Pesquisa | SciELO

Abstract Background Despite representing the largest fraction of animal life, the number of insect species whose genome has been sequenced is barely in the hundreds. The order Dermaptera (the earwigs) suffers from a lack of genomic information despite its unique position as one of the basally derived insect groups and its importance in agroecosystems. As part of a national educational and outreach program in genomics, a plan was formulated to engage the participation of high school students in a genome sequencing project. Students from twelve schools across Chile were instructed to capture earwig specimens in their geographical area, to identify them and to provide material for genome sequencing to be carried out by themselves in their schools. Results The school students collected specimens from two cosmopolitan earwig species: Euborellia annulipes (Fam. Anisolabididae) and Forficula auricularia (Fam. Forficulidae). Genomic DNA was extracted and, with the help of scientific teams that traveled to the schools, was sequenced using nanopore sequencers. The sequence data obtained for both species was assembled and annotated. We obtained genome sizes of 1.18 Gb (F. auricularia) and 0.94 Gb (E. annulipes) with the number of predicted protein coding genes being 31,800 and 40,000, respectively. Our analysis showed that we were able to capture a high percentage (≥ 93%) of conserved proteins indicating genomes that are useful for comparative and functional analysis. We were also able to characterize structural elements such as repetitive sequences and non-coding RNA genes. Finally, functional categories of genes that are overrepresented in each species suggest important differences in the process underlying the formation of germ cells, and modes of reproduction between them, features that are one of the distinguishing biological properties that characterize these two distant families of Dermaptera. Conclusions This work represents an unprecedented instance where the scientific and lay community have come together to collaborate in a genome sequencing project. The versatility and accessibility of nanopore sequencers was key to the success of the initiative. We were able to obtain full genome sequences of two important and widely distributed species of insects which had not been analyzed at this level previously. The data made available by the project should illuminate future studies on the Dermaptera.

https://doi.org/10.1186/s40659-023-00414-9

An Empirical Comparison of EM and K-means Algorithms for Binning Metagenomics Datasets
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Tapia Reyes, Patricio

; Meneses Villegas, Claudio

Ingeniare. Revista chilena de ingeniería

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Nov 2018, Volume 26 Páginas 20 - 27

Resumo: En Es | Texto: En Es | PDF: En | PDF: Es

ABSTRACT: Metagenomics is an area of microbiology that deals with the taxonomic classification of genomic samples taken directly from the environment. These samples are sequences of variable length and they may correspond to different species, some of which may be unknown or not previously stored in a genomic database. One of the main steps in metagenomics classification correspond to binning the sequence fragments into groups that may correspond to one species. Many approaches are used to perform binning, mainly machine learning algorithms to perform classification or clustering. This paper presents the results of an empirical evaluation of two well-known unsupervised algorithms to perform the metagenomics binning task: the EM versus the K-means algorithms. Both algorithms are tested on short and long reads of synthetic datasets, with different proportions and number of species. These empirical results show that K-means in general outperforms the EM algorithm, but EM results competitive in several of the short reads datasets used for evaluation.

RESUMEN: La metagenómica es un área de la microbiología que trata con la clasificación taxonómica de muestras tomadas directamente del ambiente. Estas muestras son secuencias de largo variable que pueden pertenecer a distintas especies, algunas pueden ser desconocidas o no han sido almacenadas previamente en una base de datos genómica. Uno de los pasos principales en la clasificación metagenómica corresponde al proceso de binning de los fragmentos de secuencias en grupos que pueden corresponder a una especie. Se han usado varios acercamientos para realizar binning, principalmente algoritmos de machine learning para realizar la clasificación o agrupamiento. Este artículo presenta los resultados de una evaluación empírica de dos algoritmos no supervisados bien conocidos, para realizar la tarea de binning metagenómico: EM vs. K-medias. Ambos algoritmos son probados para secuencias largas y cortas de conjuntos de datos sintéticos, con diferentes proporciones y número de especies. Estos resultados empíricos muestran que K-medias en general tiene un mejor rendimiento que el algoritmo EM, pero los resultados de EM son competitivos cuando son probados con varios conjuntos de secuencias cortas.

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CHIRAL Rh/SiO2 CATALYSTS FOR ENANTIOSELECTIVE HYDROGENATION REACTIONS: THE ROLE OF (S,S)-DIPAMP AS CHIRAL MODIFIER AND STABILIZER ON METALLIC NANOPARTICLES SYNTHESIS
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MELLA, CLAUDIO

; ÁVILA, MAURICIO

; SÁNCHEZ, ARIEL

; MARZIALETTI, TERESITA

; REYES, PATRICIO

; RUIZ, DORIS

Journal of the Chilean Chemical Society

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Dez 2013, Volume 58 Nº 4 Páginas 2125 - 2130

Resumo: En | Texto: En | PDF: En

Rhodium nanoparticles were successfully stabilized by the (S,S)-1,2-ethanediylbis[(2-ethoxyphenyl)phenylphosphine] ((S,S)-DIPAMP) deposited on SiO2 prepared by a facile reduction and impregnation method. The chiral catalysts obtained were efficient for the enantioselective hydrogenation reactions of prochiral compounds. The catalysts synthesized from [Rh(µ-OMe)(COD)]2 in the presence of different amounts of a ligand used as chiral stabilizer, showed good metal dispersion. As shown by TEM, the metal particle size ranged between 1 and 2 nm using stabilizer and 9.1 nm was achieved without chiral ligand. Other techniques were used to characterize the chiral catalysts such as X-ray diffraction (XRD), electron diffraction, thermogravimetric analysis (TGA) and N2 adsorption-desorption isotherms. (S,S)-DIPAMP was used as the stabilizer of metal particles to prevent growing and agglomeration, and it also acts as chiral modifier inducing enantioselectivity in the asymmetric hydrogenation of 3,4-hexanodione (HD), ethyl pyruvate (EP), ketopantolactone (KP), and acetophenone (AP). Under specific conditions such as 25 °C, 40 bar of H2 and substrate/Rh=100, 1%Rh-(S,S)-DIPAMP/SiO2 chiral catalysts showed excellent catalytic performance with conversion and enantiomeric excess (ee) levels up to 99% and 54% respectively.

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KINETIC STUDY OF THE HYDROGENATION OF CITRAL ON Ir PROMOTED Au/TiO2 CATALYST
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MARTÍNEZ, JOSÉ J

; ROJAS, HUGO

; REYES, PATRICIO

Journal of the Chilean Chemical Society

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Set 2013, Volume 58 Nº 3 Páginas 1799 - 1804

Resumo: En | Texto: En | PDF: En

A kinetic study of citral hydrogenation over an Au-Ir/TiO2 catalyst was performed with the aim to understand the effect of iridium on gold in this catalytic system. Au-Ir/TiO2 catalyst was prepared by co-deposition precipitation in an atomic ratio of 3/1. The effect of citral concentration, hydrogen pressure and temperature effect were also studied. The product distribution obtained is related with the proportion of Meδ+/Me0 sites. The deactivation of the catalyst occurs in the whole studied temperature range, 363 to 403 K, being more drastic as temperature increases due to the irreversible adsorbed CO blocks principally Ir0 sites. From initial reaction rates treatment an apparent global order close to 1 was determined. A Langmuir-Hinshelwood-type kinetic model involving the surface reaction as the rate limiting step between adsorbed citral and hydrogen on active sites with different nature shows good agreement with experimental initial reaction rates.

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HYDROGENATION OF NITROBENZENE ON Au/ZrO2 CATALYSTS
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GÓMEZ, SAMUEL

; TORRES, CECILIA

; GARCÍA FIERRO, JOSÉ LUIS

; APESTEGUÍA, CARLOS R

; REYES, PATRICIO

Journal of the Chilean Chemical Society

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2012, Volume 57 Nº 2 Páginas 1194 - 1198

Resumo: En | Texto: En | PDF: En

The hydrogenation of nitrobenzene at 298K and pressure of 40 bar of H2 over zirconia supported Au catalysts has been studied. Three different procedures were used to prepare 1wt% of Au/ZrO2 catalysts: i) An impregnation method using HAuCl4 as gold precursor ii)Depositation precipitation of Au nanoparticles generated in the presence of urea and iii) Deposition of Gold nanoparticles generated in presence of cetryltrimethylammonium bromide (CTMABR) as surfactant. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, XRD, TEM and XPS techniques. The reactions were carried out in a stainless steel batch reactor using ethanol as solvent. The catalysts exhibits a higher selectivity to aniline, with low accumulation of intermediate products. The kinetic study displayed orders 1 respect to hydrogen pressure and to the substrate concentration (nitrobenzene), and the activation energy was 67.2 KJ/mol.

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SILICA SUPPORTED RHODIUM METAL NANOPARTICLES STABILIZED WITH (-)-DIOP. EFFECT OF LIGAND CONCENTRATION AND METAL LOADING ON THE ENANTIOSELECTIVE HYDROGENATION OF KETONES
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RUIZ, DORIS

; MELLA, CLAUDIO

; FIERRO, JOSÉ L.G

; REYES, PATRICIO

Journal of the Chilean Chemical Society

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2012, Volume 57 Nº 4 Páginas 1394 - 1399

Resumo: En | Texto: En | PDF: En

Supported nanoparticles (NPs) in presence of chiral ligand (L) were synthesized for their use in enantioselective hydrogenation reactions. Catalysts were obtained by chemical reduction from rhodium chloride hydrate, RhCl3x3H2O, in presence of (-)-DIOP ligand ((4R,5R)-4,5-Bis(diphenylphosphino-methyl)-2,2-dimethyl-1,3-dioxolane) that allows to control NPs growing and to obtain solids having chiral surfaces. Chirally stabilized rhodium NPs on SiO2 were characterized using techniques such as: TEM, electron diffraction, EDS, nitrogen adsorption-desorption isotherms and XPS. This work includes the study of some variables such as metal loading and ligand concentration and their effect in metal core sizes, catalytic activity and enantioselectivity. Catalysts properties have also been evaluated in the hydrogenation of substrates: acetophenone (AP), 1-phenyl-1,2-propanedione (PPD), 3,4-hexanedione (HD), 2,3-butanedione (BD) and ethyl pyruvate (EP) as reaction test. Ligand plays a fundamental role in the synthesis of NPs and enantioselectivity in hydrogenations reactions. That is, due to it generates metal particle size < 5.8 nm compared with unstabilized systems that generate average diameter around 14 nm. Results indicate increased activity in catalytic systems obtained from the stabilization of NPs. Enantioselectivity levels reach values up to 53% due to the chiral ligand is on the catalysts surface.

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LIQUID-PHASE HYDROGENATION OF m-DINITROBENZENE OVER PLATINUM CATALYSTS
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ROJAS, HUGO

; BORDA, GLORIA

; REYES, PATRICIO

; BRIJALDO, MARÍA

; VALENCIA, JESÚS

Journal of the Chilean Chemical Society

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2011, Volume 56 Nº 3 Páginas 793 - 798

Resumo: En | Texto: En | PDF: En

The m-dinitrobenzene hydrogenation to m-phenylenediamine in liquid phase was studied with platinum supported on SiO2, TiO2, Al2O3 and Nb2O5 catalysts. Incipient impregnation method was used to prepare the catalysts with 1wt% of Pt. The effect of the support and the reduction temperature (473 K or 773 K) were analyzed. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption (77 K), hydrogen chemisorption (298 K), transmission electron microscopy (TEM), temperature programmed reduction (H2-TPR) and temperature programmed desorption of ammonia (NH3-TPD). The results showed that Pt/ TiO2 (HT) catalyst had a higher yield (60%) toward m- phenylenediamine and conversion level (98.2%) of m-dinitrobenzene. This behavior can be attributed to the reduction of PtO crystallites to metallic Pt, small particle size and the strong metal-support interaction due to the migration of TiO species on the Pt crystallites.

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KINETIC BEHAVIOR IN THE HYDROGENATION OF FURFURAL OVER IR CATALYSTS SUPPORTED ON TIO2
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ROJAS, HUGO

; MARTÍNEZ, JOSÉ J.

; REYES, PATRICIO

DYNA

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Set 2010, Volume 77 Nº 163 Páginas 151 - 159

Resumo: Es En | Texto: Es En | PDF: Es | PDF: En

La cinética de la hidrogenación en fase líquida de furfural a alcohol furfurilico sobre catalizadores de Ir/TiO2 se estudio en el rango de temperaturas de 323 a 373 K, también se estudio el efecto de la concentración de furfural, presión de hidrogeno y del solvente empleado. Se obtuvo una alta selectividad hacía el alcohol furfurilico. Con las velocidades iníciales de reacción se determino el orden de reacción global. Los datos experimentales pueden también explicarse usando un modelo Langmuir-Hinshelwood considerando un solo tipo de sitio activo con adsorción disociativa de hidrogeno, siendo la reacción superficial la etapa limitante de la reacción, este modelo se ajusta a los datos experimentales.

The kinetics of the liquid-phase hydrogenation of furfuraldehyde to furfuryl alcohol over Ir catalysts supported over TiO2 was studied in the temperature range of 323 to 373 K. The effect of furfural concentration, hydrogen pressure and the solvent effect were also studied. A high selectivity towards furfuryl alcohol was demonstrated. Initial rates describes the order global of the reaction. The experimental data could also be explained using the Langmuir-Hinshelwood model with of a single-site with dissociative adsorption of hydrogen and the surface reaction as the rate-controlling step provided the best fit of the experimental data.

2538 downloads Citado 2 vezes em SciELO

Estudio cinético de la hidrogenación de trans-cinamaldehído sobre catalizadores de Ir/Nb2O5
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Rojas Sarmiento, Hugo Alfonso

; Martínez Zambrano, José Jobanny

; Reyes, Patricio Alberto

Revista Facultad de Ingeniería Universidad de Antioquia

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Set 2010, Nº 55 Páginas 9 - 17

Resumo: Es En | Texto: Es En | PDF: Es | PDF: En

Se estudió la hidrogenación de trans-cinamaldehído sobre catalizadores de Ir/Nb2O5 reducidos en atmósfera de hidrógeno a 473 K (LTR) y a 773 K (HTR). Los catalizadores se caracterizaron por adsorción de N2 a 77 K, quimisorción de H2 a 298 K, TPR y TPD-NH3. El estudio cinético de la hidrogenación de trans-cinamaldehído sobre catalizadores reducidos alta temperatura (HTR) se realizó en el rango de presiones de 0,48 a 0,98 MPa, a temperaturas de reacción entre 323 a 363 K, masa del catalizador de 0,1 a 0,3 g y concentraciones de trans-cinamaldehído de 0,025 a 0,1 M, usando como solvente n-heptano. Los resultados indican que la hidrogenación procede de manera selectiva hacía el alcohol insaturado, aunque la acidez del soporte conduce a la formación de subproductos. Un mecanismo dual Langmuir-Hinshelwood con adsorción molecular de hidrógeno no competitiva con las moléculas orgánicas en la que se asumió la reacción superficial como etapa limitante de la reacción se ajusta a los datos experimentales.

The hydrogenation of trans-cinnamaldehyde was studied over Ir/Nb2O5 catalysts reduced at 473 K (LTR) and 773 K (HTR). The catalysts were characterized by N2 physisorption at 77 K, H2 chemisorption, TPR, and TPD- NH3. Kinetic study of trans-cinnamaldehyde over Ir/Nb2O5 reduced at HTR was carried out in n-heptane at hydrogen pressures in the range of 0.48 to 0.98 MPa, the reaction temperatures were 323-363 K, catalyst loadings 0.1 to 0.3 g and cinnamaldehyde concentrations 0.025 to 0.1 M. Trans-cinnamaldehyde can be selectively hydrogenated to cinnamyl alcohol although the support acidity leads to the formation of byproducts. A Langmuir-Hinshelwood model with molecular adsorption of hydrogen non competitive with organic molecules and considering the surface reaction as the rate-controlling step provided the best fit of the experimental data.

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10.

OBTENCION DE ISOPULEGOL SOBRE CATALIZADORES DE Ir/Nb2O5/SiO2. APROXIMACION CINETICA
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ROJAS, HUGO

; CASTAÑEDA, JULIO CESAR

; REYES, PATRICIO

DYNA

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Jun 2010, Volume 77 Nº 162 Páginas 5 - 12

Resumo: Es En | Texto: Es En | PDF: Es | PDF: En

La cinética de la conversión de citronelal hacia isopulegol sobre el catalizador se realizó en un intervalo de temperaturas de 303 - 343 K, presión de hidrógeno de 0.62 a 0.20 MPa y concentraciones de citronelal de 0.1M a 0.025 M. Los resultados indican que el catalizador de Iridio soportado en Nb2O5-SiO2 induce la selectividad hacia isopulegol debido a una alta acidez superficial y la presencia de sitios metálicos. Para evitar limitaciones de transferencia de masa se utilizo una agitación vigorosa y pequeñas cantidades de catalizador ( 0.05 g). El análisis de las velocidades iniciales de reacción proporcionó un orden 1 con respecto a la concentración y orden cero con respecto a la presión. Se explican los resultados usando un modelo de reacciones complejas de primer orden.

Kinetics of Citronellal conversion to isopulegol over catalyst was performed in a range of temperature 303 - 343 K, a hydrogen pressure 0.62 - 0.20 MPa and a citronelal concentrations at 0.1M to 0.025 M. The results indicate that the catalyst of Iridium supported over SiO2-Nb2O5 induces selectivity towards isopulegol due to high acidity and the presence of surface metal sites. To avoid mass transfer limitations were used a vigorous agitation and small amounts of catalyst ( 0.05 g). The analysis of rates reaction provided an initial order 1 with respect to concentration and zero order with respect to pressure. Results are explained using a model of complex reactions of the first order.

1445 downloads

11.

Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2
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Ruiz, Doris P.

; Fierro, José L. G.

; Reyes, Patricio A.

Journal of the Brazilian Chemical Society

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2010, Volume 21 Nº 2 Páginas 262 - 269

Resumo: Pt En | Texto: Pt En | PDF: Pt | PDF: En

A hidrogenação enantiosseletiva de piruvato de etila e de 1-fenil-1,2-propanodiona foi estudada a 298 K e sob 40 bar de H2 sobre um catalisador de platina coloidal estabilizado com cinchonidina (CD) e suportado em sílica. O catalisador foi preparado por impregnação da platina coloidal em sílica, atingindo 1% em massa do metal no suporte. O colóide foi preparado a partir de uma solução aquosa de H2PtCl6 estabilizada com diferentes quantidades de CD. O catalisador foi caracterizado por isotermas de adsorção-desorção de N2 a 77 K e por XPS, XRD e TEM. As reações foram efetuadas em batelada em um reator de aço inoxidável, usando cicloexano como solvente e cinchonidina como modificador quiral. A adição de CD ao catalisador permite a estabilização e o controle do tamanho de partícula da platina, e também afeta o excesso enantiomérico (ee) do sistema, levando a um maior rendimento do produto com configuração R. A relação entre a concentração de CD adicionada in situ e a enantiosseletividade apresenta uma curva do tipo sino nas duas reações estudadas; este comportamento é um indicativo da importância da adsorção competitiva do modificador e do substrato na superfície do catalisador.

The enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione was studied at 298 K and 40 bar of H2 over colloidal Pt stabilized with cinchonidine (CD) and supported on silica. The catalysts were prepared by impregnation of colloidal Pt on SiO2, leading to a metal load close to 1 wt.%. The colloid was prepared from an aqueous solution of H2PtCl6 and stabilized with different quantities of CD. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, XPS, XRD and TEM techniques. The reactions were carried out in a stainless steel batch reactor using cyclohexane as solvent and cinchonidine as chiral modifier. The addition of CD to the catalysts allows the stabilization and control of the platinum particle size and also affects the enantiomeric excess (ee) of the system, affording a higher proportion of the (R)-product. The relationship between the enantioselectivity and the CD concentration (added in situ) exhibits a bell type curve for both reactions, this being indicative of the importance of a competitive adsorption of the modifier and substrate on the catalyst surface.

2035 downloads

12.

Selective hydrogenation of furfural on Ir/TiO2 catalysts
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Reyes, Patricio

; Salinas, Daniela

; Campos, Cristian

; Oportus, Marcelo

; Murcia, Julie

; Rojas, Hugo

; Borda, Gloria

; Fierro, José Luís García

Química Nova

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2010, Volume 33 Nº 4 Páginas 777 - 780

Resumo: En | Texto: En | PDF: En

Titania-supported Ir catalysts were used in the hydrogenation of furfural. Reactions were carried out in a stirred batch type reactor at 0.62MPa and 363K using a 0.10M solution of furfural in a 1:1 mixture n-heptane -ethanol as solvent. Catalysts containing 2 wt% of Ir were reduced in H2 flow at different temperatures in the range 473-773K. The catalysts were characterized by H2 chemisorption, TEM, TPR, TPD of NH3 and XPS. Conversion of furfural is higher at lower reduction temperatures, but leads to byproducts whereas reduction at higher temperatures shows selectivity to furfuryl alcohol close to 100%.

4973 downloads

13.

ENANTIOSELECTIVE HYDROGENATION OF 1-PHENYL-1,2-PROPANODIONE ON Pt/ ZrO2 CATALYSTS
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URBINA, CLAUDIA

; PECCHI, GINA

; CAMPOS, CRISTIAN

; REYES, PATRICIO

Journal of the Chilean Chemical Society

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2010, Volume 55 Nº 1 Páginas 25 - 30

Resumo: En | Texto: En | PDF: En

The enantioselective hydrogenation of 1-phenyl-1,2-propanedione at 298K and pressure of 40 bar of H2 over zirconia supported Pt catalysts has been studied. Three different zirconia were prepared : i) ZrO2- P obtained by a precipitation procedure from ZrOCl2 ii) MSZrO2 obtained by a sol-gel procedure using cetryltrimethylammonium bromide (CTMABR) as surfactant to get a mesostructured solid iii) CNTsZrO2 obtained after impregnation of carbon nanotubes with ZrO(NO)3 followed by pyrolisis and calcination. Pt (1 wt%) was introduced on the support by impregnation of an aqueous solution of H2PtCl6. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, hydrogen chemisorption, XRD and TEM techniques. The reactions were carried out in a stainless steel batch reactor using cyclohexane as solvent and cinchonidine as chiral modifier. The presence of CD in the reaction medium is necessary to induce an enantiomeric excess (ee) of the desired product R-1phenyl-1 hydroxi-2-propanone. In all the studied systems, the relation between the enantioselectivity and the CD concentration added in situ exhibits a bell type curve; indicative of the importance of competitive adsorption between the modifier and the substrate on the catalyst surface. On the other hand, confinement effect led to an important enhancement in the activity in those catalysts supported on mesostructured supports, mainly in the Pt/CNTsZrO2 catalyst.

4847 downloads

14.

HIDROGENACIÓN DE ACROLEÍNA Y CROTONALDEHÍDO SOBRE CATALIZADORES DE IR SOPORTADO
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ROJAS, HUGO

; MURCIA, JULIE

; BORDA, GLORIA

; REYES, PATRICIO

; ROJAS, NESTOR

DYNA

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Set 2009, Volume 76 Nº 159 Páginas 125 - 134

Resumo: Es En | Texto: Es En | PDF: Es | PDF: En

Se evaluó el comportamiento de diferentes catalizadores de Ir, en la hidrogenación de aldehídos a,b-insaturados, acroleína y crotonaldehído, para la obtención de sus alcoholes insaturados alcohol alílico y crotílico respectivamente, cuya utilidad en la industria de la química fina es de amplio reconocimiento. Los aldehídos objeto de esta investigación representan un alto riesgo ambiental, por lo que la investigación presentada en este trabajo resulta de gran importancia en ese campo. En general los resultados obtenidos muestran que factores como temperatura de reducción y contenido de TiO2 en los catalizadores son determinantes en el comportamiento catalítico; análisis de caracterización permitieron establecer que en los catalizadores reducidos a alta temperatura se presenta el efecto de interacción fuerte metal soporte, conocido por su símbolo SMSI, lo que favorece la conversión, actividad inicial y TOF. De igual manera los catalizadores evaluados son altamente selectivos hacia los alcoholes insaturados que representan los productos de interés en este estudio.

The behavior of different Ir catalysts in the hydrogenation of a,b-unsaturated acrolein and crotonaldehyde aldehydes has been evaluated to obtain their allyl and crotyl unsaturated alcohols respectively; their products are used in fine chemicals industry. The present work is of great importance in this field because of the unsaturated aldehydes studied having high environmental risk besides the great academic contribution. The results show that factors such as reduction temperature and TiO2 content are critical in the catalytic behavior, through the analysis of characterization was established that the catalysts reduced at high temperature shows the Strong Metal Support Interaction effect (SMSI), which favors conversion percentage, initial activity and TOF. The analyzed catalysts were highly selective towards the unsaturated alcohols.

2296 downloads

15.

HIDROGENACIÓN DE CROTONALDEHÍDO SOBRE CATALIZADORES Ir/Tio2-siO2
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ROJAS, HUGO

; BORDA, GLORIA

; MURCIA, JULIE

; REYES, PATRICIO

; ROJAS, NÉSTOR

DYNA

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Jun 2009, Volume 76 Nº 157 Páginas 173 - 180

Resumo: Es En | Texto: Es En | PDF: Es | PDF: En

Se estudió la hidrogenación de crotonaldehído en fase líquida, sobre catalizadores Ir/TiO2-SiO2; este aldehído es altamente contaminante y proviene de fuentes tan diversas como humo de tabaco, gases de escape de motores de gasolina o diesel y humo de combustión de madera [1]. El objetivo principal de esta investigación fue la obtención del alcohol insaturado (crotil alcohol). A partir de los estudios realizados logró demostrarse que un aumento en el contenido de TiO2, lo mismo que la reducción de los catalizadores a altas temperaturas favorece parámetros como selectividad hacia el producto de interés, actividad catalítica y en general se logró mejorar de manera notable los niveles de conversión. El comportamiento observado se atribuyó principalmente a la fuerte influencia del efecto SMSI (Strong Metal Support Interaction), presente a altas temperaturas en óxidos parcialmente reducibles.

Liquid phase crotonaldehyde hydrogenation over Ir/TiO2-SiO2 catalysts was studied; this aldehyde is highly pollutant comes from cigarette smoke, exhaust from gasoline and diesel engines and the burning of wood [1]. The main objective of this research was unsaturated alcohol (crotyl alcohol) obtention. This study showed that an increase in TiO2 content and high temperature reduction in catalysts produce high selectivity to crotyl alcohol, high activity, and an increase in conversion levels. This behavior is due to SMSI (Strong Metal Support Interaction) effect, at high temperatures in partially reducible oxides.

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