Propane oxidation on Pt-WO3/gamma -AL2O3 catalytic systems

Silva, M.A.Pereira da; Cardoso, Rodolfo; Schmal, Martín

doi:10.1590/s0104-66322003000100010

Cited by 5 publications

(7 citation statements)

References 9 publications

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“…27,28 Although some works studied the stability of catalysts in the presence of steam, a detailed explanation for why specific types of catalysts do not suffer from water deactivation is lacking. 14,29 On the other hand, water could also be a beneficial agent in combustion reactions, by removing poisoning species from catalyst preparation, 30 generating more active sites, 26 or facilitating high-barrier reaction steps. 31,32 For a more complete understanding of the role of water in propane combustion, and how it is involved in deterministic parameters, systematic studies that combine these important factors are crucial.…”

Section: ■ Introductionmentioning

confidence: 99%

Support Acidity Improves Pt Activity in Propane Combustion in the Presence of Steam by Reducing Water Coverage on the Active Sites

Yang

Zhu

et al. 2021

ACS Catal.

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Support effects in catalysis are important in determining the catalytic activity of supported phases through geometric and electronic effects. Unveiling and quantifying support effects lead to the opportunity to finely tune and optimize the activity of supported catalysts. The study of support effects needs to be conducted in conditions where other important parameters, such as size and composition of the active phase, are not influencing the activity. This requirement is particularly important when the activity is affected by reactants or products that have implications in the reaction mechanism, as is the case of water in hydrocarbon combustion. Here, we present a systematic study on the effects of support acidity and water on propane combustion catalyzed by platinum-based catalysts that reveal support effects beyond the conventional geometric and electronic effects. A set of catalysts prepared from colloidal Pt nanoparticles supported on alumina, silica–alumina, and tungsten oxide-modified silica–alumina with increasing controlled Brønsted acid site density was prepared. We observed a monotonic increase in reaction rate as the same Pt particles were supported on progressively more acidic supports, with an improvement of up to 40 times in reaction rate for the sample with the highest Brønsted acid site density [Pt/WO3(10%)/30% SiO2/Al2O3] compared to the bare Pt/Al2O3 sample. Based on kinetic measurements on samples with different Pt particle sizes, we propose that (i) the metal–support perimeter participates in the reaction, and (ii) the interaction between metal and Brønsted acid sites is responsible for the increase in activity. The origin of such rate increase was found to be related to the enhanced resistance to water poisoning introduced by the acid sites: samples with higher acidity displayed nearly zero water rate order and more stable rates in the presence of steam. Using a Langmuir–Hinshelwood model, the most acidic sample was shown to display the lowest water coverage on the Pt surface. Summarizing all the observations, we propose that the Brønsted acid sites help reduce water coverage on the Pt surface through a spillover-like mechanism, which results in available sites for propane adsorption and activation and thus higher reaction rates in propane combustion. This work highlights how supports play a role not only in modifying electronic and geometric properties of supported phases, but also in the reaction mechanism through active roles in modifying surface coverages.

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Section: ■ Introductionmentioning

confidence: 99%

Support Acidity Improves Pt Activity in Propane Combustion in the Presence of Steam by Reducing Water Coverage on the Active Sites

Yang

Zhu

et al. 2021

ACS Catal.

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“…The investigations on influence of the nature of carrier including zeolites on process are well known. The investigations of catalytic activity in reaction of oxidative conversion of С3-С4 alkanes into oxygen-containing compounds (alcohols, aldehydes, acids, and ketones), С2-С4 olefins and H2 over W-, Mo-HPC with P and Si as central atoms supportedon Si-containing oxide carriers are developed[27][28][29][30][31][32][33][34][35][36].…”

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confidence: 99%

Catalytic Oxidation of C<sub>3</sub>-C<sub>4</sub> Mixture into Industrially Important Chemical Products

Baizhumanova¹,

Тунгатарова²,

Zheksenbaeva³

et al. 2018

Preprint

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The processing of alkanes (the main components of natural gas) for obtaining of industrially important chemical products is one of the most urgent environmental problems, because the major share of raw materials are burned in torches. Therefore, the main goal of the work is the development of catalysts and conditions for obtaining of important petrochemical products from light alkanes. For the preparation of catalysts, Mo, Cr and Ga oxide catalysts as well as catalysts based on heteropoly compounds, supported on natural materials were used. The catalysts were prepared by the capillary impregnation method and used in oxidative conversion in a flowing unit while varying the process conditions. It has been determined that 5 and 10% MoCrGa catalysts are optimal for obtaining of liquid and gaseous products, and 1% catalyst is more favorable for the synthesis of gaseous products. Supported catalysts from heteropoly acid Н3PW12O40 are highly active in oxidative dehydrogenation and cracking processes, which are concurrent. High activity is caused by dispersity of catalysts, formation of crystal hydrates and amorphous phase of heteropoly acid in a condition of interaction with carrier. Maximum yield of C2H4 - 35.2% at 973 K, C3H6 – 20.0% and C4H8 – 14.3% at 773 К were observed.

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“…Esta reacción ha sido estudiada usando catalizadores de Pt promovidos ya sea con W [151], Mo y W [152,153] observándose una actividad mejorada debido a las propiedades electrónicas del Mo y del W.…”

Section: 1032-catalizadores Preparados Secuencialmenteunclassified

“…Lo que es importante es que la actividad de la oxidación de propano fue mejorada por la presencia de WOx en el catalizador de Pt/Al 2 O 3 (catalizadores W3. encontrado Da Silva et al, [151]. Los autores encontraron que la adición del W al catalizador de Pt/Al 2 O 3 incremento tanto la actividad como la estabilidad en presencia de agua.…”

Section: 111--actividad Catalítica En Función De La Temperatura De Reacciónunclassified

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Efecto del Tungsteno sobre la estructura y reactividad de catalizadores de platino soportado en Alúmina

Larios

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matrícula 84260013, quien cumplió con los 180 créditos correspondientes a las unidades de enseñanza aprendizaje del plan de estudio. Con fecha veintitrés de julio del 2010 presentó la DEFENSA de su DISERTACIÓN PÚBLICA cuya denominación es: EFECTO DEL TUNGSTENO SOBRE LA ESTRUCTURA Y REACTIVIDAD DE CATALIZADORES DE PLATINO SOPORTADO EN ALUMINA Cabe mencionar que la aprobación tiene un valor de 18 0 créditos y el programa consta de 360 créditos. El jurado del examen ha tenido a bien otorgarle la calificación de: Aprobar

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Propane oxidation on Pt-WO3/gamma -AL2O3 catalytic systems

Cited by 5 publications

References 9 publications

Support Acidity Improves Pt Activity in Propane Combustion in the Presence of Steam by Reducing Water Coverage on the Active Sites

Support Acidity Improves Pt Activity in Propane Combustion in the Presence of Steam by Reducing Water Coverage on the Active Sites

Catalytic Oxidation of C<sub>3</sub>-C<sub>4</sub> Mixture into Industrially Important Chemical Products

Efecto del Tungsteno sobre la estructura y reactividad de catalizadores de platino soportado en Alúmina

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