Ethylbenzene molar concentrations

Figures 4—7. Comparison of the decomposition of ethylbenzene and yields of different products or ratios of them in relative molar concentrations at various temperatures in the NPA (9 A experiments at different runs) with...

To the mixture 22.7 g (0.54 mol) dry lithium chloride and 100 mL THF at -15°C was added 160 mL 2 molar lithium diisopropylamide (0.32 mol) in heptane/THF/ethylbenzene was added. Then a solution of 36.6 g (0.16 mol) N-[3-(lH-benzimidazol-2-yl)-propyl]-N-methylacetamide in 140 mL toluene was added, the solution was stirred for 2 hours, and a further 155 mL toluene was added. (S)-6-Fluoro-l-isopropyl-3,4-dihydro-lH-naphthalen-2-one (29.9 g, 0.15 mol), in 15 mL toluene was added. After stirring at -10°C for 4 hours, the resulting solution was added to 200 mL ice water. The pH of the resulting mixture was adjusted to 7-8 by addition of a 71 g concentrated hydrochloric acid. The organic layer washed with water, then the solvents removed under reduced pressure to give 96 g of (lS,2S)-N-[3-(lH-benzimidazol-2-yl)propyl]-... 

The presence of hydrogen theoredcally allows the conversion of the eth benzene to xylenes. In practice, the ethylbenzene is not converted if its content in the reactor feedstock is less than 8 per cent weight, a value corresponding to the thermodynamic equilibiium around 410°C. Above this concentration, it can be shown experimentally that the amount converted in relation to this threshold, called the approach to equHibrinm , does not depend on the ethylbenzene content, but on that of naphthenic Cg compounds present in the reaction medium. For example, it may be 40 per cent with 6 molar per cent of these saturated cycles, and over 70 per cent with 10 per cenL... 

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... 

Styrene is produced by the catalytic dehydrogenation of ethylbenzene at 1.2 atm and a temperature of about 575°C, as described by Smith (1981). The reaction is sufficiently endothermic, with an ATR of about —460°C, such that if the reactor were operated adiabati-cally with a feed of pure ethylbenzene, the temperature of the reacting fluid would decrease to such an extent that the reaction rate would be unduly compromised, resulting in a very large reactor volume. To maintain a reasonable temperature, a large amount of steam is added to the feed (typically with a molar ratio of steam to ethylbenzene equal to 20 1), which is preheated to 625°C before entering the reactor (Figure 6.1b). The steam is inert and is easily recovered from the reactor effluent by condensation. The presence of the steam reduces the reaction rate because the styrene concentration is reduced, but the reactor can be operated adiabatically in a simple manner. 

The optimum molar ratio of ethylene to benzene is around 0.9 as ethylene concentration increases, so the level of polyalkylated benzene derivatives rises. In order to assure high selectivity with satisfactory conversion rates, the synthesis of ethylbenzene is carried out industrially with molar ratios of ethylene to benzene of only 0.35 to 0.55. 

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