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Determination of antiscaling efficiency and dissolution capacity for calcium carbonate with ultrasonic irradiation / Xiaoli Li in Industrial & engineering chemistry research, Vol. 51 N° 27 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9266–9274 Titre : Determination of antiscaling efficiency and dissolution capacity for calcium carbonate with ultrasonic irradiation Type de document : texte imprimé Auteurs : Xiaoli Li, Auteur ; Jianguo Zhang, Auteur ; Daoyong Yang, Auteur Année de publication : 2012 Article en page(s) : pp. 9266–9274 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Calcium  carbonate  Ultrasonic  irradiation Résumé : A systematic technique has been developed to determine antiscaling efficiency and dissolution capacity for calcium carbonate in oilfield brines under various ultrasonic treating conditions. During the static experiments, effects of ultrasonic frequency, acoustic intensity, treating time, and water level on the antiscaling efficiency have been evaluated, while the underlying antiscaling mechanism is identified and determined. Physically, the formation of calcium carbonate is promoted as a result of the decreased molecular force and accelerated movement of salty ions under ultrasonic irradiation. Most of the formed scale is found to loosely suspend in the liquid, rather than tightly adhere to the solid surface. During the dynamic experiments, orthogonal tests have been designed to examine effects of interval time, treating time, and flow velocity on antiscaling efficiency. As for the dissolution experiment, dissolution capacity is measured to evaluate the effect of ultrasonic frequency on dissolution of the formed calcium carbonate. The antiscaling efficiency is found to achieve its maximum value of 81.1%, using the ultrasonic treatment with a frequency of 28 kHz, an acoustic intensity of 0.61 W/cm2, an interval time of 2 h, a treatment time of 15 min, and a flow velocity of 1.8 m/s. It is also found that dissolution capacity does not impose a dominant effect on scale prevention and that the highest dissolution capacity of 19.3% is obtained with an ultrasonic frequency of 28 kHz. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300575v [article] Determination of antiscaling efficiency and dissolution capacity for calcium carbonate with ultrasonic irradiation [texte imprimé] / Xiaoli Li, Auteur ; Jianguo Zhang, Auteur ; Daoyong Yang, Auteur . - 2012 . - pp. 9266–9274. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9266–9274 Mots-clés : Calcium  carbonate  Ultrasonic  irradiation Résumé : A systematic technique has been developed to determine antiscaling efficiency and dissolution capacity for calcium carbonate in oilfield brines under various ultrasonic treating conditions. During the static experiments, effects of ultrasonic frequency, acoustic intensity, treating time, and water level on the antiscaling efficiency have been evaluated, while the underlying antiscaling mechanism is identified and determined. Physically, the formation of calcium carbonate is promoted as a result of the decreased molecular force and accelerated movement of salty ions under ultrasonic irradiation. Most of the formed scale is found to loosely suspend in the liquid, rather than tightly adhere to the solid surface. During the dynamic experiments, orthogonal tests have been designed to examine effects of interval time, treating time, and flow velocity on antiscaling efficiency. As for the dissolution experiment, dissolution capacity is measured to evaluate the effect of ultrasonic frequency on dissolution of the formed calcium carbonate. The antiscaling efficiency is found to achieve its maximum value of 81.1%, using the ultrasonic treatment with a frequency of 28 kHz, an acoustic intensity of 0.61 W/cm2, an interval time of 2 h, a treatment time of 15 min, and a flow velocity of 1.8 m/s. It is also found that dissolution capacity does not impose a dominant effect on scale prevention and that the highest dissolution capacity of 19.3% is obtained with an ultrasonic frequency of 28 kHz. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300575v

Kinetic studies of carbon dioxide reforming of methane over ni−co/al−mg−o bimetallic catalyst / Jianguo Zhang in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 677–684 Titre : Kinetic studies of carbon dioxide reforming of methane over ni−co/al−mg−o bimetallic catalyst Type de document : texte imprimé Auteurs : Jianguo Zhang, Auteur ; Hui Wang, Auteur ; Ajay Kumar Dalai, Auteur Année de publication : 2009 Article en page(s) : p. 677–684 Note générale : chemical engenireeng Langues : Anglais (eng) Mots-clés : Bimetallic  Catalyst Résumé : The kinetics of CO2 reforming with CH4 over a Ni−Co/Al−Mg−O bimetallic catalyst was investigated in a fixed bed reactor at a temperature range of 650−750 °C and the partial pressures of CO2 and CH4 ranging from 30 to 190 kPa. Owing to the simultaneous occurrence of the CO2 reforming reaction and the reverse water−gas shift reaction (RWGS) in the system, the apparent activation energies with respect to reactant consumption and product formation were found different and they are 69.4 and 25.9 kJ/mol for CH4 and CO2 consumption and 85.1 and 61.8 kJ/mol for H2 and CO formation, respectively. It was also found that the reforming rate in terms of CH4 consumption was less sensitive to CO2 partial pressures but had stronger dependence on CH4 partial pressures. At a constant CH4 partial pressure, the increase in CO2 partial pressure did not cause significant change in the reforming rate, whereas at a constant CO2 partial pressure the reforming rate increased with the increase in CH4 partial pressure. The increase in extra CO2 at a constant CH4 pressure led to decreases in hydrogen (H2) formation but increase in carbon monoxide (CO) formation due to the simultaneous occurrence of the reverse water-gas shift reaction. A Langmuir−Hinshelwood (L–H) model was also developed assuming that the dissociation of CH4 and the reaction between the carbon species and the activated carbon dioxide are the rate determining steps over the Ni–Co/Al–Mg–O. It satisfactorily fits the experimental data as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801078p [article] Kinetic studies of carbon dioxide reforming of methane over ni−co/al−mg−o bimetallic catalyst [texte imprimé] / Jianguo Zhang, Auteur ; Hui Wang, Auteur ; Ajay Kumar Dalai, Auteur . - 2009 . - p. 677–684. chemical engenireeng Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 677–684 Mots-clés : Bimetallic  Catalyst Résumé : The kinetics of CO2 reforming with CH4 over a Ni−Co/Al−Mg−O bimetallic catalyst was investigated in a fixed bed reactor at a temperature range of 650−750 °C and the partial pressures of CO2 and CH4 ranging from 30 to 190 kPa. Owing to the simultaneous occurrence of the CO2 reforming reaction and the reverse water−gas shift reaction (RWGS) in the system, the apparent activation energies with respect to reactant consumption and product formation were found different and they are 69.4 and 25.9 kJ/mol for CH4 and CO2 consumption and 85.1 and 61.8 kJ/mol for H2 and CO formation, respectively. It was also found that the reforming rate in terms of CH4 consumption was less sensitive to CO2 partial pressures but had stronger dependence on CH4 partial pressures. At a constant CH4 partial pressure, the increase in CO2 partial pressure did not cause significant change in the reforming rate, whereas at a constant CO2 partial pressure the reforming rate increased with the increase in CH4 partial pressure. The increase in extra CO2 at a constant CH4 pressure led to decreases in hydrogen (H2) formation but increase in carbon monoxide (CO) formation due to the simultaneous occurrence of the reverse water-gas shift reaction. A Langmuir−Hinshelwood (L–H) model was also developed assuming that the dissociation of CH4 and the reaction between the carbon species and the activated carbon dioxide are the rate determining steps over the Ni–Co/Al–Mg–O. It satisfactorily fits the experimental data as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801078p

Selective hydrogenation of benzene to cyclohexene on a Ru/Al2O3/cordierite monolithic catalyst / Yujun Zhao in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4641-4647 Titre : Selective hydrogenation of benzene to cyclohexene on a Ru/Al2O3/cordierite monolithic catalyst : effect of mass transfer on the catalytic performance Type de document : texte imprimé Auteurs : Yujun Zhao, Auteur ; Jin Zhou, Auteur ; Jianguo Zhang, Auteur ; Deyi Li, Auteur Année de publication : 2008 Article en page(s) : p. 4641-4647 Note générale : Bibliogr. p. 4647 Langues : Anglais (eng) Mots-clés : Benzene  --  hydrogenation;  Monolithic  fixed-bed  reactor Résumé : A Ru/Al2O3/cordierite monolithic catalyst was prepared, characterized, and examined in selective hydrogenation of benzene to cyclohexene in a monolithic fixed-bed reactor with an aqueous solution of ZnSO4. The Carberry number and Wheeler−Weisz group were calculated to analyze the effects of external and internal diffusions of H2, benzene, and cyclohexene. According to the results of calculations, the water film, solubility, and diffusion coefficients of the three reactants (H2, benzene, and cyclohexene) play important roles in the mass-transfer rate. Under proper reaction conditions, the effects of the external mass transfer of H2 and benzene on the reaction rate are negligible. For the hydrogenation of cyclohexene, the diffusion of cyclohexene from the organic phase to the catalyst is the limiting step in the presence of water, which is the most important factor for obtaining high cyclohexene selectivity. The absence of pore diffusion of the three reactants, which is attributed to the thin eggshell distribution of in the catalyst, is another important factor for the higher cyclohexene selectivity. In addition, the optimum reaction conditions were found to be 413-423 K and 5 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071574g [article] Selective hydrogenation of benzene to cyclohexene on a Ru/Al2O3/cordierite monolithic catalyst : effect of mass transfer on the catalytic performance [texte imprimé] / Yujun Zhao, Auteur ; Jin Zhou, Auteur ; Jianguo Zhang, Auteur ; Deyi Li, Auteur . - 2008 . - p. 4641-4647. Bibliogr. p. 4647 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4641-4647 Mots-clés : Benzene  --  hydrogenation;  Monolithic  fixed-bed  reactor Résumé : A Ru/Al2O3/cordierite monolithic catalyst was prepared, characterized, and examined in selective hydrogenation of benzene to cyclohexene in a monolithic fixed-bed reactor with an aqueous solution of ZnSO4. The Carberry number and Wheeler−Weisz group were calculated to analyze the effects of external and internal diffusions of H2, benzene, and cyclohexene. According to the results of calculations, the water film, solubility, and diffusion coefficients of the three reactants (H2, benzene, and cyclohexene) play important roles in the mass-transfer rate. Under proper reaction conditions, the effects of the external mass transfer of H2 and benzene on the reaction rate are negligible. For the hydrogenation of cyclohexene, the diffusion of cyclohexene from the organic phase to the catalyst is the limiting step in the presence of water, which is the most important factor for obtaining high cyclohexene selectivity. The absence of pore diffusion of the three reactants, which is attributed to the thin eggshell distribution of in the catalyst, is another important factor for the higher cyclohexene selectivity. In addition, the optimum reaction conditions were found to be 413-423 K and 5 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071574g