Kinetic Study of Oxidative Dehydrogenation of Ethane over MoVTeNb Mixed-Oxide Catalyst

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial & Engineering Chemistry Research, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see [insert ACS Articles on Request author-directed link to Published Work, see http://doi.org/10.1021/ie402447h[EN] A MoVTeNb multimetallic mixed oxide was studied for the oxidative dehydrogenation of ethane, a promising alternative for catalytic ethylene production. Lab-scale steady-state experimental reaction data were obtained according to a 3(k) experimental design to investigate the simultaneous effect of temperature (400-480 degrees C) and space time [23-70 g(cat) h (mol of ethane) I]. A fixed-bed reactor at atmospheric pressure was employed, feeding a mixture of ethane, oxygen, and nitrogen. Ethane conversion varied from 17 to 85%, whereas selectivity for ethylene and COx varied from 94 to 76% and from 4.0 to 24%, respectively. These types of analyses are useful for determining the optimum reaction conditions to enhance the catalytic performance of the mixed oxides presented herein.This work was financially supported by the Instituto Mexicano del Petroleo. Technical support from Eng. G. Alonso-Ramirez is gratefully acknowledged.Valente, J.; Quintana-Solorzano, R.; Armendariz-Herrera, H.; Barragan-Rodriguez, G.; López Nieto, JM. (2014). Kinetic Study of Oxidative Dehydrogenation of Ethane over MoVTeNb Mixed-Oxide Catalyst. Industrial and Engineering Chemistry Research. 53(5):1775-1786. doi:10.1021/ie402447hS1775178653

Understanding the kinetic behavior of a Mo-V-Te-Nb mixed oxide in the oxydehydrogenation of ethane

Two kinetic models based on Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms were developed to describe the oxydehydrogenation of ethane to yield ethylene over a Mo-V-Te-Nb catalyst. Obtained in a lab-scale fixed-bed reactor, experimental data at the steady-state were used to estimate the kinetic models parameters via a nonisothermal regression. Experiments were performed using an ethane, oxygen and nitrogen mixture as feedstock, spanning temperatures from 673 to 753 K, inlet partial pressures of oxygen and ethane between 5.0 and 22.0 kPa, and space-time from 10 to 70 g(cat) h(molethane)- (1). Ethylene, CO and CO2 were the only detected products, the selectivity for ethylene ranged from 76% to 96% for an ethane conversion interval 4-85%. A series of tests feeding ethylene instead of ethane were also performed at 713 K, varying inlet partial pressures and space-time in the same ranges as was done for ethane. Ethylene conversion was relatively low, 3-14%, the dominant product being CO with CO/CO2 ratios from 0.73 to 0.79. The LH mechanism was found to represent better the experimental data. The oxydehydrogenation of ethane was the reaction with the lowest activation energy, 108-115 kJ mol (1). Except for the conversion of ethane into CO2, deep oxidations were detected as very energetically demanding steps, 156-193 kJ mol (1). Competitive adsorption between reagents and products occurred in the two mechanisms particularly at relatively high reaction severity, water re-adsorption being weaker in comparison with COx re-adsorption. (C) 2014 Elsevier Ltd. All rights reserved.This work was financially supported by the Instituto Mexicano del Petroleo.Quintana-Solorzano, R.; Barragan-Rodriguez, G.; Armendariz-Herrera, H.; López Nieto, JM.; Valente, JS. (2014). Understanding the kinetic behavior of a Mo-V-Te-Nb mixed oxide in the oxydehydrogenation of ethane. Fuel. 138:15-26. doi:10.1016/j.fuel.2014.07.051152613

Metal solution precursors: their role during the synthesis of MoVTeNb mixed oxide catalysts

[EN] Synthesized via the slurry method and activated at high temperature (873 K), MoVTeNb multimetallic mixed oxides are applied to catalyze the oxidative dehydrogenation of ethane to ethylene (ODHE). Mixed oxides typically contain M1 and M2 crystalline phases, the relative contribution of these phases and the respective catalytic behaviour being notably influenced by the preparation conditions of the metallic aqueous solution precursor, given the complexity of the chemical interactions of metal species in solution. Thus, detailed in situ UV-vis and Raman studies of the chemical species formed in solution during each step of the synthetic procedure are presented herein. The main role of vanadium is to form decavanadate ions, which interact with Mo species to generate an Anderson-type structure. When niobium oxalate solution is added into the MoVTe solution, a yellow-coloured gel is immediately formed due to a common ion effect. When liquid and gel phases are separated, the M1 crystalline phase is produced solely from the gel phase. Attention is also devoted to the influence and role of each metal cation (Mo, V, Te and Nb) on the formation of the active M1 crystalline phase and the catalytic behaviour in the ODHE. The catalyst constituted mostly of M1 crystalline phase is able to convert 45% of the fed ethane, with a selectivity to ethylene of around 90%.This work was financially supported by the Instituto Mexicano del Petroleo (IMP) Project D.61010. EMF thanks CONACyT Mexico and IMP. JMLN thanks DGICYT in Spain (Project CTQ2015-68951-C3-1-R).Sánchez-Valente, J.; Maya-Flores, E.; Armendariz-Herrera, H.; Quintana-Solorzano, R.; López Nieto, JM. (2018). Metal solution precursors: their role during the synthesis of MoVTeNb mixed oxide catalysts. Catalysis Science & Technology. 8(12):3123-3132. https://doi.org/10.1039/c8cy00750kS31233132812Ushikubo, T., Oshima, K., Kayou, A., Vaarkamp, M., & Hatano, M. (1997). Ammoxidation of Propane over Catalysts Comprising Mixed Oxides of Mo and V. Journal of Catalysis, 169(1), 394-396. doi:10.1006/jcat.1997.1692Ushikubo, T., Oshima, K., Kayou, A., & Hatano, M. (1997). Ammoxidation of propane over Mo-V-Nb-Te mixed oxide catalysts. Spillover and Migration of Surface Species on Catalysts, Proceedings of the 4th International Conference on Spillover, 473-480. doi:10.1016/s0167-2991(97)80871-3Ushikubo, T. (2000). Recent topics of research and development of catalysis by niobium and tantalum oxides. Catalysis Today, 57(3-4), 331-338. doi:10.1016/s0920-5861(99)00344-2Ueda, W., & Oshihara, K. (2000). Selective oxidation of light alkanes over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) oxide catalysts. Applied Catalysis A: General, 200(1-2), 135-143. doi:10.1016/s0926-860x(00)00627-xWatanabe, H., & Koyasu, Y. (2000). New synthesis route for Mo–V–Nb–Te mixed oxides catalyst for propane ammoxidation. 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The Mexican consensus on the diagnosis, treatment, and prevention of NSAID-induced gastropathy and enteropathy

Más de 30 millones de personas consumen diariamente antiinflamatorios noesteroideos (AINE) en el mundo, y este consumo se ve incrementado anualmente. Aunque losAINE poseen propiedades analgésicas y antiinflamatorias, sus eventos adversos gastrointesti-nales son bien reconocidos. En nuestro país no existía un consenso respecto al diagnóstico,tratamiento y prevención de la gastropatía y la enteropatía por AINE, por lo que la AsociaciónMexicana de Gastroenterología reunió a un grupo de expertos para establecer recomendacionesde utilidad para la comunidad médica. En este consenso se emitieron 33 recomendaciones. Elconsenso destaca que el riesgo de toxicidad gastrointestinal de los AINE varía según el fármacoempleado y su farmacocinética, lo cual debe ser considerado al momento de su prescripción. Losfactores de riesgo de complicación gastroduodenal por AINE son: antecedente de úlcera pép-tica, edad mayor a 65 a˜nos, dosis altas del AINE, infección por Helicobacter pylori (H.pylori), ypresencia de comorbilidades graves. Los síntomas y el da˜no gastroduodenal inducido por AINEson variables ya que puede cursar asintomático o manifestarse como anemia por deficiencia dehierro, hemorragia, estenosis y perforación. La cápsula endoscópica y la enteroscopia son méto-dos diagnósticos directos en la enteropatía por AINE. Respecto a la prevención, se recomiendaprescribir la dosis mínima necesaria de un AINE para obtener el efecto deseado y durante elmenor tiempo. Finalmente, los inhibidores de la bomba de protones (IBP) representan el están-dar de oro para la profilaxis y tratamiento de los efectos gastroduodenales, mas no son útilesen la enteropatía

Consenso mexicano sobre diagnóstico, prevención y tratamiento de la gastropatía y enteropatía por antiinflamatorios no esteroideos

Más de 30 millones de personas consumen diariamente antiinflamatorios no este-roideos (AINE) en el mundo y este consumo se ve incrementado a˜no tras a˜no. Aunque los AINEposeen propiedades analgésicas y antiinflamatorias, sus eventos adversos gastrointestinales sonbien reconocidos. En nuestro país no existía un consenso respecto al diagnóstico, tratamientoy prevención de la gastropatía y la enteropatía por AINE, por lo que la Asociación Mexicana deGastroenterología reunió a un grupo de expertos para establecer recomendaciones de utilidadpara la comunidad médica. En este consenso se emitieron 33 recomendaciones. El consensodestaca que el riesgo de toxicidad gastrointestinal de los AINE varía según el fármaco empleadoy su farmacocinética, lo cual debe ser considerado al momento de su prescripción. Los factoresde riesgo de complicación gastroduodenal por AINE son: antecedente de úlcera péptica, edadmayor de 65 a˜nos, dosis altas del AINE, infección por Helicobacter pylori y presencia de comor-bilidades graves. Los síntomas y el da˜no gastroduodenal inducido por AINE son variables, ya quepuede cursar asintomático o manifestarse como anemia por deficiencia de hierro, hemorragia,estenosis y perforación. La cápsula endoscópica y la enteroscopia son métodos diagnósticosdirectos en la enteropatía por AINE. Respecto a la prevención, se recomienda prescribir la dosismínima necesaria de un AINE para obtener el efecto deseado y durante el menor tiempo. Porúltimo, los inhibidores de la bomba de protones representan el estándar de oro para la profilaxisy tratamiento de los efectos gastroduodenales, mas no son útiles en la enteropatí

Catalytic cracking and coking of (cyclo)alkane/1-octene mixtures on an equilibrium catalyst

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