Documents disponibles écrits par cet auteur

Activation of waste tire char upon cyclic oxygen chemisorption-desorption / Francisco Heras in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4664–4670 Titre : Activation of waste tire char upon cyclic oxygen chemisorption-desorption Type de document : texte imprimé Auteurs : Francisco Heras, Auteur ; Noelia Alasino, Auteur ; Miguel A. Gilarranz, Auteur Année de publication : 2009 Article en page(s) : pp. 4664–4670 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Waste  tire  char  Chemisorption−desorption  BET  surface Résumé : Activation of waste tire char upon cyclic oxygen chemisorption−desorption permits a controlled development of porosity versus burnoff using air as feed gas for the activation process. A slow but monotonical increase of BET surface area is obtained from cycle to cycle. Initially the process led to the development of mesoporosity without generating micropores and then the micropore volume is increased whereas a decrease of narrow mesopore (20−80 nm) volume is observed, probably as a consequence of mesopore widening. Although the SBET reaches relatively low values (below 250 m2/g) even after 15 cycles, this surface development is associated with low burnoff values (around 22% for indicated BET surface area) and corresponds in an important percentage (up to about 50%) to external (nonmicropore) area. Temperatures around 210 and 550 °C for chemisorption and desorption, respectively, have been found as optimum for the purpose of preparing granular mesoporous carbons which can be interesting candidates as catalytic supports for liquid phase applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801764x [article] Activation of waste tire char upon cyclic oxygen chemisorption-desorption [texte imprimé] / Francisco Heras, Auteur ; Noelia Alasino, Auteur ; Miguel A. Gilarranz, Auteur . - 2009 . - pp. 4664–4670. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4664–4670 Mots-clés : Waste  tire  char  Chemisorption−desorption  BET  surface Résumé : Activation of waste tire char upon cyclic oxygen chemisorption−desorption permits a controlled development of porosity versus burnoff using air as feed gas for the activation process. A slow but monotonical increase of BET surface area is obtained from cycle to cycle. Initially the process led to the development of mesoporosity without generating micropores and then the micropore volume is increased whereas a decrease of narrow mesopore (20−80 nm) volume is observed, probably as a consequence of mesopore widening. Although the SBET reaches relatively low values (below 250 m2/g) even after 15 cycles, this surface development is associated with low burnoff values (around 22% for indicated BET surface area) and corresponds in an important percentage (up to about 50%) to external (nonmicropore) area. Temperatures around 210 and 550 °C for chemisorption and desorption, respectively, have been found as optimum for the purpose of preparing granular mesoporous carbons which can be interesting candidates as catalytic supports for liquid phase applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801764x

Catalytic hydrotreatment of crude waxes from different sources over a Ni-W/-Al2O3 catalyst / Jesús Sánchez in Industrial & engineering chemistry research, Vol. 47 N°18 (Septembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 6854–6861 Titre : Catalytic hydrotreatment of crude waxes from different sources over a Ni-W/-Al2O3 catalyst Type de document : texte imprimé Auteurs : Jesús Sánchez, Auteur ; María Fernanda Tallafigo, Auteur ; Miguel A. Gilarranz, Auteur Année de publication : 2008 Article en page(s) : p. 6854–6861 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crude  wax  Alumina-supported  catalyst  Spindle  feedstock Résumé : The hydrotreatment of crude wax from the dewaxing of spindle, light neutral, medium neutral, heavy neutral, and brightstock oil was studied to obtain refined paraffins that are suitable for high-grade applications. The runs were performed using an alumina-supported catalyst with 5.9 wt % of nickel (as NiO) and 16.2 wt % of tungsten (as WO3) that was used for >6000 h. The ease of treatment was ranked as follows: spindle > light neutral > medium neutral > heavy neutral ≫ brightstock. The use of high temperatures and pressures was needed to obtain a convenient reduction in the color of the heavier feedstocks. Spindle feedstock required a temperature of 548 K and a pressure of 9.81 MPa, whereas 623 K and 13.7 MPa were needed for heavy neutral feedstock to obtain refined paraffins with a Saybolt color of >+30. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800014u [article] Catalytic hydrotreatment of crude waxes from different sources over a Ni-W/-Al2O3 catalyst [texte imprimé] / Jesús Sánchez, Auteur ; María Fernanda Tallafigo, Auteur ; Miguel A. Gilarranz, Auteur . - 2008 . - p. 6854–6861. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 6854–6861 Mots-clés : Crude  wax  Alumina-supported  catalyst  Spindle  feedstock Résumé : The hydrotreatment of crude wax from the dewaxing of spindle, light neutral, medium neutral, heavy neutral, and brightstock oil was studied to obtain refined paraffins that are suitable for high-grade applications. The runs were performed using an alumina-supported catalyst with 5.9 wt % of nickel (as NiO) and 16.2 wt % of tungsten (as WO3) that was used for >6000 h. The ease of treatment was ranked as follows: spindle > light neutral > medium neutral > heavy neutral ≫ brightstock. The use of high temperatures and pressures was needed to obtain a convenient reduction in the color of the heavier feedstocks. Spindle feedstock required a temperature of 548 K and a pressure of 9.81 MPa, whereas 623 K and 13.7 MPa were needed for heavy neutral feedstock to obtain refined paraffins with a Saybolt color of >+30. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800014u

Denitrification of water with activated carbon-supported metallic catalysts / Luisa Calvo in Industrial & engineering chemistry research, Vol. 49 N° 12 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5603–5609 Titre : Denitrification of water with activated carbon-supported metallic catalysts Type de document : texte imprimé Auteurs : Luisa Calvo, Auteur ; Miguel A. Gilarranz, Auteur ; José A. Casas, Auteur Année de publication : 2010 Article en page(s) : pp. 5603–5609 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nitrates  Catalytic  reduction  Trickle  bed  reactor Résumé : The catalytic reduction of nitrates with hydrogen in aqueous phase was studied in a trickle bed reactor using different activated carbon-supported metallic catalysts. Continuous experiments were performed at ambient conditions (25 °C and 1 atm) at different space-time values in the range of 25.8−103.3 kgcat h/mol. The activity of monometallic catalysts based on Pd, Rh, Cu, and Ni was low in all the cases, yielding nitrate conversions below 15%. The introduction of a second metal produced a synergistic effect, improving the catalytic activity and the selectivity toward N2. That increase in activity was more pronounced when using Pd or Rh combined with Cu, reaching nitrate conversions above 80% in the case of Pd−Cu catalysts. The catalyst with a Pd/Cu mass ratio of 2:1 (Pd050Cu025) also showed the lowest selectivity to nitrite and the highest to N2. Metal leaching was always below detection limits for Pd and Rh, whereas in the case of Cu and Ni, significant metal concentrations were found in the reaction effluent, the leaching of Ni being higher. The initial pH significantly affected both activity and selectivity of the bimetallic catalysts, the maximum activity being achieved within the 6−7 range, which also led to the lowest Cu leaching. The use of a two-step reaction system was checked using two different catalysts, a bimetallic Pd−Cu in the first and a monometallic Pd catalyst in the second. With this two-step system, an important reduction of the nitrite originating in the first stage was observed, and the formation of N2 at the expense of ammonium was favored. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100838r [article] Denitrification of water with activated carbon-supported metallic catalysts [texte imprimé] / Luisa Calvo, Auteur ; Miguel A. Gilarranz, Auteur ; José A. Casas, Auteur . - 2010 . - pp. 5603–5609. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5603–5609 Mots-clés : Nitrates  Catalytic  reduction  Trickle  bed  reactor Résumé : The catalytic reduction of nitrates with hydrogen in aqueous phase was studied in a trickle bed reactor using different activated carbon-supported metallic catalysts. Continuous experiments were performed at ambient conditions (25 °C and 1 atm) at different space-time values in the range of 25.8−103.3 kgcat h/mol. The activity of monometallic catalysts based on Pd, Rh, Cu, and Ni was low in all the cases, yielding nitrate conversions below 15%. The introduction of a second metal produced a synergistic effect, improving the catalytic activity and the selectivity toward N2. That increase in activity was more pronounced when using Pd or Rh combined with Cu, reaching nitrate conversions above 80% in the case of Pd−Cu catalysts. The catalyst with a Pd/Cu mass ratio of 2:1 (Pd050Cu025) also showed the lowest selectivity to nitrite and the highest to N2. Metal leaching was always below detection limits for Pd and Rh, whereas in the case of Cu and Ni, significant metal concentrations were found in the reaction effluent, the leaching of Ni being higher. The initial pH significantly affected both activity and selectivity of the bimetallic catalysts, the maximum activity being achieved within the 6−7 range, which also led to the lowest Cu leaching. The use of a two-step reaction system was checked using two different catalysts, a bimetallic Pd−Cu in the first and a monometallic Pd catalyst in the second. With this two-step system, an important reduction of the nitrite originating in the first stage was observed, and the formation of N2 at the expense of ammonium was favored. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100838r