WO3-based catalysts prepared by non-hydrolytic sol-gel for the production of propene by cross-metathesis of ethene and 2-butene

Maksasithorn, Surasa; Praserthdam, Piyasan; Suriye, Kongkiat; Devillers, Michel; Debecker, Damien P.

doi:10.1016/j.apcata.2014.09.030

Cited by 38 publications

(28 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…three carbon atoms at 2.09(1) Å, respectively assigned to one siloxide and three neosilyl ligands. The W−OSi and W−C bond distances are in the same range as those observed in the Me 3 SiO−W(Ns) 3 28 while the WO bond distance found here for the supported complex is slightly shorter than that observed for these moieties (1.729−1.746 Å), where the oxo ligand also In comparison, for the supported bipodal complex on 16 This may indicate that the oxo and a siloxy ligand are not trans to each other in this bipodal surface complex.…”

Section: ■ Results and Discussionsupporting

confidence: 52%

“…The program FEFF8 was used to calculate theoretical files for phases and amplitudes based on model clusters of atoms. 62 The value of the scale factor, S 0 2 = 0.94, was determined from the k 2 and k 3 χ(k) spectra of a reference compound, a sample of [WO(CH 2 tBu) 3 Cl] complex diluted in BN and carefully mixed and pressed as a pellet (one oxo at 1.70(1) Å, three carbon atoms at 2.10(1) Å, and one chlorine at 2.43(1) Å in the first coordination sphere, with three carbon atoms at 3.28(3) Å). 13 The refinements were performed by fitting the structural parameters N i , R i , σ i , and the energy shift, ΔE 0 (the same for all shells).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…[W(CSiMe 3 )(CH 2 SiMe 3 ) 3 ] was synthesized following the literature procedure. 17 O-Enriched [WO-(CH 2 SiMe 3 ) 3 Cl] was prepared using 90 wt % 17 O-labeled water. Propylene (Air Liquide, 99.5%) was dried and deoxygenated before use by passing it through freshly regenerated molecular sieves (3 Å) and R-3-15 catalysts (BASF).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…CONCLUSIONThe new well-defined precatalyst [(SiO)WO(CH 2 SiMe 3 ) 3 ] (2a) was obtained by grafting the molecular [WO-(CH 2 SiMe 3 )3 Cl] (1) precursor on silica dehydroxylated at 700°C, as demonstrated by mass balance analysis, elemental analysis, IR, advanced solid-state NMR (1D and 2D 1 H,13 C, 29 Si, and 17 O), EXAFS, and DFT calculations. Furthermore, the present studies aim at the comparison of precatalysts of the type [(SiO)WO(CH 2 SiMe 3 ) 2 (X)], with X = CH 2 SiMe 3 (2a), O−Si (2b), and O−Ar (Ar = 2,6-Ad-phenoxide, 3), and [(SiO)WO(CH 2 CMe 3 ) 3 ] (2c) in propylene self-metathesis under a continuous flow reactor.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Silica-Supported Tungsten Neosilyl Oxo Precatalysts: Impact of the Podality on Activity and Stability in Olefin Metathesis

et al. 2016

View full text Add to dashboard Cite

In order to establish structure−reactivity relationships in propylene metathesis as a function of the podality of tungsten oxo species bearing neosilyl ligands, we targeted the parent tris alkyl [(SiO)WOR 3 ] and bis alkyl oxo [(SiO) 2 WOR 2 ] derivatives prone to carbene formation. Thus, [WO(CH 2 SiMe 3 ) 3 Cl] (1) was grafted onto silica dehydroxylated at 700°C (SiO 2−700 ), proceeding via W−Cl cleavage to yield well-defined monopodal species [(SiO)-WO(CH 2 SiMe 3 ) 3 ] (2a) along with HCl release. On the other hand, the corresponding bipodal species [(SiO) 2 WO(CH 2 SiMe 3 ) 2 ] (2b) was obtained on SiO 2−200 by release of both HCl and TMS. The formation of these species were demonstrated by mass balance analysis, elemental analysis, IR, advanced solid-state NMR (1D and 2D 1 H, 13 C, 29 Si, and 17 O), and EXAFS. Furthermore, DFT calculations allowed understanding and rationalizing the experimental results regarding grafting selectivity. Materials 2a and 2b proved to lead to stable and efficient supported tungsten oxo catalysts for propene metathesis under dynamic conditions at 80°C. The symmetric bipodal precatalyst (expressed as [W(E)(CHR)(X)(Y)] (X = Y, E = spectator ligand)) showed somewhat higher activity than the asymmetric (X ≠ Y) counterparts. ■ INTRODUCTIONTungsten oxide supported on silica is an efficient catalyst for olefin metathesis used in industrial processes since the 1960s on a large-scale in Phillips' neohexene process and ABB Lummus' olefins conversion technology (OCT). 1 This heterogeneous catalyst is classically prepared by incipient wetness impregnation of ammonium metatungstate followed by calcination. 2 Different surface species, difficult to distinguish, are inevitably generated upon the calcination step despite modification of the preparation procedure. 3−8 The nature of the active site still needs to be determined, but WO 3 crystallites can be excluded as an active species. 1,9 The catalytic activity is attributed to a bipodal isolated tungsten(VI) center bearing an oxo ligand and carbene fragment. 10,11 Such a surface species exists only in very low concentration in the commercialized catalyst. Other tungsten species are formed during catalyst preparation and pretreatment in the presence of water, which can enhance the mobility of WO 3 on the silica support and result in poor dispersion. In order to avoid water in the preparation steps, we have developed an anhydrous route for the preparation of supported tungsten oxo metathesis (pre)-catalysts by surface organometallic chemistry. The very first well-defined silica-supported tungsten oxo species active in olefin metathesis was prepared by grafting of [OW-(CH 2 tBu 3 ) 4 ] or [OWCl(CH 2 tBu 3 ) 3 ] complexes, both affording tungsten oxo tris-neopenyl surface species grafted on silica through a single W−O−Si bond. 12,13 As expected, this material catalyzes propylene self-metathesis after in situ generation of the tungsten carbene moiety at 80°C. The striking discovery was that this catalyst showed an enhanced stability with tim...

show abstract

Section: ■ Results and Discussionsupporting

confidence: 52%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Silica-Supported Tungsten Neosilyl Oxo Precatalysts: Impact of the Podality on Activity and Stability in Olefin Metathesis

et al. 2016

View full text Add to dashboard Cite

show abstract

“…SEM micrographs revealed spherical micrograins of about 2-5 μm formed by an agglomeration of small elementary nanoparticles in the 10-25 nm range. Another family of novel mixed oxides prepared by NHSG is represented by WO3-SiO2-Al2O3 materials [182]. WO3 contents were established at 10 and 20 wt %, while the amount of Al2O3 ranged from 5 to 20 wt %.…”

Section: New Compositionsmentioning

confidence: 99%

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

et al. 2017

View full text Add to dashboard Cite

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.

show abstract