Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we ...Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.展开更多
The Ni@Au core-shell nanoparticles had been successfully synthesized from aqueous solution by one-step route at room temperature. The Ni@Au nanoparticles can be an excellent catalyst for Ullmann reaction. The advantag...The Ni@Au core-shell nanoparticles had been successfully synthesized from aqueous solution by one-step route at room temperature. The Ni@Au nanoparticles can be an excellent catalyst for Ullmann reaction. The advantage of Ni@Au is that the catalyst does not need additional reducing agents. The Au shell can effectively protect the Ni core from oxidation. The Ni core and Au shell have both composited in structure and cooperated in function.展开更多
A new highly efficient, visible light active, silver vanadate/polymeric carbonitride “core/shell” photocatalyst was prepared mechano-chemically prepared by grinding mixtures of <i><span><span style=&q...A new highly efficient, visible light active, silver vanadate/polymeric carbonitride “core/shell” photocatalyst was prepared mechano-chemically prepared by grinding mixtures of <i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate and mesoporous graphitic carbonitride. Besides the core/shell photocatalyst, </span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate/mesoporous polymeric carbonitride composites and supported mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span><span style="white-space:nowrap;">@</span></span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadates were prepared. The materials were characterized by transmission elec</span><span>tron microscopy (TEM), X-ray diffraction (XRD), nitrogen ad- and</span><span> de-sorption, diffuse reflectance UV-Vis measurement (DRS), infrared spectroscopy, Raman microscopy, and time-resolved photoluminescence spectroscopy. The photocatalytic performance of the materials was investigated in the degradation of organics using pharmaceutical ibuprofen and 4-(isobutyl phenyl) propionic acid sodium salt as model compounds under batch conditions. Reaction intermediates were studied by electrospray ionization and time-of-flight mass spectrometry (ESI-TOF-MS). Additionally, the degree of mineralization was determined by total organic carbon TOC measurements. The core/shell photocatalyst has shown superior photocatalytic activity compared to the other prepared composites or supported photocatalysts as well as the single mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span>. Scavenger experiments showed that valence band holes and anio</span><span>nic superoxide radicals are the main active species in the photocatalytic</span><span> process. TOC measurement confirmed the mineralization of the organic compound, which was in line with ESI-TOF-MS experiments. Time-resolved photoluminescence measurements indicated that charges generated in carbonitride migrate via diffusive hopping and exhibit increased mobility in the case of the silver vanadate/polymeric carbonitride composite.</span>展开更多
In this study, a novel core-shell structure of ZSM-5@Mg(Al)O(abbreviated as Z@MA) was designed by using the sol-gel method, and the influence of different weight ratios of Mg(Al)O/ZSM-5 on the structure and catalytic ...In this study, a novel core-shell structure of ZSM-5@Mg(Al)O(abbreviated as Z@MA) was designed by using the sol-gel method, and the influence of different weight ratios of Mg(Al)O/ZSM-5 on the structure and catalytic performance was investigated. The as-obtained materials were characterized by XRD, N_2-physisorption, SEM, FT-IR, NH_3-TPD and XPS analyses. The results showed that, with the increase of the weight ratio of Mg(Al)O/ZSM-5, the thickness of Mg(Al)O shell was improved, and the pore structure and physiochemical properties of core-shell materials were directly modified. After introduction of Mg(Al)O, the acidity properties of different materials were significantly suppressed. Meanwhile, more Sn oxide species in Z@MA could facilitate the anchoring of Pt on the support. By effectively employing these modifications, the capacity of the catalysts to accommodate coke was significanty improved and the carbon deposits were migrated from active metal to the carrier. When the weight ratio was equal to 3, the catalyst PtSnNa/Z@MA showed a highest conversion and high selectivity in propane dehydrogenation.展开更多
A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of ...A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process,infiltration of Mo dopants and carbon coating,which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell.Pt Ru nanoparticles(NPs)were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP).The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC)and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25%increase in durability.The improved catalytic performance is due to several aspects including ultrafine crystals of TiO2 with abundant grain boundaries,Mofunctionalized interface with enhanced electron interactions,and core shell architecture with excellent electrical transport properties.This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.展开更多
Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation （MEO）. The structure and ...Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation （MEO）. The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry （CV） techniques. The results showed that the introduction of Ru element （2-10 wt%） into Pd 20 wt%/C （hereafter, denoted as Pd/C） produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C （hereafter, denoted as Pd@Rus/C） catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E = -0.038 V （vs. Hg/HgO） was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of dbp/dfp （the ratio of MEO peak current density in the negative scan and positive scan） were also investigated. The result demonstrated that Pd@Rus/C offering the smallest value of Jbp/Jfp displayed the best stable catalytic performance.展开更多
In order to overcome the drawback of the low degree of separation from an aqueous solution of MnO_2, Fe_3 O_4-MnO_2 core-shell nanocomposites were used as heterogeneous Fenton-like catalysts for the removal of acid or...In order to overcome the drawback of the low degree of separation from an aqueous solution of MnO_2, Fe_3 O_4-MnO_2 core-shell nanocomposites were used as heterogeneous Fenton-like catalysts for the removal of acid orange 7. On the basis of the catalyst characterization, the catalytic ability of the as-synthesized nanocomposites was examined. The results showed that Fe304-Mn02 core-shell nanocomposites had greater catalytic ability than Fe_3 O_4 or MnO_2 used alone. Meanwhile, the catalyst dosage, H_2 O_2 dosage, temperature, and initial pH had significant effects on the removal of acid orange 7. A high degree of stability and reusability were exhibited by Fe_3 O_4-MnO_2 core-shell nanocomposites. Both HO· and HO_2· were generated in the reaction and HO· was the main radical for the removal of acid orange 7. A mechanism for H_2 O_2 catalytic decomposition using Fe_3 O_4-MnO_2 core-shell nanocomposites to produce HO·is proposed.展开更多
基金Supported by the National Natural Science Foundation of China(21676238)
文摘Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.
基金Supported by the Natural Science Foundation of Jiangsu Province (BK2009678)
文摘The Ni@Au core-shell nanoparticles had been successfully synthesized from aqueous solution by one-step route at room temperature. The Ni@Au nanoparticles can be an excellent catalyst for Ullmann reaction. The advantage of Ni@Au is that the catalyst does not need additional reducing agents. The Au shell can effectively protect the Ni core from oxidation. The Ni core and Au shell have both composited in structure and cooperated in function.
文摘A new highly efficient, visible light active, silver vanadate/polymeric carbonitride “core/shell” photocatalyst was prepared mechano-chemically prepared by grinding mixtures of <i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate and mesoporous graphitic carbonitride. Besides the core/shell photocatalyst, </span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate/mesoporous polymeric carbonitride composites and supported mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span><span style="white-space:nowrap;">@</span></span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadates were prepared. The materials were characterized by transmission elec</span><span>tron microscopy (TEM), X-ray diffraction (XRD), nitrogen ad- and</span><span> de-sorption, diffuse reflectance UV-Vis measurement (DRS), infrared spectroscopy, Raman microscopy, and time-resolved photoluminescence spectroscopy. The photocatalytic performance of the materials was investigated in the degradation of organics using pharmaceutical ibuprofen and 4-(isobutyl phenyl) propionic acid sodium salt as model compounds under batch conditions. Reaction intermediates were studied by electrospray ionization and time-of-flight mass spectrometry (ESI-TOF-MS). Additionally, the degree of mineralization was determined by total organic carbon TOC measurements. The core/shell photocatalyst has shown superior photocatalytic activity compared to the other prepared composites or supported photocatalysts as well as the single mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span>. Scavenger experiments showed that valence band holes and anio</span><span>nic superoxide radicals are the main active species in the photocatalytic</span><span> process. TOC measurement confirmed the mineralization of the organic compound, which was in line with ESI-TOF-MS experiments. Time-resolved photoluminescence measurements indicated that charges generated in carbonitride migrate via diffusive hopping and exhibit increased mobility in the case of the silver vanadate/polymeric carbonitride composite.</span>
文摘In this study, a novel core-shell structure of ZSM-5@Mg(Al)O(abbreviated as Z@MA) was designed by using the sol-gel method, and the influence of different weight ratios of Mg(Al)O/ZSM-5 on the structure and catalytic performance was investigated. The as-obtained materials were characterized by XRD, N_2-physisorption, SEM, FT-IR, NH_3-TPD and XPS analyses. The results showed that, with the increase of the weight ratio of Mg(Al)O/ZSM-5, the thickness of Mg(Al)O shell was improved, and the pore structure and physiochemical properties of core-shell materials were directly modified. After introduction of Mg(Al)O, the acidity properties of different materials were significantly suppressed. Meanwhile, more Sn oxide species in Z@MA could facilitate the anchoring of Pt on the support. By effectively employing these modifications, the capacity of the catalysts to accommodate coke was significanty improved and the carbon deposits were migrated from active metal to the carrier. When the weight ratio was equal to 3, the catalyst PtSnNa/Z@MA showed a highest conversion and high selectivity in propane dehydrogenation.
基金the National Natural Science Foundation of China (Grant Nos. 21273058, 21673064, 51802059 and 21503059)China Postdoctoral Science Foundation (Grant Nos. 2018M631938, 2018T110307 and 2017M621284)+1 种基金Heilongjiang Postdoctoral Fund (LBH-Z17074)Fundamental Research Funds for the Central Universities (Grant No. HIT. NSRIF. 2019040 and 2019041)
文摘A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process,infiltration of Mo dopants and carbon coating,which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell.Pt Ru nanoparticles(NPs)were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP).The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC)and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25%increase in durability.The improved catalytic performance is due to several aspects including ultrafine crystals of TiO2 with abundant grain boundaries,Mofunctionalized interface with enhanced electron interactions,and core shell architecture with excellent electrical transport properties.This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.
基金supported by the National Basic Research Program of China(2013CB934001)the Natural Science Foundation of Beijing(2051001)the Natural Science Foundation of China(51074011)
文摘Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation （MEO）. The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry （CV） techniques. The results showed that the introduction of Ru element （2-10 wt%） into Pd 20 wt%/C （hereafter, denoted as Pd/C） produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C （hereafter, denoted as Pd@Rus/C） catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E = -0.038 V （vs. Hg/HgO） was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of dbp/dfp （the ratio of MEO peak current density in the negative scan and positive scan） were also investigated. The result demonstrated that Pd@Rus/C offering the smallest value of Jbp/Jfp displayed the best stable catalytic performance.
基金supported by the National Natural Science Foundation of China(Grant No.51508564)
文摘In order to overcome the drawback of the low degree of separation from an aqueous solution of MnO_2, Fe_3 O_4-MnO_2 core-shell nanocomposites were used as heterogeneous Fenton-like catalysts for the removal of acid orange 7. On the basis of the catalyst characterization, the catalytic ability of the as-synthesized nanocomposites was examined. The results showed that Fe304-Mn02 core-shell nanocomposites had greater catalytic ability than Fe_3 O_4 or MnO_2 used alone. Meanwhile, the catalyst dosage, H_2 O_2 dosage, temperature, and initial pH had significant effects on the removal of acid orange 7. A high degree of stability and reusability were exhibited by Fe_3 O_4-MnO_2 core-shell nanocomposites. Both HO· and HO_2· were generated in the reaction and HO· was the main radical for the removal of acid orange 7. A mechanism for H_2 O_2 catalytic decomposition using Fe_3 O_4-MnO_2 core-shell nanocomposites to produce HO·is proposed.
