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Kinetics of oxidative decarboxylation of 3,4-methylenedioxymandelic acid to piperonal with dilute nitric acid / Hongjuan Xi in Industrial & engineering chemistry research, Vol. 48 N° 23 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10425–10430 Titre : Kinetics of oxidative decarboxylation of 3,4-methylenedioxymandelic acid to piperonal with dilute nitric acid Type de document : texte imprimé Auteurs : Hongjuan Xi, Auteur ; Zhixian Gao, Auteur ; Jianguo Wang, Auteur Année de publication : 2010 Article en page(s) : pp. 10425–10430 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Kinetics--Oxidative--Decarboxylation--3,4-Methylenedioxymandelic--Acid--Piperonal--Dilute  Nitric Résumé : The oxidative decarboxylation of 3,4-methylenedioxymandelic acid (DMA) to piperonal with dilute nitric acid was investigated. This reaction was initiated by NaNO2 and catalyzed by H2SO4, but the autocatalytic behavior, which was noted in most nitric acid oxidation reactions, was not observed. Detailed kinetic study showed that the respective reaction orders of NaNO2, H2SO4, HNO3, and DMA were 0.5, 0.5, 1.2, and 1.8, and the activation energy was 59.65 kJ/mol. The gained reaction rate equation provided a good model for the reaction under other temperatures and even the condition of a slightly higher concentration of nitric acid. Additional experimental data suggested that HNO2 was the reactive species. On the basis of the results, a possible reaction mechanism was proposed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900961r [article] Kinetics of oxidative decarboxylation of 3,4-methylenedioxymandelic acid to piperonal with dilute nitric acid [texte imprimé] / Hongjuan Xi, Auteur ; Zhixian Gao, Auteur ; Jianguo Wang, Auteur . - 2010 . - pp. 10425–10430. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10425–10430 Mots-clés : Kinetics--Oxidative--Decarboxylation--3,4-Methylenedioxymandelic--Acid--Piperonal--Dilute  Nitric Résumé : The oxidative decarboxylation of 3,4-methylenedioxymandelic acid (DMA) to piperonal with dilute nitric acid was investigated. This reaction was initiated by NaNO2 and catalyzed by H2SO4, but the autocatalytic behavior, which was noted in most nitric acid oxidation reactions, was not observed. Detailed kinetic study showed that the respective reaction orders of NaNO2, H2SO4, HNO3, and DMA were 0.5, 0.5, 1.2, and 1.8, and the activation energy was 59.65 kJ/mol. The gained reaction rate equation provided a good model for the reaction under other temperatures and even the condition of a slightly higher concentration of nitric acid. Additional experimental data suggested that HNO2 was the reactive species. On the basis of the results, a possible reaction mechanism was proposed. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900961r

Methanol to olefin over ca-modified HZSM-5 zeolites / Suhong Zhang in Industrial & engineering chemistry research, Vol. 49 N° 5 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2103–2106 Titre : Methanol to olefin over ca-modified HZSM-5 zeolites Type de document : texte imprimé Auteurs : Suhong Zhang, Auteur ; Bianling Zhang, Auteur ; Zhixian Gao, Auteur Année de publication : 2010 Article en page(s) : pp. 2103–2106 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Methanol  of  Olefin;  Zeolites  HZSM-5 Résumé : A series of HZSM-5 zeolites modified with various Ca loadings were prepared by an incipient impregnation technique and characterized by Fourier transform infrared spectra of adsorbed pyridine and temperature-programmed desorption of NH3 and CO2. Methanol to olefin (MTO) over Ca-modified HZSM-5 zeolites was performed in a flow-type fixed bed reactor. The results indicated that Ca modification increased both the catalytic stability and the light olefin selectivity. However, an excess Ca loading resulted in an inferior catalytic performance. Hence, there was an optimal Ca loading for a specific HZSM-5, and the thus prepared Ca/HZSM-5 had little free Brönsted acid sites and presented the best catalytic performance of MTO. A possible mechanism for MTO involving acid−base centers on Ca-modified HZSM-5 zeolites has been suggested on the basis of the results obtained. Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901446m [article] Methanol to olefin over ca-modified HZSM-5 zeolites [texte imprimé] / Suhong Zhang, Auteur ; Bianling Zhang, Auteur ; Zhixian Gao, Auteur . - 2010 . - pp. 2103–2106. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2103–2106 Mots-clés : Methanol  of  Olefin;  Zeolites  HZSM-5 Résumé : A series of HZSM-5 zeolites modified with various Ca loadings were prepared by an incipient impregnation technique and characterized by Fourier transform infrared spectra of adsorbed pyridine and temperature-programmed desorption of NH3 and CO2. Methanol to olefin (MTO) over Ca-modified HZSM-5 zeolites was performed in a flow-type fixed bed reactor. The results indicated that Ca modification increased both the catalytic stability and the light olefin selectivity. However, an excess Ca loading resulted in an inferior catalytic performance. Hence, there was an optimal Ca loading for a specific HZSM-5, and the thus prepared Ca/HZSM-5 had little free Brönsted acid sites and presented the best catalytic performance of MTO. A possible mechanism for MTO involving acid−base centers on Ca-modified HZSM-5 zeolites has been suggested on the basis of the results obtained. Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901446m