Avoiding rhenium loss in non-hydrolytic synthesis of highly active Re–Si–Al olefin metathesis catalysts

Bouchmella, Karim; Stoyanova, Mariana; Rodemerck, Uwe; Debecker, Damien P.; Mutin, P. Hubert

doi:10.1016/j.catcom.2014.09.024

Cited by 28 publications

(19 citation statements)

References 33 publications

(36 reference statements)

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“…After calcination, ToF‐SIMS showed the presence of abundant and well‐dispersed ReO x surface species, presumably highly active in the metathesis reaction. On the other hand, calcination also resulted in the sublimation of rhenium heptoxide . Rhenium losses were especially important in Si‐rich samples.…”

Section: Non‐hydrolytic Sol‐gelmentioning

confidence: 99%

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Innovative Sol‐Gel Routes for the Bottom‐Up Preparation of Heterogeneous Catalysts

Debecker

2017

The Chemical Record

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Heterogeneous catalysts can be prepared by different methods offering various levels of control on the final properties of the solid. In this account, we exemplify bottom-up preparation routes that are based on the sol-gel chemistry and allow to tailor some decisive properties of solid catalysts. First, an emulsion templating strategy is shown to lead to macrocellular self-standing monoliths with a macroscopic 3D structure. The latter can be used as catalyst or catalyst supports in flow chemistry, without requiring any subsequent shaping step. Second, the aerosol-assisted sol-gel process allows for the one-step and continuous production of porous mixed oxides. Tailored textural properties can be obtained together with an excellent control on composition and homogeneity. Third, the application of non-hydrolytic sol-gel routes, in the absence of water, leads to mixed oxides with outstanding textural properties and with peculiar surface chemistry. In all cases, the resulting catalytic performance can be correlated with the specificities of the preparation routes presented. This is exemplified in catalytic reactions in the fields of biomass conversion, petro chemistry, enantioselective organic synthesis, and air pollution mitigation.

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Section: Non‐hydrolytic Sol‐gelmentioning

confidence: 99%

“…Under such conditions Re‐Si‐Al materials with very high specific surface areas could be obtained whatever the Si/Al ratio or Re loading. This allowed us to obtain highly active mixed oxide metathesis catalysts, showing unprecedented specific activities (101 mmol propene g −1 h −1 ) …”

Section: Non‐hydrolytic Sol‐gelmentioning

confidence: 99%

Innovative Sol‐Gel Routes for the Bottom‐Up Preparation of Heterogeneous Catalysts

Debecker

2017

The Chemical Record

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“…Also, working in organic solvents with low surface tension prevents the pores collapse during drying, which leads to highly porous materials [25,30]. NHSG routes were reported to lead to various types of metallosilicate catalysts showing high performance in many different fields of applications, including olefin metathesis [31,32], olefin epoxidation [33,34], mild oxidation of sulphur compounds [35], aminolysis [27,36], aniline photocatalytic degradation [37], etc. To the best of our knowledge, Ta oxide-based materials prepared by NHSG have never been reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Ag- and Cu-Promoted Mesoporous Ta-SiO2 Catalysts Prepared by Non-Hydrolytic Sol-Gel for the Conversion of Ethanol to Butadiene

2019

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The direct catalytic conversion of bioethanol to butadiene, also known as the Lebedev process, is one of the most promising solution to replace the petro-based production of this important bulk chemical. Considering the intricate reaction mechanism—where a combination of acid-catalyzed dehydration reactions and metal-catalyzed dehydrogenation have to take place simultaneously—tailor-made bifunctional catalysts are required. We propose to use non-hydrolytic sol-gel (NHSG) chemistry to prepare mesoporous Ta-SiO2 materials which are further promoted by Ag via impregnation. An acetamide elimination route is presented, starting from silicon tetraacetate and pentakis(dimethylamido)tantalum(V), in the presence of a Pluronic surfactant. The catalysts display advantageous texture, with specific surface area in the 600–1000 m² g−1 range, large pore volume (0.6–1.0 mL g−1), an average pore diameter of 4 nm and only a small contribution from micropores. Using an array of characterization techniques, we show that NHSG allows achieving a high degree of dispersion of tantalum, mainly incorporated as single sites in the silica matrix. The presence of these monomeric TaOx active sites is responsible for the much higher dehydration ability, as compared to the corresponding catalyst prepared by impregnation of Ta onto a pristine silica support. We attempt to optimize the butadiene yield by changing the relative proportion of Ta and Ag and by tuning the space velocity. We also demonstrate that Ag or Cu can be introduced directly in one step, during the NHSG process. Copper doping is shown to be much more efficient than silver doping to guide the reaction towards the production of butadiene.

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“…Another class of materials studied by the same group were catalysts for olefin metathesis. They prepared mesoporous mixed oxide based catalysts with the compositions of Mo-O-Si-O-Al [180,214,215] and Re-O-Si-O-Al [177,178]. All samples catalyzed the conversion of propene to ethene and butene with more than 99 % selectivity.…”

Section: Heterogeneous Catalystsmentioning

confidence: 99%

“…Several examples of new mixed oxides prepared by non-hydrolytic chemistry were published recently. Bouchmella and coworkers reported preparation of mesoporous Re-O-Si-O-Al, Re-O-Al, and Re-O-Si mixed oxides via a one-step non-hydrolytic sol-gel method with the aim of tuning the acidic properties of these solids and thus influence their catalytic performance [177,178]. The authors used the alkyl halide elimination, "ether route", involving the reaction of chloride precursors with diisopropylether at 110 • C. The Re content determined by a nominal Re/(Re + Si + Al) atomic ratio was approximately 0.03.…”

Section: New Compositionsmentioning

confidence: 99%

The Power of Non-Hydrolytic Sol-Gel Chemistry: A Review

et al. 2017

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This review is devoted to non-hydrolytic sol-gel chemistry. During the last 25 years, non-hydrolytic sol-gel (NHSG) techniques were found to be attractive and versatile methods for the preparation of oxide materials. Compared to conventional hydrolytic approaches, the NHSG route allows reaction control at the atomic scale resulting in homogeneous and well defined products. Due to these features and the ability to design specific materials, the products of NHSG reactions have been used in many fields of application. The aim of this review is to present an overview of NHSG research in recent years with an emphasis on the syntheses of mixed oxides, silicates and phosphates. The first part of the review highlights well known condensation reactions with some deeper insights into their mechanism and also presents novel condensation reactions established in NHSG chemistry in recent years. In the second section we discuss porosity control and novel compositions of selected materials. In the last part, the applications of NHSG derived materials as heterogeneous catalysts and supports, luminescent materials and electrode materials in Li-ion batteries are described.

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Avoiding rhenium loss in non-hydrolytic synthesis of highly active Re–Si–Al olefin metathesis catalysts

Cited by 28 publications

References 33 publications

Innovative Sol‐Gel Routes for the Bottom‐Up Preparation of Heterogeneous Catalysts

Innovative Sol‐Gel Routes for the Bottom‐Up Preparation of Heterogeneous Catalysts

Ag- and Cu-Promoted Mesoporous Ta-SiO2 Catalysts Prepared by Non-Hydrolytic Sol-Gel for the Conversion of Ethanol to Butadiene

The Power of Non-Hydrolytic Sol-Gel Chemistry: A Review

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