achieve the highly efficient continuous production of 4-nitro-1,1'-biphenyl through Suzuki-Miyaura coupling.展开更多
Pd/oxide/cordierite monolithic catalysts(oxide = Al_2O_3, SiO_2 and SiO_2\\Al_2O_3) were prepared by the impregnation method. The results of ICP, XRD, SEM–EDX, XPS and N_2 adsorption–desorption measurements revealed...Pd/oxide/cordierite monolithic catalysts(oxide = Al_2O_3, SiO_2 and SiO_2\\Al_2O_3) were prepared by the impregnation method. The results of ICP, XRD, SEM–EDX, XPS and N_2 adsorption–desorption measurements revealed that the Pd penetration depth increased with increasing the thickness of oxide layer, and the catalysts with Al_2O_3 layers had the larger pore size than those with SiO_2 and SiO_2\\Al_2O_3 layers. Catalytic hydrogenation of 2-ethylanthraquinone(eA Q), a key step of the H_2O_2 production by the anthraquinone process, over the various monolithic catalysts(60 °C, atmosphere pressure) showed that the monolithic catalyst with the moderate thickness of Al_2O_3 layer(about 6 μm) exhibited the highest conversion of e AQ(99.1%) and hydrogenation efficiency(10.0 g·L^(-1)). This could be ascribed to the suitable Pd penetration depth and the larger pore size, which provides a balance between the distribution of Pd and accessibility of active sites by the reactants.展开更多
通过高温焙烧和氢氟酸瞬间蚀刻修饰堇青石蜂窝陶瓷骨架和孔壁表面结构,采用XRD、SEM、TEM表征修饰前后结构和形貌变化,探究陶瓷结构对机械强度、碳纳米管形貌结构及复合载体性质的影响,考察Pd/CNTs@CHC-HFn催化剂催化聚苯乙烯(PS)加氢...通过高温焙烧和氢氟酸瞬间蚀刻修饰堇青石蜂窝陶瓷骨架和孔壁表面结构,采用XRD、SEM、TEM表征修饰前后结构和形貌变化,探究陶瓷结构对机械强度、碳纳米管形貌结构及复合载体性质的影响,考察Pd/CNTs@CHC-HFn催化剂催化聚苯乙烯(PS)加氢性能及催化剂用量与加氢度的关系。结果表明,高温焙烧消除了骨架内部孔道,陶瓷表面变得平整密实;瞬间蚀刻增大了表面粗糙度,易于CNTs在表面生长,但蚀刻次数增加,导致蚀刻由表面向骨架内部侵入、CNTs在骨架内部生长,降低载体的机械强度。CNTs@CHC-HFn载体表面的CNTs可显著提高复合催化剂的加氢性能,其中加氢活性位Pd分布均匀,平均粒径为3.6 nm,当催化剂用量为3.0 g cat·(g PS)^(-1)时,其中含0.378 g CNTs和0.054 g Pd,反应6 h加氢度可达100%。展开更多
Conventional synthesis of monolith-supported zeolite catalysts is based on a hydrothermal strategy.Here,we report a solvent-free crystallization process to coat ZSM-5 zeolite crystals on a monolithic SiC foam with a h...Conventional synthesis of monolith-supported zeolite catalysts is based on a hydrothermal strategy.Here,we report a solvent-free crystallization process to coat ZSM-5 zeolite crystals on a monolithic SiC foam with a honeycomb structure(ZSM-5/SiC).Characterizations of the ZSM-5/SiC by scanning electron microscopy,N2 sorption,and X-ray diffraction indicate that the zeolite sheath has been ideally coated on the surface of the SiC foam with high purity and crystallinity.Fixing Pd nanoparticles within the ZSM-5 zeolite crystals delivers a bifunctional Pd@ZSM-5/SiC catalyst,which exhibits high activity and selectivity toward diesel range paraffins in the hydrodeoxygenation of methyl oleate,a model molecule for biofuel.In comparison to the powder Pd@ZSM-5,the Pd@ZSM-5/SiC monolith catalyst shows more efficiency,which is attributed to the fast mass transfer and high heat conductivity on the honeycomb SiC structure.The durability test indicates that the Pd@ZSM-5/SiC catalyst is stable under the reaction and high-temperature regeneration conditions.展开更多
基金supported by the National Natural Science Foundation of China(21173153)the National High Technology Research and Development Program of China(863 project)(2013AA065304)
文摘A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic reduction（SCR） performance and SO2-resistant ability of TiO2-SiO2-WO3 were greatly enhanced by the introduction of cerium. The catalyst containing 10% CeO2 showed the highest NO conversion in a wide temperature range and good N2 selectivity with broad operation temperature window at the gas hourly space velocity（GHSV） of 30000 h–1, which was a very promising catalyst for NOx abatement from diesel engine exhaust. The catalysts were characterized by X-ray diffraction（XRD）, scanning electron microscopy with energy dispersive X-ray spectroscopy（SEM-EDS）, N2 adsorption-desorption（BET） and X-ray photoelectron spectroscopy（XPS）. The characterization results showed that the bigger pore radius, higher surface atomic concentration and dispersion of Ce and the abundant adsorbed oxygen on the surface of catalyst contributed to the best NH3-SCR performance of CeO2/TiO2-SiO2-WO3 catalyst containing 10% CeO2.
基金supported by the Ministry of Science and Technology of Beijing (20081D0500500142)
文摘A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...
基金This work was supported by the National Key R&D Program of China(No.2018YFA0702003)the National Natural Science Foundation of China(No.21890383,21971137)Beijing Municipal Science&Technology Commission(No.Z191100007219003)。
文摘Metal isolated single atomic sites catalysts have attracted intensive attention in recent years owing to their maximized atom utilization and unique structure.Despite the success of single atom catalyst synthesis,directly anchoring metal single atoms on three-dimensional(3D)macro support,which is promising to achieve the heterogenization of homogeneous catalysis,remains a challenge and a blank in this field.Herein,we successfully fabricate metal single atoms(Pd,Pt,Ru,Au)on porous carbon nitride/reduced graphene oxide(C3N4/rGO)foam as highly efficient catalysts with convenient recyclability.C3N4/rGO foam features two-dimensional microstructures with abundant N chelating sites for the stabilization of metal single atoms and vertically-aligned hierarchical mesostructure that benefits the mass diffusion.The obtained Pdi/C3N4/rGO monolith catalyst exhibits much enhanced activity over its nanoparticle counterpart for Suzuki-Miyaura reaction.Moreover,the Pdi/C3N4/rGO monolith catalyst can be readily assembled in a flow reactor to achieve the highly efficient continuous production of 4-nitro-1,1'-biphenyl through Suzuki-Miyaura coupling.
基金Supported by the Sinopec Corp.Scientific Research Projects(414076)
文摘Pd/oxide/cordierite monolithic catalysts(oxide = Al_2O_3, SiO_2 and SiO_2\\Al_2O_3) were prepared by the impregnation method. The results of ICP, XRD, SEM–EDX, XPS and N_2 adsorption–desorption measurements revealed that the Pd penetration depth increased with increasing the thickness of oxide layer, and the catalysts with Al_2O_3 layers had the larger pore size than those with SiO_2 and SiO_2\\Al_2O_3 layers. Catalytic hydrogenation of 2-ethylanthraquinone(eA Q), a key step of the H_2O_2 production by the anthraquinone process, over the various monolithic catalysts(60 °C, atmosphere pressure) showed that the monolithic catalyst with the moderate thickness of Al_2O_3 layer(about 6 μm) exhibited the highest conversion of e AQ(99.1%) and hydrogenation efficiency(10.0 g·L^(-1)). This could be ascribed to the suitable Pd penetration depth and the larger pore size, which provides a balance between the distribution of Pd and accessibility of active sites by the reactants.
文摘通过高温焙烧和氢氟酸瞬间蚀刻修饰堇青石蜂窝陶瓷骨架和孔壁表面结构,采用XRD、SEM、TEM表征修饰前后结构和形貌变化,探究陶瓷结构对机械强度、碳纳米管形貌结构及复合载体性质的影响,考察Pd/CNTs@CHC-HFn催化剂催化聚苯乙烯(PS)加氢性能及催化剂用量与加氢度的关系。结果表明,高温焙烧消除了骨架内部孔道,陶瓷表面变得平整密实;瞬间蚀刻增大了表面粗糙度,易于CNTs在表面生长,但蚀刻次数增加,导致蚀刻由表面向骨架内部侵入、CNTs在骨架内部生长,降低载体的机械强度。CNTs@CHC-HFn载体表面的CNTs可显著提高复合催化剂的加氢性能,其中加氢活性位Pd分布均匀,平均粒径为3.6 nm,当催化剂用量为3.0 g cat·(g PS)^(-1)时,其中含0.378 g CNTs和0.054 g Pd,反应6 h加氢度可达100%。
文摘Conventional synthesis of monolith-supported zeolite catalysts is based on a hydrothermal strategy.Here,we report a solvent-free crystallization process to coat ZSM-5 zeolite crystals on a monolithic SiC foam with a honeycomb structure(ZSM-5/SiC).Characterizations of the ZSM-5/SiC by scanning electron microscopy,N2 sorption,and X-ray diffraction indicate that the zeolite sheath has been ideally coated on the surface of the SiC foam with high purity and crystallinity.Fixing Pd nanoparticles within the ZSM-5 zeolite crystals delivers a bifunctional Pd@ZSM-5/SiC catalyst,which exhibits high activity and selectivity toward diesel range paraffins in the hydrodeoxygenation of methyl oleate,a model molecule for biofuel.In comparison to the powder Pd@ZSM-5,the Pd@ZSM-5/SiC monolith catalyst shows more efficiency,which is attributed to the fast mass transfer and high heat conductivity on the honeycomb SiC structure.The durability test indicates that the Pd@ZSM-5/SiC catalyst is stable under the reaction and high-temperature regeneration conditions.
