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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

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

Hydrolysis of ethyl lactate coupled by vapor permeation using polydimethylsiloxane / ceramic composite membrane / Weixing Li in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11244–11249 Titre : Hydrolysis of ethyl lactate coupled by vapor permeation using polydimethylsiloxane / ceramic composite membrane Type de document : texte imprimé Auteurs : Weixing Li, Auteur ; Xiujuan Zhang, Auteur ; Weihong Xing, Auteur Année de publication : 2011 Article en page(s) : pp. 11244–11249 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrolysis  Composite  membrane Résumé : As a reversible reaction, the hydrolysis conversion of ethyl lactate is controlled by thermodynamic equilibrium. In order to improve the yield and conversion rate of hydrolysis of ethyl lactate, ethanol in the products should be removed in time. Hydrolysis of ethyl lactate coupled by vapor permeation (VP) for removing ethanol in the products was proposed. Here, the vapor permeation was carried out with a new polydimethylsiloxane (PDMS)/ceramic composite membrane prepared by our team. The PDMS/ceramic composite membrane was first characterized by scanning electron microscopy (SEM) images, pervaporation, and vapor permeation of ethanol/water mixtures. The characterization results showed that the PDMS/ceramic composite membrane was dense and uniform and had good separation performances. The permeate flux of pervaporation of 5 wt % ethanol arrived at 2541 g·m−2·h−1, and the separation factor was 7.5 at 353 K. As for vapor permeation of 10 wt % ethanol, the permeate flux was above 400 g·m−2·h−1 and separation factor was around 11. Then, the VP aided hydrolysis of ethyl lactate was investigated with the prepared PDMS/ceramic composite membrane. By coupling with VP, the final conversion of the ethyl lactate increased from 77.1% to 98.2% with the initial molar ratio of water to ethyl lactate 10:1 at 358 K. The larger initial molar ratio of water to ethyl lactate was helpful to improve the conversion of VP aided hydrolysis of ethyl lactate. The VP aided hydrolysis of ethyl lactate with the prepared PDMS/ceramic composite membrane was significantly enhanced. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100413n [article] Hydrolysis of ethyl lactate coupled by vapor permeation using polydimethylsiloxane / ceramic composite membrane [texte imprimé] / Weixing Li, Auteur ; Xiujuan Zhang, Auteur ; Weihong Xing, Auteur . - 2011 . - pp. 11244–11249. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11244–11249 Mots-clés : Hydrolysis  Composite  membrane Résumé : As a reversible reaction, the hydrolysis conversion of ethyl lactate is controlled by thermodynamic equilibrium. In order to improve the yield and conversion rate of hydrolysis of ethyl lactate, ethanol in the products should be removed in time. Hydrolysis of ethyl lactate coupled by vapor permeation (VP) for removing ethanol in the products was proposed. Here, the vapor permeation was carried out with a new polydimethylsiloxane (PDMS)/ceramic composite membrane prepared by our team. The PDMS/ceramic composite membrane was first characterized by scanning electron microscopy (SEM) images, pervaporation, and vapor permeation of ethanol/water mixtures. The characterization results showed that the PDMS/ceramic composite membrane was dense and uniform and had good separation performances. The permeate flux of pervaporation of 5 wt % ethanol arrived at 2541 g·m−2·h−1, and the separation factor was 7.5 at 353 K. As for vapor permeation of 10 wt % ethanol, the permeate flux was above 400 g·m−2·h−1 and separation factor was around 11. Then, the VP aided hydrolysis of ethyl lactate was investigated with the prepared PDMS/ceramic composite membrane. By coupling with VP, the final conversion of the ethyl lactate increased from 77.1% to 98.2% with the initial molar ratio of water to ethyl lactate 10:1 at 358 K. The larger initial molar ratio of water to ethyl lactate was helpful to improve the conversion of VP aided hydrolysis of ethyl lactate. The VP aided hydrolysis of ethyl lactate with the prepared PDMS/ceramic composite membrane was significantly enhanced. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100413n

Modeling of cross-flow filtration processes in an airlift ceramic membrane reactor / Feng Zhang in Industrial & engineering chemistry research, Vol. 48 N° 23 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10637–10642 Titre : Modeling of cross-flow filtration processes in an airlift ceramic membrane reactor Type de document : texte imprimé Auteurs : Feng Zhang, Auteur ; Wenheng Jing, Auteur ; Weihong Xing, Auteur Année de publication : 2010 Article en page(s) : pp. 10637–10642 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Modeling--Cross-Flow--Filtration--Processes--Airlift--Ceramic--Membrane--Reactor Résumé : Air sparging is recognized as an effective way to overcome concentration polarization in membrane filtration processes. The mechanism of flux enhancement in the case of slug flow in tubular ceramic membrane is discussed in this Article. The region near the gas slug is divided into three different zones: gas slug zone, wake zone, and remaining liquid slug zone. Air sparging significantly increases shear stress and flow instabilities, and consequently lowers concentration polarization for the gas slug zone and the wake zone. A novel model based on hydrodynamics of air−liquid two-phase flow is developed to predicting permeate flux in such processes. The dimensionless groups of filtrate resistance number and shear stress number are used to analyze the cake resistance induced by the concentration polarization, and, from these, the average permeate flux for air sparged ultrafiltration can be calculated. The model was tested by the ultrafiltration of T2000 dextran at different gas flow rates with an external-loop airlift ceramic membrane reactor. The model is validated with experimental data with an error of 10%. Experimental results show that air sparging can enhance the permeate flux significantly. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900512g [article] Modeling of cross-flow filtration processes in an airlift ceramic membrane reactor [texte imprimé] / Feng Zhang, Auteur ; Wenheng Jing, Auteur ; Weihong Xing, Auteur . - 2010 . - pp. 10637–10642. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10637–10642 Mots-clés : Modeling--Cross-Flow--Filtration--Processes--Airlift--Ceramic--Membrane--Reactor Résumé : Air sparging is recognized as an effective way to overcome concentration polarization in membrane filtration processes. The mechanism of flux enhancement in the case of slug flow in tubular ceramic membrane is discussed in this Article. The region near the gas slug is divided into three different zones: gas slug zone, wake zone, and remaining liquid slug zone. Air sparging significantly increases shear stress and flow instabilities, and consequently lowers concentration polarization for the gas slug zone and the wake zone. A novel model based on hydrodynamics of air−liquid two-phase flow is developed to predicting permeate flux in such processes. The dimensionless groups of filtrate resistance number and shear stress number are used to analyze the cake resistance induced by the concentration polarization, and, from these, the average permeate flux for air sparged ultrafiltration can be calculated. The model was tested by the ultrafiltration of T2000 dextran at different gas flow rates with an external-loop airlift ceramic membrane reactor. The model is validated with experimental data with an error of 10%. Experimental results show that air sparging can enhance the permeate flux significantly. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900512g