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115 results on '"Tong, Dong Shen"'

23. Tuning the Acidity of Montmorillonite by H3PO4-Activation and Supporting WO3 for Catalytic Dehydration of Glycerol to Acrolein.

Author

Yu, Wei Hua, Zhu, Bao, Tong, Dong Shen, Deng, Kai, Fu, Chao Peng, Huang, Tian Hao, and Zhou, Chun Hui

Subjects
ACROLEIN, GLYCERIN, X-ray photoelectron spectroscopy, ACIDITY, LEWIS acidity, X-ray powder diffraction, MONTMORILLONITE
Abstract

Montmorillonite (Mnt)-based solid acids have a wide range of applications in catalysis and adsorption of pollutants. For such solid acids, the acidic characteristic often plays a significant role in these applications. The objective of the current study was to examine the effects of H3PO4-activation and supporting WO3 on the textural structure and surface acidic properties of Mnt. The Mnt-based solid acid materials were prepared by H3PO4 treatment and an impregnation method with a solution of ammonium metatungstate (AMT) and were examined as catalysts in the dehydration of glycerol to acrolein. The catalysts were characterized by nitrogen adsorption-desorption, powder X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopy, temperature programmed desorption of NH3 (NH3-TPD), diffuse reflectance Fourier-transform infrared (DR FTIR) spectroscopy of adsorbed pyridine, and thermogravimetric (TG) analyses. The phosphoric acid treatment of Mnt created Brönsted and Lewis acid sites and led to increases in specific surface areas, porosity, and acidity. WO3 species influenced total acidity, acid strength, the numbers of Brönsted and Lewis acid sites, and catalytic performances. A high turnover frequency (TOF) value (31.2 h−1) based on a maximal 60.7% yield of acrolein was reached. The correlation of acrolein yield with acidic properties indicated that the cooperative role of Brönsted and Lewis acid sites was beneficial to the formation of acrolein and a little coke deposition (<3.3 wt.%). This work provides a new idea for the design of solid acid catalysts with cooperative Brönsted and Lewis acidity for the dehydration of glycerol. [ABSTRACT FROM AUTHOR]

Published
2022
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26. Tuning the Acidity of Montmorillonite by H3PO4-Activation and Supporting WO3for Catalytic Dehydration of Glycerol to Acrolein

Author

Yu, Wei Hua, Zhu, Bao, Tong, Dong Shen, Deng, Kai, Fu, Chao Peng, Huang, Tian Hao, and Zhou, Chun Hui

Abstract

Montmorillonite (Mnt)-based solid acids have a wide range of applications in catalysis and adsorption of pollutants. For such solid acids, the acidic characteristic often plays a significant role in these applications. The objective of the current study was to examine the effects of H3PO4-activation and supporting WO3on the textural structure and surface acidic properties of Mnt. The Mnt-based solid acid materials were prepared by H3PO4treatment and an impregnation method with a solution of ammonium metatungstate (AMT) and were examined as catalysts in the dehydration of glycerol to acrolein. The catalysts were characterized by nitrogen adsorption-desorption, powder X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopy, temperature programmed desorption of NH3(NH3-TPD), diffuse reflectance Fourier-transform infrared (DR FTIR) spectroscopy of adsorbed pyridine, and thermogravimetric (TG) analyses. The phosphoric acid treatment of Mnt created Brönsted and Lewis acid sites and led to increases in specific surface areas, porosity, and acidity. WO3species influenced total acidity, acid strength, the numbers of Brönsted and Lewis acid sites, and catalytic performances. A high turnover frequency (TOF) value (31.2 h−1) based on a maximal 60.7% yield of acrolein was reached. The correlation of acrolein yield with acidic properties indicated that the cooperative role of Brönsted and Lewis acid sites was beneficial to the formation of acrolein and a little coke deposition (<3.3 wt.%). This work provides a new idea for the design of solid acid catalysts with cooperative Brönsted and Lewis acidity for the dehydration of glycerol.

Published
2022
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32. [Degradation of dimethyl phthalate by Ti (IV)-catalyzed O3/H2O2 under acidic conditions]

Author

Yan, Gao, Tong-Dong, Shen, Yao, Chen, Hui-Hua, Zhou, and Shao-Ping, Tong

Subjects
Titanium, Ozone, Phthalic Acids, Hydrogen Peroxide, Gas Chromatography-Mass Spectrometry, Water Pollutants, Chemical
Abstract

The degradation efficiencies of dimethyl phthalate (DMP) by O3, O3/H2O2, Ti(IV)/O3 and Ti(IV)/O3/H2O2 were investigated under acidic conditions. The results indicated that Ti(IV)/O3/H2O2 was the best system with the highest degradation efficiency and mineralization rate of DMP, and the highest utilization rate of ozone at pH 2.8. The apparent rate constants of DMP degradation by O3, O3/H2O2, Ti(IV)/O3 and Ti(IV)/O3/H2O2 under the same conditions were 3.96 x 10(-4) s(-1), 9.54 x 10(-4) s(-1) 1.07 x 10(-3) s(-1) and 6.41 x 10(-3) s(-1), respectively. The ozone utilization rate of Ti(IV)/O3/H2O2 was improved by 6.51% compared with that of ozonation alone. The experimental results showed that the optimized concentrations of Ti(IV) and H2O2 were 1.4 mg x L(-1) and 10 mg x L(-1), respectively. According to the results of gas chromatography-mass spectrometry (GC/MS) and ion chromatography analysis, the possible reaction pathway of DMP degradation by Ti(IV)/O3/H2O2 was proposed and discussed.

Published
2014

49. Transesterification of dimethyl carbonate with phenol to diphenyl carbonate over V2O5 catalyst

Author

Tong, Dong-Shen, Yao, Jie, Wang, Yue, Niu, Hong-Ying, and Wang, Gong-Ying

Subjects
*PHENOL, *SPECTRUM analysis, *CHEMICAL inhibitors, *ETHANES
Abstract

Abstract: A novel heterogeneous catalyst, pure V2O5 catalyst prepared by calcination of NH4VO3 at 550°C in air, was used for the synthesis of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol. The effects of V2O5 amount, reaction time and molar ratio of dimethyl carbonate to phenol were investigated. Under the conditions of mass fraction of catalyst 1.6%, molar ratio of DMC/phenol of 1.5:1 and a reaction time 9h, the maximum conversion of phenol and total yields of methyl phenyl carbonate (MPC) and DPC were 42.0 and 40.1%, respectively. Reuse of the catalysts revealed an appreciable deactivation. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) characteristics of the fresh and used catalyst samples had been recorded. The results showed that the deactivation of the catalyst was mainly ascribed to the conversion of crystal structure. Moreover, the deactivated catalyst could be easily reactivated by calcination in air, and the regenerated catalyst showed the catalytic activity almost as high as that of the fresh sample. However, a small difference in catalytic activities between regenerated and fresh catalysts was possibly owing to the sintering of the regenerated catalyst. [Copyright &y& Elsevier]

Published
2007
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50. Coking of Catalysts in Catalytic Glycerol Dehydration to Acrolein

Author

Martino Di Serio, Chun Hui Zhou, Jun Rui Zhang, Riccardo Tesser, Dong Shen Tong, Xue Chao Jiang, Jiang, Xue Chao, Zhou, Chun Hui, Tesser, Riccardo, Di Serio, Martino, Tong, Dong Shen, and Zhang, Jun Rui

Subjects
inorganic chemicals, General Chemical Engineering, chemistry.chemical_element, 02 engineering and technology, Raw material, 010402 general chemistry, complex mixtures, 01 natural sciences, Oxygen, Industrial and Manufacturing Engineering, Catalysis, chemistry.chemical_compound, Glycerol, Chemical Engineering (all), Chemistry, organic chemicals, Chemistry (all), Acrolein, technology, industry, and agriculture, General Chemistry, Glycerol dehydration, Coke, 021001 nanoscience & nanotechnology, respiratory tract diseases, 0104 chemical sciences, Chemical engineering, 0210 nano-technology, Literature survey
Abstract

Catalytic glycerol dehydration provides a sustainable route to produce acrolein because glycerol is a bioavailable platform chemical. However, in this process catalysts are rapidly deactivated due to coking. This paper examines and discusses recent insights into coking of catalysts during catalytic glycerol dehydration. The nature and location of coke and the rate of coking depend on feedstock, operating conditions, and the acidity and pore structure of the solid catalysts. Several methods have been suggested for inhibiting the coking and slowing the deactivation of catalyst, including (1) cofeeding of oxygen, (2) tuning of the pore size of the solid acid catalysts, (3) doping noble metals (Ru, Pt, Pd) into the solid acid catalysts, and (4) designing new reactors. The present methods for inhibiting coking are still unsatisfactory. The deactivated catalysts can be regenerated by removing coke. Nevertheless, the rapid deactivation of the regenerated catalyst remains problematic. The literature survey indicates that the exact chemical compositions of the coke on the catalyst during glycerol dehydration remain elusive. The thermodynamics, kinetics, and mechanism of coking need to be probed so as to advance the development of a catalyst with high activity, selectivity, and resistance to coking to put the catalytic glycerol dehydration into practice.

Published
2018

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