Aromax process

Aromatic 100 solvent Aromatic 150 solvent Aroma transport Aromax process Aromizing Process AromoxC/12 AromoxDMld AromoxDMCD Aromox DMHTD AromoxT/12 Aron alpha Arosolvan process Arosurf Aroxtex 5C... 

Currendy, there are three commercially available PX adsorption processes UOP s Parex, IFP s Eluxyl, and Toray s Aromax (not to be confused with Chevron s Aromax process for reforming naphtha into aromatics). In all of these processes, the feed and desorbent inlets and the product oudet ports are moved around the bed, simulating a moving bed. 

The Aromax process was developed in the early 1970s by Toray Industries, Inc. in Japan (95—98). The adsorption column consists of a horizontal series of independent chambers containing fixed beds of adsorbent. Instead of a rotary valve, a sequence of specially designed on—off valves under computer control is used to move inlet and withdrawal ports around the bed. Adsorption is carried out in the Hquid phase at 140°C, 785—980 kPA, and 5—13 L/h. PX yields per pass is reported to exceed 90% with a typical purity of 99.5%. The first Aromax unit was installed at Toray s Kawasaki plant in March 1973. In 1994, IFP introduced the Eluxyl adsorption process (59,99). The proprietary adsorbent used is designated SPX 3000. Individual on-off valves controlled by a microprocessor are used. Raman spectroscopy to used to measure concentration profiles in the column. A 10,000 t/yr demonstration plant was started and successfully operated at Chevron s Pascagoula plant from 1995—96. IFP has Hcensed two hybrid units. 

Such a concept was originally used in a process developed and Hcensed by UOP under the name UOP Sorbex (59,60). Other versions of the SMB system are also used commercially (61). Toray Industries built the Aromax process for the production of -xylene (20,62,63). Illinois Water Treatment and Mitsubishi have commercialized SMB processes for the separation of fmctose from dextrose (64—66). The foUowing discussion is based on the UOP Sorbex process. 

Displacement-purge forms the basis for most simulated continuous countercurrent systems (see hereafter) such as the UOP Sorbex processes. UOP has licensed close to one hundred Sorbex units for its family of processes Parex to separate p-xylene from C3 aromatics, Molex tor /i-paraffin from branched and cyclic hydrocarbons, Olex for olefins from paraffin, Sarex for fruc tose from dextrose plus polysaccharides, Cymex forp- or m-cymene from cymene isomers, and Cresex for p- or m-cresol from cresol isomers. Toray Industries Aromax process is another for the production of p-xylene [Otani, Chem. Eng., 80(9), 106-107, (1973)]. Illinois Water Treatment [Making Wave.s in Liquid Processing, Illinois Water Treatment Company, IWT Adsep System, Rockford, IL, 6(1), (1984)] and Mitsubishi [Ishikawa, Tanabe, and Usui, U.S. Patent 4,182,633 (1980)] have also commercialized displacement-purge processes for the separation of fructose from dextrose. 

Aromax process, 1 665 25 171, 176 Aromizing-Aroformer process, 25 175 Arosolvan process, 3 606 P-Aroylacrylic acids, 15 486 2-Aroylbenzofurans, microwave-assisted synthesis of, 16 578 Array detector, 23 143 Array methodologies, 12 513-517 Arrays, large, 16 390 Array spotting/synthesis, in microarray fabrication, 16 385-387 Arrhenius equation, 10 85 14 622 ... 

Pt-KBaL catalyst than over conventional reforming catalysts. However, the advantage diminishes as carbon number increases, so these technologies are primarily of interest for benzene production. It is therefore more efficient to complement conventional reforming with the zeolitic reforming process when a broader range of aromatic products is desired. Relatively large crystal size has been claimed to be beneficial for example in CP Chem s AROMAX process. Residual acidity on the catalyst has been shown to be detrimental [86]. 

Aromax process -for xylenes [XYLENES AND ETHYLBENZENE] (Supplement)... 

In the Aromax process, the adsorbent can be easily loaded, unloaded or regenerated at the level of each stage. Its total life is about 10 years. The operation takes place at a temperature below 200 0 at less than 2.10 Pa absolute. The number of stages can be increased by placing two or more horizontal adsorbers in series, depending on tbe type and volume of tbe feed to be treated and the performance required. 

Fig. 4.18. S iaration of /hxykae by adsorption. Toray Aromax process.

Ahhou platinum alone or on a variety of neutral supports selectively converts n-hexane to benzene most of these catalysts deactivate rapidly due to coke formation. With the neutral zeolite KL as a support, however, much longer on-stream times are feasible and within a few years of Bernard s origind publication [130] 4e Aromax process had been developed by Chevron [131], Table 6 corrqrares the aromatic selectivity obtained with Pt-Ba KL and Pt Re Sn / AI2O3 - Cl reforming catalysts [58]. Associated with the much hi er aromatic selectivity is a lower amount of light gas production. 

The Aromax process developed by Toray (Japan) to recover p-xylene operates in a similar way to the Parex process the process is carried out at around 180 °C and a pressure of 20 bar. The yield of p-xylene is over 90%. 

The zeolites of Linde type L (LTL) were shown to exhibit the shape-selectivity effect due to a specific confinement of n-hexane as a 6-ring pseudocycle inside the zeolite structure (Maxwell in Ref. [2]). Chevron researchers published the results on hexane aromatization on Pt/Cs-B-BEA zeolite and developed the AROMAX process [28]. The reaction proceeds at 460 80°C with a rather high selectivity close to 80%, but the catalyst is sulfiir-sensitive and the commercial application can hardly be envisioned. 

The commercial catalysts described and nsed in the Chevron Aromax process were partly exchanged withbarinm ions and contained platinum (0.6-0.8%) as small particles, corresponding to an approximate formula Pt/Ba2K5Al9Si270 72. Direct dehydrocyclization of paraffins is an alternative to isomerization and reforming to increase octane nnmber of light straight-run... 

---