Isomerization of n-butane

Analogously, tnflic acid isomerizes n-butane into 2 methylpropane [80, 81] Interestingly, perfluorobutanesulfonic acid, which is of similar strength as tnflic acid, does not catalyze the isomerization of n-butane [50]... 

Figure 6-8. The UOP Butamer process for isomerization of n-butane to isobu-...

E. Baburek and J. Novakova, Isomerization of n-butane over acid zeolites, role of Brpnsted and Lewis acid sites, Appl. Catal. A Gen., 185 (1999) 123-130. 

In a typical reaction, for example the isomerization of n-butane to Ao-butane, the rate of the reaction can be described either by the disappearance of a reactant or the appearance of a product with time (Equation 2.3). The rate can also be determined by measuring the increase in concentration of the products, for example ... 

S. Bettina, T. Markus, and K. C. Bettina, Supercritical isomerization of n-butane over sulfated zirconia. Part 1 catalyst lifetime, Ind. Eng. Chem. Res. 40, 2161—2112 (2001). 

A. Corma, M. I. Juan-Rajadell, J. M. Lopez-Nieto, A. Martinez, and C. Martinez, A comparative smdy of S04 /Zr02 and zeolite Beta as catalysts for the isomerization of n-butane and the alkylation of isobutane with 2-butene, Appl. Catal. A 111, 175-189 (1994). 

These reactions can also be performed over a strong acid catalyst at reaction temperatures that are lower than over zeolites. Because of this, isomerization of M-butane over Zr02-supported sulfate catalysts was initially proposed by Hino and Arata. They proposed these catalysts as being effective in butane isomerization at room temperature, a reaction that does not take place, even in 100% sulphuric acid. For this reason, these catalysts were considered as solid superacids, since they are active and selective in the isomerization of n-butane to isobutane at... 

Figure 13.4 Isomerization of n-butane to isobutane on beta zeolite and sulfated zirconia catalysts at different reaction temperatures.

Kumar, N., Villegas, J.I., Salmi, T., Murzin, D.Y., and Heikkila, T. (2005) Isomerization of n-butane to isobutane over Pt-SAPO-5, SAPO-5, Pt-H-morden-ite and H-mordenite catalysts. Catal. Today, 100, 355-361. 

D.Y. (2006) Isomerization of n-butane to isobutane over Pt-modified beta and ZSM-5 zeolite catalyst catalyst deactivation and regeneration. Chem. Eng. ]., 120, 83-89. 

Brouwer, D.M. (1968) HF-SbFs catalyzed isomerization of n-butane-1-13C. Recueil, 87. 

AH these processes faced competition from the on-demand production of isobutene through a combined process of isomerization of n-butane to isobutane... 

According to an early report, sulfated zirconia promoted with 1.5% Fe and 0.5% Mn increased the rate of isomerization of n-butane to isobutane by several orders of magnitude at modest temperature (28°C).299 This reactivity is surprising, since the isomerization of n-butane in strong liquid acids takes place at a rate much lower than that of higher alkanes, which is due to the involvement of the primary carbocationic intermediate. In addition, other solid acids, such as zeolites, did not show activity under such mild conditions. Evidence by isotope labeling studies with double-labeled n-butane unequivocally shows, however, that the isomerization of... 

Studies with unpromoted and Pt-promoted solid acids, specifically, H morde-nite,308 Pt Beta-zeolite,313 and acidic polyoxometalate cesium salts314,315 applied in the presence of hydrogen, showed that the isomerization of n-butane follows a monomolecular pathway. This consists of dehydrogenation on the metal site and isomerization on acidic sites. A new study using isotope labeling provided direct... 

Solid superacids may be made by treating ordinary solid add catalysts with strong Br0nsted or Lewis acids. For example, if freshly precipitated titanium hydroxide or zirconium hydroxide is treated with sulfuric acid and calcined in air at 500 °C. a very active solid acid catalyst results. The solids consist mainly of the metal dioxides with sulfate ions coordinated to the metal ions on the surface. Likewise, a superacid solid catalyst can be made by treating these metal oxides with antimony penlafluonde. Both catalysts contain both Br nsted and Lewis acid sites, and they arc sufficiently active to catalyze the isomerization of n-butane at room temperature.26... 

The combination of Pt or Pd with CS25H0.5PW12O40 (Cs2.5) is also very effective for the isomerization of n-butane to isobutane (381). The reaction rate and selectivity for conversion to isobutane are summarized in Table XXXIV (381, 382). The activity in the presence of H2 changed little with time. Pt- and Pd-Cs2.5 show very high selectivities (94-96%) relative to those of Pt/SO -/ Zr02 (47%) and Pt/HZSM-5 (34%), whereas the activities of Pt- and Pd-Cs2.5 for the formation of isobutane are comparable to those of Pt/HZSM-5 and Pt/S04 /Zr02. Pt-Cs2.5 catalyzes the reaction even at 473 K and 0.05 atm of H2. 

Activity and Selectivity for Skeletal Isomerization of n-Butane in the Presence of H2 and Metal-Promoted Catalysts at 573 K (381. 382)... 

The ability to introduce several components into solution during the sol-gel step makes this approach especially attractive for the preparation of multicomponent oxides and bimetallic catalysts. Of course, the solution chemistry becomes more complex with additional components. But many of the concepts that we have discussed, such as matching relative precursor reactivity and changing the microstructure of the gel network, remain valid in principle. Furthermore, a promoter or an active species can be introduced the same way. There have been recent reports on the onc-step preparation of zirconia-sulfate aerogels [45] and Li/MgO catalysts [46], These samples arc active in the isomerization of n-butane and the oxidative coupling of methane, respectively. 

Isomerization of n-butane to /-butane increases octane from 94 to 101. 

Table 1. Isomerizations of n-butane comparison of estimated and experimental values for the heats of reaction...

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