Tungsten Oxide on Silica Catalyst for Phillips' Triolefin Process

Heckelsberg, Louis F.; Banks, R. L.; Bailey, G. C.

doi:10.1021/i360025a007

Cited by 45 publications

(12 citation statements)

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“…The stability of WOx surface species and their tendency to react with the olefins is also dictated by the structure of the surface tungsten oxide species [15]. Well dispersed tetrahedral tungsten species react better with the olefins to yield the desired carbene species [11,13,35]. On comparing the catalytic performance of the pristine catalysts (Fig.…”

Section: Metathesis Activity and Selectivitymentioning

confidence: 99%

NaOH modified WO3/SiO2 catalysts for propylene production from 2-butene and ethylene metathesis

Maksasithorn

Debecker

Praserthdam

et al. 2014

Chinese Journal of Catalysis

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Section: Metathesis Activity and Selectivitymentioning

confidence: 99%

NaOH modified WO3/SiO2 catalysts for propylene production from 2-butene and ethylene metathesis

Maksasithorn

Debecker

Praserthdam

et al. 2014

Chinese Journal of Catalysis

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“…1 While dispersed Re and Mo oxides are active at low to moderate temperatures, W oxide offers better stability, easier regeneration, and greater resistance to poisoning than supported Mo or Re oxides, and for these reasons dispersed W oxide is often preferred for large-scale industrial processes. 3,8,9 Extensive work on the characterization of supported tungsten oxides demonstrates the presence of species such as isolated mono-oxo ((SiO) 4 WO) or dioxo ((SiO) 2 W(O) 2 ) structures and dimeric and oligomeric tungsten surface species as well as bulk WO 3 nanoparticles. 10−12 Previous investigations of propene metathesis over supported WO x have shown that the rate of metathesis is approximately first order in the partial pressure of propene 13 and that pretreatment of the catalyst under an inert 7,14 or reducing gas 15 can enhance its activity relative to that observed after pretreatment in air.…”

Section: Introductionmentioning

confidence: 99%

Propene Metathesis over Supported Tungsten Oxide Catalysts: A Study of Active Site Formation

Howell

Bell

2016

ACS Catal.

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A detailed investigation was conducted on the factors influencing the properties of silica-supported tungsten oxide catalysts for propene metathesis. A principal goal of this work was to identify the processes involved in the formation of catalytically active sites. To probe the influence of dispersion, samples were prepared across a range of W loadings using two methods of catalyst preparation: incipient wetness impregnation of amorphous silica and ion exchange of mesoporous SBA-15. The samples were characterized by nitrogen adsorption, UV−vis, Raman, and X-ray absorption spectroscopy (XAS). Catalytic activity was observed to increase with W surface concentration up to the point where WO 3 nanoparticles formed. The catalytic performance of all samples was enhanced 2-fold by pretreatment in He, in comparison to pretreatment in air. In situ characterization of samples pretreated in He by Raman and XAS shows an increase in the relative concentration of isolated dioxo W(6+) species relative to mono-oxo W(6+) species, and in situ XAS data collected during propene metathesis indicated that a similar conversion occurs for air-pretreated samples in the presence of propene. For both air-and He-pretreated catalysts an activation period was observed, during which the activity increased and attained steady-state activity. This period was significantly longer for air-pretreated catalysts and was accompanied by the transient formation of acetone. While acetone was not observed during the much shorter transient of He-pretreated samples, in situ XAS provided evidence of reduction occurring in these samples upon contact with propene. It is also notable that, independent of the manner of catalyst preparation or pretreatment, the rate of propene metathesis is first order in propene and exhibits an activation energy of 200 kJ/mol. A model is proposed to explain why only a fraction of the isolated tungstate species is active for propene metathesis (∼5%) and why this fraction increases with increasing concentration of W dispersed on silica.

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“…Olefin metathesis has been an intensely studied reaction due to its wide use [ 1 ], in industrial applications, especially in petrochemistry [ 2 ], i.e., the Phillips Triolefin (PTP) process or the Shell Higher Olefin Process (SHOP) [ 3 – 4 ]. Additionally, the olefin metathesis reaction has provided a useful tool in polymerisation [ 5 – 6 ], as well as in the pharmaceutical industry in the formation of C=C bonds.…”

Section: Introductionmentioning

confidence: 99%

The activity of indenylidene derivatives in olefin metathesis catalysts

Voccia

Nolan

Cavallo

et al. 2018

Beilstein J. Org. Chem.

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The first turnover event of an olefin metathesis reaction using a new family of homogenous Ru-based catalysts bearing modified indenylidene ligands has been investigated, using methoxyethylene as a substrate. The study is carried out by means of density functional theory (DFT). The indenylidene ligands are decorated with ortho-methyl and isopropyl groups at both ortho positions of their phenyl ring. DFT results highlight the more sterically demanding indenylidenes have to undergo a more exothermic first phosphine dissociation step. Overall, the study emphasises advantages of increased steric hindrance in promoting the phosphine release, and the relative stability of the corresponding metallacycle over classical ylidene ligands. Mayer bond orders and steric maps provide structural reasons for these effects, whereas NICS aromaticity and conceptual DFT confirm that the electronic parameters do not play a significant role.

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Tungsten Oxide on Silica Catalyst for Phillips' Triolefin Process

Cited by 45 publications

References 0 publications

NaOH modified WO3/SiO2 catalysts for propylene production from 2-butene and ethylene metathesis

NaOH modified WO3/SiO2 catalysts for propylene production from 2-butene and ethylene metathesis

Propene Metathesis over Supported Tungsten Oxide Catalysts: A Study of Active Site Formation

The activity of indenylidene derivatives in olefin metathesis catalysts

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