Application of a WO3/SiO2 catalyst in an industrial environment: part I

Schalkwyk, C. van; Spamer, A.; Moodley, D.J.; Dubé, Tiffany; Reynhardt, Jan P. K.; Botha, J.M.

doi:10.1016/s0926-860x(03)00534-9

Cited by 50 publications

(28 citation statements)

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“…The yield of higher alkenes also stabilized after 3 h. The higher alkene yield for the standard catalyst exhibited a distinct maximum at 2 h, unlike the potassium-doped catalysts that maintained the corresponding yield up to 6 h online. The yield of ethylene and propylene showed similar trends to those reported by van Schalkwyk et al for the metathesis of 1-heptene [4].…”

Section: Preliminary Experimentssupporting

confidence: 87%

“…The higher operating temperature required for tungsten-based systems is beneficial as it renders the catalyst resilient to these poisons but also reduces the yield of primary products due to the increased propensity for isomerization, cracking, and secondary metathesis reactions catalyzed by strong acid sites on the catalyst surface [4]. The yield of primary reaction products may be improved through the use of alkali metal acid site inhibitors, e.g., potassium ions [5].…”

Section: Introductionmentioning

confidence: 99%

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Metathesis of 1‐Hexene over Heterogeneous Tungsten‐Based Catalysts

2015

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1-Hexene metathesis was performed over standard and potassium-doped WO 3 /SiO 2 catalysts. The samples were tested at various reaction temperatures, molar feed compositions, and space times. Under the applied reaction conditions, doping with potassium reduced the isomerization and cracking activity of the catalyst by at least half and improved the yield of detergent-range alkenes twofold. However, increasing the potassium loading to a higher amount resulted in a significant reduction in the metathesis activity as both Brønsted and Lewis acid sites were affected. Optimum operating conditions for the yield of detergent-range alkenes were identified using response surface methodology.

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Section: Preliminary Experimentssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Metathesis of 1‐Hexene over Heterogeneous Tungsten‐Based Catalysts

2015

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“…The reaction takes place in the presence of a WO 3 /SiO 2 catalyst at [260°C and 30-35 bar [4]. WO 3 /SiO 2 catalyst is of the most commonly used among supported metathesis catalysts [5,6], and in many cases there are indications of chemical interaction between the silica support and tungsten compounds [7]. The metathesis activity is highly dependent on the structure and properties of surface tungsten compound influenced by the loading amount of W [8].…”

Section: Introductionmentioning

confidence: 99%

Effect of tungsten oxide loading on metathesis activity of ethene and 2-butene over WO3/SiO2 catalysts

Zhao

Chen

Gao

et al. 2009

Transition Met Chem

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The metathesis of ethene and 2-butene to propene was studied over WO 3 /SiO 2 catalysts with various WO 3 loadings (2, 4, 8, 12, 16, and 24 wt%). The 2-butene conversion and propene selectivity increased greatly with WO 3 loading increasing from 2 to 8 wt%, reached maximum at 8-12 wt% WO 3 loading, and then decreased when the WO 3 loading was higher than 12 wt%. From the above results and taking the economics into account, the optimal amount of WO 3 loading was *8 wt%. The catalysts were characterized by physico-chemical and spectroscopic techniques to elucidate the effect of different tungsten oxide loadings on the metathesis reactivity of ethene and 2-butene. The characterization data indicated that three types of tungsten species (i.e., surface tetrahedral tungsten species, surface octahedral polytungstate species, and WO 3 crystallites) were present in the catalysts. It was found that WO 3 was not the active centers, and surface tetrahedral tungsten species might be more active than octahedral polytungstate species in metathesis reaction. The reduced form of tungsten species [W ?4 , W ?5 , and W ?(6-y) (0 \ y \ 1)] may be the suitable state of W species acting as metathesis active centers.

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“…-see Table 3) is rather low (3-13 C%) and can only partially explain the high propene selectivity. Coke formation is typically observed in the metathesis over supported tungsten catalysts [19,20]. Coke formation was observed over all catalyst (with exception of WO 3 / SiO 2 ) in the limited run time of these experiments (see Fig.…”

Section: Resultsmentioning

confidence: 74%

“…45 wt%. Formation of coke on metal oxide catalysed reactions is thought to be catalysed by the acid sites present within the catalyst [20]. Both Lewis acid sites and Brønsted acid sites may catalyse the formation of coke, the former by strongly interacting with basic species in the feed, and the latter via the normal carbocation route for coke formation [21].…”

Section: Introductionmentioning

confidence: 99%

On the Product Formation in 1-Butene Metathesis over Supported Tungsten Catalysts

2010

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1-Butene metathesis was performed over 8 wt% tungsten catalysts supported on silica, silica-alumina and c-Al 2 O 3 . Under the applied reaction conditions, 1-butene metathesis yields with a relatively large selectivity iso-butene in addition to the expected metathesis products. The isobutene selectivity is high for catalysts with a relative low activity and decreases with increasing metathesis activity. It is deduced that iso-butene formation involves surface tungsten complexes, whose formation inhibits the metathesis activity.

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Application of a WO3/SiO2 catalyst in an industrial environment: part I

Cited by 50 publications

References 9 publications

Metathesis of 1‐Hexene over Heterogeneous Tungsten‐Based Catalysts

Metathesis of 1‐Hexene over Heterogeneous Tungsten‐Based Catalysts

Effect of tungsten oxide loading on metathesis activity of ethene and 2-butene over WO3/SiO2 catalysts

On the Product Formation in 1-Butene Metathesis over Supported Tungsten Catalysts

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