Quantitative determination of oxygen defects, surface lewis acidity, and catalytic properties of mesoporous MoO3/SBA-15 catalysts

González, Julia García; Wang, Jinan; Chen, Lifang; Manríquez, Ma.; Salmones, J.; Limas, Roberto; Arellano, U.

doi:10.1016/j.jssc.2018.04.005

Cited by 48 publications

(26 citation statements)

References 65 publications

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“…The calculated lattice parameters for the cubic phase are a= 8.3762, 8.3889, and 8.4091 Å for CoF‐1, CoF‐2, and CoF‐3, respectively. From the refinement values of oxygen occupancy, the oxygen defect percentage is calculated from: O defect [%]=(theoretical occupency number−actual occupancy number after refinement)/theoretical occupancy number×100 …”

Section: Resultsmentioning

confidence: 99%

“…The calculated lattice parameters for the cubic phase are a = 8.3762, 8.3889, and 8.4091 for CoF-1, CoF-2, and CoF-3, respectively.F rom the refinement values of oxygen occupancy, the oxygen defectp ercentage is calculated from:Odefect [%] = (theoretical occupency numberÀactual occupancy number after refinement)/theoretical occupancy number100. [37] Although AP-CoFe 2 O 4 has negligible ( % 0.2 %) defects, the amount of oxygen defects increases with increasingc alcination temperature, that is, 2, 9, and 10 %f or CoF-1, CoF-2, and CoF-3, respectively.M oreover,t here is no noticeable secondary phase observed from the fitting.…”

Section: Structural and Morphological Analysesmentioning

confidence: 96%

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Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

et al. 2020

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The scope of any metal oxide as a catalyst for driving electrocatalytic reactions depends on its electronic structure, which is correlated to its oxygen‐defect density. Likewise, to transform a spinel oxide, such as cobalt ferrite (CoFe2O4), into a worthy universal‐pH, bifunctional electrocatalyst for the hydrogen and oxygen evolution reactions (HER and OER, respectively), oxygen defects need to be regulated. Prepared by coprecipitation and inert calcination at 650 °C, CoFe2O4 nanoparticles (NPs) require 253 and 300 mV OER overpotentials to reach current densities of 10 and 100 mA cm−2, respectively, if nickel foam is used as a substrate. With cost‐effective carbon fiber paper, the OER overpotential increases to 372 mV at 10 mA cm−2 at pH 14. The NPs prepared at 550 °C require HER overpotentials of 218, 245, and 314 mV at −10 mA cm−2 in alkaline, acidic, and neutral pH, respectively. The intrinsic activity is reflected from turnover frequencies of >3 O2 s−1 and >5 H2 s−1 at overpotentials of 398 and 259 mV, respectively. If coupled for overall water splitting, the extremely durable two‐electrode electrolyzer requires a cell potential of only 1.63 V to reach 10 mA cm−2 at pH 14. The homologous couple also splits seawater at impressively low cell voltages of 1.72 and 1.47 V at room temperature and 80 °C, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Structural and Morphological Analysesmentioning

confidence: 96%

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

et al. 2020

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“…4a, there were no peaks related to the MoO 3 species, due to the fact that these active species are well dispersed in the channels of the SBA-15 catalytic precursor. González et al [39] investigated the crystalline and chemical structure of MoO 3 /SBA-15 catalysts with different MoO 3 contents (5, 10, 15, 20 and 25% by mass) to evaluate their catalytic activity for the oxidation of 4.6-DMDBT; the study proved that the active species may not be detected in the XRD due to the support having multiple pores, which causes the species to disperse inside the pores. It is observed that as the MoO 3 content increases, there is an increase in the intensity of the peaks, indicating the appearance of the crystalline phase corresponding to MoO 3 on the surface of the SBA-15.…”

Section: X-ray Diffractometry (Xrd)mentioning

confidence: 99%

Preparation, characterization and evaluation of x-MoO3/Al-SBA-15 catalysts for biodiesel production

Figueiredo

Alves

Freire

et al. 2021

Mater Renew Sustain Energy

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Biodiesel is an alternative source of renewable energy that can be produced by a transesterification of vegetable oils. Mesoporous molecular sieves, such as SBA-15, due to high surface area and thermal stability are promising precursors for heterogeneous catalysts in the transesterification reaction. In this work, Al-SBA-15 precursor was obtained by direct hydrothermal synthesis, impregnated with different MoO3 contents (5, 10 and 15 wt%) by the pore saturation method, and evaluated as heterogeneous catalyst in the production of biodiesel from a transesterification of soybean oil with methanol. Al-SBA-15 precursor as well as MoO3/Al-SBA-15 catalyst were characterized for its structural characteristic by X-ray diffraction, textural characteristic by N2 adsorption analysis, and thermal stability by thermogravimetric analysis. An experimental planning 22 + 3 CtPt was used to evaluate the influence of MoO3 content and reaction time on biodiesel yield from soybean oil and methanol. The biodiesel content in the final product was obtained by gas chromatography. An average biodiesel yield of 96% was obtained with the catalyst 10%MoO3/Al-SBA-15 under the following reaction conditions: 20:1 methanol/soybean oil molar ratio, and 3 wt% of catalyst loading at 150 °C in 3 h. After five consecutive reaction cycles, the biodiesel yield decreased by about 34%. The density and acidity of the biodiesel produced are within the specified values for commercialization according to international standards. Graphical abstract

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“…The role that the defective structure of dispersed MoO 3 active sites can play in the ODS procedure was successively evaluated by a deep analysis of the oxidation behavior of 4,6-DMDBT with the MoO 3 /SBA-15 catalyst [126]. MoO 3 /SBA-15 was prepared via impregnation of SBA-15 with different amounts of ammonium heptamolybdate (from 5 wt/% to 25 wt/%) as molybdenum precursor.…”

Section: Molybdenum Oxidesmentioning

confidence: 99%

SBA-15 Anchored Metal Containing Catalysts in the Oxidative Desulfurization Process

2019

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Recalcitrant sulfur compounds are common impurities in crude oil. During combustion they produce SOx derivatives that are able to affect the atmospheric ozone layer, increasing the formation of acid rains, and reducing the life of the engine due to corrosion. In the last twenty years, many efforts have been devoted to develop conventional hydrodesulfurization (HDS) procedures, as well as alternative methods, such as selective adsorption, bio-desulfurization, oxidative desulfurization (ODS) under extractive conditions (ECODS), and others. Among them, the oxidative procedures have been usually accomplished by the use of toxic stoichiometric oxidants, namely potassium permanganate, sodium bromate and carboxylic and sulfonic peracids. As an alternative, increasing interest is devoted to selective and economical procedures based upon catalytic methods. Heterogeneous catalysis is of relevance in industrial ODS processes, since it reduces the leaching of active species and favors the recovery and reuse of the catalyst for successive transformations. The heterogenization of different types of high-valent metal transition-based organometallic complexes, able to promote the activation of stoichiometric benign oxidants like peroxides, can be achieved using various solid supports. Many successful cases have been frequently associated with the use of mesoporous silicas that have the advantage of easy surface modification by reaction with organosilanes, facilitating the immobilization of homogeneous catalysts. In this manuscript the application of SBA-15 as efficient support for different active metal species, able to promote the catalytic ODS of either model or real fuels is reviewed, highlighting its beneficial properties such as high surface area, narrow pore size distribution and tunable pore diameter dimensions. Related to this topic, the most relevant advances recently published, will be discussed and critically described.

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Quantitative determination of oxygen defects, surface lewis acidity, and catalytic properties of mesoporous MoO3/SBA-15 catalysts

Cited by 48 publications

References 65 publications

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

Preparation, characterization and evaluation of x-MoO3/Al-SBA-15 catalysts for biodiesel production

SBA-15 Anchored Metal Containing Catalysts in the Oxidative Desulfurization Process

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