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Density functional theory study on the mechanism of calcium sulfate reductive decomposition by carbon monoxide / Xuemei Zhang in Industrial & engineering chemistry research, Vol. 51 N° 18 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 18 (Mai 2012) . - pp. 6563-6570 Titre : Density functional theory study on the mechanism of calcium sulfate reductive decomposition by carbon monoxide Type de document : texte imprimé Auteurs : Xuemei Zhang, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur Année de publication : 2012 Article en page(s) : pp. 6563-6570 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Density  functional  method Résumé : The reductive decomposition of calcium sulfate (CaSO4) to calcium sulfide (CaS) was one of the most important methods for anhydrite resource utilization. When CaSO4 was decomposed reductively by carbon monoxide (CO), usually there were CaS and/or calcium oxide (CaO) in the decomposition products of CaSO4 depending on the reaction temperature and readant concentrations. In this paper, the mechanism of CaSO4 reductive decomposition by CO was studied in the framework of density functional theory (DFT). In the calculation, the exchange-correlation term was approximated by Perdew―Wang (PW91), a functional within the generalized gradient approximation (GGA) family. To study the interaction of CO and CaSO4, the transition states of CaSO4 decomposition and the minimum energy path (MEP) were analyzed. The results showed that the CaS product could be obtained when CaSO4 was reduced by CO with the 4:1 stoichiometric ratio of CO and CaSO4, and the decomposition of CaSO4 to CaSO3 was the rate-determining step, and activation energy in this step was 191.19 kJ/mol. With the inaease of the reaction temperature, the CaO product could be obtained with a 1:1 stoichiometric ratio of CO and CaSO4, and the activation energy is 318.28 kj/mol during the process. It was found that the CaS product was formatted at a lower reaction temperature and a higher mole ratio of CO and CaSO4, and the CaO product was preferred at a higher reaction temperature and a lower mole ratio of CO and CaSO4. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25867306 [article] Density functional theory study on the mechanism of calcium sulfate reductive decomposition by carbon monoxide [texte imprimé] / Xuemei Zhang, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur . - 2012 . - pp. 6563-6570. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 18 (Mai 2012) . - pp. 6563-6570 Mots-clés : Density  functional  method Résumé : The reductive decomposition of calcium sulfate (CaSO4) to calcium sulfide (CaS) was one of the most important methods for anhydrite resource utilization. When CaSO4 was decomposed reductively by carbon monoxide (CO), usually there were CaS and/or calcium oxide (CaO) in the decomposition products of CaSO4 depending on the reaction temperature and readant concentrations. In this paper, the mechanism of CaSO4 reductive decomposition by CO was studied in the framework of density functional theory (DFT). In the calculation, the exchange-correlation term was approximated by Perdew―Wang (PW91), a functional within the generalized gradient approximation (GGA) family. To study the interaction of CO and CaSO4, the transition states of CaSO4 decomposition and the minimum energy path (MEP) were analyzed. The results showed that the CaS product could be obtained when CaSO4 was reduced by CO with the 4:1 stoichiometric ratio of CO and CaSO4, and the decomposition of CaSO4 to CaSO3 was the rate-determining step, and activation energy in this step was 191.19 kJ/mol. With the inaease of the reaction temperature, the CaO product could be obtained with a 1:1 stoichiometric ratio of CO and CaSO4, and the activation energy is 318.28 kj/mol during the process. It was found that the CaS product was formatted at a lower reaction temperature and a higher mole ratio of CO and CaSO4, and the CaO product was preferred at a higher reaction temperature and a lower mole ratio of CO and CaSO4. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25867306

Kinetic study of H2 oxidation in the preferential oxidation of CO on a nanosized Au / CeO2 catalyst / Jing Xu in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4149–4155 Titre : Kinetic study of H2 oxidation in the preferential oxidation of CO on a nanosized Au / CeO2 catalyst Type de document : texte imprimé Auteurs : Jing Xu, Auteur ; Ping Li, Auteur ; Xingfu Song, Auteur Année de publication : 2010 Article en page(s) : pp. 4149–4155 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Kinetic  Oxidation  Catalyst Résumé : Kinetic study of H2 oxidation in the preferential oxidation (PROX) of CO was implemented over a nanosize Au/CeO2 catalyst in a temperature range 313−353 K. The Langmuir−Hinshelwood mechanism was proposed to be mainly responsible for H2 oxidation, and CO oxidation can be accelerated by coadsorbed H at low temperatures. On the other hand, the water in the system has proved to suppress both CO and H2 oxidation by increasing the energy bars. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO adsorption on the Au surface indicates that linear CO−Au bond can be weakened in the presence of H2; meanwhile, water can be a poison taking effects via the bonding of water and the lattice oxygen at the interface of Au/CeO2. The irreversible loss of activity during reaction may be caused by the reconstruction of Au particles, at least in part. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100325y [article] Kinetic study of H2 oxidation in the preferential oxidation of CO on a nanosized Au / CeO2 catalyst [texte imprimé] / Jing Xu, Auteur ; Ping Li, Auteur ; Xingfu Song, Auteur . - 2010 . - pp. 4149–4155. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4149–4155 Mots-clés : Kinetic  Oxidation  Catalyst Résumé : Kinetic study of H2 oxidation in the preferential oxidation (PROX) of CO was implemented over a nanosize Au/CeO2 catalyst in a temperature range 313−353 K. The Langmuir−Hinshelwood mechanism was proposed to be mainly responsible for H2 oxidation, and CO oxidation can be accelerated by coadsorbed H at low temperatures. On the other hand, the water in the system has proved to suppress both CO and H2 oxidation by increasing the energy bars. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO adsorption on the Au surface indicates that linear CO−Au bond can be weakened in the presence of H2; meanwhile, water can be a poison taking effects via the bonding of water and the lattice oxygen at the interface of Au/CeO2. The irreversible loss of activity during reaction may be caused by the reconstruction of Au particles, at least in part. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100325y

Optimization Design for DTB Industrial Crystallizer of Potassium Chloride / Xingfu Song in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10297-10302 Titre : Optimization Design for DTB Industrial Crystallizer of Potassium Chloride Type de document : texte imprimé Auteurs : Xingfu Song, Auteur ; Menghua Zhang, Auteur ; Jin Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 10297-10302 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Crystallizer  Design  Optimization Résumé : A computational fluid dynamics (CFD) model was developed for the simulation and optimization of an existing continuous DTB crystallizer with KCl productivity of 0.1 million tons per year. The multiple reference frame (MRF) method was used in the CFD simulation. Both the hexagonal grid and the tetrahedral grid were adopted to divide meshes in this industrial DTB crystallizer, and in total 866 388 cells were used for CFD simulation. The fluid flow field in the DTB crystallizer was calculated using FLUENT6.3 software with the Reynolds-averaged Navier-Stokes equation combined with the widely used κ―ε turbulence model. The crystal size distribution and the coefficient of variation of crystal product were studied by CFD simulation of two-phase flow model. The impeller shapes and various operating conditions were optimized to reduce the energy consumption of the crystallization process and to increase the KCl product quality. Based on the CFD optimization design, a new impeller was retrofitted into an existing continuous DTB crystallizer with the KCl productivity of 0.1 million tons per year located at Qinghai salt lake plant in China, and its excellent performance was confirmed against data collected using the original impeller. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447920 [article] Optimization Design for DTB Industrial Crystallizer of Potassium Chloride [texte imprimé] / Xingfu Song, Auteur ; Menghua Zhang, Auteur ; Jin Wang, Auteur . - 2011 . - pp. 10297-10302. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10297-10302 Mots-clés : Crystallizer  Design  Optimization Résumé : A computational fluid dynamics (CFD) model was developed for the simulation and optimization of an existing continuous DTB crystallizer with KCl productivity of 0.1 million tons per year. The multiple reference frame (MRF) method was used in the CFD simulation. Both the hexagonal grid and the tetrahedral grid were adopted to divide meshes in this industrial DTB crystallizer, and in total 866 388 cells were used for CFD simulation. The fluid flow field in the DTB crystallizer was calculated using FLUENT6.3 software with the Reynolds-averaged Navier-Stokes equation combined with the widely used κ―ε turbulence model. The crystal size distribution and the coefficient of variation of crystal product were studied by CFD simulation of two-phase flow model. The impeller shapes and various operating conditions were optimized to reduce the energy consumption of the crystallization process and to increase the KCl product quality. Based on the CFD optimization design, a new impeller was retrofitted into an existing continuous DTB crystallizer with the KCl productivity of 0.1 million tons per year located at Qinghai salt lake plant in China, and its excellent performance was confirmed against data collected using the original impeller. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447920

Simulation analysis of multiphase flow and performance of hydrocyclones at different atmospheric pressures / Yanxia Xu in Industrial & engineering chemistry research, Vol. 51 N° 1 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 443–453 Titre : Simulation analysis of multiphase flow and performance of hydrocyclones at different atmospheric pressures Type de document : texte imprimé Auteurs : Yanxia Xu, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur Année de publication : 2012 Article en page(s) : pp. 443–453 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Multiphase  flow  Hydrocyclones Résumé : A hydrocyclone, as a common liquid/solid grading instrument, was chosen to separate calcium sulfate particles from crude carnallite during the KCl production process on the Tibetan Plateau in China, because CaSO4 particles are independent of KCl particles and have a smaller particle size distribution. The local altitude on the Tibetan Plateau in China is over 3000 m, so the effects of low atmospheric pressure on the separation performance of the hydrocyclone should be considered. In this article, the computational fluid dynamics (CFD) simulation technique was used to investigate the hydrodynamics and particles separation performance of an industrial hydrocyclone with a 428-mm diameter at both plain and plateau atmospheric pressures. In this CFD approach, the Reynolds stress model (RSM) was used to describe the turbulent fluid flow, the volume of fluid (VOF) multiphase model was used to simulate the interface between the liquid phase and the air core, and the stochastic Lagrangian model was used to track the particle flow. The mathematical models deveoped for the industrial hydrocyclone were tested by comparing the predicted results with the flow fields measured by Hsieh (Ph.D. Thesis, The University of Utah, Salt Lake City, UT, 1988). According to the simulation results, the environmental atmospheric pressures on the plain and plateau had effects mainly on the flow field inside the air core and near the interface between the air core and the liquid phase. It was found the direction of the axial velocity on the cylinder part and the values of the tangential velocity changed under the different environmental atmospheric pressures. When the industrial hydrocyclone was operated in the plateau environment, the separation efficiency for small particles decreased about 10% at the overflow, which was not good for CaSO4 removal, but there was no effect on the particles size larger than 350 μm, and more energy was consumed, although the difference in the split ratio was small. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201147e [article] Simulation analysis of multiphase flow and performance of hydrocyclones at different atmospheric pressures [texte imprimé] / Yanxia Xu, Auteur ; Xingfu Song, Auteur ; Ze Sun, Auteur . - 2012 . - pp. 443–453. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 443–453 Mots-clés : Multiphase  flow  Hydrocyclones Résumé : A hydrocyclone, as a common liquid/solid grading instrument, was chosen to separate calcium sulfate particles from crude carnallite during the KCl production process on the Tibetan Plateau in China, because CaSO4 particles are independent of KCl particles and have a smaller particle size distribution. The local altitude on the Tibetan Plateau in China is over 3000 m, so the effects of low atmospheric pressure on the separation performance of the hydrocyclone should be considered. In this article, the computational fluid dynamics (CFD) simulation technique was used to investigate the hydrodynamics and particles separation performance of an industrial hydrocyclone with a 428-mm diameter at both plain and plateau atmospheric pressures. In this CFD approach, the Reynolds stress model (RSM) was used to describe the turbulent fluid flow, the volume of fluid (VOF) multiphase model was used to simulate the interface between the liquid phase and the air core, and the stochastic Lagrangian model was used to track the particle flow. The mathematical models deveoped for the industrial hydrocyclone were tested by comparing the predicted results with the flow fields measured by Hsieh (Ph.D. Thesis, The University of Utah, Salt Lake City, UT, 1988). According to the simulation results, the environmental atmospheric pressures on the plain and plateau had effects mainly on the flow field inside the air core and near the interface between the air core and the liquid phase. It was found the direction of the axial velocity on the cylinder part and the values of the tangential velocity changed under the different environmental atmospheric pressures. When the industrial hydrocyclone was operated in the plateau environment, the separation efficiency for small particles decreased about 10% at the overflow, which was not good for CaSO4 removal, but there was no effect on the particles size larger than 350 μm, and more energy was consumed, although the difference in the split ratio was small. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201147e