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Kinetic model of NOx SCR using urea on commercial Cu−zeolite catalyst / Atul Pant in Industrial & engineering chemistry research, Vol. 50 N° 9 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 5490-5498 Titre : Kinetic model of NOx SCR using urea on commercial Cu−zeolite catalyst Type de document : texte imprimé Auteurs : Atul Pant, Auteur ; Steven J. Schmieg, Auteur Année de publication : 2011 Article en page(s) : pp. 5490-5498 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Modeling  Catalyst  Zeolite  Selective  catalytic  reduction  Kinetic  model Résumé : Analysis of catalyst performance data over a commercial Cu―zeolite SCR catalyst shows that NH3 oxidation leads to NO formation at temperatures above 500 °C. This contributes to the reduction ín NO conversion efficiency at high temperatures. It is shown that the conversion of NH, to NO should be second order in NH3 concentration. A kinetic model incorporating this reaction is developed for a commercial SCR catalyst. The kinetic parameters are estimated using NO and NH3 conversion data collected over varying temperatures, flow rates, NH3 to NOx ratios, and NO2 to NOx ratios using actual engine exhaust. The optimized pre-exponential factors and activation energy are reported. The model is validated by comparing predictions with catalyst performance data over other engine operating conditions. The model predictions are in reasonable agreement with the measurements except at low temperatures and flow rates. The R2 value for NO conversion efficiency predictions is 0.88 and for NH3 slip is 0.76 excluding the predictions at low temperature and flow. Substoichiometric and superstoichiometric consumption of ammonia is observed while using urea for NOx SCR. It is proposed that lower ammonia consumption is due to direct reduction of NOx by unconverted urea or intermediates formed during urea to ammonia conversion. More than the stoichiometric amount of NH3 consumption at low temperature cannot be attributed to ammonia oxidation. The model shows that the predictions for this data can be significantly improved by allowing for incomplete conversion of urea to ammonia. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24128672 [article] Kinetic model of NOx SCR using urea on commercial Cu−zeolite catalyst [texte imprimé] / Atul Pant, Auteur ; Steven J. Schmieg, Auteur . - 2011 . - pp. 5490-5498. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 5490-5498 Mots-clés : Modeling  Catalyst  Zeolite  Selective  catalytic  reduction  Kinetic  model Résumé : Analysis of catalyst performance data over a commercial Cu―zeolite SCR catalyst shows that NH3 oxidation leads to NO formation at temperatures above 500 °C. This contributes to the reduction ín NO conversion efficiency at high temperatures. It is shown that the conversion of NH, to NO should be second order in NH3 concentration. A kinetic model incorporating this reaction is developed for a commercial SCR catalyst. The kinetic parameters are estimated using NO and NH3 conversion data collected over varying temperatures, flow rates, NH3 to NOx ratios, and NO2 to NOx ratios using actual engine exhaust. The optimized pre-exponential factors and activation energy are reported. The model is validated by comparing predictions with catalyst performance data over other engine operating conditions. The model predictions are in reasonable agreement with the measurements except at low temperatures and flow rates. The R2 value for NO conversion efficiency predictions is 0.88 and for NH3 slip is 0.76 excluding the predictions at low temperature and flow. Substoichiometric and superstoichiometric consumption of ammonia is observed while using urea for NOx SCR. It is proposed that lower ammonia consumption is due to direct reduction of NOx by unconverted urea or intermediates formed during urea to ammonia conversion. More than the stoichiometric amount of NH3 consumption at low temperature cannot be attributed to ammonia oxidation. The model shows that the predictions for this data can be significantly improved by allowing for incomplete conversion of urea to ammonia. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24128672

A Model development for evaluating soot-NOx interactions in a blended 2-Way diesel particulate filter/selective catalytic reduction / Soo-Youl Park in Industrial & engineering chemistry research, Vol. 51 N° 48 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 48 (Décembre 2012) . - pp. 15582-15592 Titre : A Model development for evaluating soot-NOx interactions in a blended 2-Way diesel particulate filter/selective catalytic reduction Type de document : texte imprimé Auteurs : Soo-Youl Park, Auteur ; Kushal Narayanaswamy, Auteur ; Steven J. Schmieg, Auteur Année de publication : 2013 Article en page(s) : pp. 15582-15592 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Selective  catalytic  reduction  Soot  Modeling Résumé : The 2-way diesel particulate filter/selective catalytic reduction (DPF/SCR) emission reduction system has been considered as a potential candidate for future emission standards owing to its advantages in cost savings and packaging flexibility. For the 2-way device, Cu―zeolite is coated inside the DPF substrate as nitrogen oxide (NOx) reducing (DeNOx) catalytic material. Therefore, when exhaust gas passes through the 2-way device, NOx reduction and soot filtration occur simultaneously. However, the operating characteristics of the combinatorial device might be different from individual DPF and SCR devices. In this work, a previously developed model was improved to include soot filtration and oxidation. The model has been tested and validated with experimental data from a reactor flow bench in a systematic manner and applied to capture the effect of soot deposits on NOx reduction performance in a 2-way DPF/SCR device. Accordingly, the soot oxidation characteristics of a 2-way device are investigated with various feed gas compositions. Then the effect of soot deposit on the SCR reaction is investigated in terms of deterioration of DeNOx performance and the interaction between soot oxidation reactions and DeNOx SCR reactions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26710596 [article] A Model development for evaluating soot-NOx interactions in a blended 2-Way diesel particulate filter/selective catalytic reduction [texte imprimé] / Soo-Youl Park, Auteur ; Kushal Narayanaswamy, Auteur ; Steven J. Schmieg, Auteur . - 2013 . - pp. 15582-15592. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 48 (Décembre 2012) . - pp. 15582-15592 Mots-clés : Selective  catalytic  reduction  Soot  Modeling Résumé : The 2-way diesel particulate filter/selective catalytic reduction (DPF/SCR) emission reduction system has been considered as a potential candidate for future emission standards owing to its advantages in cost savings and packaging flexibility. For the 2-way device, Cu―zeolite is coated inside the DPF substrate as nitrogen oxide (NOx) reducing (DeNOx) catalytic material. Therefore, when exhaust gas passes through the 2-way device, NOx reduction and soot filtration occur simultaneously. However, the operating characteristics of the combinatorial device might be different from individual DPF and SCR devices. In this work, a previously developed model was improved to include soot filtration and oxidation. The model has been tested and validated with experimental data from a reactor flow bench in a systematic manner and applied to capture the effect of soot deposits on NOx reduction performance in a 2-way DPF/SCR device. Accordingly, the soot oxidation characteristics of a 2-way device are investigated with various feed gas compositions. Then the effect of soot deposit on the SCR reaction is investigated in terms of deterioration of DeNOx performance and the interaction between soot oxidation reactions and DeNOx SCR reactions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26710596