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De Chen - One of the best experts on this subject based on the ideXlab platform.
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Improved selectivity and coke resistance of core-shell alloy catalysts for Propane Dehydrogenation from first principles and microkinetic analysis
Chemical Engineering Journal, 2019Co-Authors: Ling Xiao, Xinggui Zhou, De Chen, Fang Ma, Jinghong Zhou, Wei-kang YuanAbstract:Abstract Microkinetic analysis combined with the results obtained from density functional theory calculations has been performed to examine the catalytic activity and selectivity of Pt-based core-shell alloy catalysts for Propane Dehydrogenation. Calculated results indicate that substitution of 11 late transition metals for the core region of Pt nanoparticles would significantly modify the electronic structure of the surface Pt atoms through the strain effect and charge transfer. The core-shell catalysts are found to have less negative propylene adsorption energies and higher activation energies for the Dehydrogenation reactions than Pt, thus giving rise to a lower catalytic activity and a higher selectivity toward propylene. Linear chemisorption energy and transition state energy scaling relations hold very well in the present work, and the adsorption energy of propylene is identified to be a good descriptor to represent the overall kinetics. The scaling relations also suggest that a higher catalyst selectivity toward propylene can only be achieved at the expense of a lower catalytic activity for Propane Dehydrogenation. If a compromise is made between catalytic activity and catalyst selectivity, Co@Pt is proposed to be the best core-shell catalyst for Propane Dehydrogenation.
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Insights into the effects of steam on Propane Dehydrogenation over a Pt/Al2O3 catalyst
Catalysis Science & Technology, 2015Co-Authors: Yu-ling Shan, De Chen, Xinggui ZhouAbstract:Catalytic Propane Dehydrogenation over an alumina supported Pt catalyst in the presence of steam is carried out and it is found that the catalyst activity is increased and the apparent activation energy is lowered due to the presence of steam. Three possible mechanisms, i.e. co-adsorption, Langmuir–Hinshelwood and Eley–Rideal, of changes in energetics and pathways for Propane Dehydrogenation due to the presence of steam are explored by DFT calculation. The results show that co-adsorption of C3 species with surface oxygenated species would elevate Dehydrogenation energy barriers due to repulsive interactions between them. Surface –OH is more active than surface –O in activating the C–H bond in Propane and propyl species through either the Langmuir–Hinshelwood or Eley–Rideal mechanism and plays an important role in Propane Dehydrogenation with steam. The Langmuir–Hinshelwood mechanism is kinetically favorable, in which the activations of the first H in Propane by surface −OH are the rate determining steps, but the activation energies are higher than that on a clean Pt(111) surface. The observed enhanced catalyst's activity is ascribed to the lowered coking rates as well as the changes in surface coverage due to the co-adsorption of water and the surface oxygenated species.
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Tuning selectivity and stability in Propane Dehydrogenation by shaping Pt particles: A combined experimental and DFT study
Journal of Molecular Catalysis A-chemical, 2014Co-Authors: Minglei Yang, Xinggui Zhou, Yingda Yu, De ChenAbstract:Abstract Shaped metal particles are known to possess distinct catalytic properties, which is often attributed to the catalytic activities of different particle facets. In this contribution, Propane Dehydrogenation on Pt particles of different shapes is investigated by a combination of experiments and DFT calculations. The selectivity toward propylene and catalyst stability in Propane Dehydrogenation can be enhanced by shaping Pt nanoparticles under industrially relevant conditions. Octahedral particles (12.0 nm) dominated by the Pt(1 1 1) surface have higher selectivity toward propylene production and better stability than cubic particles (11.5 nm) that are dominated by the Pt(1 0 0) surface. Combined experiments and DFT calculations suggest that the weakened binding strength of propylene and increased energy barrier for the C–H bond cleavage in propylene Dehydrogenation on Pt(1 1 1) compared to Pt(1 0 0) and Pt(2 1 1) contribute to the higher selectivity toward propylene by lowering the formation possibility of the deeply dehydrogenated intermediates. When coke is formed on the Pt surface, the d -band of surrounding Pt atoms is shifted farther below the Fermi level, leading to the deactivation of Pt catalyst. Our DFT calculations provide a rational interpretation of the experimental observations regarding the shape effects on Propane Dehydrogenation.
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first principles calculations of Propane Dehydrogenation over ptsn catalysts
ACS Catalysis, 2012Co-Authors: Minglei Yang, Xinggui Zhou, De ChenAbstract:Density functional theory calculations have been performed to investigate the effect of Sn on the catalytic activity and selectivity of Pt catalyst in Propane Dehydrogenation. Five models with different Sn to Pt surface molar ratios are constructed to represent the PtSn surfaces. With the increase of the Sn content, the d-band of Pt is broadened, which gives rise to a downshift in the d-band center on the PtSn surfaces. Consequently, the bonding strength of propyl and propylene on the alloyed surfaces is lowered. With the decomposition of the adsorption energy, the change in the surface deformation energy is predicted to be the dominant factor that determines the variation in the adsorption energy on the surface alloys, while on the bulk alloys the change in the binding energy makes a major contribution. The introduction of Sn lowers the energy barrier for propylene desorption and simultaneously increases the activation energy for propylene Dehydrogenation, which has a positive effect on the selectivity t...
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kinetics of Propane Dehydrogenation over pt sn al2o3 catalyst
Applied Catalysis A-general, 2011Co-Authors: Qing Li, Xinggui Zhou, De ChenAbstract:Abstract Langmuir–Hinshelwood kinetic models for catalytic Propane Dehydrogenation on Pt -Sn/Al2O3 are proposed based on the reaction mechanisms that take into account the one step or two-step Dehydrogenation and are evaluated by fitting the experiments. When taking into consideration the fitting accuracy, the number of fitting parameters and the rigorousness of the reaction mechanism, the kinetics of Propane Dehydrogenation based on the assumptions of step-wise Dehydrogenation, the first step Dehydrogenation as the rate-determining step, and low surface coverage of C3H7 outperforms other kinetic models. The change of catalyst activity with time-on-stream is related to the rate of coke formation that depends on the partial pressures of propene and hydrogen. Finally a complete kinetic model, which includes Propane Dehydrogenation and cracking and catalyst deactivation because of coking, is developed, which is found to agree well with the changes of Propane conversions with time-on-stream under different operating conditions. Direct measurement of coke formation is avoided by the approach employed in this study for the prediction of catalyst deactivation by coke deposition.
Jinlong Gong - One of the best experts on this subject based on the ideXlab platform.
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Facilitating the reduction of V–O bonds on VOx/ZrO2 catalysts for non-oxidative Propane Dehydrogenation
Chemical Science, 2020Co-Authors: Sai Chen, Zhi-jian Zhao, Rentao Mu, Jinlong GongAbstract:Supported vanadium oxide is a promising catalyst in Propane Dehydrogenation due to its competitive performance and low cost. Nevertheless, it remains a grand challenge to understand the structure–performance correlation due to the structural complexity of VOx-based catalysts in a reduced state. This paper describes the structure and catalytic properties of the VOx/ZrO2 catalyst. When using ZrO2 as the support, the catalyst shows six times higher turnover frequency (TOF) than using commercial γ-Al2O3. Combining H2-temperature programmed reduction, in situ Raman spectroscopy, X-ray photoelectron spectroscopy and theoretical studies, we find that the interaction between VOx and ZrO2 can facilitate the reduction of V–O bonds, including VO, V–O–V and V–O–Zr. The promoting effect could be attributed to the formation of low coordinated V species in VOx/ZrO2 which is more active in C–H activation. Our work provides a new insight into understanding the structure–performance correlation in VOx-based catalysts for non-oxidative Propane Dehydrogenation.
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Nature of the Active Sites of VOx/Al2O3 Catalysts for Propane Dehydrogenation
ACS Catalysis, 2016Co-Authors: Zhi-jian Zhao, Tengfang Wu, Liang Zeng, Jinlong GongAbstract:Supported VOx catalysts are promising for use in Propane Dehydrogenation (PDH) because of the relatively superior activity and stable performance upon regeneration. However, the nature of the active sites and reaction mechanism during PDH over VOx-based catalysts remains elusive. We examined active species by attaining various fractions of V5+, V4+, and V3+ ions by adjusting the surface vanadium density on an alumina support. The results reveal a close relationship between TOF and the fraction of V3+ ion, indicating that V3+ was more active for PDH. In situ diffuse reflectance infrared Fourier transform spectroscopy showed the same strong adsorbed species during both Propane Dehydrogenation and propylene hydrogenation. The results indicated that such an intermediate may correspond to V species containing a C═C bond, i.e., V–C3H5, and a reaction mechanism was proposed accordingly.
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Propane Dehydrogenation over pt tio2 al2o3 catalysts
ACS Catalysis, 2015Co-Authors: Feng Jiang, Liang Zeng, Shuirong Li, Shengping Wang, Jinlong GongAbstract:This paper describes an investigation on understanding catalytic consequences of Pt nanoparticles supported on a TiO2–Al2O3 binary oxide for Propane Dehydrogenation (PDH). The TiO2–Al2O3 supports were synthesized by a sol–gel method, and the Pt/TiO2–Al2O3 catalysts were prepared by an incipient wetness impregnation method. Both as-prepared and post-experiment catalysts were characterized employing N2 adsorption–desorption, X-ray diffraction, Raman spectra, H2–O2 titration, temperature-programmed desorption, thermogravimetric analysis, temperature-programmed oxidation, transmission electron microscopy, and Fourier-transform infrared spectra of chemisorbed CO. We have shown that TiO2 is highly dispersed on Al2O3, and the addition of appropriate amount of TiO2 improves propylene selectivity and catalytic stability, which is ascribed to the electron transfer from partially reduced TiOx (x < 2) to Pt atoms. The increased electron density of Pt could reduce the adsorption of propylene and facilitate the migrati...
Xinggui Zhou - One of the best experts on this subject based on the ideXlab platform.
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Improved selectivity and coke resistance of core-shell alloy catalysts for Propane Dehydrogenation from first principles and microkinetic analysis
Chemical Engineering Journal, 2019Co-Authors: Ling Xiao, Xinggui Zhou, De Chen, Fang Ma, Jinghong Zhou, Wei-kang YuanAbstract:Abstract Microkinetic analysis combined with the results obtained from density functional theory calculations has been performed to examine the catalytic activity and selectivity of Pt-based core-shell alloy catalysts for Propane Dehydrogenation. Calculated results indicate that substitution of 11 late transition metals for the core region of Pt nanoparticles would significantly modify the electronic structure of the surface Pt atoms through the strain effect and charge transfer. The core-shell catalysts are found to have less negative propylene adsorption energies and higher activation energies for the Dehydrogenation reactions than Pt, thus giving rise to a lower catalytic activity and a higher selectivity toward propylene. Linear chemisorption energy and transition state energy scaling relations hold very well in the present work, and the adsorption energy of propylene is identified to be a good descriptor to represent the overall kinetics. The scaling relations also suggest that a higher catalyst selectivity toward propylene can only be achieved at the expense of a lower catalytic activity for Propane Dehydrogenation. If a compromise is made between catalytic activity and catalyst selectivity, Co@Pt is proposed to be the best core-shell catalyst for Propane Dehydrogenation.
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Process simulation and optimization of Propane Dehydrogenation combined with selective hydrogen combustion
Chemical Engineering and Processing, 2019Co-Authors: Rui Hu, Xin Li, Guanghua Ye, Xinggui ZhouAbstract:Abstract A co-fed process combining Propane Dehydrogenation (PDH) with selective hydrogen combustion (SHC) is proposed, simulated, and optimized. The co-fed process uses adiabatic moving bed radial flow reactors as PDH reactors and adiabatic fixed bed reactors as SHC reactors. This co-fed process is proven to be very advantageous over the Oleflex process in some aspects, showing a propylene yield 6.0-46.1% higher and saving 2.86-7.24 × 106 kJ per ton of propylene under different operating conditions. These advantages are attributed to the utilization of SHC reactors: they consume some hydrogen in the process, which shifts the reaction equilibrium towards propylene; they also provide much heat to drive the highly endothermic PDH reaction. For the co-fed process, a feed temperature of 873 K, a total pressure of 1 bar, and using four PDH reactors are preferable; the optimal oxygen input is significantly affected by feed temperature and number of PDH reactors. Besides, under these preferable conditions, a SHC catalyst should have a minimum hydrogen combustion selectivity of 60.4% to reproduce and exceed the Oleflex efficiency. This work should provide useful guidelines for the development of co-fed processes for Propane Dehydrogenation.
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Insights into the effects of steam on Propane Dehydrogenation over a Pt/Al2O3 catalyst
Catalysis Science & Technology, 2015Co-Authors: Yu-ling Shan, De Chen, Xinggui ZhouAbstract:Catalytic Propane Dehydrogenation over an alumina supported Pt catalyst in the presence of steam is carried out and it is found that the catalyst activity is increased and the apparent activation energy is lowered due to the presence of steam. Three possible mechanisms, i.e. co-adsorption, Langmuir–Hinshelwood and Eley–Rideal, of changes in energetics and pathways for Propane Dehydrogenation due to the presence of steam are explored by DFT calculation. The results show that co-adsorption of C3 species with surface oxygenated species would elevate Dehydrogenation energy barriers due to repulsive interactions between them. Surface –OH is more active than surface –O in activating the C–H bond in Propane and propyl species through either the Langmuir–Hinshelwood or Eley–Rideal mechanism and plays an important role in Propane Dehydrogenation with steam. The Langmuir–Hinshelwood mechanism is kinetically favorable, in which the activations of the first H in Propane by surface −OH are the rate determining steps, but the activation energies are higher than that on a clean Pt(111) surface. The observed enhanced catalyst's activity is ascribed to the lowered coking rates as well as the changes in surface coverage due to the co-adsorption of water and the surface oxygenated species.
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Tuning selectivity and stability in Propane Dehydrogenation by shaping Pt particles: A combined experimental and DFT study
Journal of Molecular Catalysis A-chemical, 2014Co-Authors: Minglei Yang, Xinggui Zhou, Yingda Yu, De ChenAbstract:Abstract Shaped metal particles are known to possess distinct catalytic properties, which is often attributed to the catalytic activities of different particle facets. In this contribution, Propane Dehydrogenation on Pt particles of different shapes is investigated by a combination of experiments and DFT calculations. The selectivity toward propylene and catalyst stability in Propane Dehydrogenation can be enhanced by shaping Pt nanoparticles under industrially relevant conditions. Octahedral particles (12.0 nm) dominated by the Pt(1 1 1) surface have higher selectivity toward propylene production and better stability than cubic particles (11.5 nm) that are dominated by the Pt(1 0 0) surface. Combined experiments and DFT calculations suggest that the weakened binding strength of propylene and increased energy barrier for the C–H bond cleavage in propylene Dehydrogenation on Pt(1 1 1) compared to Pt(1 0 0) and Pt(2 1 1) contribute to the higher selectivity toward propylene by lowering the formation possibility of the deeply dehydrogenated intermediates. When coke is formed on the Pt surface, the d -band of surrounding Pt atoms is shifted farther below the Fermi level, leading to the deactivation of Pt catalyst. Our DFT calculations provide a rational interpretation of the experimental observations regarding the shape effects on Propane Dehydrogenation.
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first principles calculations of Propane Dehydrogenation over ptsn catalysts
ACS Catalysis, 2012Co-Authors: Minglei Yang, Xinggui Zhou, De ChenAbstract:Density functional theory calculations have been performed to investigate the effect of Sn on the catalytic activity and selectivity of Pt catalyst in Propane Dehydrogenation. Five models with different Sn to Pt surface molar ratios are constructed to represent the PtSn surfaces. With the increase of the Sn content, the d-band of Pt is broadened, which gives rise to a downshift in the d-band center on the PtSn surfaces. Consequently, the bonding strength of propyl and propylene on the alloyed surfaces is lowered. With the decomposition of the adsorption energy, the change in the surface deformation energy is predicted to be the dominant factor that determines the variation in the adsorption energy on the surface alloys, while on the bulk alloys the change in the binding energy makes a major contribution. The introduction of Sn lowers the energy barrier for propylene desorption and simultaneously increases the activation energy for propylene Dehydrogenation, which has a positive effect on the selectivity t...
Yiwei Zhang - One of the best experts on this subject based on the ideXlab platform.
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Morphology-controlled fabrication of biomorphic alumina-based hierarchical LDH compounds for Propane Dehydrogenation reaction
New Journal of Chemistry, 2017Co-Authors: Hongxing Zhang, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Chao Zhang, Jiasheng Fang, Shuo ZhaoAbstract:A new material, MgAl-LDHs/Al2O3 fiber (abbreviated as MAF), was prepared using the classical hydrothermal method with a modification in this paper. The influence of different pH values on the structure and catalytic performance of catalysts for Propane Dehydrogenation was studied. The as-prepared materials were characterized by XRD, SEM, TEM, SAED, N2-physisorption, NH3-TPD, and TPO. Experimental results show that the pH value of the solution directly controlled the vertical growth of LDH sheets on Al2O3 fibers. After the suitable growth of LDH sheets, the dispersed state of active metal Pt was improved and the sizes were stabilized successfully at high temperature. Due to the effect of these LDH sheets, the BET surface and the regular pore system of the PtSn/15MAF catalysts were enhanced compared with the PtSn/CPMA catalysts. Finally, the Propane Dehydrogenation performance indicates that, when the pH was equal to 8.5, the catalysts (PtSn/15MAF) showed the highest conversion, selectivity and stability.
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The synthesis of new coke-resistant support and its application in Propane Dehydrogenation to propene
Journal of Chemical Technology & Biotechnology, 2015Co-Authors: Shijian Zhou, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Zewu ZhangAbstract:BACKGROUND ZSM-5 zeolite has been used as a common support for PtSn-based catalyst in the Propane Dehydrogenation reaction. But owing to its high acidy, coke accommodation and stability of the catalyst are not satisfactory. Here, in order to improve the performance, the new hierarchical-porous ZSM-5 (abbreviated henceforth as ZQ) has been synthesized. RESULTS By the introduction of hierarchical-pores in ZQ, the pore structure was changed, the acid content was decreased, and the surface properties were promoted. These modifications to zeolite greatly improved the capacity of catalysts to accommodate coke. Moreover, the coke deposit on PtSnNa/ZQ migrated from active metal to the support. As expected, by using the catalyst PtSnNa/ZQ, the catalytic performance of Propane Dehydrogenation to propene and the stability of the catalyst were significantly promoted. CONCLUSIONS The new hierarchical-porous ZSM-5 support (ZQ) exhibits enhanced capacity to accommodate coke, and PtSnNa/ZQ enabled better Propane conversion and improved catalyst stability. © 2015 Society of Chemical Industry
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Synthesis of Ce-doped mesoporous γ-alumina with enhanced catalytic performance for Propane Dehydrogenation
Journal of Materials Science, 2015Co-Authors: Shijian Zhou, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Zewu ZhangAbstract:Ce-doped mesoporous γ-alumina with different contents of Ce was prepared by the sol–gel synthesis method and applied for the synthesis of Propane Dehydrogenation catalysts. To investigate the influence of different Ce contents on the properties of the supports, the prepared samples were characterized by several techniques, such as XRD, N2-physisorption, TEM, XPS, NH3-TPD, and hydrogen chemisorption. The results showed that, by the incorporation of Ce, the pore structure was changed, the acid content was decreased, and the properties of the metallic Pt particles were promoted significantly. Based on these effects, the coke deposits on the active center were suppressed and even migrated to the external surface of the support. As expected, when the content of Ce is suitable (0.6 wt%), the catalytic performance of Propane Dehydrogenation and the stability of the catalyst were highly promoted.
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Effect of ultrasonic irradiation on the catalytic performance of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation.
Ultrasonics Sonochemistry, 2010Co-Authors: Shaobo Zhang, Yuming Zhou, Yiwei Zhang, Li HuangAbstract:Effects of ultrasonic irradiation on the catalytic performance of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation were studied. XRD, TEM and TPDA were used to characterize the catalysts. From the results of XRD, the structure of ZSM-5 was not destroyed by the ultrasound. Ultrasound promoted the dispersion of Pt on the surface of the carrier during impregnation and decreased the size of Pt particles. Compared with the catalyst prepared by conventional impregnation, the supported catalyst prepared by ultrasonic irradiation showed better catalytic activity in Propane Dehydrogenation.
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Influence of the different dechlorination time on catalytic performances of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation
Fuel Processing Technology, 2009Co-Authors: Yiwei Zhang, Yuming Zhou, Linyang Bo, Menghan TangAbstract:Abstract Catalytic Dehydrogenation of Propane has recently received considerable attention because of the increasing demand for propene. Among several catalysts, PtSnNa/ZSM-5 catalyst is one of the most suitable ones. In this study, PtSnNa/ZSM-5 catalysts with different content of chlorine were prepared by changing the time of catalyst dechlorination. The obtained catalysts were characterized by X-ray fluorescence (XRF), XRD, nitrogen adsorption, 27 Al MAS NMR, NH 3 -TPD, H 2 chemisorption and TPR. It was found that with the increase of treatment time, more framework aluminum atoms were removed from tetrahedral positions, leading to the loss of Sn species and the decrease of catalyst acidity. Meantime, the porous properties and the interactions between Pt and Sn of the catalysts changed remarkably, which was disadvantageous to the reaction. Compared with the dechlorinated catalysts, the fresh sample with suitable content of chlorine exhibited the best reaction activity and stability. The average yield of propene was about 30.4% over 45 h for the reaction of Propane Dehydrogenation at 590 °C. Finally, a model was proposed for the influence of dechlorinated treatment on catalytic properties of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation.
Yuming Zhou - One of the best experts on this subject based on the ideXlab platform.
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Morphology-controlled fabrication of biomorphic alumina-based hierarchical LDH compounds for Propane Dehydrogenation reaction
New Journal of Chemistry, 2017Co-Authors: Hongxing Zhang, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Chao Zhang, Jiasheng Fang, Shuo ZhaoAbstract:A new material, MgAl-LDHs/Al2O3 fiber (abbreviated as MAF), was prepared using the classical hydrothermal method with a modification in this paper. The influence of different pH values on the structure and catalytic performance of catalysts for Propane Dehydrogenation was studied. The as-prepared materials were characterized by XRD, SEM, TEM, SAED, N2-physisorption, NH3-TPD, and TPO. Experimental results show that the pH value of the solution directly controlled the vertical growth of LDH sheets on Al2O3 fibers. After the suitable growth of LDH sheets, the dispersed state of active metal Pt was improved and the sizes were stabilized successfully at high temperature. Due to the effect of these LDH sheets, the BET surface and the regular pore system of the PtSn/15MAF catalysts were enhanced compared with the PtSn/CPMA catalysts. Finally, the Propane Dehydrogenation performance indicates that, when the pH was equal to 8.5, the catalysts (PtSn/15MAF) showed the highest conversion, selectivity and stability.
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The synthesis of new coke-resistant support and its application in Propane Dehydrogenation to propene
Journal of Chemical Technology & Biotechnology, 2015Co-Authors: Shijian Zhou, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Zewu ZhangAbstract:BACKGROUND ZSM-5 zeolite has been used as a common support for PtSn-based catalyst in the Propane Dehydrogenation reaction. But owing to its high acidy, coke accommodation and stability of the catalyst are not satisfactory. Here, in order to improve the performance, the new hierarchical-porous ZSM-5 (abbreviated henceforth as ZQ) has been synthesized. RESULTS By the introduction of hierarchical-pores in ZQ, the pore structure was changed, the acid content was decreased, and the surface properties were promoted. These modifications to zeolite greatly improved the capacity of catalysts to accommodate coke. Moreover, the coke deposit on PtSnNa/ZQ migrated from active metal to the support. As expected, by using the catalyst PtSnNa/ZQ, the catalytic performance of Propane Dehydrogenation to propene and the stability of the catalyst were significantly promoted. CONCLUSIONS The new hierarchical-porous ZSM-5 support (ZQ) exhibits enhanced capacity to accommodate coke, and PtSnNa/ZQ enabled better Propane conversion and improved catalyst stability. © 2015 Society of Chemical Industry
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Synthesis of Ce-doped mesoporous γ-alumina with enhanced catalytic performance for Propane Dehydrogenation
Journal of Materials Science, 2015Co-Authors: Shijian Zhou, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Zewu ZhangAbstract:Ce-doped mesoporous γ-alumina with different contents of Ce was prepared by the sol–gel synthesis method and applied for the synthesis of Propane Dehydrogenation catalysts. To investigate the influence of different Ce contents on the properties of the supports, the prepared samples were characterized by several techniques, such as XRD, N2-physisorption, TEM, XPS, NH3-TPD, and hydrogen chemisorption. The results showed that, by the incorporation of Ce, the pore structure was changed, the acid content was decreased, and the properties of the metallic Pt particles were promoted significantly. Based on these effects, the coke deposits on the active center were suppressed and even migrated to the external surface of the support. As expected, when the content of Ce is suitable (0.6 wt%), the catalytic performance of Propane Dehydrogenation and the stability of the catalyst were highly promoted.
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Effect of ultrasonic irradiation on the catalytic performance of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation.
Ultrasonics Sonochemistry, 2010Co-Authors: Shaobo Zhang, Yuming Zhou, Yiwei Zhang, Li HuangAbstract:Effects of ultrasonic irradiation on the catalytic performance of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation were studied. XRD, TEM and TPDA were used to characterize the catalysts. From the results of XRD, the structure of ZSM-5 was not destroyed by the ultrasound. Ultrasound promoted the dispersion of Pt on the surface of the carrier during impregnation and decreased the size of Pt particles. Compared with the catalyst prepared by conventional impregnation, the supported catalyst prepared by ultrasonic irradiation showed better catalytic activity in Propane Dehydrogenation.
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Influence of the different dechlorination time on catalytic performances of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation
Fuel Processing Technology, 2009Co-Authors: Yiwei Zhang, Yuming Zhou, Linyang Bo, Menghan TangAbstract:Abstract Catalytic Dehydrogenation of Propane has recently received considerable attention because of the increasing demand for propene. Among several catalysts, PtSnNa/ZSM-5 catalyst is one of the most suitable ones. In this study, PtSnNa/ZSM-5 catalysts with different content of chlorine were prepared by changing the time of catalyst dechlorination. The obtained catalysts were characterized by X-ray fluorescence (XRF), XRD, nitrogen adsorption, 27 Al MAS NMR, NH 3 -TPD, H 2 chemisorption and TPR. It was found that with the increase of treatment time, more framework aluminum atoms were removed from tetrahedral positions, leading to the loss of Sn species and the decrease of catalyst acidity. Meantime, the porous properties and the interactions between Pt and Sn of the catalysts changed remarkably, which was disadvantageous to the reaction. Compared with the dechlorinated catalysts, the fresh sample with suitable content of chlorine exhibited the best reaction activity and stability. The average yield of propene was about 30.4% over 45 h for the reaction of Propane Dehydrogenation at 590 °C. Finally, a model was proposed for the influence of dechlorinated treatment on catalytic properties of PtSnNa/ZSM-5 catalyst for Propane Dehydrogenation.
