Preparation by the method of catalytic reduction of catalysts Pt-Re-Ge/Al2o3 and Pt-Re-Sn/Al2O3 the naphtha reforming. Characterization and regeneration

En catalizadores PtReGe/Al2O3 y PtReSn/Al2O3 el tercer metal se depositó empleando distintas técnicas, en reducción catalítica (RC) se varió el medio de impregnación y el porcentaje del tercer metal. La función metálica se evaluó por TPR, FTIR-CO, quimisorción de CO y de H2, deshidrogenación de ciclohexano e hidrogenólisis de ciclopentano. La función ácida se estudió mediante TPD de piridina, isomerización de 3, 3-dimetil-1-buteno, FTIR-piridina e isomerización de n-pentano. Ambas funciones se evaluaron mediante reformado de n-heptano a 5 atm y a presión atmosférica. El coque depositado se determinó por TPO. El aumento del pH de la solución de impregnación favorece la deposición de Ge o Sn. La interacción entre Ge o Sn y la fase activa (Pt-Re) depende del medio de impregnación. La adición de Ge o Sn por RC disminuye la actividad hidrogenolítica y deshidrogenante, la acidez Brønsted y en consecuencia la acidez total. La acidez Lewis no es modificada. La disminución de la acidez producida por el Sn es más marcada que el del Ge debido a su carácter básico. El Ge posee mayor interacción con la fase activa (Pt-Re) que el Sn. El agregado de Ge o Sn independientemente del método usado aumenta la estabilidad de los catalizadores. Se estudió la desactivación y regeneración variando el flujo (oxígeno y ozono) y el tiempo sobre los catalizadores preparados por RC de mejor performance. El quemado de coque es no selectivo y ocurre segregación del metal no activo de la fase metálica, siendo mayor cuando se regenera con oxigeno.In catalysts PtReGe/Al2O3 and PtReSn/Al2O3 the third metal was deposited employing different methods, in catalytic reduction (RC) there was changed the impregnation media and the percentage of the third metal. The metallic function was evaluated by TPR, FTIR-CO, chemisorption of CO and of H2, cyclohexane dehydrogenation and cyclopentane hydrogenolysis. The acid function studied by means of TPD, isomerization of 3, 3-dimethyl-1-butene, FTIR-pyridine and isomerization of n-pentane. Both functions were evaluated by means of n-heptane reforming to 5 atm and to atmospheric pressure. The deposited coke was characterized TPO. The increase of the pH of the solution of impregnation favors the deposition of Ge or Sn. Interaction between Ge or Sn and the active phase (Pt-Re) depends of the impregnation media. The addition of Ge or Sn for RC diminishes the hydrogenolytic and dehydrogenating activity, the Brønsted acidity and in consequence the total acidity. The acidity Lewis is not modified. The decrease of the acidity produced by the Sn is more marked that of the Ge due to his basic character. The Ge possesses major interaction with the active phase (Pt-Re) that the Sn. The addition of Ge and Sn regardless of the method used increases the stability of the catalysts. The deactivation and regeneration were studied changing the flow (O2 and O3) and the time on the catalysts prepared by RC of better performance. The burning of coke is not selective and occurs segregation of non active metal of the metallic phase, being higher when it regenerates with O2.Consejo Nacional de Investigaciones Científicas y TécnicasAgencia Nacional de Promoción Científica y Tecnológic

Optimal Ir/Pt ratio for the ring opening of decalin in zeolite supported catalysts

The aim of this study was to study the ring opening of decalin at 300 and 350 °C using Pt-Ir/HY zeolite catalysts. Monometallic Ir(x = 1.0, 1.5%wt) and Pt(y = 1.0, 1.5%wt) and bimetallic Ir(1.0)Pt(y = 0.5, 1.0, 1.5%wt), Ir(1.5)Pt(y = 0.5, 1.0, 1.5%wt) catalysts were prepared and catalytically tested. Catalysts were characterized by TPR, pyridine TPD, CO-FTIR, cyclohexane dehydrogenation and cyclopentane hydrogenolysis activity. It was found that the acidic character of Ir oxides species increased the amount of strong acid sites of the support. On the other hand, the Pt content increase favored the formation of medium strength acid sites. The catalysts with higher content of Ir had the higher hydrogenolytic activity, while an increase in the Pt content decreased the hydrogenolytic activity. The presence of Pt promoted the dehydrogenation of cyclohexane. Higher yields of dehydrogenated products and increased conversion of cis-decalin were observed at the highest temperature level. It seems that catalysts Ir(1.0)Pt(1.0) at 350 °C and Ir(1.5)Pt(1.5) at 300 °C, which showed a good performance, have an adequate balance between metal and acid functions that favors the opening of naphthenic rings.Fil: D'ippolito, Silvana Andrea. 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: Gutierrez, Laura Beatriz. 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: Pieck, Carlos Ariel. 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

Influence of Support Acidity and Ir Content on the Selective Ring Opening of Decalin over Ir/SiO 2 –Al 2 O 3

The influence of the addition of HCl and Ir (1 wt %) to different SiO2−Al2O3 supports of varying silica content was studied in the reaction of selective ring opening of decalin. The addition of HCl to silica−alumina supports containing 70 and 80 wt % SiO2 was found to have little influence in the distribution of reaction products compared to the calcined supports. The incorporation of Ir to the silica−alumina catalysts has a beneficial effect, increasing the decalin conversion, being this effect more noticeable in the low acidity supports, i.e., those containing 30−40 wt % SiO2. The iridium-containing materials display the highest yield of cracking products, ring opening products, and ring contraction products. Increasing the reaction temperature promotes cracking and dehydrogenation but markedly decreases the selectivity to ring contraction products. At 350 °C a slight decrease in selectivity to ring opening products occurs, though the overall increase in conversion results in an increased yield of these products. An optimum ratio between the acid sites and metal activity that favors the formation of ring opening products was found. At lower acid sites/metal activity ratios the isomerization reaction which leads to C5 cycle isomers is low, and ring opening by hydrogenolysis is limited as a consequence. On the other hand, at high acid sites/metal activity ratios the cracking reactions are favored, decreasing the yield of RO products.Fil: D'ippolito, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Pieck, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Selective ring opening of methylcyclohexane and decalin over Rh-Pd supported catalysts: Effect of the preparation method

Bimetallic Rh-Pd catalysts prepared by various impregnation methods were evaluated in the selective ring-opening of decalin and methylcyclohexane (MCH) used as model molecules of hydrogenated aromatics of the Light Cycle Oil fraction. Rh and Pt were deposited on Al2O3 and SiO2-Al2O3 (S40) by coimpregnation (CI) or successive impregnations (SI) with different orders of metal addition. Catalysts were characterized by H2 chemisorption, temperature programmed reduction, temperature-programmed desorption of pyridine, and test reactions of cyclopentane hydrogenolysis and isomerization of 3,3-dimethyl-1-butene. Their catalytic behaviors for the ring-opening reaction were deeply influenced by the acidity of the support, and in a lesser extent by the metal deposition method. On both supports, the CI catalysts, displaying the highest dispersion values, exhibited the best ring opening performances. In the case of the SI catalysts, the addition order of both metals modified in a moderate way the properties of the catalyst. The yield to ring opening products obtained in MCH ring opening with CI catalysts supported on Al2O3 was 39-69% higher than those prepared by SI (conversion = 55-60%) while for the catalysts supported on S40, the yield to ring opening products was 8-48% higher for the CI catalysts compared to SI catalysts (conversion = 72-77%). The conversion of decalin for the bimetallic catalysts supported on Al2O3 was lower than 20% being dehydrogenated compounds the main reaction products regardless the preparation method. The catalyst supported on S40 showed decalin conversion values between 46-53% and yield to ring opening near to 30%. Moreover, the CI catalysts have yield to ring opening 10 to 20% higher than the catalysts prepared by SI. The catalyst prepared by coimpregnation supported on S40 was the most appropriate for opening the MCH and decalin due to an optimal balance between the metal and acid functions.Fil: D'ippolito, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Especel, Catherine. Université de Poitiers; FranciaFil: Epron, Florence. Université de Poitiers; FranciaFil: Pieck, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Selective ring opening of decalin on Rh-Pd/SiO2-Al2O3 bifunctional systems: Catalytic performance and deactivation

International audienceRing opening of decalin was studied using Rh-Pd(x) catalysts supported on SiO2-Al2O3, prepared by coimpregnation with a variable total metallic content (x = 1, 1.5 and 2 wt%) while maintaining constant the Rh/Pd atomic ratio (equal to 1). The catalytic performances of these bimetallic systems were compared to those of monometallic Pd and Rh (1 wt%) catalysts. Bimetallic Rh-Pd(x) catalysts were unable to achieve decalin conversion and ring opening selectivity as high as those obtained using the Rh catalyst (~71 and ~67%, respectively, after 6 h reaction time). The principal cause was the reduction of the hydrogenolytic activity and acidity caused by the combination of Pd and Rh. In the case of the bimetallic Rh-Pd(x) samples, an increase in the metal content favored the formation of dehydrogenated products, reduced cracking (by reducing the concentration of strong acid sites) and increased coke deposition during decalin ring opening. Conversely, the Rh catalyst showed less deactivation since its efficient hydrogenolytic character eliminates coke precursors

Propane oxidative dehydrogenation on V-Sb/ZrO2 catalysts

The catalytic properties of V?Sb/ZrO2 and bulk Sb/V catalysts for the oxidative dehydrogenation of propane were studied. Samples were characterized by nitrogenadsorption, temperature-programmed reduction, temperature-programmed pyridine desorption and photoelectron spectroscopic techniques. Vanadia promotes the transition of tetragonal to monoclinic zirconia and the formation of ZrV2O7. Surface V and Sb oxide species do not appear to interact among them below monolayer coverage, but SbVO4 forms above monolayer. Simultaneously the excessof antimony forms a-Sb2O4. Activity and selectivity show no dependence on the acidity of the catalysts. However, there is a strong dependence of activity/selectivity on composition; surface vanadium species are active for propane oxidative dehydrogenation and the presence of Sb, affording rutile VSbO4 phase makes the system selective to C3H6, this is believed to be related to the redox cycle involving dispersed V5+ species and lattice reduced vanadium site in the rutile VSbO4 phase.Fil: D'ippolito, Silvana Andrea. 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: Bañares, Miguel. Instituto de Catálisis y Petroleoquímica; EspañaFil: García Fierro, José Luis. Instituto de Catálisis y Petroleoquímica; EspañaFil: Pieck, Carlos Luis. 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

Deglycerolization of biodiesel streams by adsorption over silica beds

A simple method for the almost complete removal of glycerol from methanol-free biodiesel streams coming out from industrial transesterification reactors is presented. The method is posed as a "dry" alternative to the conventional "wet" methods involving water washing. It is based on the use of silica beds and relies on the adsorption at room temperature to retain the small amounts of glycerol dissolved in the solutions of fatty acid methyl esters and adjust their content to the quality standards for biodiesel fuel. Fresh silica has a great processing capacity and the breakthrough of the bed depends mainly on the feed rate, the concentration of glycerol, and the mass of adsorbent. In the case of the silica gel used, the saturation capacity was found to be 0.13 g of glycerol per gram of silica. If the particle diameter is 1-1.5 mm, the breakthrough and saturation point almost coincide and the full capacity of the bed is used. However, industrial adsorption units with 1/8 in silica beads suffer from mass-transfer limitations inside the pellet pores, and for this particle size, the breakthrough point (C/C0 = 0.01) is located at about one-half of the time of full saturation. For a glycerol concentration of 0.11-0.25% typical of biodiesel streams issuing from gravity settling tanks and an entrance velocity of 11 cm min-1, a 2 m high silica bed with 1/8 in. beads has a breakthrough point of 8 h and a net processing capacity of 0.01-0.02 m3 biodiesel, kgsilica -1. The breakthrough curves were studied using approximate solutions to the set of differential equations. Assuming a linear isotherm gives erroneous results; fitting the experimental breakthrough curves produces underestimated values of the Henry's adsorption constant and of the mass-transfer resistances. Modeling the high dilution regime with the UNIFAC method gives more realistic values of the Henry's constant (1.1 m3 kg-1). The experimentally measured saturation capacity is close to the monolayer capacity (13-15% w/w). These values give a Langmuir isotherm which can be fairly well approximated by a square irreversible isotherm. Accordingly, breakthrough curves were fairly well predicted using an irreversible isotherm, a shrinking-core adsorption model, and common correlations for the mass-transfer coefficients. The silica bed was succesfully regenerated eluting 4 bed volumes of methanol and drying in a nitrogen stream for 1 h. Temperature programmed oxidation tests of fresh, regenerated, and glycerol impregnated silica pellets indicated that desorption of glycerol was practically complete. In the industrial practice, the eluted volume can be recycled to the transesterification reactors with no waste of products or reactants. Evaporation of the adsorbed methanol during drying of the bed produced a decrease of the bed temperature and about 200 kJ kgsilica -1 should be provided in order to maintain the temperature.Fil: Yori, Juan Carlos. 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: D'ippolito, Silvana Andrea. 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: Pieck, Carlos Luis. 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: Vera, Carlos Roman. 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

Influence of the Brønsted acidity, SiO2/Al2O3 ratio and Rh-Pd content on the ring opening. Part II. Selective ring opening of methylcyclohexane

Monometallic and bimetallic Pd-Rh catalysts with various Rh/Pd atomic ratios (=0.5, 1 and 2) and a total metal charge of 1 wt% supported on SiO2-Al2O3(SIRAL 40, 20, 5) were studied for the ring opening of methylcyclohexane (MCH). The results were compared with those obtained previously for ring opening of decalin. It was found that the total acidity and the Brønsted acidity of the support have a higher influence on the activity for ring opening of naphthenic bicycles than on the activity for opening single rings. The influence of the metal charge is more important on the reaction of MCH. All the catalysts display a high MCH conversion, which increases with the reaction temperature. The bimetallic catalyst with the Rh/Pdratio equal to 2 and supported on SIRAL 40 has the highest yield to ring opening products.Fil: D'ippolito, Silvana Andrea. 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: Especel, Catherine. Universite de Poitiers. Laboratoire de Catalyse En Chimie Oranique; FranciaFil: Vivier, Laurence. Universite de Poitiers. Laboratoire de Catalyse En Chimie Oranique; FranciaFil: Epron, Florence. Universite de Poitiers. Laboratoire de Catalyse En Chimie Oranique; FranciaFil: Pieck, Carlos Luis. 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

O-2 and O-3 regeneration of PtReSn/Al2O3 and PtReGe/Al2O3 naphtha reforming catalysts prepared by catalytic reduction

International audienceThe deactivation and regeneration of naphtha reforming PtReGe/Al2O3 and PtReSn/Al2O3 catalysts prepared by catalytic reduction were studied. The extent and nature of coke deposition as determined by TPO were related to catalyst properties such as dispersion, acidity and Cl content. The PtReSn catalyst was the most resistant to coke deactivation. Regeneration was performed by calcination in oxygen at 450 degrees C or ozone at 125 degrees C at variable regeneration times. Regenerated catalysts were evaluated by cyclopentane hydrogenolysis, cyclohexane dehydrogenation and n-heptane reaction tests. Regeneration by oxygen burning-off was the most effective for decoking. However, oxygen combustion produced more segregation of the metal function than ozone regeneration. With the regeneration conditions used in this work, the original acidity of the catalysts cannot be recovered

Pt-Mg-Ir/Al2O3 and Pt-Ir/HY zeolite catalysts for SRO of decalin. Influence of Ir content and support acidity

Pt-Ir/HY and Pt-Mg-Ir/Al2O3 catalysts were studied and tested in the reaction of ring opening of decalin.The acidity of the alumina support was modified by addition of 3% Mg and the acidity of the zeolite by ion exchange with NH4Cl. The Pt content of the catalysts was fixed at 1% (mass basis) while the Ir content was adjusted between 0.1 and 0.6%. The catalysts were characterized by temperature programmed reduction, temperature programmed desorption of pyridine and FTIR of adsorbed CO. They were further tested with the reactions of cyclohexane dehydrogenation, cyclopentane hydrogenolysis and n-C5 isomerization.It was found that the Pt-Ir/HY catalyst was substantially more acid than Pt-Mg-Ir/Al2O3. Increasing the Ir content produced an increase of the hydrogenolytic activity and a decrease of the dehydrogenating activity of both catalysts. The n-pentane isomerization reaction results revealed that in the case of the alumina catalyst increasing the Ir content promoted both the catalyst stability and the cracking selectivity to C5 isomers. The opposite was found for the Pt-Ir/HY zeolite catalysts. The zeolite supported Pt-Ir catalysts performed better for decalin ring opening than those supported on alumina. Higher Ir content favored the formation of ring-opening products in all cases.Fil: D'ippolito, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; ArgentinaFil: Gutierrez, Laura Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; ArgentinaFil: Vera, Carlos Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; ArgentinaFil: Pieck, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; Argentin