Isomerization of 1-Butene to Isobutene at Low Temperature

Klerk, Arno de

doi:10.1021/ie049585m

Cited by 28 publications

(38 citation statements)

References 30 publications

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“…However, Quan et al [10] showed that 1-hexene is readily isomerised by ZSM-5 and a wide spread of different hexene isomers are formed. This is also observed by authors who used SPA as catalyst [11], [12] and [13]. Since it is known that the reactivity, as well as the selectivity towards dimerisation, of the different isomers increase, with the degree of substitution of the carbocation [14], [15] and [16], the quality of the gasoline product produced can vary according to the distribution of the different isomers [17].…”

Section: Introductionsupporting

confidence: 62%

Kinetic model for the dimerisation of 1-hexene over a solid phosphoric acid catalyst

Schwarzer

Toit

Nicol

2008

Applied Catalysis A: General

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Batch kinetic experiments at 150 °C, 200 °C and 250 °C showed that the reaction can be modeled with a three step sequential reaction scheme. This involves firstly linear isomerisation of 1-hexene followed by skeletal isomerisation and finally dimerisation and cracking. The first and last steps in the sequence are modeled as reversible reactions. When first order reaction kinetics is assumed for each of the reactions, the model gave a very good representation of the experimental data. In order to test the validity of the series pathway hypothesis, the reaction was repeated with a skeletal hexene isomer -2,3-dimethyl-2-butene (DMB) -as reactant. Although the rate and equilibrium constants for the third reaction step as obtained from the 1-hexene conversion data gave a good prediction of the DMB conversion at 200 °C and 250 °C, it failed to predict the reaction rate at 150 °C. This suggests that a different reaction pathway -where linear hexene isomers are directly converted to dimer product -becomes more significant at lower temperatures. The relatively high activation energy of the linear to skeletal hexene reaction may be to blame for this observation. However, this needs to be confirmed be further experimental work. The same equilibrium conversions of both 1-hexene and DMB were observed at all three temperatures investigated-suggesting that the equilibrium conversion is independent of the type of hexene isomer in the reaction mixture. Graphical abstractA sequential reaction pathway is proposed for this reaction. The three reaction steps included in the model are firstly linear isomerisation of 1-hexene followed by skeletal isomerisation and finally dimerisation and cracking (see figure). The model is tested by using a skeletal hexene isomer -2,3-dimethyl-2-butene (DMB) -as reactant.

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Section: Introductionsupporting

confidence: 62%

Kinetic model for the dimerisation of 1-hexene over a solid phosphoric acid catalyst

Schwarzer

Toit

Nicol

2008

Applied Catalysis A: General

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“…This could also be seen from the TMP and TMB contents ( Figure 3) and the fact that TMB was formed at all (because it implies the formation of a primary carbocation 1 ). It has been suggested that 1-butene plays an important role in the formation of highly branched products via a lowtemperature isomerization pathway, 30 which could offer an explanation for these observations. The importance of 1-butene in the feed has been recognized in some oligomerization models as well.…”

Section: Resultsmentioning

confidence: 99%

Oligomerization of Fischer−Tropsch Olefins: Effect of Feed and Operating Conditions on Hydrogenated Motor-Gasoline Quality

Klerk

Engelbrecht

Boikanyo

2004

Ind. Eng. Chem. Res.

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Oligomerization of Fischer-Tropsch-derived olefins over a solid phosphoric acid catalyst was studied to improve the quality of the hydrogenated motor-gasoline. It was shown that, with a narrow-cut Fischer-Tropsch butene mixture, rich in 1-butene and low in isobutene, a hydrogenated motor-gasoline with an RON and an MON of 86-88 could be produced at 80% olefin conversion. The influence of propene and pentenes was investigated, and a reactivity sequence for C 3 -C 5 mixtures could be established: isobutene > methylbutenes > n-butenes ) propene > n-pentenes. It was noted that 1-butene was closer in behavior to isobutene than to 2-butene and had to be treated as such to yield the highest-quality product. It was advantageous to oligomerize 1-butene-rich feed at 160°C or less and to exclude propene and n-pentenes from the reaction mixture. These effects could be explained.

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“…Apparently, the double-bond shift reaction (DBS) is faster than skeletal rearrangement since it involves the migration of only one hydrogen atom instead of an alkyl group. Additionally, a series of other complex reactions such as disproportionation, cyclization, polymerization, oligomerization and cracking, may occur alongside with DBI reaction [3][4][5][6][7][8][9][10]. Catalyst type and operational temperature are key factors for the selectivity of DBI reaction, while an increase of the catalyst acidity contributes to raise the yield of side products [11].…”

Section: Introductionmentioning

confidence: 99%

“…Most transition metals metal oxides or metallocene alkyne complexes are capable to catalyze DBI reactions [4,[7][8][9] as well as alumina as catalyst treated with HCl or as support shows a high yielding rate for DBS reaction [10]. Additionally, based on reaction mechanism, it is expected that sulfate metal oxides would also catalyze DBI reactions, although, other reactions such as oligomerization or cracking require also catalysts with strong acid sites [3,21].…”

Section: Introductionmentioning

confidence: 99%

1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

et al. 2008

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Sulfated mixed oxides, SO 4 = /Ni-Al-O and SO 4 = / Zr-Al-O were evaluated for double bond isomerization (DBI) of 1-hexene using helium and hydrogen as carrier gases. The increase of temperature from 100 to 200°C seems to favor the deprotonation pathway and contribute to increase the 1-hexene conversion for both catalysts and without regard of the carrier gas. The results indicate that temperature it is the main factor that contributes to improve both conversion and selectivity towards (cis ? trans)-2-hexene, while the reductive atmosphere beneficiate only the SO 4 = /Ni-Al-O catalyst performance, as hydrogen prevents this catalyst from a fast deactivation.

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Isomerization of 1-Butene to Isobutene at Low Temperature

Cited by 28 publications

References 30 publications

Kinetic model for the dimerisation of 1-hexene over a solid phosphoric acid catalyst

Kinetic model for the dimerisation of 1-hexene over a solid phosphoric acid catalyst

Oligomerization of Fischer−Tropsch Olefins: Effect of Feed and Operating Conditions on Hydrogenated Motor-Gasoline Quality

1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

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