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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

Poly (ethyleneimine) - loaded silica monolith with a hierarchical pore structure for H2S adsorptive removal / Qingjun Chen 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. 11408-11414 Titre : Poly (ethyleneimine) - loaded silica monolith with a hierarchical pore structure for H2S adsorptive removal Type de document : texte imprimé Auteurs : Qingjun Chen, Auteur ; Feichao Fan, Auteur ; Donghui Long, Auteur Année de publication : 2011 Article en page(s) : pp. 11408-11414 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrogen  sulfides  Pore  structure  Monolithic  construction Résumé : Poly(ethyleneimine) (PEI) loaded hierarchical porous silica monolith has been developed as a recycle H2S sorbent at low temperature. The sorbent was characterized by N2 adsorption, scanning electron microscope, transmission electron microscope, Fourier transform infrared spectra, and activity tests. The effects of the amount of PEI loading, the operating temperature, and the PEI polymerization degree on H2S removal were studied. The sorbent demonstrated a large H2S breakthrough capacity of 1.27 mmol of H2S/(g of sorbent) at 22 °C, which is about 60% larger than that of PEI-loaded SBA-15 or MCM-41 sorbent. The optimal PEI loading is 65 wt %, and the most ideal PEI molecular weight is 600. As the decrease of the temperature, the sorption performance of the sorbent increases greatly. There are two important factors affecting the performance of H2S sorption: the amount of available PEI in the sorbent and the interaction between H2S and amine functional groups of PEI. In addition, the developed sorbent can be regenerated easily at 75 °C, and it exhibits excellent regenerability and stability. These results indicate that PEI-loaded hierarchical porous silica sorbent will be promising for removing H2S in the future. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437839 [article] Poly (ethyleneimine) - loaded silica monolith with a hierarchical pore structure for H2S adsorptive removal [texte imprimé] / Qingjun Chen, Auteur ; Feichao Fan, Auteur ; Donghui Long, Auteur . - 2011 . - pp. 11408-11414. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11408-11414 Mots-clés : Hydrogen  sulfides  Pore  structure  Monolithic  construction Résumé : Poly(ethyleneimine) (PEI) loaded hierarchical porous silica monolith has been developed as a recycle H2S sorbent at low temperature. The sorbent was characterized by N2 adsorption, scanning electron microscope, transmission electron microscope, Fourier transform infrared spectra, and activity tests. The effects of the amount of PEI loading, the operating temperature, and the PEI polymerization degree on H2S removal were studied. The sorbent demonstrated a large H2S breakthrough capacity of 1.27 mmol of H2S/(g of sorbent) at 22 °C, which is about 60% larger than that of PEI-loaded SBA-15 or MCM-41 sorbent. The optimal PEI loading is 65 wt %, and the most ideal PEI molecular weight is 600. As the decrease of the temperature, the sorption performance of the sorbent increases greatly. There are two important factors affecting the performance of H2S sorption: the amount of available PEI in the sorbent and the interaction between H2S and amine functional groups of PEI. In addition, the developed sorbent can be regenerated easily at 75 °C, and it exhibits excellent regenerability and stability. These results indicate that PEI-loaded hierarchical porous silica sorbent will be promising for removing H2S in the future. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437839

Role of pore structure of activated carbon fibers in the catalytic oxidation of H2S / Qingjun Chen in Industrial & engineering chemistry research, Vol. 49 N° 7 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3152–3159 Titre : Role of pore structure of activated carbon fibers in the catalytic oxidation of H2S Type de document : texte imprimé Auteurs : Qingjun Chen, Auteur ; Zhi Wang, Auteur ; Donghui Long, Auteur Année de publication : 2010 Article en page(s) : pp. 3152–3159 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Activated  Carbon  Fibers  Catalytic  Oxidation  Pore  H2S Résumé : Na2CO3-impregnated activated carbon fibers (ACFs) have been developed as low-concentration H2S oxidation catalysts at ambient temperature. Two series of commercial pitch-based and poly(acrylonitrile)-based ACFs were used to evaluate the role of pore structure in the oxidation of H2S. The initial, impregnated, and exhausted materials were characterized using elemental analysis, N2 adsorption, scanning electron microscopy (SEM), thermogravimetry analysis, and activity tests. The catalytic oxidation of H2S continued until all effective pores of the catalysts were blocked by the oxidation products. The saturation sulfur capacity was found to be in the range of 0.10−0.81 g of H2S/g of catalyst, with the value strongly dependent on the pore structure (especially the volume of pores larger than 0.7 nm) but independent of the nitrogen functional groups. Further quantitative analysis suggested that elemental sulfur as a dominant product mostly deposited in large pores (d > 0.7 nm), whereas sulfuric acid was preferably produced in small micropores (d < 0.7 nm). A possible mechanism of H2S oxidation with respect to the pore size of catalysts is proposed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901223j [article] Role of pore structure of activated carbon fibers in the catalytic oxidation of H2S [texte imprimé] / Qingjun Chen, Auteur ; Zhi Wang, Auteur ; Donghui Long, Auteur . - 2010 . - pp. 3152–3159. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3152–3159 Mots-clés : Activated  Carbon  Fibers  Catalytic  Oxidation  Pore  H2S Résumé : Na2CO3-impregnated activated carbon fibers (ACFs) have been developed as low-concentration H2S oxidation catalysts at ambient temperature. Two series of commercial pitch-based and poly(acrylonitrile)-based ACFs were used to evaluate the role of pore structure in the oxidation of H2S. The initial, impregnated, and exhausted materials were characterized using elemental analysis, N2 adsorption, scanning electron microscopy (SEM), thermogravimetry analysis, and activity tests. The catalytic oxidation of H2S continued until all effective pores of the catalysts were blocked by the oxidation products. The saturation sulfur capacity was found to be in the range of 0.10−0.81 g of H2S/g of catalyst, with the value strongly dependent on the pore structure (especially the volume of pores larger than 0.7 nm) but independent of the nitrogen functional groups. Further quantitative analysis suggested that elemental sulfur as a dominant product mostly deposited in large pores (d > 0.7 nm), whereas sulfuric acid was preferably produced in small micropores (d < 0.7 nm). A possible mechanism of H2S oxidation with respect to the pore size of catalysts is proposed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901223j