Isomerization octane number

The financial benefit of integrating the membrane separation unit was evaluated by comparing the additional expenses (investment costs and operating costs) induced by installing and operating the membrane separator and the gain related to the increase in the isomerate octane number induced by installing the membrane separator. 

The preceding information indicates the paths to follow in order to obtain stocks of high octane number by refining. The orientation must be towards streams rich in aromatics (reformate) and in isoparaffins (isomerization, alkylation). The olefins present essentially in cracked gasolines can be used only with moderation, considering their low MONs, even if their RONs are attractive. 

As a complementary process to reforming, isomerization converts normal paraffins to iso-paraffins, either to prepare streams for other conversions nCi —> /C4 destined for alkylation or to increase the motor and research octane numbers of iight components in the gasoiine pooi, i.e., the C5 or Cs-Ce fractions from primary distillation of the crude, or light gasoline from conversion processes, having low octane numbers. 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

The Hysomer process produces an increase of about 12 octane numbers in suitable naphtha feedstocks. The process can be operated in conjunction with the Isosiv process (Union Carbide Corp.) for the separation of normal and isoparaffins, achieving complete isomerization of a C-5—C-6 stream. The combined process is trade named TIP (total isomerization process), and results in increases in octane numbers of about 20, rather than the 12 obtained with a once-through Hysomet treatment. 

Isomerization. Isomerization of any of the butylene isomers to increase supply of another isomer is not practiced commercially. However, their isomerization has been studied extensively because formation and isomerization accompany many refinery processes maximization of 2-butene content maximizes octane number when isobutane is alkylated with butene streams using HF as catalyst and isomerization of high concentrations of 1-butene to 2-butene in mixtures with isobutylene could simplify subsequent separations (22). One plant (Phillips) is now being operated for this latter purpose (23,24). The general topic of isomerization has been covered in detail (25—27). Isomer distribution at thermodynamic equiUbrium in the range 300—1000 Kis summarized in Table 4 (25). 

Like propane, n-hutane is mainly obtained from natural gas liquids. It is also a hy-product from different refinery operations. Currently, the major use of n-hutane is to control the vapor pressure of product gasoline. Due to new regulations restricting the vapor pressure of gasolines, this use is expected to he substantially reduced. Surplus n-butane could be isomerized to isobutane, which is currently in high demand for producing isobutene. Isobutene is a precursor for methyl and ethyl tertiary butyl ethers, which are important octane number boosters. Another alternative outlet for surplus n-butane is its oxidation to maleic anhydride. Almost all new maleic anhydride processes are based on butane oxidation. 

Octahedral Having the symmetry of a regular octahedron. In an octahedral species, a central atom is surrounded by six other atoms, one above, one below, and four at the comers of a square, 176 complex in transitional metals, 418-420 geometric isomerism, 415 Octane number, 584... 

Some other processes are based on a severe hydrotreatment followed by a stage for octane recovery. Octgain from ExxonMobil [57] and ISAL from UOP-Intevep [58], Deep desulfurization is achieved by an increase in severity, causing lost in octane by olefins saturation. In the first case, in a second reactor octane number is recovered by a combination of cracking and isomerization reactions. In the latter case, the catalyst employed during desulfurization possess isomerization capabilities inhibiting an excessive octane lost. Other mentioned functionalities of the catalyst include dealkylation and conversion. 

In the HTFT oil refinery the light oil and <345°C fraction of the decanted oil (obtained by passing the decanted oil through a vacuum flash drum) were clay treated. Clay treatment is similar to Bauxite treatment and is used to increase the octane number of the naphtha by acidic isomerization and to reduce the oxygenate content of the oil. Processing the LTFT and HTFT in separate (and different)... 

Acidic isomerization of the C5-C6 naphtha and some heavy alcohols from the aqueous product refinery (not shown in Figure 18.5) produced a reasonable-quality olefinic motor gasoline (Table 18.10). The octane value varied depending on the carbon number distribution of the feed, which could result in a product with an octane number up to ten units higher. 

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. 

Penex [Pentane and hexane isomerization] A process for converting n-pentane and n-hexane and their mixtures into branched-chain pentanes and hexanes of higher octane number by catalytic isomerization. The catalyst is similar to the Butamer catalyst. The product is used in high-octane gasoline. First commercialized by UOP in 1958. More than 75 units were operating as of 1996. 

Tenex-Plus A process for increasing the octane number of gasoline by a combination of hydrogenation and isomerization. See also Ben-Sat. 

Isomerization (Figure 4.15) converts n-butane, n-pentane and n-hexane into then-respective isoparaffins of substantially higher octane number. The straight-chain... 

Olefins, unlike paraffins, do not show significant gains in octane number with skeletal isomerization (see Table 14.2). As a result, olefin isomerization is not a useful octane boosting strategy. However, tertiary olefins (olefins with three alkyl substituents on the double bond), do react fairly readily with olefins to form ethers, which do have good octane numbers-for example, methyl tert-butyl ether (MTBE). 

Isomerization of paraffins using current octane catalysts under current conditions is favorably away from equilibrium. Additional isomerization activity would make more normal paraffins and a lower octane at FCC temperatures. A much more olefinic gasoline is a possibility. However, additional olefins above the current olefin levels of 10-30% would have decreased effectiveness, especially on the motor octane number. 

While such data are not included in this report, our work has also shown that in FCC operations the acidic matrix is able to better crack and isomerize more n-paraffins, thus reducing the n-paraffin content in middle distillate and thereby the characteristic high cloud point associated with it, while also raising octane number by removing or isomerizing n-paraffins in the gasoline fraction. 

Chromium hexacarbonyl is used as an additive to gasoline to increase the octane number as a catalyst in isomerization and polymerization reactions and in the preparation of chromium mirror or plate. 

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