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Effect of boron on ZSM-5 catalyst for methanol to propylene conversion

100%
Xu A., Ma H., Zhang H., Weiyong D., Fang D.
Polish Journal of Chemical Technology
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2013
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vol. 15
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issue 4
95-101
EN
B-ZSM-5 catalysts were prepared by various modification methods with boric acid, including ion-exchange, impregnation and direct synthesis. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), NH3-Temperature Programmed Desorption (NH3-TPD), N2 adsorption-desorption, Fourier Transform Infrared spectrometry (FT-IR), 27Al and 11B MAS NMR spectra. The results revealed that the weak acidity of catalysts was significantly increased by modification. The catalytic activity was measured in a fixed bed at 460°C for methanol to propylene (MTP) reaction. The results of MTP reaction showed a great increment of the propylene selectivity for the boron modified samples, especially for the directly synthesized B-ZSM-5 which also displayed high activity and selectivity towards C2 =-C4 = olefins. It was found that the remarkable selectivity strongly depended on the intensity of weak acidity.
2
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Process simulation of dimethyl ether synthesis via methanol vapor phase dehydration

100%
Bai Z., Ma H., Zhang H., Ying W., Fang D.
Polish Journal of Chemical Technology
|
2013
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vol. 15
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issue 2
122-127
EN
The production processes included catalytic dehydration of methanol in an adiabatic fixed-bed reactor and two columns product separations. In this study, the technological process for dimethyl ether (DME) synthesis is built on PRO/II platform based on the combined parameters of the reaction dynamic model for methanol dehydration reaction, the improved NRTL model of the liquid phase, the PR model of vapor phase. In order to validate the proposed model, the simulation results have been compared with the available data from a set of industrial production equipment with a production capacity of 200 000 tonnes per annum. A comparison between the calculated and measured results has proved that these results are satisfactory. The bed height and the volume of the catalytic bed are calculated aim at one million t/a DME yields and while taking account of high-purity DME production. After discussing the influence of feed stage location and reflux ratio for DME product purity, the suitable unit operation conditions are chosen. Accordingly, accurate process simulation results provide the basis and guidance for an improvement and development of the similar industrial device.
3
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Impact of heating rate and solvent on Ni-based catalysts prepared by solution combustion method for syngas methanation

100%
Zeng Y., Ma H., Zhang H., Ying W., Fang D.
Polish Journal of Chemical Technology
|
2014
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vol. 16
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issue 4
95-100
EN
Ni-Al2O3 catalysts prepared by solution combustion method for syngas methanation were enhanced by employing various heating rate and different solvent. The catalytic properties were tested in syngas methanation. The result indicates that both of heating rate and solvent remarkably affect Ni particle size, which is a key factor to the catalytic activity of Ni-Al2O3 catalysts for syngas methanation. Moreover, the relationship between Ni particle size and the production rate of methane per unit mass was correlated. The optimal Ni-Al2O3 catalyst prepared in ethanol at 2°C/min, achieves a maximum production rate of methane at the mean size of 20.8 nm.
4
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The effect of preparation method on the performance of PtSn/Al2O3catalysts for acetic acid hydrogenation

100%
Zhang K., Zhang H., Ma H., Ying W., Fang D.
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EN
PtSn/Al2O3 catalysts with a given loading of 1 wt% Pt and 1 wt% Sn were prepared by co-impregnation or successive impregnation with aqueous solutions of Pt, Sn precursors and a commercial alumina. The catalysts were characterized by N2 adsorption, H2-TPR (H2 temperature-programmed reduction), H2-pulse chemisorption, XPS (X-ray photoelectron spectroscopy) and CO-FTIR (Fourier transform infrared spectroscopy), and tested in the hydrogenation of acetic acid. The results showed that the preparation method affected both the chemical properties and their performance in the hydrogenation of acetic acid. Sn enrichment on the catalysts surface was observed on the co-impregnated catalyst and catalyst in which the Pt precursor had been loaded first. It was found that the modification of Pt was a function of the sequence of Sn addition as revealed by CO-FTIR. Co-impregnated catalyst showed the highest activity and ethanol selectivity.
5
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One-dimensional isothermal multicomponent diffusion-reaction model and its application to methanol synthesis over commercial Cu-based catalyst

100%
Lei K., Ma H., Zhang H., Ying W., Fang D.
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EN
The present work was a study on global reaction rate of methanol synthesis. We measured experimentally the global reaction rate in the internal recycle gradientless reactor over catalyst SC309. The diffusion-reaction model of methanol synthesis was suggested. For model we chose the hydrogenation of CO and CO2 as key reaction. CO and CO2 were key components in our model. The internal diffusion effectiveness factors of CO and CO2 in the catalyst were calculated by the numerical integration. A comparison with the experiment showed that all the absolute values of the relative error were less than 10%. The simulation results showed that decreasing reaction temperature and catalyst diameter were conducive to reduce the influence of the internal diffusion on the methanol synthesis.
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