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Your search keyword '"Zhao, Yu-Zhen"' showing total 119 results
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119 results on '"Zhao, Yu-Zhen"'

4. Physical Grinding of Prefabricated Co 3 O 4 and MCM-22 Zeolite for Fischer–Tropsch Synthesis: Impact of Pretreatment Procedure on the Dispersion and Catalytic Performance.

Author

Ren, Hua-Ping, Xie, Zhi-Xia, Tian, Shao-Peng, Ding, Si-Yi, Ma, Qiang, Zhao, Yu-Zhen, Zhang, Zhe, Fu, Jiao-Jiao, and Hao, Qing-Qing

Subjects
ZEOLITE catalysts, DISPERSION (Chemistry), PARTICLE size distribution, CATALYST synthesis, OXYGEN reduction, ION exchange (Chemistry)
Abstract

To improve the mess-specific activity of Co supported on zeolite catalysts in Fischer–Tropsch (FT) synthesis, the Co-MCM-22 catalyst was prepared by simply grinding the MCM-22 with nanosized Co3O4 prefabricated by the thermal decomposition of the Co(II)-glycine complex. It is found that this novel strategy is effective for improving the mess-specific activity of Co catalysts in FT synthesis compared to the impregnation method. Moreover, the ion exchange and calcination sequence of MCM-22 has a significant influence on the dispersion, particle size distribution, and reduction degree of Co. The Co-MCM-22 prepared by the physical grinding of prefabricated Co3O4 and H+-type MCM-22 without a further calcination process exhibits a moderate interaction between Co3O4 and MCM-22, which results in the higher reduction degree, higher dispersion, and higher mess-specific activity of Co. Thus, the newly developed method is more controllable and promising for the synthesis of metal-supported catalysts. [ABSTRACT FROM AUTHOR]

Published
2024
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24. Superior Circularly Polarized Luminescence Brightness Achieved with Chiral Heteroleptic Nine-Coordinate Coumarin-Based Tb3+Complexes

Author

Liu, Jiaxiang, Song, Wenqi, Niu, Huizhe, Lu, Ying, Yang, Haiyan, Li, Wentao, Zhao, Yu-zhen, and Miao, Zongcheng

Abstract

In order to facilitate the practical application of circularly polarized luminescence (CPL) active molecules, the CPL brightness (BCPL) must be optimized. We have applied a binary modular strategy to synthesize two chiral organo-Tb3+complexes, [Tb(Coum)3(1R,2R-Ph-PyBox)] (2) and [Tb(Coum)3(1S,2S-Ph-PyBox)] (5), combining 3-acetyl-4-hydroxy-coumarin (Coum) and enantiopure 2,6-bis(4-phenyl-2-oxazolin-2-yl) pyridine (1R,2R/1S,2S-Ph-PyBox). The photophysical properties of these novel complexes have been fully characterized. The combined point-chiral induction capability of chiral bis(oxazoline) derivatives and the outstanding photophysical properties of the coumarin-derived ligand have resulted in an intense excited-state chiroptical activity (|glum| = 0.097–0.103) for both Tb3+enantiomers, with a bright Tb3+-centered high-purity green emission (ΦPL= 74%) and enhanced antenna-centered absorption behavior (ε320 nm= 47820–47940 M–1cm–1). A superior BCPL(1132.7–1205.8 M–1cm–1at 5D4→ 7F5) has been established for complexes 2and 5. The strategy adopted in this work provides a new route to chiroptical organo-Tb3+luminophores with outstanding comprehensive performance.

Published
2024
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35. A High-Performance Ni/SiO2Prepared by the Complexed-Impregnation Method with Citric Acid for Carbon Dioxide Reforming of Methane

Author

Ren, Hua-Ping, Hao, Qing-Qing, Ding, Si-Yi, Zhao, Yu-Zhen, Zhu, Min, Tian, Shao-Peng, Ma, Qiang, Song, Wen-Qi, Miao, Zongcheng, and Liu, Zhao-Tie

Abstract

A group of Ni/SiO2catalysts was prepared via the complexed-impregnation method with different amounts of citric acid (Ni–C/SiO2). The Ni–C/SiO2and Ni/SiO2prepared by the conventional impregnation method were respectively tested for carbon dioxide reforming of methane (CDR) at CO2/CH4= 1.0, a gas hourly space velocity of 60 000 mL·g–1·h–1, and a reaction temperature of 750 °C. The characterization results indicated that Ni–C/SiO2showed higher Ni dispersion and stronger Ni–support interaction than Ni/SiO2. As a result, superior anti-coke and anti-sintering of Ni were obtained over the Ni–C/SiO2during the period of CDR operation. Importantly, a highly active and stable catalyst was obtained by optimizing the amount of citric acid added, and an unobservable deactivation was exhibited over Ni–C/SiO2with a molar ratio of citric acid to Ni of 2.0 for the CDR testing within the time on stream of 100 h.

Published
2018
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44. Effect of Al4C3Particle Size Distribution in a Al–2.5C Master Alloy on the Refining Efficiency of the AZ31 Alloy

Author

Zhao, Yu-Zhen, Liu, Xiao-Teng, and Hao, Hai

Abstract

The Al–2.5C master alloy is prepared to investigate the effect of the Al4C3particle size distribution on the refining efficiency of the AZ31 alloy. The results indicate that the Al4C3particles are potent nucleation substrates for primary α-Mg grains. With 1.0 wt% master alloy addition, the grain size is reduced from 204 to 70 μm. The grain refining efficiency of the Al4C3particles on the AZ31 alloy is calculated to be 0.04%–0.75%. Such low refining efficiency is mainly attributed to the size distribution of the Al4C3particles. The particle sizes are in the range from 0.18 to 7.08 μm, and their distribution is well fitted by a log-normal function. The optimum particle size range for significant grain refinement is proposed to be around 5.0–7.08 μm in the present conditions.

Published
2017
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