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852 results on '"Fan, Xiaoqiang"'

201. The Preparation of Mn-Modified CeO 2 Nanosphere Catalysts and Their Catalytic Performance for Soot Combustion.

Author

Gao, Siyu, Yu, Di, Zhou, Shengran, Zhang, Chunlei, Wang, Lanyi, Fan, Xiaoqiang, Yu, Xuehua, and Zhao, Zhen

Subjects
CERIUM oxides, SOOT, CATALYSTS, COMBUSTION, CATALYTIC activity, DIESEL motor exhaust gas
Abstract

With the increasing stringency of environmental protection regulations, reducing the severe pollution caused by soot particles from diesel vehicle exhaust has become a widespread concern. Catalytic purification technology is currently an efficient method for eliminating soot particles, which needs to develop high-activity catalysts. This work uses a two-step hydrothermal method to synthesize MnOx/CeO2 nanosphere catalysts, which have synergistic effects between manganese and cerium, and have high reactive oxygen species. Among them, the MnCe-1:4 catalyst represents the optimal catalytic activity, and the values of T10, T50, and T90 are 289, 340, and 373 °C, respectively. On account of their simple synthetic procedure and low cost, the prepared MnOx/CeO2 nanosphere catalysts have good prospects for practical applications. [ABSTRACT FROM AUTHOR]

Published
2023
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202. Construction of cerium-based oxide catalysts with abundant defects/vacancies and their application to catalytic elimination of air pollutants.

Author

Gao, Siyu, Yu, Di, Zhou, Shengran, Zhang, Chunlei, Wang, Lanyi, Fan, Xiaoqiang, Yu, Xuehua, and Zhao, Zhen

Abstract

As environmental regulations become more stringent and public awareness of the need for environmental protection increases, air pollution has become an issue of widespread concern. Catalytic purification technology is considered one of the most effective strategies for the elimination of air pollutants, although the development of highly efficient catalysts has become a key hurdle in the widespread application of this technology. In recent years, cerium-based oxide catalysts have been widely used for the catalytic removal of air pollutants owing to their excellent redox properties, oxygen storage/release capacity, and low cost. Investigating the construction of abundant oxygen vacancies/defects on CeO2 surfaces is important for improving the performance of these catalysts. This review first summarizes recent advances in the preparation of CeO2 catalysts featuring abundant oxygen vacancies/defects, such as the hydrothermal, template, sol–gel, solid-phase synthesis, and coprecipitation methods. Next, the catalytic elimination of air pollutants, including CO, NOx, volatile organic compounds, soot, and SOx, by cerium-based oxide catalysts is discussed. Finally, the problems and prospects of cerium-based oxide catalysts with abundant defects/vacancies for the catalytic elimination of air pollutants are described. [ABSTRACT FROM AUTHOR]

Published
2023
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221. Alkali Metals and Cerium-Modified La–Co-Based Perovskite Catalysts: Facile Synthesis, Excellent Catalytic Performance, and Reaction Mechanisms for Soot Combustion

Author

Yu, Di, primary, Wang, Lanyi, additional, Zhang, Chunlei, additional, Peng, Chao, additional, Yu, Xuehua, additional, Fan, Xiaoqiang, additional, Liu, Bing, additional, Li, Kaixiang, additional, Li, Zhenguo, additional, Wei, Yuechang, additional, Liu, Jian, additional, and Zhao, Zhen, additional

Published
2022
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222. Phase I Open-Label Single-Arm Study of BCMA/CD19 Dual-Targeting FasTCAR-T Cells (GC012F) As First-Line Therapy for Transplant-Eligible Newly Diagnosed High-Risk Multiple Myeloma

Author

Du, Juan, primary, Fu, Weijun, additional, Lu, Jing, additional, Qiang, Wanting, additional, He, Haiyan, additional, Liu, Jin, additional, Yang, Ying, additional, Feng, Zhongyuan, additional, Jin, Lina, additional, Fan, Xiaoqiang, additional, Liu, Jia, additional, Zhang, Qi, additional, Shen, Lianjun, additional, Weng, Lihong, additional, and Cao, Wei, additional

Published
2022
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230. One‐pot synthesis of V doped mesoporous SiO2 catalysts for selective oxidation of ethane and propane.

Author

Song, Jiaxin, Fan, Xiaoqiang, Yu, Xuehua, Kong, Lian, Xiao, Xia, Xie, Zean, and Zhao, Zhen

Subjects
*ETHANES, *PROPANE, *SELECTIVE catalytic oxidation, *TRANSMISSION electron microscopy, *OXIDATION, *CATALYSTS, *NEAR infrared reflectance spectroscopy, *REFLECTANCE spectroscopy
Abstract

A series of vanadium‐doped mesoporous SiO2 catalysts were prepared using a one‐pot emulsion method. The effects of VOx species with different structures on C−H bond activation and product selectivity in ethane and propane selective oxidation were investigated using X‐ray diffraction (XRD), N2 adsorption‐desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, ultraviolet‐visible diffuse reflectance spectroscopy (UV‐Vis DRS), hydrogen temperature programmed reduction (H2‐TPR), and ammonia temperature programmed desorption (NH3‐TPD) characterizations. The results revealed that the highly dispersed isolated tetrahedral VOx species on the catalyst gradually polymerized into highly dispersed oligomeric VOx species with the increased V loading. The former is beneficial for the formation of olefins and total aldehydes during the selective oxidation of propane. Oligomeric VOx species are conducive to improving the selectivity of ethylene and acetaldehyde in the selective oxidation of ethane. The highest catalytic performances for selective oxidation of ethane and propane were obtained at a temperature of 650 °C. The conversion of ethane was 41.6 %, with a corresponding yield of ethylene and acetaldehyde of 23.6 % over a 0.5 V−SiO2 catalyst. In contrast, the propane conversion was 61.5 %, with a corresponding total yield of olefins and aldehydes of 41.3 % over a 1.0 V−SiO2 catalyst. [ABSTRACT FROM AUTHOR]

Published
2023
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231. Recent progress in catalytic dehydrogenation of propane over Pt-based catalysts.

Author

Shan, Yiou, Hu, Huimin, Fan, Xiaoqiang, and Zhao, Zhen

Abstract

Light alkenes are the key building blocks in the chemical industry. As a propene on-purpose production technology, propane dehydrogenation has drawn particular attention due to the growing demand for propene and the discovery of large reserves of shale gas. The development of highly active and stable propane dehydrogenation catalysts is significant in the world-wide research field. Supported platinum-based catalysts are widely studied for propane dehydrogenation. This article reviews the developments of platinum-based catalysts in propane dehydrogenation, particularly focusing on the influence of the promoter effect and support effect on the structure and catalytic performance and especially on how promoters and supports enable Pt to form highly dispersed and stable active sites. At the end, we propose the prospective research directions of propane dehydrogenation. [ABSTRACT FROM AUTHOR]

Published
2023
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234. Forced oscillation phenomenon of normal/oblique shock trains in a rectangular duct at Mach 2 and 3

Author

Wang Yi, Xiong Bing, and Fan Xiaoqiang

Subjects
Physics, 020301 aerospace & aeronautics, Shock (fluid dynamics), Oscillation, Isolator, Aerospace Engineering, 02 engineering and technology, Mechanics, 01 natural sciences, law.invention, symbols.namesake, 0203 mechanical engineering, Mach number, law, Intermittency, 0103 physical sciences, symbols, Harmonic, Oblique shock, 010303 astronomy & astrophysics, Freestream
Abstract

The forced shock train oscillation is a common phenomenon in a practical working scramjet isolator. To evaluate the similarities and differences between the forced normal shock train oscillation and the forced oblique shock train oscillation, experiments were conducted in a rectangular duct at Mach 2 and 3. The normal/oblique shock trains were forced to oscillate for different back-pressure levels by changing the mechanical throttling ratio. High-frequency pressure measurements were mainly utilized for data acquisition and analysis. The frequency contents, the intermittency characteristics and the perturbation propagation of forced shock train oscillations were investigated in this work. Experimental results illustrate that the forced oscillation at Mach 3 is a composite pattern, which is dominated by the excited frequency and coupled with the inherent unsteadiness. This phenomenon is not obvious for the forced oscillation at Mach 2. For the forced oscillations at Mach 2 and 3, the maximum zero-crossing frequency is close to the downstream excitation frequency, and the whole intermittent region almost holds this value, which is very different from the self-excited oscillation pattern. By using the cross-spectral analysis, the frequency-dependent correlation was evaluated. It shows that the excitations and its harmonic contents can propagate upstream to affect the intermittent region and its downstream. Besides the excitation frequency and its harmonic contents, low-frequency contents (tens to more than a hundred Hz) can propagate nearby the separation region, and the propagation to downstream the separation bubble is very weak. Considering the time-lag between different transducers, the propagation speed of perturbations can be obtained. It implies that the propagation speed is independent of the magnitude of the back-pressure, but affected by the velocity of the incoming flow. Specifically, the higher the freestream Mach number is, the greater the propagation speed will be.

Published
2021

239. K-modified MnOδ catalysts with tunnel structure and layered structure: Facile preparation and catalytic performance for soot combustion.

Author

Peng, Chao, Ren, Yu, Yu, Di, Wang, Lanyi, Zhang, Chunlei, Fan, Xiaoqiang, Yu, Xuehua, Zhao, Zhen, Wei, Yuechang, and Liu, Jian

Subjects
CATALYST structure, COMBUSTION, PARTICULATE matter, POLLUTION, SOOT, DENSITY functional theory, AIR pollution
Abstract

Air pollution from particulate matter produced by incomplete combustion of diesel fuel has become a serious environmental pollution problem, which can be addressed by catalytic combustion. In this work, a series of K-modified MnOδ catalysts with different microstructures were synthesized by the hydrothermal method, and the relationship between structure of the catalysts and their catalytic performance for soot combustion was studied by characterization techniques and density functional theory (DFT) calculations. Results showed that the prepared catalysts had good catalytic performance for soot combustion and could completely oxidize soot at temperatures below 400 °C. The cryptomelane-type K2−xMn8O16 (K-OMS-2) with tunnel structure had excellent NO oxidation capacity and abundance of Mn4+ ions (Mn4+/Mn3+ = 1.24) with good redox ability, and it demonstrated better soot combustion performance than layered birnessite-type K2Mn4O8 (K-OL-1). The T10, T50, and T90 temperatures of K-OMS-2 were 269, 314, and 346 °C, respectively. The K-OMS-2 catalyst also showed excellent stability after five catalytic cycles, with T10, T50, and T90 values holding in the ranges of 270 ± 2, 316 ± 2, and 348 ± 3 °C, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
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