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Adding microsized silica particles to the catalysis/ultrafiltration system / Zhaoxiang Zhong in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4933–4938 Titre : Adding microsized silica particles to the catalysis/ultrafiltration system : catalyst dissolution inhibition and flux enhancement Type de document : texte imprimé Auteurs : Zhaoxiang Zhong, Auteur ; Xin Liu, Auteur ; Rizhi Chen, Auteur Année de publication : 2009 Article en page(s) : pp. 4933–4938 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Catalytic  reactionCrossflow  ultrafiltration  Microsized  silica  particles Résumé : A system combining catalytic reaction with crossflow ultrafiltration (UF) was used to catalytic ammoximation of cyclohexanone to the oxime over titanium silicalite-1 (TS-1) catalysts. The effect of microsized silica particles on the performance of the catalysis/UF system was investigated in terms of catalytic activity and membrane filterability through dissolution and ultrafiltration experiments. Adding silica particles in the system inhibits the dissolution of TS-1 catalysts and increases both the reaction conversion and the selectivity significantly. Further characterizations (XRF, XRD, FTIR, etc.) indicated that the presence of silica particles remarkably limits the ammonia damage to the microstructure frame of TS-1 catalyst. In addition, silica particles play an important role in substantially removing the deposited TS-1 cake from the membrane surface, benefiting from the scouring effect. According to the results of visual observation to the tested membranes and the estimation of hydrodynamic forces acting on particles, microsized particles are hard to deposit on the membrane surface at the studied conditions and therefore a flux improvement has been achieved. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801774a [article] Adding microsized silica particles to the catalysis/ultrafiltration system : catalyst dissolution inhibition and flux enhancement [texte imprimé] / Zhaoxiang Zhong, Auteur ; Xin Liu, Auteur ; Rizhi Chen, Auteur . - 2009 . - pp. 4933–4938. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4933–4938 Mots-clés : Catalytic  reactionCrossflow  ultrafiltration  Microsized  silica  particles Résumé : A system combining catalytic reaction with crossflow ultrafiltration (UF) was used to catalytic ammoximation of cyclohexanone to the oxime over titanium silicalite-1 (TS-1) catalysts. The effect of microsized silica particles on the performance of the catalysis/UF system was investigated in terms of catalytic activity and membrane filterability through dissolution and ultrafiltration experiments. Adding silica particles in the system inhibits the dissolution of TS-1 catalysts and increases both the reaction conversion and the selectivity significantly. Further characterizations (XRF, XRD, FTIR, etc.) indicated that the presence of silica particles remarkably limits the ammonia damage to the microstructure frame of TS-1 catalyst. In addition, silica particles play an important role in substantially removing the deposited TS-1 cake from the membrane surface, benefiting from the scouring effect. According to the results of visual observation to the tested membranes and the estimation of hydrodynamic forces acting on particles, microsized particles are hard to deposit on the membrane surface at the studied conditions and therefore a flux improvement has been achieved. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801774a

Continuous Acetone Ammoximation over TS-1 in a Tubular Membrane Reactor / Zhaohui Li in Industrial & engineering chemistry research, Vol. 49 N° 14 (Juillet 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6309–6316 Titre : Continuous Acetone Ammoximation over TS-1 in a Tubular Membrane Reactor Type de document : texte imprimé Auteurs : Zhaohui Li, Auteur ; Rizhi Chen, Auteur ; Weihong Xing, Auteur Année de publication : 2010 Article en page(s) : pp. 6309–6316 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Tubular  membrane  reactor Résumé : A new tubular membrane reactor based on tubular metallic membrane is developed, which can solve the problem concerning in situ separation of catalyst from the reaction mixture and make the production process continuous. In this article, the feasibility of continuous ammoximation of acetone to acetone oxime over titanium silicalites-1 (TS-1) in the tubular membrane reactor was investigated. It has demonstrated that the tubular membrane reactor system can maintain a more long-term steady production of acetone oxime than that of a side-stream ceramic membrane reactor and has a higher productivity than the batch reactor. The effects of operation conditions (stirring rate, residence time, temperature, catalyst concentration, molar ratio of NH3/acetone, H2O2/acetone, and t-butanol/acetone) on the performances of the reaction system were examined via single factor experiments. Results show that the operation conditions greatly affect the conversion, selectivity of acetone ammoximation, and the filtration resistance. The acetone conversion is >94.5% and the acetone oxime selectivity remains stable at 98% in a 30-h continuous run. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901912e [article] Continuous Acetone Ammoximation over TS-1 in a Tubular Membrane Reactor [texte imprimé] / Zhaohui Li, Auteur ; Rizhi Chen, Auteur ; Weihong Xing, Auteur . - 2010 . - pp. 6309–6316. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6309–6316 Mots-clés : Tubular  membrane  reactor Résumé : A new tubular membrane reactor based on tubular metallic membrane is developed, which can solve the problem concerning in situ separation of catalyst from the reaction mixture and make the production process continuous. In this article, the feasibility of continuous ammoximation of acetone to acetone oxime over titanium silicalites-1 (TS-1) in the tubular membrane reactor was investigated. It has demonstrated that the tubular membrane reactor system can maintain a more long-term steady production of acetone oxime than that of a side-stream ceramic membrane reactor and has a higher productivity than the batch reactor. The effects of operation conditions (stirring rate, residence time, temperature, catalyst concentration, molar ratio of NH3/acetone, H2O2/acetone, and t-butanol/acetone) on the performances of the reaction system were examined via single factor experiments. Results show that the operation conditions greatly affect the conversion, selectivity of acetone ammoximation, and the filtration resistance. The acetone conversion is >94.5% and the acetone oxime selectivity remains stable at 98% in a 30-h continuous run. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901912e

Effect of catalyst morphology on the performance of submerged nanocatalysis/membrane filtration system / Rizhi Chen in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6600–6607 Titre : Effect of catalyst morphology on the performance of submerged nanocatalysis/membrane filtration system Type de document : texte imprimé Auteurs : Rizhi Chen, Auteur ; Yan Du, Auteur ; Qinqin Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 6600–6607 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nanocatalysis/membrane  filtration  system  Tubular  ceramic  membrane  Liquid-phase  hydrogenation  X-ray  diffractometry Résumé : Coupling systems of nanocatalysis and membrane filtration (nanocatalysis/MF) are features of convenience for the in situ separation of nanocatalysts from the reaction mixture. In this work, a submerged nanocatalysis/MF system with a tubular ceramic membrane as the separation unit was developed for the liquid-phase hydrogenation of p-nitrophenol to p-aminophenol over nickel nanoparticles with various particle morphologies obtained by hydrogen annealing at different temperatures. We extensively characterized the nickel nanoparticles using X-ray diffractometry (XRD), nitrogen adsorption, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and we determined that the annealing temperature significantly influenced the particle size, specific surface area, and crystalline morphology of the nickel nanoparticles. We then evaluated the catalytic performance and separation efficiency of the submerged nanocatalysis/MF system. The nickel nanoparticles annealed at different temperature showed remarkably different catalytic activity, because of their specific structural properties. There was an unexpected nonlinear relationship between the nickel particle size and the flux, which was due to the changed nature of the cake layer formed on the membrane surface and a pore blocking effect. The results from both aspects of catalysis and separation performance indicated that the nickel nanoparticles annealed at 100 °C displayed a best balanced catalytic performance and separation efficiency for the submerged nanocatalysis/MF system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900033m [article] Effect of catalyst morphology on the performance of submerged nanocatalysis/membrane filtration system [texte imprimé] / Rizhi Chen, Auteur ; Yan Du, Auteur ; Qinqin Wang, Auteur . - 2009 . - pp. 6600–6607. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6600–6607 Mots-clés : Nanocatalysis/membrane  filtration  system  Tubular  ceramic  membrane  Liquid-phase  hydrogenation  X-ray  diffractometry Résumé : Coupling systems of nanocatalysis and membrane filtration (nanocatalysis/MF) are features of convenience for the in situ separation of nanocatalysts from the reaction mixture. In this work, a submerged nanocatalysis/MF system with a tubular ceramic membrane as the separation unit was developed for the liquid-phase hydrogenation of p-nitrophenol to p-aminophenol over nickel nanoparticles with various particle morphologies obtained by hydrogen annealing at different temperatures. We extensively characterized the nickel nanoparticles using X-ray diffractometry (XRD), nitrogen adsorption, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and we determined that the annealing temperature significantly influenced the particle size, specific surface area, and crystalline morphology of the nickel nanoparticles. We then evaluated the catalytic performance and separation efficiency of the submerged nanocatalysis/MF system. The nickel nanoparticles annealed at different temperature showed remarkably different catalytic activity, because of their specific structural properties. There was an unexpected nonlinear relationship between the nickel particle size and the flux, which was due to the changed nature of the cake layer formed on the membrane surface and a pore blocking effect. The results from both aspects of catalysis and separation performance indicated that the nickel nanoparticles annealed at 100 °C displayed a best balanced catalytic performance and separation efficiency for the submerged nanocatalysis/MF system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900033m

Fabrication and catalytic properties of palladium nanoparticles deposited on a silanized asymmetric ceramic support / Rizhi Chen in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4405–4411 Titre : Fabrication and catalytic properties of palladium nanoparticles deposited on a silanized asymmetric ceramic support Type de document : texte imprimé Auteurs : Rizhi Chen, Auteur ; Yuanguo Jiang, Auteur ; Weihong Xing, Auteur Année de publication : 2011 Article en page(s) : pp. 4405–4411 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalytic  properties  Asymmetric  ceramic Résumé : We developed an improved fabrication technique for the deposition of palladium nanoparticles on a ceramic membrane support in which the support surface was silanized with amino-functional silane. In the present work, the ceramic membrane support was used for catalyst immobilization only. The as-fabricated Pd-loaded ceramic membrane support was extensively characterized by ICP emission spectroscopy, XRD, FESEM, EDS, XPS, HRTEM, and TPR, and its catalytic properties were tested in the liquid-phase hydrogenation of p-nitrophenol to p-aminophenol. A comparative study was also made with palladium nanoparticles deposited on the ceramic membrane support without silanization. Higher catalytic activity and stability were observed for the palladium nanoparticles deposited on the surface-silanized ceramic membrane support. The reason proposed for the higher catalytic activity is the higher dispersion of the palladium nanoparticles. The palladium nanoparticles were loaded onto the surface-silanized ceramic membrane support with chemical bonds; thus, it was not easy for the palladium nanoparticles to detach from the silanized membrane support, and a superior catalytic stability could be obtained. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1022578 [article] Fabrication and catalytic properties of palladium nanoparticles deposited on a silanized asymmetric ceramic support [texte imprimé] / Rizhi Chen, Auteur ; Yuanguo Jiang, Auteur ; Weihong Xing, Auteur . - 2011 . - pp. 4405–4411. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4405–4411 Mots-clés : Catalytic  properties  Asymmetric  ceramic Résumé : We developed an improved fabrication technique for the deposition of palladium nanoparticles on a ceramic membrane support in which the support surface was silanized with amino-functional silane. In the present work, the ceramic membrane support was used for catalyst immobilization only. The as-fabricated Pd-loaded ceramic membrane support was extensively characterized by ICP emission spectroscopy, XRD, FESEM, EDS, XPS, HRTEM, and TPR, and its catalytic properties were tested in the liquid-phase hydrogenation of p-nitrophenol to p-aminophenol. A comparative study was also made with palladium nanoparticles deposited on the ceramic membrane support without silanization. Higher catalytic activity and stability were observed for the palladium nanoparticles deposited on the surface-silanized ceramic membrane support. The reason proposed for the higher catalytic activity is the higher dispersion of the palladium nanoparticles. The palladium nanoparticles were loaded onto the surface-silanized ceramic membrane support with chemical bonds; thus, it was not easy for the palladium nanoparticles to detach from the silanized membrane support, and a superior catalytic stability could be obtained. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1022578

A novel dual-membrane reactor for continuous heterogeneous oxidation catalysis / Hong Jiang in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10458-10464 Titre : A novel dual-membrane reactor for continuous heterogeneous oxidation catalysis Type de document : texte imprimé Auteurs : Hong Jiang, Auteur ; Lie Meng, Auteur ; Rizhi Chen, Auteur Année de publication : 2011 Article en page(s) : pp. 10458-10464 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalysis  Oxidation  Membrane  reactor Résumé : A novel dual-membrane reactor is proposed for heterogeneous catalysis over ultrafine catalyst particles. In this reactor, one tubular porous ceramic membrane is employed as a distributor controlling the supply of reactant, while the other is employed as a membrane separator for in situ separation of ultrafine catalysts from the products. To evaluate the feasibility and the performance of the dual-membrane reactor, phenol hydroxylation with hydrogen peroxide (H2O2) over TS-1 catalyst was selected as a model reaction. As compared to traditional H2O2 feeding modes, the use of the porous ceramic membrane distributor allows a uniform injection of H2O2 into the reaction system, and as a result significantly promotes the dihydroxybenzene selectivity. The phenol conversion and the DHB selectivity above 15% and about 95%, respectively, can be achieved in a continuous operation of 30 h. TS-1 catalysts can be retained almost completely in the reactor system by the membrane separator. Our study demonstrates the advantages of the novel dual-membrane reactor in enhancing selectivity and catalysts separation in a continuous heterogeneous catalytic reaction. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523867 [article] A novel dual-membrane reactor for continuous heterogeneous oxidation catalysis [texte imprimé] / Hong Jiang, Auteur ; Lie Meng, Auteur ; Rizhi Chen, Auteur . - 2011 . - pp. 10458-10464. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10458-10464 Mots-clés : Catalysis  Oxidation  Membrane  reactor Résumé : A novel dual-membrane reactor is proposed for heterogeneous catalysis over ultrafine catalyst particles. In this reactor, one tubular porous ceramic membrane is employed as a distributor controlling the supply of reactant, while the other is employed as a membrane separator for in situ separation of ultrafine catalysts from the products. To evaluate the feasibility and the performance of the dual-membrane reactor, phenol hydroxylation with hydrogen peroxide (H2O2) over TS-1 catalyst was selected as a model reaction. As compared to traditional H2O2 feeding modes, the use of the porous ceramic membrane distributor allows a uniform injection of H2O2 into the reaction system, and as a result significantly promotes the dihydroxybenzene selectivity. The phenol conversion and the DHB selectivity above 15% and about 95%, respectively, can be achieved in a continuous operation of 30 h. TS-1 catalysts can be retained almost completely in the reactor system by the membrane separator. Our study demonstrates the advantages of the novel dual-membrane reactor in enhancing selectivity and catalysts separation in a continuous heterogeneous catalytic reaction. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523867