Ethylbenzene, calculated benzene

Styrene, used in the manufacture of polystyrene plastics, is made by the extraction of hydrogen atoms from ethylbenzene. The product obtained contains about 38% styrene (C6HsCH=CH2) and 62% ethylbenzene (C6HsCH2CH3),by mass. The mixture is separated by fractional distillation at 90 °C. Determine the composition of the vapor in equilibrium with this 38%-62% mixture at 90 °C. The vapor pressure of ethylbenzene is 182 mmHg and that of styrene is 134 mmHg. Calculate benzene-toluene liquid solution... 

For example, ia the iadustriaHy important alkylation of benzene with ethylene to ethylbenzene, polyethylbenzenes are also produced. The overall formation of polysubstituted products is minimized by recycling the higher ethylation products for the ethylation of fresh benzene (14). By adding the calculated equiUbrium amount of polyethylbenzene to the benzene feed, a high conversion of ethylene to monoethylbenzene can be achieved (15) (see also... 

The fraction of benzene, toluene, styrene and ethylbenzene condensed can be determined from phase equilibrium calculations. The percent of the various components entering... 

Have you wondered about those funny curves drawn over the NMR peaks They re electronic integrations and they can tell you how many protons there are at each chemical shift. Measure the distances between the horizontal lines just before and just after each group. With a cheap plastic ruler I get 52 mm for the benzene ring protons, 21 mm for the —CH2— protons, and about 30 mm for the —CH3 protons. Now you divide all the values by the smallest one. Well, 21 mm is the smallest, and without a calculator I get 2.47 1 1.43. Not even close. And how do you get that 0.47 or 0.43 proton Try for the simplest whole number ratio. Multiply everything by 2, and you ll have 4.94 2 2.86. This is very close to 5 2 3, the actual number of protons in ethylbenzene. Use other whole numbers the results are not as good and you can t justify the splitting pattern—3 split BY 2 and 2 split BY 3—with other ratios. Don t use each piece of information in a vacuum. 

The ethylbenzene CSTR considered in Chapter 2 (Section 2.8) is used in this section as an example to illustrate how dynamic controllability can be studied using Aspen Dynamics. In the numerical example the 100-m3 reactor operates at 430 K with two feedstreams 0.2 kmol/s of ethylene and 0.4 kmol/s of benzene. The vessel is jacket-cooled with a jacket heat transfer area of 100.5 m2 and a heat transfer rate of 13.46 x 106 W. As we will see in the discussion below, the steady-state simulator Aspen Plus does not consider heat transfer area or heat transfer coefficients, but simply calculates a required UA given the type of heat removal specified. 

These are described in the next section. Note that when atom balances are used, Dluzniewski and Adler (17) show that "fictitious elements" prevent reaction. Consider a reactor that produces ethylbenzene by reaction of benzene and ethylchloride in the presence of AICI3 catalyst. For calculation of phase equilibrium, downstream of the reactor, fictitious element A replaces a hydrogen atom in benzene (C0H5A) and the moles of each species remain unchanged. 

The by-product benzene plus toluene and the fuel gas rates are calculated, from Eqs. (2) and (3), to be 5.2 and 3.6 lb/h, respectively. The raw materials and product values can be compared again. The benzene-toluene mixture is valued at 0.10/lb and the fuel gas at 0.18/lb (both based on heating value) condensed water has no value. The value of the feeds, ethylbenzene and steam, is 33.54/104 lb of styrene. The value of the product plus the by-products and fuel gas is 44.84/104 lb of styrene. The value of the outputs still exceeds that of the inputs, but the margin has narrowed. 

Figure 4.10 Typical results of the calculations of expected variations in the stationary concentrations of components at the benzene (B) alkylation with ethylene (E) along a plug-flow reactor of length L at 210 C x is the distance from the inlet of the reactor. The calculations were performed in terms of the Horiuti-Boreskov-Onsager reciprocity relations to optimize the composition of the initial reaction mixture so the outlet and inlet diethylbenzene (DBE) concentrations would be identical, which means 100% selectivity of the process in respect to the target product ethylbenzene (EB).

Table I compares calculated concentrations of benzene, toluene, and ethylbenzene at several locations near the refinery with reported values for typical urban, rural, and remote settings from past EPA studies (Shah and Heyerdahl, 1988). For benzene, refinery impacts at the fenceline were similar to those observed in a rural environment. At the nearby residence, benzene concentrations were similar to those observed in a remote pristine setting. Ethylbenzene impacts were similar to benzene. Toluene impacts were somewhat higher, falling between typical rural and urban air quality. No comparable data were available for xylene. Automobiles and an adjacent power plant contribute some of these chemicals to the air. Biogenic (natural) sources also contribute. In the entire middle Atlantic region, natural sources provide about 40% of airborne hydrocarbons, with a higher percentage in more rural areas like Yorktown (Placet and Streets, 1989).

A mixture of three components (60% benzene, 30% toluene and 10% ethylbenzene) is separated in a DWG with sieve plates and lateral downcomers. The vapor pressures Ry of components were calculated on the basis of Antoine equation, and the trays efficiency was set at value 1 (equilibrium trays). 

We are tempted to proceed a little bit further, and examine the development of the whole flowsheet in relation with the reaction system. Let s suppose that the feedstock is of high purity ethylene and benzene. Because recycling a gas is much more costly than a liquid, we consider as design decision the total conversion of ethylene. The benzene will be in excess in order to ensure higher conversion rate, but also to shift the equilibrium. The equilibrium calculation can predict with reasonable accuracy the composition of the product mixture for given reaction conditions. Then polyalkylates, mainly diethylbenzene can be reconverted to ethylbenzene in a second reactor. 

The gas phase alkylation of toluene with methanol was carried out in a fixed-bed tubular reactor at atmospheric pressure. Samples were sieved to retain particles with 0.35-0.40 mm in diameter for catafytic measurements. A mixture of toluene/methanol of 1 1 molar ratio was vaporized in a preheating section and delivered to the reactor. The reaction was carried out at 400 °C, employing a space velocity (WHSV) of 2 h. Toluene conversion (Xtoi) was calculated as Xtoi (%) = [EYj / (ZYj + Ytoi.)]100, where ZYj is the molar fiactions of the aromatic reaction products, including benzene, and Ytoi is the outlet molar fiaction of toluene. The selectivity to product j was determined as Sj (%) = [Y/EYj.lOO. The Sei-bz selectivity includes the sum of ethylbenzene and styrene, which are the side-chain alkylation products. In-situ poisoning experiments were carried out by doping the toluene/methanol mixture with either acetic acid or 3,5-dimethyl pyridine in a concentration range between 0-15000 ppm... 

Two standard tables (American and metric system of units) are used to calculate weight and volume of benzene, toluene, xylenes mixture and isomers, styrene, cumene, and ethylbenzene as well as aromatic hydrocarbons and cyclohexane. Tables provide volume corrections for these solvents in a temperature range from -5 to 109 F (-20.5 to 43°C). 

Properties Colorless to white, odorless, tasteless crystals. Mp 161°C bp decomposes H-ti/2 16 years at 25°C and pH 7 log 2.96 (calculated) log 3.20 (calculated) S soluble in acetone, benzene, 1,4-dioxane, ethanol, ethylbenzene, ethyl ether, hexane, methyl ethyl ketone, pentane, toluene, xylene and many other common organic solvents but is only moderately soluble in methanol, isopropanol and some oils S 17 mg/L at 20°C. 

Properties Golden yellow leaflets or crystals. Mp 193°C (sublimes >32°C) bp 275°C at 2 mmHg log 4.19 (calculated) log 5.62 (calculated) S moderately soluble in acetone, acetic acid, benzene, o-dichlorobenzene ( 4 wt %), TVyA-dimethylformamide, 1,4-dioxane, ethanol, ethylbenzene, ethyl ether, ethyl acetate, toluene, xylene ( 4 wt %) and many other organic solvents S 1.0 mg/L at 25" C. 

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