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Carbonation of CaO - based sorbents enhanced by steam addition / Vasilije Manovic in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9105–9110 Titre : Carbonation of CaO - based sorbents enhanced by steam addition Type de document : texte imprimé Auteurs : Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur Année de publication : 2010 Article en page(s) : pp. 9105–9110 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Carbonation  Combustion  Thermogravimetric  analyzer Résumé : The carbonation reaction has recently been intensively investigated as a means of CO2 capture from gas mixtures such as flue gas produced during fossil fuel combustion. Unfortunately, this gas−solid reaction is limited due to formation of the solid product (CaCO3) at the reacting surface and sintering, all of which reduce the carrying capacity of the sorbent. In this work the enhancement of carbonation conversion by means of steam addition to the carbonating gas was studied. Seven limestones of different origin and composition as well as one synthetic sorbent (calcium aluminate pellets) were tested. A thermogravimetric analyzer (TGA) was employed for the carbonation tests at different temperatures (350−800 °C) in a gas mixture containing typically 20% CO2 and 10 or 20% H2O(g). The samples tested were calcined under an N2 (800 °C) or CO2 (950 °C) atmosphere to explore the influence of different levels of sample sintering, and the results obtained were compared with those seen for carbonation in dry (no steam) gas mixtures. The morphology of samples after carbonation under different conditions was examined by a scanning electron microscope (SEM). It was found that carbonation is enhanced by steam, but this is more pronounced at lower temperatures and for more sintered samples. With increasing temperature and carbonation time, the enhancement of carbonation becomes negligible because the conversion reaches a “maximum” value (75−80% for samples calcined in N2) even without steam. Carbonation of samples calcined in CO2 is enhanced at different levels depending on the sorbent tested. The shape of carbonation profiles and morphology of carbonated samples show that steam enhances solid state diffusion and, consequently, conversion during carbonation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101352s [article] Carbonation of CaO - based sorbents enhanced by steam addition [texte imprimé] / Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur . - 2010 . - pp. 9105–9110. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9105–9110 Mots-clés : Carbonation  Combustion  Thermogravimetric  analyzer Résumé : The carbonation reaction has recently been intensively investigated as a means of CO2 capture from gas mixtures such as flue gas produced during fossil fuel combustion. Unfortunately, this gas−solid reaction is limited due to formation of the solid product (CaCO3) at the reacting surface and sintering, all of which reduce the carrying capacity of the sorbent. In this work the enhancement of carbonation conversion by means of steam addition to the carbonating gas was studied. Seven limestones of different origin and composition as well as one synthetic sorbent (calcium aluminate pellets) were tested. A thermogravimetric analyzer (TGA) was employed for the carbonation tests at different temperatures (350−800 °C) in a gas mixture containing typically 20% CO2 and 10 or 20% H2O(g). The samples tested were calcined under an N2 (800 °C) or CO2 (950 °C) atmosphere to explore the influence of different levels of sample sintering, and the results obtained were compared with those seen for carbonation in dry (no steam) gas mixtures. The morphology of samples after carbonation under different conditions was examined by a scanning electron microscope (SEM). It was found that carbonation is enhanced by steam, but this is more pronounced at lower temperatures and for more sintered samples. With increasing temperature and carbonation time, the enhancement of carbonation becomes negligible because the conversion reaches a “maximum” value (75−80% for samples calcined in N2) even without steam. Carbonation of samples calcined in CO2 is enhanced at different levels depending on the sorbent tested. The shape of carbonation profiles and morphology of carbonated samples show that steam enhances solid state diffusion and, consequently, conversion during carbonation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101352s

CO2 carrying behavior of calcium aluminate pellets under high-temperature/high-CO2 concentration calcination conditions / Vasilije Manovic in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6916–6922 Titre : CO2 carrying behavior of calcium aluminate pellets under high-temperature/high-CO2 concentration calcination conditions Type de document : texte imprimé Auteurs : Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur Année de publication : 2010 Article en page(s) : pp 6916–6922 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Calcium  aluminate  High-CO2. Résumé : Sintering and a resulting loss of activity during calcination/carbonation can introduce substantial economic penalties for a CO2 looping cycle using CaO-based sorbents. In a real system, sorbent regeneration must be done at a high temperature to produce an almost pure CO2 stream, and this will increase both sintering and loss of sorbent activity. The influence of severe calcination conditions on the CO2 carrying behavior of calcium aluminate pellets is investigated here. Up to 30 calcination/carbonation cycles were performed using a thermogravimetric analyzer apparatus. The maximum temperature during the calcination stage in pure CO2 was 950 °C, using different heating/cooling rates between two carbonation stages (700 °C, 20% CO2). For comparison, cycles were also done using N2 during the calcination stages. In addition, the original Cadomin limestone, used for pelletization, was also examined in its original form and the results obtained were compared with those for the aluminate pellets. As expected, high temperature during calcination strongly reduced CO2 carrying capacities of both sorbents. However, aluminate pellets showed better resistance to these severe conditions. The conversion profiles obtained are significantly different to those obtained under milder conditions, with significant increased activity during the slower, diffusion-controlled, carbonation stage. Moreover, scanning electron microscopy analysis of samples after prolonged carbonation showed that pore filling occurred at the sorbent particle surfaces preventing diffusion of CO2 toward the particle interior. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901795e [article] CO2 carrying behavior of calcium aluminate pellets under high-temperature/high-CO2 concentration calcination conditions [texte imprimé] / Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur . - 2010 . - pp 6916–6922. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6916–6922 Mots-clés : Calcium  aluminate  High-CO2. Résumé : Sintering and a resulting loss of activity during calcination/carbonation can introduce substantial economic penalties for a CO2 looping cycle using CaO-based sorbents. In a real system, sorbent regeneration must be done at a high temperature to produce an almost pure CO2 stream, and this will increase both sintering and loss of sorbent activity. The influence of severe calcination conditions on the CO2 carrying behavior of calcium aluminate pellets is investigated here. Up to 30 calcination/carbonation cycles were performed using a thermogravimetric analyzer apparatus. The maximum temperature during the calcination stage in pure CO2 was 950 °C, using different heating/cooling rates between two carbonation stages (700 °C, 20% CO2). For comparison, cycles were also done using N2 during the calcination stages. In addition, the original Cadomin limestone, used for pelletization, was also examined in its original form and the results obtained were compared with those for the aluminate pellets. As expected, high temperature during calcination strongly reduced CO2 carrying capacities of both sorbents. However, aluminate pellets showed better resistance to these severe conditions. The conversion profiles obtained are significantly different to those obtained under milder conditions, with significant increased activity during the slower, diffusion-controlled, carbonation stage. Moreover, scanning electron microscopy analysis of samples after prolonged carbonation showed that pore filling occurred at the sorbent particle surfaces preventing diffusion of CO2 toward the particle interior. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901795e

Core - in - shell CaO / CuO - Based composite for CO2 capture / Vasilije Manovic in Industrial & engineering chemistry research, Vol. 50 N° 22 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12384–12391 Titre : Core - in - shell CaO / CuO - Based composite for CO2 capture Type de document : texte imprimé Auteurs : Vasilije Manovic, Auteur ; Yinghai Wu, Auteur ; Ian He, Auteur Année de publication : 2012 Article en page(s) : pp. 12384–12391 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Composite  materials Résumé : This paper describes the preparation of composite materials containing both CaO as a reversible CO2 sorbent and CuO, serving as an oxygen carrier, which allows the spent Ca sorbent to be regenerated in a fuel gas stream after it has been used for CO2 capture. Calcium aluminate cement is used as a support to enhance pellet strength. The pellets were prepared in a mechanical pelletizer for granulation of powdered materials with addition of spray water. Three types of pellets were prepared: (i) core-in-shell with 50% CuO and 50% CaO (75% CuO and 25% CaO in the core), (ii) core-in-shell with 50% CuO, 40% CaO, and 10% cement (75% CuO and 25% CaO in the core), and (iii) homogeneous pellets with 50% CuO, 40% CaO, and 10% cement addition as a binder. CO2/O2 carrying activity of the pellets was then tested in a thermogravimetric analyzer (TGA). The attrition resistance of the obtained material was examined during attrition tests in a bubbling fluidized bed (i.d. 50 mm). The oxygen carrying capacity of pellets indicates that 25% CaO in the core is sufficient to support the CuO and prevent decay of its activity as an oxygen carrier during reduction/oxidation cycles. To demonstrate that the pellets produced actually have a core-in-shell pattern, larger cross-sectioned particles were analyzed using the scanning electron microscope/energy dispersive X-ray method (SEM/EDX). The SEM/EDX analyses clearly showed different morphology and elemental composition of the core and shell, with a higher content of CuO in the core. The results of attrition tests showed that after fluidization for 2 h, particle size distribution changed negligibly and high temperature did not cause significantly more pronounced attrition. These tests clearly showed that the procedure employed is suitable for large-scale preparation of core-in-shell CaO/CuO-based pellets which have numerous benefits. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201427g [article] Core - in - shell CaO / CuO - Based composite for CO2 capture [texte imprimé] / Vasilije Manovic, Auteur ; Yinghai Wu, Auteur ; Ian He, Auteur . - 2012 . - pp. 12384–12391. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12384–12391 Mots-clés : Composite  materials Résumé : This paper describes the preparation of composite materials containing both CaO as a reversible CO2 sorbent and CuO, serving as an oxygen carrier, which allows the spent Ca sorbent to be regenerated in a fuel gas stream after it has been used for CO2 capture. Calcium aluminate cement is used as a support to enhance pellet strength. The pellets were prepared in a mechanical pelletizer for granulation of powdered materials with addition of spray water. Three types of pellets were prepared: (i) core-in-shell with 50% CuO and 50% CaO (75% CuO and 25% CaO in the core), (ii) core-in-shell with 50% CuO, 40% CaO, and 10% cement (75% CuO and 25% CaO in the core), and (iii) homogeneous pellets with 50% CuO, 40% CaO, and 10% cement addition as a binder. CO2/O2 carrying activity of the pellets was then tested in a thermogravimetric analyzer (TGA). The attrition resistance of the obtained material was examined during attrition tests in a bubbling fluidized bed (i.d. 50 mm). The oxygen carrying capacity of pellets indicates that 25% CaO in the core is sufficient to support the CuO and prevent decay of its activity as an oxygen carrier during reduction/oxidation cycles. To demonstrate that the pellets produced actually have a core-in-shell pattern, larger cross-sectioned particles were analyzed using the scanning electron microscope/energy dispersive X-ray method (SEM/EDX). The SEM/EDX analyses clearly showed different morphology and elemental composition of the core and shell, with a higher content of CuO in the core. The results of attrition tests showed that after fluidization for 2 h, particle size distribution changed negligibly and high temperature did not cause significantly more pronounced attrition. These tests clearly showed that the procedure employed is suitable for large-scale preparation of core-in-shell CaO/CuO-based pellets which have numerous benefits. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201427g

Long-term behavior of CaO-based pellets supported by calcium aluminate cements in a long series of CO2 capture cycles / Vasilije Manovic in Industrial & engineering chemistry research, Vol. 48 N° 19 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8906–8912 Titre : Long-term behavior of CaO-based pellets supported by calcium aluminate cements in a long series of CO2 capture cycles Type de document : texte imprimé Auteurs : Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur Année de publication : 2009 Article en page(s) : pp. 8906–8912 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CaO-based  pellets  CO2  carrying  capacity  Thermogravimetric  analyzer  Scanning  electron  microscopy Résumé : A series of carbonation/calcination tests consisting of 1000 cycles was performed with CaO-based pellets prepared using hydrated lime and calcium aluminate cement. The change in CO2 carrying capacity of the sorbent was investigated in a thermogravimetric analyzer (TGA) apparatus and the morphology of residues after those cycles in the TGA was examined by scanning electron microscopy (SEM). Larger quantities of sorbent pellets underwent 300 carbonation/calcination cycles in a tube furnace (TF), and their properties were examined by nitrogen physisorption tests (BET and BJH). The crushing strength of the pellets before and after the CO2 cycles was determined by means of a custom-made strength testing apparatus. The results showed high CO2 carrying capacity in long series of cycles with an extremely high residual activity of the order of 28%. This superior performance is a result of favorable morphology due to the existence of large numbers of nanosized pores suitable for carbonation. This morphology is relatively stable during cycles due to the presence of mayenite (Ca12Al14O33) in the CaO structure. However, the crushing tests showed that pellets lost strength after 300 carbonation/calcination cycles, and this appears to be due to the cracks formed in the pellets. This effect was not observed in smaller particles suitable for use in fluidized bed (FBC) systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9011529 [article] Long-term behavior of CaO-based pellets supported by calcium aluminate cements in a long series of CO2 capture cycles [texte imprimé] / Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur . - 2009 . - pp. 8906–8912. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8906–8912 Mots-clés : CaO-based  pellets  CO2  carrying  capacity  Thermogravimetric  analyzer  Scanning  electron  microscopy Résumé : A series of carbonation/calcination tests consisting of 1000 cycles was performed with CaO-based pellets prepared using hydrated lime and calcium aluminate cement. The change in CO2 carrying capacity of the sorbent was investigated in a thermogravimetric analyzer (TGA) apparatus and the morphology of residues after those cycles in the TGA was examined by scanning electron microscopy (SEM). Larger quantities of sorbent pellets underwent 300 carbonation/calcination cycles in a tube furnace (TF), and their properties were examined by nitrogen physisorption tests (BET and BJH). The crushing strength of the pellets before and after the CO2 cycles was determined by means of a custom-made strength testing apparatus. The results showed high CO2 carrying capacity in long series of cycles with an extremely high residual activity of the order of 28%. This superior performance is a result of favorable morphology due to the existence of large numbers of nanosized pores suitable for carbonation. This morphology is relatively stable during cycles due to the presence of mayenite (Ca12Al14O33) in the CaO structure. However, the crushing tests showed that pellets lost strength after 300 carbonation/calcination cycles, and this appears to be due to the cracks formed in the pellets. This effect was not observed in smaller particles suitable for use in fluidized bed (FBC) systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9011529

Pilot - scale study of CO2 capture by CaO - based sorbents in the presence of steam and SO2 / Robert T. Symonds in Industrial & engineering chemistry research, Vol. 51 N° 21 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 21 (Mai 2012) . - pp. 7177-7184 Titre : Pilot - scale study of CO2 capture by CaO - based sorbents in the presence of steam and SO2 Type de document : texte imprimé Auteurs : Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Vasilije Manovic, Auteur Année de publication : 2012 Article en page(s) : pp. 7177-7184 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Water  vapor  Carbon  dioxide Résumé : Calcium looping cycles require an oxy-fired calciner burning coal for sorbent regeneration. Thus, in addition to O2 and CO2, the flue gases will include both steam and SO2, and similarly, carbonation of real flue-gases will occur in the presence of steam. However, to date, most research has been done without either of these two gaseous components present. Here, batch combustion experiments were performed in a pilot-scale fluidized-bed reactor to study the effects of steam and SO2 addition on CO2 capture by limestone-based sorbents calcined under oxygen-enriched air and oxy-fuel conditions. The initial fast kinetically controlled CO2 capture stage was dramatically reduced when the sorbent was calcined at realistic temperatures in the presence of SO2. This is attributed to both greater sintering due to higher local 2calcination temperatures required by high CO2 concentrations and CaSO4 formation. By contrast, steam in the synthetic flue gas during carbonation extended the initial, high-efficiency CO2 capture period compared with that observed during carbonation with dry synthetic flue gases. A comparison between pilot-scale fluidized-bed combustion (FBC) and thermogravimetric analysis (TGA) results showed that sorbent reactivity was considerably lower during pilot-scale FBC testing, as anticipated given the higher calcination temperatures employed in the FBC reactor and the presence of the other feed gases. The enhanced CO2 capture efficiency in FBC reactors with steam present was also confirmed by TGA tests. These results are important because they demonstrate how sorbent deactivation effects seen in realistic FBC calcium-looping operation can be successfully reduced by the presence of steam in the carbonator. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25948458 [article] Pilot - scale study of CO2 capture by CaO - based sorbents in the presence of steam and SO2 [texte imprimé] / Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Vasilije Manovic, Auteur . - 2012 . - pp. 7177-7184. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 21 (Mai 2012) . - pp. 7177-7184 Mots-clés : Water  vapor  Carbon  dioxide Résumé : Calcium looping cycles require an oxy-fired calciner burning coal for sorbent regeneration. Thus, in addition to O2 and CO2, the flue gases will include both steam and SO2, and similarly, carbonation of real flue-gases will occur in the presence of steam. However, to date, most research has been done without either of these two gaseous components present. Here, batch combustion experiments were performed in a pilot-scale fluidized-bed reactor to study the effects of steam and SO2 addition on CO2 capture by limestone-based sorbents calcined under oxygen-enriched air and oxy-fuel conditions. The initial fast kinetically controlled CO2 capture stage was dramatically reduced when the sorbent was calcined at realistic temperatures in the presence of SO2. This is attributed to both greater sintering due to higher local 2calcination temperatures required by high CO2 concentrations and CaSO4 formation. By contrast, steam in the synthetic flue gas during carbonation extended the initial, high-efficiency CO2 capture period compared with that observed during carbonation with dry synthetic flue gases. A comparison between pilot-scale fluidized-bed combustion (FBC) and thermogravimetric analysis (TGA) results showed that sorbent reactivity was considerably lower during pilot-scale FBC testing, as anticipated given the higher calcination temperatures employed in the FBC reactor and the presence of the other feed gases. The enhanced CO2 capture efficiency in FBC reactors with steam present was also confirmed by TGA tests. These results are important because they demonstrate how sorbent deactivation effects seen in realistic FBC calcium-looping operation can be successfully reduced by the presence of steam in the carbonator. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25948458

SO2 retention by CaO-based sorbent spent in CO2 looping cycles / Vasilije Manovic in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

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