Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6A...Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6Al2O9 composite oxides are obtained by the calcination of ZnxAly（OH）2（CO3）z·x H2 O precursor,and the Ni/Zn O-Zn6Al2O9（6.0 wt% Ni O） adsorbents are prepared by wetness impregnation method. The phase,acid strength,acid type and quantity,morphology,and thermal properties were characterized by X-ray diffraction,temperature-programmed desorption of ammonia,pyridine-adsorbed infrared spectrum,high-resolution transmission electron microscopy,and Thermo Gravimetry-Derivative Thermo Gravimetry（TG-DTG）,respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/gcat. The kinetic studies indicated that the active energy of RADS（49.4 k J/mol） could reach nano-sized Zn O,the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high SBET. Also,there are some extents of aromatization reactions that occur,which can be contributed to the B？nsted acid rooted in Zn6Al2O9 composite oxide,and the octane number of products can be preserved well.展开更多
ZnO nanoparticles were synthesized via precipitation-pyrolysis (P&P), where the precursor zinc hydroxide carbonate (Zn5(CO3)2(OH)6) was obtained and then pyrolyzed. The results of TEM indicate that pyrolysis tempe...ZnO nanoparticles were synthesized via precipitation-pyrolysis (P&P), where the precursor zinc hydroxide carbonate (Zn5(CO3)2(OH)6) was obtained and then pyrolyzed. The results of TEM indicate that pyrolysis temperature is the predominant factor for controlling mean sizes of nanoparticles, ranging from 8 nm to 80 nm. Increasing the pyrolysis temperature enhances the mean size. The results of XRD show that nanoparticles are all of crystalline zincite. The mean size observed by TEM is in agreement with that calculated from the specific surface area(SSA) and the crystalline size calculated from the XRD patterns, indicating that the primary particles are rather uniform in size and have single crystals. The growth behaviors of epitaxy along the C-axis are responsible for the morphology of ZnO changing from sphere to rod-like shape, and then to reticulation. Compared with other synthesis approaches, P&P can get fairly good product with a relatively low cost.展开更多
We report a new kagome quantum spin liquid candidate CuaZn（OH）6FBr, which does not experience any phase transition down to 50inK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature （-20...We report a new kagome quantum spin liquid candidate CuaZn（OH）6FBr, which does not experience any phase transition down to 50inK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature （-200 K）. A clear gap opening at low temperature is observed in the uniform spin susceptibility obtained from 19F nuclear magnetic resonance measurements. We observe the characteristic magnetic field dependence of the gap as expected for fractionalized spin-1/2 spinon excitations. Our experimental results provide firm evidence for spin fractionalization in a topologically ordered spin system, resembling charge fraetionalization in the fractional quantum Hall state.展开更多
The title compound H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X ray diffraction. The crystal belongs to mo...The title compound H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X ray diffraction. The crystal belongs to monoclinic, space group C2/m, a=2.0654(4)nm, b=1.3306(3)nm, c=1.3194(3)nm, β=119.59(3)°, V=3.1531(11)nm3, Dc=3.606Mg·m-3, Z=2, R=0.0462, Rw=0.0836. The title compound comprises of a 2+ unit, a polyanion and a free (CH3)2NH molecule. The ESR spectrum of the title compound shows that charge transfer between organic groups and polyanion takes place under irradiation of the sunlight in solid state. The TG study of the title compound shows that it had four stages of the weight loss, and the increase of the decomposition temperature for the polyanion shows that the stability of the polyanion was enhanced due to the influence of Zn2+ ion. CCDC:175866.展开更多
文摘Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6Al2O9 composite oxides are obtained by the calcination of ZnxAly（OH）2（CO3）z·x H2 O precursor,and the Ni/Zn O-Zn6Al2O9（6.0 wt% Ni O） adsorbents are prepared by wetness impregnation method. The phase,acid strength,acid type and quantity,morphology,and thermal properties were characterized by X-ray diffraction,temperature-programmed desorption of ammonia,pyridine-adsorbed infrared spectrum,high-resolution transmission electron microscopy,and Thermo Gravimetry-Derivative Thermo Gravimetry（TG-DTG）,respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/gcat. The kinetic studies indicated that the active energy of RADS（49.4 k J/mol） could reach nano-sized Zn O,the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high SBET. Also,there are some extents of aromatization reactions that occur,which can be contributed to the B？nsted acid rooted in Zn6Al2O9 composite oxide,and the octane number of products can be preserved well.
基金Project(50371024) supported by the National Natural Science Foundation of China
文摘ZnO nanoparticles were synthesized via precipitation-pyrolysis (P&P), where the precursor zinc hydroxide carbonate (Zn5(CO3)2(OH)6) was obtained and then pyrolyzed. The results of TEM indicate that pyrolysis temperature is the predominant factor for controlling mean sizes of nanoparticles, ranging from 8 nm to 80 nm. Increasing the pyrolysis temperature enhances the mean size. The results of XRD show that nanoparticles are all of crystalline zincite. The mean size observed by TEM is in agreement with that calculated from the specific surface area(SSA) and the crystalline size calculated from the XRD patterns, indicating that the primary particles are rather uniform in size and have single crystals. The growth behaviors of epitaxy along the C-axis are responsible for the morphology of ZnO changing from sphere to rod-like shape, and then to reticulation. Compared with other synthesis approaches, P&P can get fairly good product with a relatively low cost.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFA0300502,2016YFA0300503,2016YFA0300604,2016YF0300300 and 2016YFA0300802the National Natural Science Foundation of China under Grant Nos 11421092,11474330,11574359,11674406,11374346 and 11674375+3 种基金the National Basic Research Program of China(973 Program)under Grant No 2015CB921304the National Thousand-Young-Talents Program of Chinathe Strategic Priority Research Program(B) of the Chinese Academy of Sciences under Grant Nos XDB07020000,XDB07020200 and XDB07020300supported by DOE-BES under Grant No DE-FG02-04ER46148
文摘We report a new kagome quantum spin liquid candidate CuaZn（OH）6FBr, which does not experience any phase transition down to 50inK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature （-200 K）. A clear gap opening at low temperature is observed in the uniform spin susceptibility obtained from 19F nuclear magnetic resonance measurements. We observe the characteristic magnetic field dependence of the gap as expected for fractionalized spin-1/2 spinon excitations. Our experimental results provide firm evidence for spin fractionalization in a topologically ordered spin system, resembling charge fraetionalization in the fractional quantum Hall state.
文摘The title compound H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X ray diffraction. The crystal belongs to monoclinic, space group C2/m, a=2.0654(4)nm, b=1.3306(3)nm, c=1.3194(3)nm, β=119.59(3)°, V=3.1531(11)nm3, Dc=3.606Mg·m-3, Z=2, R=0.0462, Rw=0.0836. The title compound comprises of a 2+ unit, a polyanion and a free (CH3)2NH molecule. The ESR spectrum of the title compound shows that charge transfer between organic groups and polyanion takes place under irradiation of the sunlight in solid state. The TG study of the title compound shows that it had four stages of the weight loss, and the increase of the decomposition temperature for the polyanion shows that the stability of the polyanion was enhanced due to the influence of Zn2+ ion. CCDC:175866.
