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Kinetics and mechanism study of Low-temperature selective catalytic reduction of NO with urea supported on pitch-based spherical activated carbon / Zhi Wang in Industrial & engineering chemistry research, Vol. 50 N° 10 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6017–6027 Titre : Kinetics and mechanism study of Low-temperature selective catalytic reduction of NO with urea supported on pitch-based spherical activated carbon Type de document : texte imprimé Auteurs : Zhi Wang, Auteur ; Yanli Wang, Auteur ; Donghui Long, Auteur Année de publication : 2011 Article en page(s) : pp. 6017–6027 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Kinetics  Mechanism  Catalytic  reduction Résumé : The kinetics and mechanism of selective catalytic reduction (SCR) of NO with urea supported on pitch-based spherical activated carbons (PSACs) were studied at low temperatures. NO oxidation to NO2 catalyzed by the 0.5−0.8 nm micropores in PSACs was found to be the rate-limiting step in urea−SCR reaction, which was confirmed by both the apparent activation energy calculations and the kinetics results of urea−SCR reaction and NO oxidation on PSAC. These two reactions gave very similar negative apparent activation energies (−16.5 kJ/mol for urea−SCR reaction and −15.2 kJ/mol for NO oxidation), indicating that the adsorption of reactants on PSAC is of key importance in these two reactions. Moreover, these two reactions were both approximately first-order with respect to NO and one-half order with respect to O2. It was found that NO3 from the disproportionation of the produced NO2 was quickly reduced by supported urea into N2. After the complete consumption of supported urea, NO2 started to release, and the carbon surface was gradually oxidized by adsorbed NOx species. NO3 was found to be stably adsorbed on the oxidized carbon surface. On the basis of the results obtained, a reaction mechanism of low-temperature urea-SCR reaction on PSAC was proposed and discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102506q [article] Kinetics and mechanism study of Low-temperature selective catalytic reduction of NO with urea supported on pitch-based spherical activated carbon [texte imprimé] / Zhi Wang, Auteur ; Yanli Wang, Auteur ; Donghui Long, Auteur . - 2011 . - pp. 6017–6027. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6017–6027 Mots-clés : Kinetics  Mechanism  Catalytic  reduction Résumé : The kinetics and mechanism of selective catalytic reduction (SCR) of NO with urea supported on pitch-based spherical activated carbons (PSACs) were studied at low temperatures. NO oxidation to NO2 catalyzed by the 0.5−0.8 nm micropores in PSACs was found to be the rate-limiting step in urea−SCR reaction, which was confirmed by both the apparent activation energy calculations and the kinetics results of urea−SCR reaction and NO oxidation on PSAC. These two reactions gave very similar negative apparent activation energies (−16.5 kJ/mol for urea−SCR reaction and −15.2 kJ/mol for NO oxidation), indicating that the adsorption of reactants on PSAC is of key importance in these two reactions. Moreover, these two reactions were both approximately first-order with respect to NO and one-half order with respect to O2. It was found that NO3 from the disproportionation of the produced NO2 was quickly reduced by supported urea into N2. After the complete consumption of supported urea, NO2 started to release, and the carbon surface was gradually oxidized by adsorbed NOx species. NO3 was found to be stably adsorbed on the oxidized carbon surface. On the basis of the results obtained, a reaction mechanism of low-temperature urea-SCR reaction on PSAC was proposed and discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102506q

Low - temperature selective catalytic reduction of NO with urea supported on pitch - based spherical activated carbon / Zhi Wang 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. 6317-6322 Titre : Low - temperature selective catalytic reduction of NO with urea supported on pitch - based spherical activated carbon Type de document : texte imprimé Auteurs : Zhi Wang, Auteur ; Yanli Wang, Auteur ; Dengjun Wang, Auteur Année de publication : 2010 Article en page(s) : pp. 6317-6322 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Activated  carbon  Selective  catalytic  reduction  Low  temperature Résumé : Urea as a reducing agent supported on pitch-based spherical activated carbon (PSAC) was studied for NO reduction at low temperatures (30−90 °C). The results showed that PSAC with 8 wt % urea loading exhibited high activity in the selective catalytic reduction (SCR) of NO at 30 °C. The SCR activity decreased markedly when urea loading was increased above 8 wt % due to pore plugging, which restricted the adsorption of gas phase reactants on PSAC, although the NOx removal period was extended. A low reaction temperature was favorable for NO reduction on account of the increased NO adsorption on PSAC. It was found that the SCR activity was improved by increasing NO or O2 concentration in the feed gas, owing to the enhanced NO oxidation by O2 to NO2, which was then reduced by urea to form N2. Increasing space velocity not only decreased the SCR activity but also shortened the NOx removal period. More than 85% NOx conversion for 55 h could be achieved over PSAC with 8 wt % urea loading at 30 °C under the conditions of 500 ppmv NO, 21 vol % O2, and a space velocity of 2000 h−1. Furthermore, PSAC showed a superior hydrodynamic property, and the pressure drop ratio of PSAC to a commercial granule activated carbon with the equivalent particle size was about 35% with the apparent air flow velocity in a range of 0.120.51 m/s. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23040385 [article] Low - temperature selective catalytic reduction of NO with urea supported on pitch - based spherical activated carbon [texte imprimé] / Zhi Wang, Auteur ; Yanli Wang, Auteur ; Dengjun Wang, Auteur . - 2010 . - pp. 6317-6322. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6317-6322 Mots-clés : Activated  carbon  Selective  catalytic  reduction  Low  temperature Résumé : Urea as a reducing agent supported on pitch-based spherical activated carbon (PSAC) was studied for NO reduction at low temperatures (30−90 °C). The results showed that PSAC with 8 wt % urea loading exhibited high activity in the selective catalytic reduction (SCR) of NO at 30 °C. The SCR activity decreased markedly when urea loading was increased above 8 wt % due to pore plugging, which restricted the adsorption of gas phase reactants on PSAC, although the NOx removal period was extended. A low reaction temperature was favorable for NO reduction on account of the increased NO adsorption on PSAC. It was found that the SCR activity was improved by increasing NO or O2 concentration in the feed gas, owing to the enhanced NO oxidation by O2 to NO2, which was then reduced by urea to form N2. Increasing space velocity not only decreased the SCR activity but also shortened the NOx removal period. More than 85% NOx conversion for 55 h could be achieved over PSAC with 8 wt % urea loading at 30 °C under the conditions of 500 ppmv NO, 21 vol % O2, and a space velocity of 2000 h−1. Furthermore, PSAC showed a superior hydrodynamic property, and the pressure drop ratio of PSAC to a commercial granule activated carbon with the equivalent particle size was about 35% with the apparent air flow velocity in a range of 0.120.51 m/s. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23040385

MnOx – CeO2 / activated carbon honeycomb catalyst for selective catalytic reduction of NO with NH3 at low temperatures / Yanli Wang in Industrial & engineering chemistry research, Vol. 51 N° 36 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 36 (Septembre 2012) . - pp. 11667–11673 Titre : MnOx – CeO2 / activated carbon honeycomb catalyst for selective catalytic reduction of NO with NH3 at low temperatures Type de document : texte imprimé Auteurs : Yanli Wang, Auteur ; ChuanZhang Ge, Auteur ; Liang Zhan, Auteur Année de publication : 2012 Article en page(s) : pp. 11667–11673 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst Résumé : Activated carbon honeycomb supported manganese and cerium oxides (MnOx–CeO2/ACH) catalysts were investigated for selective catalytic reduction (SCR) of NO at low temperatures of 80–200 °C. Compared with ACH supported manganese oxide catalyst (MnOx/ACH), MnOx–CeO2/ACH catalysts show much higher SCR activity and higher selectivity to N2. NO conversion can be improved by the addition of CeO2 from less than 50% to 100% at 80–160 °C. The N2 selectivity of higher than 99.8% is obtained over the Ce(1)Mn/ACH catalyst at 80–200 °C. Results indicate that the addition of CeO2 improves the distribution of MnOx and enhances the oxidation of NO to NO2, producing more absorbed NO3– on the catalyst surface, which is then reduced into N2 by NH3. These behaviors account for the promoting effect of CeO2 on the SCR activity. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300555f [article] MnOx – CeO2 / activated carbon honeycomb catalyst for selective catalytic reduction of NO with NH3 at low temperatures [texte imprimé] / Yanli Wang, Auteur ; ChuanZhang Ge, Auteur ; Liang Zhan, Auteur . - 2012 . - pp. 11667–11673. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 36 (Septembre 2012) . - pp. 11667–11673 Mots-clés : Catalyst Résumé : Activated carbon honeycomb supported manganese and cerium oxides (MnOx–CeO2/ACH) catalysts were investigated for selective catalytic reduction (SCR) of NO at low temperatures of 80–200 °C. Compared with ACH supported manganese oxide catalyst (MnOx/ACH), MnOx–CeO2/ACH catalysts show much higher SCR activity and higher selectivity to N2. NO conversion can be improved by the addition of CeO2 from less than 50% to 100% at 80–160 °C. The N2 selectivity of higher than 99.8% is obtained over the Ce(1)Mn/ACH catalyst at 80–200 °C. Results indicate that the addition of CeO2 improves the distribution of MnOx and enhances the oxidation of NO to NO2, producing more absorbed NO3– on the catalyst surface, which is then reduced into N2 by NH3. These behaviors account for the promoting effect of CeO2 on the SCR activity. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300555f