Effect of water on silica-supported phosphotungstic acid catalysts for 1-butene double bond shift and alkane skeletal isomerization

Bardin, Billy B.; Davis, Robert J.

doi:10.1016/s0926-860x(00)00651-7

Cited by 60 publications

(36 citation statements)

References 51 publications

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“…Figure 5 shows the only crystalline phase present for all loadings corresponded to H 3 PW 12 O 40 [17,18]. There were no reflections present due to WO 3 formation.…”

Section: Evolution Of Surface Speciesmentioning

confidence: 95%

On the active site in H3PW12O40/SiO2 catalysts for fine chemical synthesis

et al. 2005

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The surface environment and structural evolution of silica supported phosphotungstic acid (H 3 PW 12 O 40 ) catalysts have been investigated as a function of acid loading. H 3 PW 12 O 40 clusters are deposited intact upon the silica surface, adopting a StranksiKrastanov growth mode forming a two-dimensional adlayer which saturates at 45wt% acid. Intimate contact with the silica support perturbs the local chemical environment of three tungstate centres, which become inequivalent with those in the remaining cluster, suggesting an adsorption mode involving three terminal W@O groups. Above the monolayer, H 3 PW 12 O 40 clusters form threedimensional crystallites with physico-chemical properties indistinguishable from those in the bulk heteropoly acid. These H 3 PW 12 O 40 /SiO 2 materials are efficient for the solventless isomerisation of a-pinene under mild reaction conditions. Activity scales directly with the number of accessible perturbed tungstate sites at the silica interface; these are the active species.

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“…Figure 5 shows the only crystalline phase present for all loadings corresponded to H 3 PW 12 O 40 [17,18]. There were no reflections present due to WO 3 formation.…”

Section: Evolution Of Surface Speciesmentioning

confidence: 95%

On the active site in H3PW12O40/SiO2 catalysts for fine chemical synthesis

et al. 2005

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“…S2). [32,51,53] and their subsequent thermal transformation to tungstate and phosphate species, accompanied by the liberation of reactively-formed protons; [52,[54][55][56] these are unlikely to play a role in low temperature catalytic processes, wherein the primary Keggin structure and entrained water remain intact. Integrated peak intensities for the 200 C desorption (Fig.…”

Section: Eqmentioning

confidence: 99%

Support enhanced α-pinene isomerization over HPW/SBA-15

Frattini

Isaacs

Parlett

et al. 2017

Applied Catalysis B: Environmental

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Corresponding Author: a.f.lee@aston.ac.uk; +44(0)121 2044036 2 GRAPHICAL ABSTRACT Highlights  Mesoporous SBA-15 facilitates dispersion of low dimensional polyoxometallate clusters  HPW/SBA-15 is highly active for α-pinene isomerization under mild conditions  Selectivity to mono-versus polycyclic products is controlled by polyoxometallate acidity Abstract 3 A family of mesoporous SBA-15 supported H3PW12O40 (HPW) catalysts were synthesized by wetimpregnation and compared with fumed silica analogues for the solventless isomerization of α-pinene under mild conditions. Structural and acidic properties of supported HPW materials were characterized by powder XRD, HRTEM, XPS, TGA, N2 porosimetry, DRIFTS, and ammonia and propylamine chemisorption and TPD. The high area, mesoporous SBA-15 architecture facilitates the formation of highly dispersed (isolated or low dimensional) HPW clusters and concomitant high acid site densities (up to 0.54 mmol.g -1 ) relative to fumed silica wherein large HPW crystallites are formed even at low HPW loadings. α-Pinene exhibits a volcano dependence on HPW loading over the SBA-15 support due to competition between the number and accessibility of acid sites to the non-polar reactant, with the superior acid site accessibility for HPW/SBA-15 conferring a 10-fold rate enhancement with respect to HPW/fumed silica and pure HPW. Monocyclic limonene and terpinolene products are favoured over polycyclic camphene and β-pinene by weaker polyoxometallate analogues over SBA-15.

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“…The peak can be assigned to NH 3 weak acid sites [30,31]. The peak area broadly increased with the yield of 2-butene enhanced, suggesting the surface weak acid sites have positive impacts on the catalytic performances as reported [32][33][34].…”

Section: Effect Of the Surface Acidity On Catalytic Performancementioning

confidence: 99%

Room-temperature isomerization of 1-butene to 2-butene over palladium-loaded silica nanospheres catalyst

Yang

et al. 2016

Chemical Engineering Journal

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Effect of water on silica-supported phosphotungstic acid catalysts for 1-butene double bond shift and alkane skeletal isomerization

Cited by 60 publications

References 51 publications

On the active site in H3PW12O40/SiO2 catalysts for fine chemical synthesis

On the active site in H3PW12O40/SiO2 catalysts for fine chemical synthesis

Support enhanced α-pinene isomerization over HPW/SBA-15

Room-temperature isomerization of 1-butene to 2-butene over palladium-loaded silica nanospheres catalyst

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