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Methanol conversion to dimethyl ether over H-SAPO-34 catalyst / Grigore Pop in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7065–7071 Titre : Methanol conversion to dimethyl ether over H-SAPO-34 catalyst Type de document : texte imprimé Auteurs : Grigore Pop, Auteur ; Grigore Bozga, Auteur ; Rodica Lipsa, Auteur Année de publication : 2009 Article en page(s) : pp. 7065–7071 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methanol  conversion  Dimethyl  ether  H-SAPO-34  molecular  sieve  Catalyst Résumé : The process of methanol conversion to dimethyl ether over an H-SAPO-34 molecular sieve was studied, using the catalyst as synthesized or formulated in an alumina matrix. The experiments were performed on the temperature interval 100−250 °C, liquid space velocities of 1−5 h−1, and pressures between 1 and 10 bar. The results evidenced a high catalytic activity of the H-SAPO-34 molecular sieve, providing in these conditions a practically total methanol transformation to dimethyl ether. Also, a special run, performed at 180 °C, with an output composition close to chemical equilibrium, showed no significant change of catalyst activity during an on-stream time of 50 h, this proving a good stability and resistance to deactivation. A published rate expression for the methanol dehydration reaction was selected and adapted to describe the experimentally observed process kinetics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900532y [article] Methanol conversion to dimethyl ether over H-SAPO-34 catalyst [texte imprimé] / Grigore Pop, Auteur ; Grigore Bozga, Auteur ; Rodica Lipsa, Auteur . - 2009 . - pp. 7065–7071. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7065–7071 Mots-clés : Methanol  conversion  Dimethyl  ether  H-SAPO-34  molecular  sieve  Catalyst Résumé : The process of methanol conversion to dimethyl ether over an H-SAPO-34 molecular sieve was studied, using the catalyst as synthesized or formulated in an alumina matrix. The experiments were performed on the temperature interval 100−250 °C, liquid space velocities of 1−5 h−1, and pressures between 1 and 10 bar. The results evidenced a high catalytic activity of the H-SAPO-34 molecular sieve, providing in these conditions a practically total methanol transformation to dimethyl ether. Also, a special run, performed at 180 °C, with an output composition close to chemical equilibrium, showed no significant change of catalyst activity during an on-stream time of 50 h, this proving a good stability and resistance to deactivation. A published rate expression for the methanol dehydration reaction was selected and adapted to describe the experimentally observed process kinetics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900532y

Thermal degradation of carboxymethyl starch–g-poly(lactic acid) copolymer by TG–FTIR–MS analysis / Nita Tudorachi in Industrial & engineering chemistry research, Vol. 51 N° 48 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 48 (Décembre 2012) . - pp. 15537–15545 Titre : Thermal degradation of carboxymethyl starch–g-poly(lactic acid) copolymer by TG–FTIR–MS analysis Type de document : texte imprimé Auteurs : Nita Tudorachi, Auteur ; Rodica Lipsa, Auteur ; Fanica R. Mustata, Auteur Année de publication : 2013 Article en page(s) : pp. 15537–15545 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Carboxymethyl  starch Résumé : In this study, carboxymethyl starch (CMS) was grafted with l(+)-lactic acid (LA) in a CMS/LA molar ratio of 1/36, resulting in the CMS–g-PLA copolymer. The grafting reaction was carried out via a solution polycondensation procedure, in the presence of stannous 2-ethyl hexanoate [Sn(Oct)2] as a catalyst. Poly(lactic acid) (PLA) was synthesized under the same conditions with the copolymer, for comparative analyses of the thermal properties. The CMS–g-PLA copolymer, CMS, and PLA were structurally characterized by Fourier transform infrared (FTIR) spectroscopy, while thermal degradation products were characterized by thermogravimetry analysis coupled with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS). The thermal degradation was achieved in a nitrogen atmosphere, in a temperature interval of 30–600 °C. The thermal degradation of CMS and PLA was studied under the same conditions to highlight the products resulted by the thermal decomposition of CMS–g-PLA copolymer. By processing the achieved data via thermal degradation at three different heating speeds (5, 7.5, and 10 °C min–1) and using the multivariate nonlinear regression method (MNLR), the kinetic parameters were determined. The dependence of the activation energy of the degradation process versus the extent of conversion was evaluated using the Friedman and Ozawa–Flynn–Wall model-free analyses. This variation suggests that the degradation process is a complex one and can be divided in one or two steps, depending on the chemical structure of the compounds. The kinetic parameters and the most probable thermal degradation mechanisms were given. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300625c [article] Thermal degradation of carboxymethyl starch–g-poly(lactic acid) copolymer by TG–FTIR–MS analysis [texte imprimé] / Nita Tudorachi, Auteur ; Rodica Lipsa, Auteur ; Fanica R. Mustata, Auteur . - 2013 . - pp. 15537–15545. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 48 (Décembre 2012) . - pp. 15537–15545 Mots-clés : Carboxymethyl  starch Résumé : In this study, carboxymethyl starch (CMS) was grafted with l(+)-lactic acid (LA) in a CMS/LA molar ratio of 1/36, resulting in the CMS–g-PLA copolymer. The grafting reaction was carried out via a solution polycondensation procedure, in the presence of stannous 2-ethyl hexanoate [Sn(Oct)2] as a catalyst. Poly(lactic acid) (PLA) was synthesized under the same conditions with the copolymer, for comparative analyses of the thermal properties. The CMS–g-PLA copolymer, CMS, and PLA were structurally characterized by Fourier transform infrared (FTIR) spectroscopy, while thermal degradation products were characterized by thermogravimetry analysis coupled with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS). The thermal degradation was achieved in a nitrogen atmosphere, in a temperature interval of 30–600 °C. The thermal degradation of CMS and PLA was studied under the same conditions to highlight the products resulted by the thermal decomposition of CMS–g-PLA copolymer. By processing the achieved data via thermal degradation at three different heating speeds (5, 7.5, and 10 °C min–1) and using the multivariate nonlinear regression method (MNLR), the kinetic parameters were determined. The dependence of the activation energy of the degradation process versus the extent of conversion was evaluated using the Friedman and Ozawa–Flynn–Wall model-free analyses. This variation suggests that the degradation process is a complex one and can be divided in one or two steps, depending on the chemical structure of the compounds. The kinetic parameters and the most probable thermal degradation mechanisms were given. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300625c