Octane catalysts zeolite catalyst

Octane-Enhancing Zeolitic FCC Catalysts, Julius Scherzer... 

Jacobs et al. employed an acidic zeolite catalyst for the racemization of sec-alcohols, which occurs through the formation of carbocations [44] (Figure 4.19). The KR is catalyzed by CALB in the presence of vinyl octanoate as acyl donor. DKR takes place successfully in a biphasic system (octane/H2O, 1 1) at 60 °C. 

ISAL A hydrotreating process for removing sulfur and nitrogen compounds from petroleum fractions without reducing their octane values. Developed by Intevep SA, the research and technology arm of Venezuela s state petroleum company PDVSA. A proprietary zeolite catalyst first saturates the olefins and then isomerizes them to higher octane-value compounds. 

Octgain A hydrofinishing process which reduces the sulfur and olefin content of gasoline without reducing its octane number. A zeolite catalyst is used. Developed by Mobil in 1994. Chem. Eng. (N.Y.), 1994,101(7), 25. 

Par-Isom [Paraffin isomerization] A process for isomerizing light naphtha in order to improve the octane number. The proprietary catalyst was developed by Cosmo Oil Company and Mitsubishi Heavy Industries, and the process was developed by UOP. The oxide catalyst is claimed to be more efficient than zeolite catalysts currently used for this process. 

Butane isomerization is usually carried out to have a source of isobutane which is often reacted with C3-C5 olefins to produce alkylate, a high octane blending gasoline [13]. An additional use for isobutane was to feed dehydrogenation units to make isobutene for methyl tert-butyl ether (MTBE) production, but since the phaseout of MTBE as an oxygenate additive for gasoline, this process has decHned in importance. Zeolitic catalysts have not yet been used industriaUy for this transformation though they have been heavily studied (Table 12.1). 

There are three different kinds of octane catalysts in current use. Some are based in part on an active non-zeolite matrix composed of a porous silica/alumina component. Others are based on low cell size (2.425-2.428 nm) ultra stable faujasite (USY), a catalyst composition developed in 1975 (2) for the purpose of octane enhancement. A third catalyst system makes use of a small amount (1-2%) of ZSM-5 as an additive. While the net effect in all cases is an increase in the measured octane number, each of the three catalytic systems have different characteristic effects on the composition and yield of the gasoline. The effects of the ZSM-5 component on cracking is described in other papers of this symposium and will not be discussed here. 

By avoiding the acid catalysis mechanism of the conventional FCC zeolite catalyst (optimized over the years for high octane gasoline), the novel MAB catalyst will produce substantially lower aromatics in the liquid products than is possible by less extreme FCC catalyst adaptations. By changing the FCC reaction system, it is possible to overcome the MAB catalyst low activity drawback and achieve slurry yields compatible with those observed in maximum distillate operation in today s FCC units. 

Scherzer, J. Octane-Enhancing Zeolitic FCC Catalyst Scientific and Technical Aspects. New York Marcel Dekker, 1990. 

In this paper, the results of the isomerization of hexane, heptane and octane over a Mo2C-oxygen-modified-catalyst, a Mo03-carbon-modified catalyst and a Pt//l-zeolite catalyst, at atmospheric pressure, are presented. Also, the results for a conventional Pt/Al203 catalyst are presented for the isomerization of hexane. Then, the effect of pressure on the isomerization of heptane and octane over the molybdenum catalysts and the Pt//l-zeolite catalyst is shown. Finally, the ability of the molybdenum catalysts to catalyse the isomerization reaction at high conversion with high selectivity even with hydrocarbons larger than hexane is demonstrated this is not possible over the Pt catalysts. The differences between the catalysts are discussed in terms of the reaction mechanisms. 

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