Solid phosphoric acid catalysts: The effect of free acid composition on selectivity and activity for 1-hexene dimerisation

Schwarzer, Renier Bernhard; Toit, E. Du; Nicol, Willie

doi:10.1016/j.apcata.2009.09.002

Cited by 12 publications

(12 citation statements)

References 22 publications

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“…Besides, not only temperature indicated that 1-hexene molecular transformation took place, but also the acid strength and pressure among others variables. Schwarzer et al [17] reported the effect of SPA acid strength on products distribution for 1-hexene dimerization. They suggested that, at lower acid strength, after a fast double-bond shift isomerization, linear hexenes were directly oligomerized and, at high SPA acid strength, linear hexenes were first isomerizated to skeletal hexene isomers before dimerization.…”

Section: Calculationsmentioning

confidence: 98%

“…In addition, by considering that the proposed mechanism for dimerization considered the presence of one adsorbed carbocation, the most appropriate kinetic model would be a heterogeneous one. However, for simplicity and in view of the good results obtained for 1-hexene [17] and isoamylene heterogeneously catalyzed dimerization [21], a homogeneous kinetic model will be used. When all these observations are taken into consideration, the irreversible dimerization reaction, with the stoichiometry 2 hexene ?…”

Section: Effect Of Temperaturementioning

confidence: 99%

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Liquid-Phase Oligomerization of 1-Hexene Catalyzed by Macroporous Ion-Exchange Resins

et al. 2011

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Oligomerization of pure 1-hexene catalyzed by macroporous ion-exchange resins was performed in batch experiments at 350-390 K and 2 MPa. At 373 K, after 6 h, 1-hexene conversion was practically complete and the selectivity to dimers was 56%, that to trimers 0.8 and 43.2% to double-bond isomerization. By assuming an homogeneous kinetic model for olefin dimerization of second order reaction, a value of 64-68 kJ mol -1 for apparent activation energy was obtained.

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Section: Calculationsmentioning

confidence: 98%

Section: Effect Of Temperaturementioning

confidence: 99%

Liquid-Phase Oligomerization of 1-Hexene Catalyzed by Macroporous Ion-Exchange Resins

et al. 2011

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“…Schwarzer et al [5] reported the effect of solid phosphoric acid (SPA) acid strength on products distribution for 1-hexene dimerization. They suggested that, at lower acid strength, after a fast double bond shift isomerization, linear hexenes were directly oligomerizated and, at high SPA acid strength, linear hexenes were first isomerizated to skeletal hexene isomers before dimerization.…”

Section: Reaction Networkmentioning

confidence: 99%

“…Oligomerization of light olefins (C 3 -C 5 ) [1][2][3][4] is widely found in the literature. Some works have recently appeared concerning C 6 olefins oligomerization [5][6][7][8][9] over different solid catalysts. As for 1-octene oligomerization only a few works are available in the open literature.…”

Section: Introductionmentioning

confidence: 99%

Study of the oligomerization of 1-octene catalyzed by macroreticular ion-exchange resins

Bringué

Cadenas

Fité

et al. 2012

Chemical Engineering Journal

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Oligomerization of 1-octene is a feasible alternative to improve the properties and the quality of fuels and lubricants oils. The performance of macroreticular ion-exchange resins as catalysts for such reaction has been evaluated. The experimental setup consisted of a batch stirred-tank reactor that operated at 353-393 K and 2 MPa. 1-octene conversion was practically complete and the selectivity to double-bond isomerization and dimers after 6 hours at 373 K was up to 95%, and 12%, respectively. The accessible acidity of the catalysts was the most important structural parameter for these reactions.Selectivity to dimers and branched isomers increased with increasing temperature.Cracking compounds were not detected at all. The theoretical equations derived from the proposed kinetic model fit well the experimental results.

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“…A related class of materials, solid phosphoric acid (SPA) catalysts, have been utilized for olefin oligomerization reactions for the better part of the last century. [12][13][14][15] However, there are notable differences between them and P-zeosils. For example, while Si-O-P linkages have not been detected on SPA catalyts, 16 their presence has been recently established in P-SPP.…”

mentioning

confidence: 99%

On the Acid Sites of Phosphorous Modified Zeosils

Kumar¹,

Ren²,

Pang³

et al. 2021

Preprint

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The acid sites of phosphorus-containing zeosils were probed through a combination of solid acid characterization, density functional theory calculations, and kinetic interrogations, establishing their weakly Brønsted acidic character. Due to the disparity in acid-site strength, P-zeosils catalyzed the probe chemistry of isopropanol dehydration slower than aluminosilicate zeolites by an order of magnitude on an active site basis. Propene selectivity during isopropanol dehydration remained 20-30% higher than that of aluminosilicates, illustrating the distinct nature of the weakly acidic phosphorus active sites that favored unimolecular dehydration routes. Regardless of the confining siliceous environment, the nature of phosphorous active sites was unchanged, indicated by identical apparent uni- and bi-molecular dehydration energy barriers. Kinetic isotope experiments with deuterated isopropanol feeds implicated an E2-type elimination to propene formation on phosphorus-containing materials. Comparison of KIEs between phosphorus-containing zeosils and aluminosilicates pointed to an unchanged isopropanol dehydration mechanism, with changes in apparent energetic barriers attributed to weaker binding on phosphorous-active sites that lead to a relatively destabilized alcohol dimer adsorbate. Both ex-situ alkylamine Hofmann elimination and in-situ pyridine titration characterization methods exhibited phosphorous acid site counts dependent on probe molecules identity and/or concentration, underpinning the limitations of extending common characterization techniques for Brønsted-acid catalysis to weakly acidic materials.

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Solid phosphoric acid catalysts: The effect of free acid composition on selectivity and activity for 1-hexene dimerisation

Cited by 12 publications

References 22 publications

Liquid-Phase Oligomerization of 1-Hexene Catalyzed by Macroporous Ion-Exchange Resins

Liquid-Phase Oligomerization of 1-Hexene Catalyzed by Macroporous Ion-Exchange Resins

Study of the oligomerization of 1-octene catalyzed by macroreticular ion-exchange resins

On the Acid Sites of Phosphorous Modified Zeosils

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