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Adsorption/desorption studies of 224-trimethylpentane in β-Zeolite and mesoporous materials using a tapered element oscillating microbalance (TEOM) / Kening Gong in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9490–9497 Titre : Adsorption/desorption studies of 224-trimethylpentane in β-Zeolite and mesoporous materials using a tapered element oscillating microbalance (TEOM) Type de document : texte imprimé Auteurs : Kening Gong, Auteur ; Tiepan Shi, Auteur ; Palghat A. Ramachandran, Auteur Année de publication : 2010 Article en page(s) : pp. 9490–9497 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : 224-Trimethylpentane  β-Zeolite  Mesoporous  materials Résumé : The facile desorption of C8 and heavier products from solid acid alkylation catalysts is essential to thwart catalyst deactivation by fouling. To better understand this phenomenon, a tapered element oscillating microbalance (TEOM) was employed to investigate the adsorption/desorption characteristics of 224-trimethylpentane (224-TMP), a proxy C8 alkylate product, on β-zeolite and mesoporous materials (T = 298−473 K, P224-TMP = 0−0.3 bar). It is found that the 224-TMP desorption rates from saturated β-zeolite (by helium purging) are characterized by a rapid initial “burst” of 224-TMP followed by a rather long desorption phase. Complementary experimental and modeling investigations using pelletized β-zeolites of known sizes indicate that the adsorption rate and initial desorption (during the burst phase) rate of 224-TMP are controlled by meso-/macropore diffusion resistance external to the β-zeolite crystals and that the long transient could be due to pore diffusion resistance within the β-zeolite crystals. In contrast, mesoporous silica materials provide facile pore accessibility for large alkylate molecules such as 224-TMP, as evidenced by complete desorption of 224-TMP even at mild temperatures. These insights provide guidance for rational engineering of stable solid acid alkylation catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900334g [article] Adsorption/desorption studies of 224-trimethylpentane in β-Zeolite and mesoporous materials using a tapered element oscillating microbalance (TEOM) [texte imprimé] / Kening Gong, Auteur ; Tiepan Shi, Auteur ; Palghat A. Ramachandran, Auteur . - 2010 . - pp. 9490–9497. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9490–9497 Mots-clés : 224-Trimethylpentane  β-Zeolite  Mesoporous  materials Résumé : The facile desorption of C8 and heavier products from solid acid alkylation catalysts is essential to thwart catalyst deactivation by fouling. To better understand this phenomenon, a tapered element oscillating microbalance (TEOM) was employed to investigate the adsorption/desorption characteristics of 224-trimethylpentane (224-TMP), a proxy C8 alkylate product, on β-zeolite and mesoporous materials (T = 298−473 K, P224-TMP = 0−0.3 bar). It is found that the 224-TMP desorption rates from saturated β-zeolite (by helium purging) are characterized by a rapid initial “burst” of 224-TMP followed by a rather long desorption phase. Complementary experimental and modeling investigations using pelletized β-zeolites of known sizes indicate that the adsorption rate and initial desorption (during the burst phase) rate of 224-TMP are controlled by meso-/macropore diffusion resistance external to the β-zeolite crystals and that the long transient could be due to pore diffusion resistance within the β-zeolite crystals. In contrast, mesoporous silica materials provide facile pore accessibility for large alkylate molecules such as 224-TMP, as evidenced by complete desorption of 224-TMP even at mild temperatures. These insights provide guidance for rational engineering of stable solid acid alkylation catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900334g

Economic and environmental impact analyses of solid acid catalyzed isoparaffin/Olefin alkylation in supercritical carbon dioxide / Kening Gong in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9072–9080 Titre : Economic and environmental impact analyses of solid acid catalyzed isoparaffin/Olefin alkylation in supercritical carbon dioxide Type de document : texte imprimé Auteurs : Kening Gong, Auteur ; Steve Chafin, Auteur ; Kent Pennybaker, Auteur Année de publication : 2009 Article en page(s) : p. 9072–9080 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Economic  and  Environmental  Analyses  of  Solid  Acid  Catalyzed  Isoparaffin  Supercritical  Carbon  Dioxide Résumé : HYSYS-based process simulation was accomplished for a recently reported 1-butene + isobutane alkylation concept that employs SiO2-supported Nafion catalyst in dense CO2 media to obtain stable C8 alkylates production (solid acid/CO2 process). Semiquantitative economic and environmental impact assessments were conducted for this novel process design along with comparative assessments for a conventional sulfuric acid catalyzed alkylation process (at equivalent production capacities). The simulations are commercial scale and are based on available data and reasonable process assumptions. The total capital investment of the solid acid/CO2 process is approximately 20−30% higher than that of the sulfuric acid process. Sensitivity analysis shows that, if the olefin space velocity can be increased by a factor of 4 from the base-case value while maintaining the same C8 alkylate productivity, the total capital investments along with the utility and chemical costs would be nearly the same for both processes. The environmental impact assessment shows that the conventional sulfuric acid process has a 3.9 times higher adverse environmental impact potential than the solid acid/CO2 process. For the sulfuric acid process, the major contributors to the environmental impact are acid rain (66%) and inhalation toxicity (32%). The main pollution comes from the SO2 emissions during sulfuric acid regeneration (53%) and acid leakage in the alkylation unit (10%). For the solid acid/CO2 process, the major contributors to the environmental impact are inhalation toxicity (83%), global warming (10%), and acid rain (6%). For the solid acid/CO2 process, the main pollution sources are fugitive emissions. This evaluation illustrates the advantages and shortcomings of the novel process and provides rational research guidance. For example, the analyses established performance targets, such as catalyst activity and operating pressure, for the solid acid/CO2 process to be commercially viable. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800399s [article] Economic and environmental impact analyses of solid acid catalyzed isoparaffin/Olefin alkylation in supercritical carbon dioxide [texte imprimé] / Kening Gong, Auteur ; Steve Chafin, Auteur ; Kent Pennybaker, Auteur . - 2009 . - p. 9072–9080. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9072–9080 Mots-clés : Economic  and  Environmental  Analyses  of  Solid  Acid  Catalyzed  Isoparaffin  Supercritical  Carbon  Dioxide Résumé : HYSYS-based process simulation was accomplished for a recently reported 1-butene + isobutane alkylation concept that employs SiO2-supported Nafion catalyst in dense CO2 media to obtain stable C8 alkylates production (solid acid/CO2 process). Semiquantitative economic and environmental impact assessments were conducted for this novel process design along with comparative assessments for a conventional sulfuric acid catalyzed alkylation process (at equivalent production capacities). The simulations are commercial scale and are based on available data and reasonable process assumptions. The total capital investment of the solid acid/CO2 process is approximately 20−30% higher than that of the sulfuric acid process. Sensitivity analysis shows that, if the olefin space velocity can be increased by a factor of 4 from the base-case value while maintaining the same C8 alkylate productivity, the total capital investments along with the utility and chemical costs would be nearly the same for both processes. The environmental impact assessment shows that the conventional sulfuric acid process has a 3.9 times higher adverse environmental impact potential than the solid acid/CO2 process. For the sulfuric acid process, the major contributors to the environmental impact are acid rain (66%) and inhalation toxicity (32%). The main pollution comes from the SO2 emissions during sulfuric acid regeneration (53%) and acid leakage in the alkylation unit (10%). For the solid acid/CO2 process, the major contributors to the environmental impact are inhalation toxicity (83%), global warming (10%), and acid rain (6%). For the solid acid/CO2 process, the main pollution sources are fugitive emissions. This evaluation illustrates the advantages and shortcomings of the novel process and provides rational research guidance. For example, the analyses established performance targets, such as catalyst activity and operating pressure, for the solid acid/CO2 process to be commercially viable. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800399s