Authors: Possato, Luiz Gustavo; Diniz, Rosiane N.; Garetto, Teresita Francisca; Pulcinelli, Sandra H.; Santilli, Celso V.; Martins, Leandro
Publication Date: 2013.
Language: English.
Abstract:
The catalytic properties of monomodal microporous and bimodal micro-mesoporous zeolites were investigated in the gas-phase dehydration of glycerol. The desilication methodology used to produce the mesoporous zeolites minimized diffusion limitations and increased glycerol conversion in the catalytic reaction due to the hierarchical system of secondary pores created in the zeolite crystals. The chemical and structural properties of the catalyst were studied by X-ray diffraction, nitrogen adsorption?desorption isotherms, NH3-TPD and pyridine chemisorption followed by IR-spectroscopy. Although the aim was to desilicate to create mesoporosity in the zeolite crystals, the desilication promoted the formation of extra-framework aluminum species that affected the conversion of glycerol and the products distribution. The results clearly show that the mesoporous zeolites with designed mesopore structure allowed a rapid diffusion and consequently improved the reaction kinetics. However, especial attention must be given to the desilication procedure because the severity of the treatment negatively interfered on the Brønsted and Lewis acid sites relative concentration and, consequently, in the efficiency of the catalysis performed by these materials. On the other hand, during the catalytic reaction, the intracrystalline mesopores allowed carbonaceous compounds to be deposited herein, resulting in less blocked micropores and catalysts with higher long-term stability.
Author affiliation: Possato, Luiz Gustavo. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil
Author affiliation: Diniz, Rosiane N.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil
Author affiliation: Garetto, Teresita Francisca. 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"; Argentina
Author affiliation: Pulcinelli, Sandra H.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil
Author affiliation: Santilli, Celso V.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil
Author affiliation: Martins, Leandro. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Abstract:
Objective: Storage time without use (STWU) in the supporting electrolyte solution for time periods beyond 30 hours deactivates poly(o-aminophenol) (POAP) films. Observations: Deactivated POAP films exhibit a lower conductivity than freshly prepared (nondeactivated) films Considering the interest in POAP synthesized in acid medium in both basic and applied research, not much attention has been paid to the decay of the electroactivity of POAP caused by its extensive use. Conclusion: Deactivation of poly(o-aminophenol) (POAP) film electrodes by STWU in the supporting electrolyte solution is reviewed in this work.
Author affiliation: Tucceri, Ismael Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Padro, Cristina; Apesteguia, Carlos Rodolfo
Publication Date: 2005.
Language: English.
Abstract:
The deactivation mechanism of the gas-phase synthesis of o-hydroxyacetophenone (o-HAP) via acylation of phenol with acetic acid was studied on Al-MCM-41 and zeolites HY, HBeta and HZSM-5. The o-HAP yield remained constant with time-on-stream on HZSM-5 but drastically decreased on the other samples because of coke formation. The origin and nature of coke precursor species were studied by employing as reactants, the key reaction intermediates and products involved in the phenol acylation reaction network. It was found that coke precursors are formed from consecutive condensation reactions and not from any ketene formation by phenyl acetate decomposition. Specifically, it is proposed that o-acetoxyacetophenone (o-AXAP), which is formed by reaction between o-HAP and acetic acid, is the key intermediate specie responsible for the formation of carbonaceous deposits and consequently, for the activity decay observed on Al-MCM-41, HY and HBeta samples. The narrow pore size structure of zeolite HZSM-5 would hinder the formation of bulky o-AXAP, thereby, decreasing drastically the formation of coke.
Author affiliation: Padro, Cristina. 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
Author affiliation: Apesteguia, Carlos Rodolfo. 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
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Publication Date: 2013.
Language: English.
Abstract:
The deactivation of supported catalysts CsNO3 and LiNO3 for diesel soot combustion is studied in this work. The effect of hydro-treatment at high temperature and presence of CO2 in feed flow were investigated. Catalysts were characterized by means of X ray diffraction, DSC technique and FTIR. A fixed bed reactor was used to measure activity of fresh and deactivated catalysts with NO2/O2 feed. Thermogravimetrical system with air/CO2 feed was used to study the deactivation with CO2. Catalysts with LiNO3 were the most resistant to deactivation by hydro-treatment, and they are not deactivated by CO2. It is postulated that the cesium nitrate solubilizes in water and is eliminated during the hydro-treatment, instead, lithium species interacted more strongly with the support and generate more resistance species.
Author affiliation: Ruiz, Maria Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina;
Author affiliation: Lick, Ileana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina;
Author affiliation: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina;
Author affiliation: Ponzi, Esther Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina;
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Publication Date: 2018.
Language: English.
Abstract:
The impact of the composition of the various hydrocarbon fractions in a conventional VGO (saturated SF, aromatic AF and resin RF) and the whole VGO on the coke formed in their catalytic cracking was evaluated over two Y zeolites with different degree of mesoporosity. The parent zeolite was in its protonic form, Si/Al relationship of 30 and the modified sample was desilicated by alkaline treatment. The fractions were separated from the VGO by means of ASTM D2007-11 method. The catalytic conversion experiments were performed in a batch, fluidized bed laboratory Riser Simulator reactor at 500 °C in the 0.7–3.0 s reaction time range, with a zeolite mass of 0.2 g and a zeolite/reactant mass of 1. Independent of zeolite, fraction SF was the easiest to crack. In the case of the AF fraction, the modified zeolite, with the highest intracrystalline mesoporosity, was more active than the parent zeolite. Gasoline was always the main product, with selectivities from 60 to 70%. All the feedstocks produced more coke on the modified zeolite; however, in spite of the higher coke yields, this zeolite suffered a lower loss of total acidity. As expected, a negative change in both acidity and textural properties (specific surface area and pore volume) were observed as a consequence of the formation of coke. The reactivity of VGO over both zeolites differed from that of fraction SF, even though it was the major fraction (68%). This behavior could be the consequence of interactions between the various fractions composing VGO.
Author affiliation: Fals Guerra, Jayson. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Author affiliation: García, Juan Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Author affiliation: Falco, Marisa Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Author affiliation: Sedran, Ulises Anselmo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Meyer, Camilo Ignacio; Marchi, Alberto Julio; Monzón Bescós, Antonio; Garetto, Teresita Francisca
Publication Date: 2009.
Language: English.
Abstract:
In this work, the deactivation of a Cu(10%)/SiO2 catalyst in the gas-phase hydrogenation of maleic anhydride (MA) was studied. The reaction was performed between 170 and 220 °C, at atmospheric pressure and using two contact times (W / FM A0): 11.9 and 23.8 g cat. h/mol MA. The Cu(10%)/SiO2 catalyst was prepared by the wetness impregnation method and characterized by N2 physisorption at -196 °C, N2O decomposition at 90 °C, X-ray diffraction and temperature programmed reduction. From this characterization, it was concluded that catalyst is formed by large metal copper crystallites with little or none interaction with silica surface. Under the conditions used in this work, the Cu(10%)/SiO2 catalyst was highly selective to succinic anhydride (SA) while MA conversion dropped drastically with time. Both high selectivity to SA and rapid catalyst deactivation can be explained considering different types of MA interaction with the large metal copper crystallites. Catalyst regeneration feasibility under two different atmospheres, oxidizing and reducing, was also analyzed. The experimental results were successfully fitted, by non-linear regression, using a deactivation model with residual activity (DMRA). This model predicts satisfactorily the deactivation of Cu(10%)/SiO2 in the gas-phase hydrogenation of MA, both for fresh and regenerated catalysts, under the experimental conditions used in this work.
Author affiliation: Meyer, Camilo Ignacio. 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
Author affiliation: Marchi, Alberto Julio. 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
Author affiliation: Monzón Bescós, Antonio. Universidad de Zaragoza; España
Author affiliation: Garetto, Teresita Francisca. 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
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Publication Date: 2009.
Language: English.
Abstract:
Deactivation and regeneration of Pt/Al2O3 catalysts during the hydrodechlorination of carbon tetrachloride were studied. The effect of reactant partial pressures and temperature on the catalyst deactivation was investigated. A deactivation model with residual activity was developed to quantify the kinetic deactivation parameters. The effect of the regeneration atmosphere was also investigated. Regeneration under air allowed for the full recovery of the catalytic performance of fresh catalysts while treatments under flowing hydrogen resulted in a superior catalytic performance, increasing both the initial and residual activities. This was ascribed to a combined effect, redispersion of the metallic phase and formation of surface defects.
Author affiliation: Garetto, Teresita Francisca. 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
Author affiliation: Vignatti, Charito Ivana. 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
Author affiliation: Borgna, Armando. Institute Of Chemical And Engineering Sciences, A-star, Singapore;
Author affiliation: Monzón, A.. Universidad de Zaragoza; España
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Luggren, Pablo Jorge; Di Cosimo, Juana Isabel
Publication Date: 2018.
Language: English.
Abstract:
A “platform molecule” (2-hexanol) obtained from the primary conversion of sugars was upgraded to liquid transportation fuel precursors under gas phase conditions at 573 K and 101.3 kPa. Reaction was promoted by Cu-Mg-Al mixed oxides with different copper loading (0.3–61.2%) and a Mg/Al = 1.5 (molar ratio). Products were mainly low oxygen content C9-C24 oxygenates and hydrocarbons. The product pool average molecular weight and the oxygenates/hydrocarbons ratio increase with the catalyst copper loading, but the latter might be diminished by augmenting the contact time. A slow catalyst deactivation process occurs in the first 2 h of reaction. Temperature-programmed oxidation, BET surface are measurements and X-ray photoelectron and Auger electron spectroscopies of the spent catalysts indicated that the main reasons for the activity decay during reaction are carbon deposition on the active sites and, to a lesser degree, partial oxidation of the surface copper particles. Oxygenates (reactant or products) are the chemical species responsible for deactivation. The initial deactivation rate (rd0) depends on the copper content and contact time. On catalysts with low Cu content, rd0 is higher at short contact times, which is consistent with coke formed directly from the reactant. Contrarily, at high Cu loadings rd0 increases with contact time and parallels formation of heavy unsaturated oxygenates. Oxidation/reduction/catalytic test cycles of spent Cu-Mg-Al mixed oxides were implemented to explore catalyst reusability.
Author affiliation: Luggren, Pablo Jorge. 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
Author affiliation: Di Cosimo, Juana Isabel. 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
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Grzona, Liliana Myriam; Masini, Omar; Comelli, Nora Alejandra; Ponzi, Esther Natalia; Ponzi, Marta Isabel
Publication Date: 2005.
Language: English.
Abstract:
The deactivation of the H3PW12O40 (HPW) catalyst supported on TiO2 used in the isomerization reaction of α-pinene and its regeneration were studied. The regeneration of the deactivated catalyst was carried out with an air flow at 300 and 500ºC, with an ozone-enriched oxygen flow at 150ºC and by extraction with solvent and acid treatment. Only the last treatment permitted to recover its activity restoring it in 48% of its initial value.
Author affiliation: Grzona, Liliana Myriam. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina
Author affiliation: Masini, Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina
Author affiliation: Comelli, Nora Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina
Author affiliation: Ponzi, Esther Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas ; Argentina
Author affiliation: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Abstract:
Deactivation of ferrierite during the skeletal isomerization of 1-butene at atmospheric pressure and 0.15 atm 1-butene partial pressure was studied. At 300°C, the carbon content shows a sharp increase during the first 30 min-on-stream, with a slower growth thereafter. Temperature-programmed oxidation profiles corresponding to different times-on-stream are similar, showing two well-defined combustion peaks centered at about 325 and 640°C, respectively. When starting the 1-butene feed with the catalytic bed at 100 or 200°C and then increasing the temperature up to 300°C, no significant difference is observed, neither in carbon content nor in oxidation profiles. Important differences in the profiles are observed by comparing at the same time at each temperature. The lower the temperature, the higher the reactivity toward oxidation at low temperature. The carbonaceous deposit formed at 100°C shows the main combustion peak at the lowest temperature (135°C) and a more olefinic character; it could be related to a strong adsorption of reactant molecules. At 200°C, the proportion of saturated species associated to oligomers increases; while at 300°C, coke shows both aromatic and olefinic species.
Author affiliation: Brascó, Gerónimo. 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
Author affiliation: Comelli, Raul Alberto. 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
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas