Insight into Phosphine Effects on the Homogeneous Hydrogenation of Avermectins to Ivermectin Catalyzed by In-Situ Formed Rhodium Complexes

A kinetic study of the homogeneous catalytic hydrogenation of avermectins is reported for a series of isosteric p-substituted arylphosphines as ligands. The activity of the rhodium complexes formed in situ from [RhCl(COD)]2 increased with increasing the electron-donor capacity of the P(p-XC6H4)3: P(p-ClC6H4)3 < P(C6H5)3 < P(p-CH3C6H4)3 < P(p-OCH3C6H4)3. As expected, this trend was also observed when using preformed complexes thereof. Linear correlations based on Hammett and Kabachnik treatments are provided as useful tools to guide the exploration work towards improved [RhCl(COD)]2/P(p-XC6H4)3 catalytic systems.Fil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Cabrera, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Grau, Ricardo José Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

A Comparison of Homogeneous and Biphasic Hydrogenation Systems of Macrocyclic Lacton with In Situ Formed Rhodium Complexes

Homogeneous and biphasic hydrogenation of avermectins catalyzed by rhodium complexes in situ formed from [RhCl(COD)]2 and triphenylphosphine or sulphonated arylphosphines, respectively, was studied under mild reaction conditions. Effects of adding TBAB and bis-QACs as phase transfer agents, Tween® 80 as non-ionic surfactant, β-cyclodextrin as inverse phase-transfer agent, and triphenylphosphine as co-ligand, are reported for the biphasic system.Fil: Cabrera, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Grau, Ricardo José Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Kinetics of the homogeneous hydrogenation of avermectins catalyzed by RhCl(Ph3P)3 complexes

The kinetics of the hydrogenation of avermectins B1a and B1b catalyzed by RhCl(Ph3P)3 complexes was studied in a temperature range of 298–328 K at 275.7 kN m2, using catalyst loading in the range of 0.75–7.25 wt.% with respect to the avermectins in toluene solution. The effects on the hydrogenation rate of the catalyst, avermectins, and hydrogen concentrations were determined under complete induction time suppression and without catalyst deactivation. Rate equations were developed for various kinetic schemes on the basis of the main steps suggested by Wilkinson for simple olefin hydrogenation and fitted to the experimental data. A statistical analysis of regression using three plausible mechanisms of reaction allows a discussion on the adequacy of the models to approach the observed half-order reaction with respect to the catalyst loading and first-order to avermectins and hydrogen concentrations. A reaction mechanism featuring non-extensive simple dissociation of the catalyst precursor and reaction pathway along the hydride route with the rate-determining olefin coordination step proved fair enough to describe the hydrogenation of this macrocyclic lactone. The physical reasonability of the equilibrium and kinetic parameters was also discussed.Fil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Cabrera, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Grau, Ricardo José Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Formation of different promoted metallic phases in PtFe and PtSn catalysts supported on carbonaceous materials used for selective hydrogenation

In this paper, a study on the selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols (UA) by using two series of PtSn and PtFe catalysts with different metallic loadings and supported on carbon nanotubes and carbon Vulcan is reported. The catalysts were prepared by conventional impregnation using the corresponding metallic precursors, H 2PtCl6, SnCl2, and FeCl3. Once reduced under hydrogen flow, the supported catalysts were characterized by temperature-programmed reduction (TPR), H2 chemisorption, test reactions of the metallic phase, and X-ray photoelectron spectroscopy (XPS). Hydrogenation results show that the addition of a second metal to Pt leads to important modification of the selectivity, although the highest selectivities to UA are reached with very different Fe or Sn loadings. The performance of the catalysts in the citral hydrogenation was related to the characteristics of the bimetallic phase. It was found that the Fe addition to Pt catalysts results in a typical behavior such as for an usual ionic promoter in contact with the active metal, reaching high selectivities to UA as the Fe loading and the Fe ionic species percentage increases, while for PtSn catalysts, a high selectivity to UA was found only with a very low amount of Sn ionic species in contact with a very high percentage of Sn reduced species. The best selectivity to UA (about 98%) was found for PtSn(1wt%)/CN-P catalyst treated with N2 at high temperature.Fil: Stassi, Julieta Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Scelza, Osvaldo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Bimetallic catalysts supported on novel spherical MgAl2O4-coated supports for dehydrogenation processes

Novel Pt and PtSn catalysts were developed from structured supports of α-Al2O3 spheres coated with MgAl2O4 by two methods: advanced Bohemite-nitrate with purification (BNAP) and citrate-nitrate with two layers (CN2). Both structured supports showed a thin porous layer of MgAl2O4 with a high specific surface area of around 130 m2 g−1. A stable and uniform MgAl2O4 layer on the spherical nuclei was achieved by both synthesized coating methods. Therefore, a good interaction with the metals which leads to high metallic dispersions was obtained. These catalysts were used in the production of butenes by n-butane dehydrogenation reaction. The bimetallic catalysts showed both high values of n-butane conversion (25–30 %) and selectivity to butenes (89–95 %). The PtSn catalyst supported on spheres coated by CN2 method displayed high values of yield to butenes (about 30%), which are higher than those of a catalyst used in the industry.Fil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Vilella, Irene María Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

New trimetallic catalysts supported on coprecipitated MgAl2O4 for n-paraffins selective dehydrogenation processes

Trimetallic PtSnIn and PtSnGa catalysts supported on coprecipitated MgAl2O4 display better behaviors in n-butane conversion, selectivity to butenes and deactivation due to coke formation, than bimetallic PtSn/MgAl2O4 catalysts, and much better than the mometallic catalyst. The addition of Sn and In to Pt produces mainly an important decrease of the metallic particle sizes and geometric modifications of the metallic phase, these facts being the cause for the excellent performance. For PtSnGa/MgAl2O4, not only geometric but also electronic effects on the metallic phase would be present.Fil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Scelza, Osvaldo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Synthesis of spherical structured catalysts by dip-coating: Application to n-butane dehydrogenation

This work analyzes the deposition conditions of thin layers of γ-Al2O3 by dip-coating on a spherical substrate of α-Al2O3 spheres. Results showed that under controlled deposition conditions, a structured support of α-Al2O3 spheres coated by a uniform γ-Al2O3 layer (thickness≈15μm) of good adherence can be attained. Optimal preparation conditions for the coating, that involved pretreatment of the substrate, gel formation, deposition conditions, and thermal treatments, were obtained. Pt catalysts supported on this structured material can be used as promising dehydrogenation systems. In this sense, a monometallic structured catalyst showed both good metallic dispersion and catalytic performance in n-butane dehydrogenation reaction compared to another conventional catalytic system.Fil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina. Universidad Nacional del Litoral; ArgentinaFil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina. Universidad Nacional del Litoral; Argentin

Design and applications of structured catalytic supports synthesized by coating in spherical geometry: a review

The methods used to synthesize structured catalytic supports by coating in spherical geometry are reviewed. The different procedures are influenced by the pretreatments of the substrate, the deposition technique of the layers, the coating materials, like Al2O3, MgAl2O4 or ZnAl2O4, and the final treatments to achieve coating layers with suitable conditions of thickness and resistance to cracking and peeling under the severe operating conditions of the process. These novel structured materials have commercial applications, mainly as supports of mono and bimetallic catalysts for the reaction of paraffin dehydrogenation reaction at high temperatures. In addition, other coating methods on spheres with applications in photocatalysis are included.Fil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

n-butane dehydrogenation on PtSnIn and PtSnGa trimetallic catalysts supported on structured materials prepared by washcoating

The aim of this work was to evaluate PtSnIn and PtSnGa catalysts supported on structured materials, composed of a thin layer of γ- Al2O3 deposited on compact spheres of α-Al2O3, in the non-oxidative dehydrogenation of n-butane to n-butene. The trimetallic catalysts supported on γ-A-wc showed better catalytic behaviour in terms of activity, selectivity to all butenes, and a low deactivation along the reaction time, compared to the monometallic catalyst. PtSnIn/γ-A-wc and PtSnGa/γ-A-wc catalysts with the highest In or Ga loading showed better performance than those with a lower content of promoters. The results of the pulse experiments clearly indicated the important effect of the promoters added to Pt, both by sharply increasing the selectivity to butenes and by decreasing the carbon formation during the first steps of the reaction. The characterization of the metallic phase showed that the addition of promoters such as Sn and In or Sn and Ga produce geometric effects, dilution and blocking effects on Pt atoms. XPS results confirmed the presence of surface metallic Pt(0), In(0) or Ga(III), Sn(II)/Sn(IV) species in a high concentration and minor amounts of surface Sn(0), probably forming alloy particles with Pt and the third metal. The PtSnIn (0.5)/γ-A-wc catalyst which showed the best catalytic behaviour in flow experiments was submitted to successive reaction-regeneration cycles in order to determine its catalytic stability. There was a small yield decrease in the first two cycles, but from the third cycle onwards the yields to butenes proved to be more stable. These results were very promising mainly if compared to those obtained for the monometallic Pt catalyst. Characterization results of the catalyst after cycles showed that the metallic phase did not undergo significant modifications.Fil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Stability studies of PtSn structured catalysts supported on thin layers of MAl2O4 (M: Mg or Zn) for paraffins dehydrogenation reactions

In order to determine the catalytic stability, PtSn structured catalysts supported on thin films of MgAl2O4 or ZnAl2O4 deposited on α-Al2O3 spheres were studied through five reaction-regeneration cycles in the n-butane dehydrogenation. Bimetallic catalysts show good catalytic stability along the five reaction-regeneration cycles. Among the different synthesized catalysts, the PtSn/Sp-Zn-CN catalyst showed the best catalytic behaviour, showing very good values of yields to butenes and excellent catalytic stability along the cycles, even better than the one of a structured commercial catalyst used industrially for the dehydrogenation of paraffins. The characterization results by temperature-programmed reduction and X-ray photoelectron spectroscopy showed some modifications in the metallic phase of the catalysts after the cycles, mainly in the Sn/Pt surface ratios and in segregation effects in some catalysts. However, the transmission electron microscopy (TEM) results are conclusive in the sense that, after the cycles, the bimetallic catalysts maintained a very high proportion of particles with sizes between 1–2 nm, and therefore, preserved a high metallic dispersion.Fil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Zgolicz, Patricia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin