Ethylbenzene-xylene system

Figure 5. Transalkylation reactions in the ethylbenzene-xylene system.

The low relative volatility of the ethylbenzene/xylenes system requires supcrfracdo-natioQ of the aromanc Cg cut, in ocher words operation with a large number of trays and a hiah reflux ratio. 

Quantitative analysis. Spectroscopic analysis is widely used in the analysis of vitamin preparations, mixtures of hydrocarbons (e.y., benzene, toluene, ethylbenzene, xylenes) and other systems exhibiting characteristic electronic spectra. The extinction coefficient at 326 mp, after suitable treatment to remove other materials absorbing in this region, provides the best method for the estimation of the vitamin A content of fish oils. 

Nonpolar aromatic solvents such as toluene, ethylbenzene, xylene [1,2,54-57], and substituted aniline [470-471], The salts in these systems are usually a combination of AlBr3 and KBr [1,2,54-57],... 

Monton, J. B. Llopis, F. J. Isobaric vapor-liquid equihbria of ethylbenzene + m-xylene and ethylbenzene + o-xylene systems at 6.66 and 26.66 kPa J. them. Eng. Data 1994,39, 50-52... 

Chianese, A. Marrdli, L. Isobaric vapor-liquid equilibria of the ethylbenzene - p-xylene system J. Chem. Eng. Data 1985,30, 424-427... 

Alkylated aromatics have excellent low temperature fluidity and low pour points. The viscosity indexes are lower than most mineral oils. These materials are less volatile than comparably viscous mineral oils, and more stable to high temperatures, hydrolysis, and nuclear radiation. Oxidation stabihty depends strongly on the stmcture of the alkyl groups (10). However it is difficult to incorporate inhibitors and the lubrication properties of specific stmctures maybe poor. The alkylated aromatics also are compatible with mineral oils and systems designed for mineral oils (see Benzene Toulene Xylenes and ethylbenzene). ... 

Njlene Separation. -Xylene is separated from mixed xylenes and ethylbenzene by means of the Parex process (Universal Oil Products Company). A proprietary adsorbent and process cycle are employed in a simulated moving-bed system. High purity -xylene is produced. 

Figure 14.11 Typical cln omatogram obtained by using the aromatics analyser system. Peak identification is as follows 1, non-aromatics 2, benzene IS, internal standard (MEK) 3, ethylbenzene 4, p-and m-xylenes.

Monton and Llopis (1994) presented VLE data at 6.66 and 26.66 kPa for binary systems of ethylbenzene with m-xylene and o-xylene. The accuracy of the temperature measurement was 0.1 K and that of the pressure was 0.01 kPa. The standard deviations of the measured mole fractions were less than 0.001. The data at 26.66 for the ethylbenzene (1) - o-Xylene (2) are given in Table 15.8 and the objective is to estimate the NRTL and UNIQUAC parameters based on these data. 

Chen, H., Wagner, J. (1994c) Mutual solubilities of alkylbenzene + water systems at temperatures from 303 to 373 K Ethylbenzene, p-xylene, 1,3,5-trimethylbenzene, and n-butylbenezene. J. Chem. Eng. Data 39, 679-684. 

The effect of different zeolite structures and pore systems is also reflected in the data of Table II. With the intermediate pore ZSM-5, xylene is apparently much less reactive than ethylbenzene, both as an alkyl donor and acceptor, than it is with the large pore zeolites, ZSM-4 and synthetic mordenite. 

Acid sites were shown to be located in the three-pore system of protonated samples (HMWW), and methods were recently proposed for determining the distribution of these sites as well as their respective role in o-, m-, and p-xylene transformations. While xylene transformation was shown to occur in the three locations, benzene alkylation with ethylene was catalyzed by the acidic sites of the external hemicups only. Indeed, the activity for this reaction is completely suppressed by adding a base molecule (collidine) to the feed that is too bulky to enter the inner micropores. Moreover, adsorption experiments show that collidine does not influence the rate of ethylbenzene adsorption, so that the suppression of alkylation activity was not caused by pore mouth blocking. ... 

Aromatization of hydrocarbons with more than six carbon atoms is thermodynamically even more favorable than the reaction of n-hexane 28). These hydrocarbons offer more than one way of cyclization, for example, n-octane may give either o-xylene or ethylbenzene. -Nonane can even give bicyclic products (indane system) (72). 

If a stepwise cyclization mechanism is assumed—for example, for /j-Cg—two octatriene intermediates may be formed, viz. 1,3,5-octatriene would lead to ethylbenzene, and 2,4,6-octatriene to o-xylene (Scheme II). The dehydrogenation of the latter would give octatetraene, which, in turn, gives styrene via vinylcyclohexadiene. Dehydrogenation and cyclization of octatriene were reported to compete over chromia and molybdena catalysts (67) with less hydrogen present (e.g., in a pulse system with in helium carrier gas), styrene formation is enhanced. 

Abbreviations dichloroethene (DCE) trichloroethylene (TCE) perchloroethylene (PCE) tiichloroethane (TCA) benzene, toluene, ethylbenzene, and xylene (BTEX) polychlorinated biphenyls (PCBs). Pump-and-treat system only. 

The SS-SBR system can treat a wide range of contaminants, including nonhalogenated semivolatUe compounds, polynuclear aromatic (PNA) compounds, and benzene, toluene, ethylbenzene, and xylenes (BTEX). According to the vendor, the system has the advantage of control and reliability with readily adjustable soU/water ratios, nutrient amendments, and cosubstrate additions. 

At a former manufactured gas plant, 3 million gallons of wastewater contaminated with polycyclic aromatic hydrocarbons (PAHs) oil benzene, toluene, ethylbenzene, and xylenes (BTEX) and heavy metals were treated using an organoclay treatment train. The system consisted of an oil/water separator bag filters 9000 lb of organoclay and 6000 lb of GAC. Treatment costs were approximately 0.12/gal of treated water (D21556F, p. 12 D17268T, p. 29). 

VESTRIP is a system designed for the in situ treatment of soils contaminated with volatile organic compounds (VOCs) benzene, toluene, ethylbenzene, and xylenes (BTEX) and other contaminants that are amenable to soil vapor extraction (SVE). The vendor, Ejector Systems, Inc. (ESI) has combined the key components of SVE systems with an air stripper to form a product that performs the functions of both. The name, VESTRIP, is a contraction of VES (vapor extraction system) and air stripping. 

Researchers at Lehigh University have investigated the ability of ground tire rubber to sorb organic compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) to determine the feasibility of using the rubber as the sorbent media in reactive permeable barrier systems. Thus far, no field-scale work has been performed on this technology. Both batch and packed-bed column tests have been conducted. All information is from the researchers and has not been independently verified. 

NEPCCO SoilPurge soil vapor extraction systems are noncontacting, oil-free, explosion-proof vacuum systems designed to remove volatile organic compounds (VOCs) from soil in situ. According to the vendor, benzene, toluene, ethylbenzene, and xylenes (BTEX), chlorinated solvents and other hydrocarbons can be treated with SoilPurge systems. The technology can also remove radon from soil. 

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