Processes ISOMAR

Isomaltose [499-40-1] Isomaltulose Isomanmde Isomar process Isomenthone [491-07-6]... 

Commercial processes which use a dual-functional catalyst are Octafining, Isomar, and Isolene. 

UOP s Isomar process (56,117—119) was originally developed to use dual-functional catalysts. The first-generation catalyst contained Pt and halogen on alumina. Operating conditions using this catalyst were 399°C 1.25 MPa 2 LHSV and H2/hydrocarbon ratio of 6 1. A Cg naphthene concentration of... 

In 1993, UOP commercialized an improved Pt-based catalyst, 1-210. This catalyst is based on a molecular sieve, but not an alurninosihcate zeoHte. UOP claims that yields ate about 10% better than those for 1-9 catalyst. EB to xylenes conversion is about 22—25% with a Cg aromatics per pass loss of about 1.2—1.5%. As discussed below, UOP s Isomar process can also use zeoHte catalysts which convert EB to benzene rather than to xylenes. UOP has hcensed over 40 Isomar units. 

Xylenes. The main appHcation of xylene isomers, primarily p- and 0-xylenes, is in the manufacture of plasticizers and polyester fibers and resins. Demands for xylene isomers and other aromatics such as benzene have steadily been increasing over the last two decades. The major source of xylenes is the catalytic reforming of naphtha and the pyrolysis of naphtha and gas oils. A significant amount of toluene and Cg aromatics, which have lower petrochemical value, is also produced by these processes. More valuable p- or 0-xylene isomers can be manufactured from these low value aromatics in a process complex consisting of transalkylation, eg, the Tatoray process and Mobil s toluene disproportionation (M lDP) and selective toluene disproportionation (MSTDP) processes isomerization, eg, the UOP Isomar process (88) and Mobil s high temperature isomerization (MHTI), low pressure isomerization (MLPI), and vapor-phase isomerization (MVPI) processes (89) and xylene isomer separation, eg, the UOP Parex process (90). 

Isolene II A catalytic process for converting ethylbenzene to mixed xylenes. The catalyst is platinum on an acidic support. Developed by Toray Industries, Japan. See also Isomar. Otani, S., Chem. Eng. (N.Y.), 1973, 80(21), 106. 

Isomar [Isomerization of aromatics] A catalytic process for isomerizing xylene isomers and ethylbenzene into equilibrium isomer ratios. Usually combined with an isomer separation process such as Parex (1). The catalyst is a zeolite-containing alumina catalyst with platinum. Developed by UOP and widely licensed by them. It was first commercialized in 1967 by 1992, 32 plants had been commissioned and 8 others were in design or construction. See also Isolene II. 

Processes such as UOP s Isomar process are used to carry out isomerization of C8 aromatic species so that p-xylene can be removed selectively from the mixture of xylenes. The reaction is equilibrium controlled, so a continuous isomerization process is used. As is seen below, both aluminophosphate and aluminosilicate zeotypes are capable of catalyzing the reaction (Table 12.13). 

The catalysts for xylene isomerization with EB dealkylahon are dominated by MFI zeolite. The de-ethylation reaction is particularly facile over this zeolite. There have been several generations of catalyst technology developed by Mobil, now ExxonMobil [84]. The features in their patents include selectivation and two-catalyst systems in which the catalysts have been optimized separately for deethylation of EB and xylene isomerization [85-87]. The crystallite size used for de-ethylation is significantly larger than in the second catalyst used for xylene isomerization. Advanced MHAI is one example. The Isolene process is offered by Toray and their catalyst also appears to be MFI zeoUte-based, though some patents claim the use of mordenite [88, 89]. The metal function favored in their patents appears to be rhenium [90]. Bimetallic platinum catalysts have also been claimed on a variety of ZSM-type zeolites [91]. There are also EB dealkylation catalysts for the UOP Isomar process [92]. The zeolite claimed in UOP patents is MFI in combination with aluminophosphate binder [93]. 

Commercial plants UOP is the world s leading licensor of process technology for aromatics production. UOP has licensed more than 600 separate process units for aromatics production, including over 200 CCR Platforming units, 134 Sulfolane units, 80 Parex units, 61 Isomar units, 44 Tatoray units and 38 THDA units. 

Application To produce a desired xylene isomer (or isomers) from a mixture of C8 aromatics using the UOP Isomar and Parex processes. 

Application The Isomar process isomerizes C8 aromatics to mixed xylenes, to maximize the recovery of paraxylene in a UOP aromatics complex. Depending on the type of catalyst used, ethylbenzene (EB) is also converted into xylenes or benzene. 

Description The Isomar process re-establishes an equilibrium distribution of xylene isomers, essentially creating additional paraxylene from the remaining ortho- and meta-xylenes. The feed typically contains less than 1 wt% of paraxylene and is first combined with hydrogen-rich recycle gas and makeup gas. The combined feed is then preheated by an exchanger (1) with reactor effluent, heated in a fired heater (2) and raised to the reactor operating temperature. The hot feed vapor is then sent to the reactor (3), where it is passed radially through a fixed-bed catalyst. 

Economics A summary of the investment cost and the utility consumption for a typical Isomar unit (processing capacity of 1.84 million mtpy) is shown below. The estimated inside battery limits (ISBL) erected cost for the unit assumes construction on a US Gulf Coast site in 2003 ... 

Tables 4.15 a and 4.15 b provide an idea of the peifonnance of the Octahning process and of the Isomar catalyst for different ethylbenzene contents in the feed.

Berger, C V. "Match Isomar with Pares". Hydrocarbon Processing, 52(9) 173-174(1973). 

Economics A summary of the investment cost and the utility consumption for a typical Isomar unit (processing capacity of 3.56 million metric... 

Octafining Increasing prop, of p-xylene 10-30 425-480 Pt/2 olite Hz Comparable with Isomar (UOF)y Isoforming Exxori) and Isarom IFF) processes... 

Silady PJ. UOP isomar process. In Meyers RA, editor. Handbook of Petroleum Refining Processes, 3rd edition. New York McGraw-Hill 2004. 

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