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19 pages, 3571 KiB

Open AccessArticle

Effective Interactions of Ag Nanoparticles on the Surface of SBA-15 in Performing Deep Desulfurization of Real Diesel Fuel

by Clenildo de Longe, Rafael Viana Sales, Anne Beatriz Figueira Câmara, Heloise Oliveira Medeiros de Araújo Moura, Enrique Rodríguez-Castellón, Sibele Berenice Castellã Pergher, Leila Maria Aguilera Campos, Maritza Montoya Urbina and Luciene Santos de Carvalho

Catalysts 2020, 10(5), 593; https://doi.org/10.3390/catal10050593 - 25 May 2020

Cited by 7 | Viewed by 2566

Abstract

SBA-15 materials as-synthesized and impregnated with Ag nanoparticles were applied to perform adsorptive desulfurization of real diesel fuel. High-angle annular dark-field scanning transmission electron microscopy and field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (HAADF-STEM-EDX and FESEM-EDX) and X-ray photoelectron spectroscopy (XPS) [...] Read more.

SBA-15 materials as-synthesized and impregnated with Ag nanoparticles were applied to perform adsorptive desulfurization of real diesel fuel. High-angle annular dark-field scanning transmission electron microscopy and field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (HAADF-STEM-EDX and FESEM-EDX) and X-ray photoelectron spectroscopy (XPS) results confirmed that there is uniform distribution of Ag nanodomains on the surface and in the channels of a 2AgSBA-15 (2% Ag) sample. The interaction between sulfur compounds and adsorbent mainly occurred via π-complexation mechanisms, as observed via XPS and equilibrium data. The kinetic results for 2AgSBA-15 were better fitted to the pseudo-second-order model (R² > 0.9999), indicating that the determining step of the adsorptive process is chemisorption, whereas the equilibrium results were better fitted to the Langmuir model (R² > 0.9994), thus indicating that the adsorption occurs on the adsorbent surface monolayer with significant adsorption capacity (q_m = 20.30 mgS/g), approximately two times greater than that observed for pure SBA-15. The mean desulfurization reached by the adsorbents was up to 86.8% for six recycling steps. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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18 pages, 9018 KiB

Open AccessArticle

Preparation of Ruthenium Olefin Metathesis Catalysts Immobilized on MOF, SBA-15, and 13X for Probing Heterogeneous Boomerang Effect

by Artur Chołuj, Wojciech Nogaś, Michał Patrzałek, Paweł Krzesiński, Michał J. Chmielewski, Anna Kajetanowicz and Karol Grela

Catalysts 2020, 10(4), 438; https://doi.org/10.3390/catal10040438 - 17 Apr 2020

Cited by 12 | Viewed by 3905

Abstract

Promoted by homogeneous Ru-benzylidene complexes, the olefin metathesis reaction is a powerful methodology for C-C double bonds formation that can find a number of applications in green chemical production. A set of heterogeneous olefin metathesis pre-catalysts composed of ammonium-tagged Ru-benzylidene complexes 4 (commercial [...] Read more.

Promoted by homogeneous Ru-benzylidene complexes, the olefin metathesis reaction is a powerful methodology for C-C double bonds formation that can find a number of applications in green chemical production. A set of heterogeneous olefin metathesis pre-catalysts composed of ammonium-tagged Ru-benzylidene complexes 4 (commercial FixCat™ catalyst) and 6 (in-house made) immobilized on solid supports such as 13X zeolite, metal-organic framework (MOF), and SBA-15 silica were obtained and tested in catalysis. These hybrid materials were doped with various amounts of ammonium-tagged styrene derivative 5—a precursor of a spare benzylidene ligand—in order to enhance pre-catalyst regeneration via the so-called release-return “boomerang effect”. Although this effect was for the first time observed inside the solid support, we discovered that non-doped systems gave better results in terms of the resulting turnover number (TON) values, and the most productive were hybrid catalysts composed of 4@MOF, 4@SBA-15, and 6@SBA-15. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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21 pages, 4939 KiB

Open AccessArticle

The Effect of Temperature and Time of the Hydrothermal Treatment in the SBA-15 Synthesis Process on the Structure and Textural Properties and the Ability to Reduce the Evolution of Tars in Tobacco Smoking

by Nerea Juárez-Serrano, Javier Asensio, Isabel Martínez-Castellanos, Maribel Beltrán and Antonio Marcilla

Catalysts 2020, 10(3), 272; https://doi.org/10.3390/catal10030272 - 1 Mar 2020

Cited by 4 | Viewed by 2730

Abstract

Different SBA-15 (SBA, Santa Barbara Amorphous) materials were synthetized at different temperature and time during of the hydrothermal treatment. The obtained SBA-15 were characterized by N₂ adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (DRX), and density in order to establish the [...] Read more.

Different SBA-15 (SBA, Santa Barbara Amorphous) materials were synthetized at different temperature and time during of the hydrothermal treatment. The obtained SBA-15 were characterized by N₂ adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (DRX), and density in order to establish the influence of these variables on their properties. Mixtures of the obtained catalysts with 3R4F tobacco were prepared and smoked under the ISO 3308 conditions. Temperature of the hydrothermal treatment slightly affects the tars that evolved in the smoking process of the corresponding catalyst tobacco mixtures. Contrarily, the time of the hydrothermal treatment has a marked effect on the reductions of toxic compounds in the smoke. Developed porosity has a positive correlation with the observed tar reduction, whereas the apparent density has a negative correlation with the reduction in toxicity. Moreover, the removal of the supernatant liquors during the hydrothermal treatment does not strongly modify the properties of the materials and may represent an interesting simplification of the process. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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14 pages, 2643 KiB

Open AccessArticle

Hydrotreating of Methyl Esters to Produce Green Diesel over Co- and Ni-Containing Zr-SBA-15 Catalysts

by Cristina Ochoa-Hernández, Juan M. Coronado and David P. Serrano

Catalysts 2020, 10(2), 186; https://doi.org/10.3390/catal10020186 - 5 Feb 2020

Cited by 12 | Viewed by 2937

Abstract

This work explores the performance of Zr-SBA-15 as a support for the conversion of methyl esters into green diesel. Thereby, a series of SBA-15 samples incorporating different amounts of Zr into the walls have been synthesized and impregnated with Ni and Co as [...] Read more.

This work explores the performance of Zr-SBA-15 as a support for the conversion of methyl esters into green diesel. Thereby, a series of SBA-15 samples incorporating different amounts of Zr into the walls have been synthesized and impregnated with Ni and Co as hydrogenating species. All materials have been characterized, pelletized and tested in the hydrotreating of methyl esters using a fixed-bed tubular reactor at 300 °C, 30 bar of H₂ and a continuous flow of 0.1 mL/min for 6 h. Co and Ni phases are present both over the surface and within the pores of the support. Interactions between the metals and the Zr species are more pronounced for Co-containing samples, leading to smaller Co particles at low Si/Zr ratios. Materials having higher Zr contents resulted in more methyl ester conversion, although an adequate metal-support combination was required to promote the hydrodeoxygenation (HDO) route. Co/Zr-SBA-15 materials exhibited more conversion (>90%) and higher yields of C₁₁-C₂₀ hydrocarbons (>60%) than their Ni-based counterpart catalysts. Specifically, Co/Zr-SBA-15(17) sample showed remarkable behavior, favoring the HDO pathway (n-C₁₈/(n-C₁₈ + n-C₁₇) > 0.5), while keeping the methyl esters’ conversion close to 100% along the time on stream. These results evidence a synergistic effect between Co and Zr. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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12 pages, 4589 KiB

Open AccessArticle

Mesoporous Silica Nanosheets with Tunable Pore Lengths Supporting Metal Nanoparticles for Enhanced Hydrogenation Reactions

by Xiaohui Wang, Xin Ding and Houbing Zou

Catalysts 2020, 10(1), 12; https://doi.org/10.3390/catal10010012 - 20 Dec 2019

Cited by 7 | Viewed by 3117

Abstract

The channel lengths of mesoporous materials have a crucial impact on the catalytic performances of as-loaded active components. However, it remains a challenge to precisely tune the mesochannel length in a wide range from ≤50 nm to 200 nm. In this paper, we [...] Read more.

The channel lengths of mesoporous materials have a crucial impact on the catalytic performances of as-loaded active components. However, it remains a challenge to precisely tune the mesochannel length in a wide range from ≤50 nm to 200 nm. In this paper, we developed a top-down strategy, that is to say, crushing hollow microspheres, for preparing mesoporous silica nanosheets (MSSs) with perpendicular mesochannels and tunable thicknesses. Owing to the heterogeneous growth of the mesoporous silica layer on the surfaces of polystyrene microspheres (hard template), it was achieved to regulate the mesochannel length continuously in the range of 20–200 nm. The obtained materials were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of channel lengths on the catalytic activity of metal nanoparticles was then investigated in the selective hydrogenation reaction of nitroarenes. It was found that a short channel not only favored dispersing metal nanoparticles uniformly and then avoiding pore blocking, but also improved the accessibility of metal nanoparticles largely during reactions. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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12 pages, 770 KiB

Open AccessArticle

Heterogeneous Synergistic Catalysis for Promoting Aza-Michael–Henry Tandem Reaction for the Synthesis of Chiral 3-Nitro-1,2-Dihydroquinoline

by Zhe An, Lifeng Chen, Yitao Jiang and Jing He

Catalysts 2019, 9(9), 713; https://doi.org/10.3390/catal9090713 - 24 Aug 2019

Cited by 2 | Viewed by 3140

Abstract

Heterogeneous synergistic catalysis by SBA-15 immobilized chiral amines catalysts has promoted efficient aza-Michael–Henry tandem reaction for the synthesis of chiral 3-Nitro-1,2-Dihydroquinoline. Final products in the asymmetric aza-Michael–Henry cascade reactions between 2-aminobenzaldehyde and β-nitrostyrolene were afforded in a yield of 85% and an enantiomeric [...] Read more.

Heterogeneous synergistic catalysis by SBA-15 immobilized chiral amines catalysts has promoted efficient aza-Michael–Henry tandem reaction for the synthesis of chiral 3-Nitro-1,2-Dihydroquinoline. Final products in the asymmetric aza-Michael–Henry cascade reactions between 2-aminobenzaldehyde and β-nitrostyrolene were afforded in a yield of 85% and an enantiomeric excess (ee) value of 98% on (S)-(–)-2-aminomethyl-1-ethylpyrrolidine immobilized SBA-15. SBA-15-AEP catalyst has been also extended to the asymmetric aza-Michael–Henry cascade reaction of substituted R1-2-aminobenzaldehyde and R2-substituted nitroolefin. The heterogeneous synergistic mechanism for both tertiary amine and secondary amine immobilized mesoporous has been proposed in detail including the geometrical constraints in the ee promotion. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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Review

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30 pages, 3061 KiB

Open AccessReview

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

by Marcello Crucianelli, Bruno Mattia Bizzarri and Raffaele Saladino

Catalysts 2019, 9(12), 984; https://doi.org/10.3390/catal9120984 - 23 Nov 2019

Cited by 41 | Viewed by 8441

Abstract

Recalcitrant sulfur compounds are common impurities in crude oil. During combustion they produce SO_x 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 [...] Read more.

Recalcitrant sulfur compounds are common impurities in crude oil. During combustion they produce SO_x 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. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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18 pages, 7637 KiB

Open AccessReview

SBA-15 as a Support for Effective Olefin Metathesis Catalysts

by Hynek Balcar and Jiří Čejka

Catalysts 2019, 9(9), 743; https://doi.org/10.3390/catal9090743 - 2 Sep 2019

Cited by 11 | Viewed by 3955

Abstract

Olefin metathesis is the catalytic transformation of olefinic substrates, finding a wide range of applications in organic synthesis. The mesoporous molecular sieve Santa Barbara Amorphous (SBA-15) has proven to be an excellent support for metathesis catalysts thanks to its regular mesoporous structure, high [...] Read more.

Olefin metathesis is the catalytic transformation of olefinic substrates, finding a wide range of applications in organic synthesis. The mesoporous molecular sieve Santa Barbara Amorphous (SBA-15) has proven to be an excellent support for metathesis catalysts thanks to its regular mesoporous structure, high BET area, and large pore volume. A survey of catalysts consisting of (i) molybdenum and tungsten oxides on SBA-15, and (ii) molybdenum and ruthenium organometallic complexes (Schrock and Grubbs-type carbenes) on SBA-15 is provided together with their characterization and catalytic performance in various metathesis reactions. The comparison with catalysts based on other supports demonstrates the high quality of the mesoporous molecular sieve SBA-15 as an advanced catalyst support. Full article

(This article belongs to the Special Issue SBA-15 and Catalysis)

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