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Thermal degradation of aqueous piperazine for CO2 capture. 1. effect of process conditions and comparison of thermal stability of CO2 capture amines / Stephanie Anne Freeman in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7719–7725 Titre : Thermal degradation of aqueous piperazine for CO2 capture. 1. effect of process conditions and comparison of thermal stability of CO2 capture amines Type de document : texte imprimé Auteurs : Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur Année de publication : 2012 Article en page(s) : pp. 7719–7725 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermal  degradation  Aqueous  piperazine  Thermal  stability Résumé : The effect of process conditions on the rate of thermal degradation of concentrated, aqueous piperazine (PZ) was investigated. At 150 °C, 8 m (m) PZ degrades with a first order rate constant, k1, of 6.1 × 10–9 s–1. Thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity demonstrated an Arrhenius dependence on temperature with an activation energy of 184 kJ/mol. Degradation at 175 °C was negligible with no dissolved CO2, while the k1 increased from 65 to 71 × 10–9 s–1 at 0.1 to 0.4 mol CO2/mol alkalinity and decreased to 24 × 10–9 s–1 at 0.47 mol CO2/mol alkalinity. In an industrial system with a simple stripper, losses due to thermal degradation are expected to be 0.043 mmol PZ/mol CO2 captured. In the case of a 2-stage flash, losses are expected to be only 0.0086 mmol PZ/mol CO2 captured. A Maximum Estimated Stripper Temperature (MEST) was calculated for a variety of amines to provide the same thermal degradation rate of MEA at 120 °C based on first order rate constants for amine loss during thermal degradation and the expected Arrhenius dependence on temperature for all amines. Substituted and unsubstituted 6-member amine rings were found to be the most thermally stable. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201916x [article] Thermal degradation of aqueous piperazine for CO2 capture. 1. effect of process conditions and comparison of thermal stability of CO2 capture amines [texte imprimé] / Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur . - 2012 . - pp. 7719–7725. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7719–7725 Mots-clés : Thermal  degradation  Aqueous  piperazine  Thermal  stability Résumé : The effect of process conditions on the rate of thermal degradation of concentrated, aqueous piperazine (PZ) was investigated. At 150 °C, 8 m (m) PZ degrades with a first order rate constant, k1, of 6.1 × 10–9 s–1. Thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity demonstrated an Arrhenius dependence on temperature with an activation energy of 184 kJ/mol. Degradation at 175 °C was negligible with no dissolved CO2, while the k1 increased from 65 to 71 × 10–9 s–1 at 0.1 to 0.4 mol CO2/mol alkalinity and decreased to 24 × 10–9 s–1 at 0.47 mol CO2/mol alkalinity. In an industrial system with a simple stripper, losses due to thermal degradation are expected to be 0.043 mmol PZ/mol CO2 captured. In the case of a 2-stage flash, losses are expected to be only 0.0086 mmol PZ/mol CO2 captured. A Maximum Estimated Stripper Temperature (MEST) was calculated for a variety of amines to provide the same thermal degradation rate of MEA at 120 °C based on first order rate constants for amine loss during thermal degradation and the expected Arrhenius dependence on temperature for all amines. Substituted and unsubstituted 6-member amine rings were found to be the most thermally stable. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201916x

Thermal degradation of aqueous piperazine for CO2 capture / Stephanie Anne Freeman in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7726–7735 Titre : Thermal degradation of aqueous piperazine for CO2 capture : 2. Product types and generation rates Type de document : texte imprimé Auteurs : Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur Année de publication : 2012 Article en page(s) : pp. 7726–7735 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermal  degradation  Aqueous  piperazine Résumé : The generation of degradation products at 135 to 175 °C was investigated for concentrated, aqueous piperazine (PZ) loaded with CO2. From 135 to 175 °C, N-formylpiperazine, ammonium, N-(2-aminoethyl)piperazine, and 2-imidazolidone were found to be the most abundant products. These species accounted for 63% of nitrogen and 49% of carbon lost as PZ and CO2 during degradation. Thermal degradation of PZ is believed to be initiated by the nucleophilic attack of PZ at the α-carbon to a protonated amino function on H+PZ to create a ring opened PZ structure. H+PZ was found to be the active and likely initiating species required for the initial reactions of thermal degradation. Further SN2 substitution reactions can produce a variety of products. CO2 is not required for thermal degradation to proceed but is reduced to create formate or formyl amides, reacts with amines to form stable ureas, and dictates the overall product mix. The mechanism for CO2 reduction to formate or formyl amides is not clear but indicates the severity of thermal degradation conditions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201917c [article] Thermal degradation of aqueous piperazine for CO2 capture : 2. Product types and generation rates [texte imprimé] / Stephanie Anne Freeman, Auteur ; Gary Thomas Rochelle, Auteur . - 2012 . - pp. 7726–7735. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7726–7735 Mots-clés : Thermal  degradation  Aqueous  piperazine Résumé : The generation of degradation products at 135 to 175 °C was investigated for concentrated, aqueous piperazine (PZ) loaded with CO2. From 135 to 175 °C, N-formylpiperazine, ammonium, N-(2-aminoethyl)piperazine, and 2-imidazolidone were found to be the most abundant products. These species accounted for 63% of nitrogen and 49% of carbon lost as PZ and CO2 during degradation. Thermal degradation of PZ is believed to be initiated by the nucleophilic attack of PZ at the α-carbon to a protonated amino function on H+PZ to create a ring opened PZ structure. H+PZ was found to be the active and likely initiating species required for the initial reactions of thermal degradation. Further SN2 substitution reactions can produce a variety of products. CO2 is not required for thermal degradation to proceed but is reduced to create formate or formyl amides, reacts with amines to form stable ureas, and dictates the overall product mix. The mechanism for CO2 reduction to formate or formyl amides is not clear but indicates the severity of thermal degradation conditions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201917c