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ethylbenzene to styrene

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Ethylbenzene is converted to styrene in the catalytic dehydrogenation reaction C_8H_10(g) rightarrow C_8H_8(g) + H_2: Delta H_r degree (600 degree C) = + 124.5 kJ A flowchart of a simplified version of the commercial process is shown here. It is shown that using exergy analysis could improve the exergetic efficiency of the process and reduce the lost work of the unit. Then, a modified method is proposed to evaluate and optimize the energy consumption of the unit. It is evident in Figure 6 that by decreasing the operating pressure, the duty of reboiler is significantly reduced; however, the duty of condenser is slightly increased. They always go hand-in-hand and cannot be separated. In practice, 10 reactions occur during styrene production. After having worked on catalytic dehydrogenation reactions in steam, in nitrogen, in carbon dioxide and with oxygen, it appeared that these reactions show many parallels. Exergy and energy are important tools for finding the optimum energy conditions of a process.25 Exergy analysis of several processes and phenomena has been investigated by researchers;26,27 however, for EB dehydrogenation process, the exergy analysis is not performed properly. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Table 6. Therefore, six main reactions are considered for dehydrogenation process.28, According to the dehydrogenation of EB catalytic dual-site mechanism, EB is adsorbed in active sites of the catalyst, so the dehydrogenation is performed and styrene is produced along with hydrogen leaving the catalytic surface. Thus, it is essential to improve the energy consumption of processes. The potential and kinetic exergy of streams are negligible compared to total exergy of the system. A yield of 90% is typical with 65% conversion on a per pass basis.7 The distillation train is run at low pressures in order to maintain low temperatures and avoid polymerization. Figure 8. 4 Feed ratios of steam to ethylbenzene are typically between 10 and 15. Thus, it is not proposed to inject the oxygen to the first reactor. Pressure variation effects on (a) reboiler and condenser duty, (b) toluene and benzene purity at the top of the column. In this paper, exergetic analysis for dehydrogenation of ethylbenzene over a potassium-promoted iron oxide catalyst for styrene monomer production is investigated. It is a highly flammable, colorless liquid with an odor similar to that of gasoline. Also, increasing the oxygen injection rate increases the exergetic efficiency of the second reactor. Styrene is an important precursor to polystyrene, an important synthetic material. The mentioned columns consist of EB/SM tower, SM tower, EB tower, and toluene/benzene tower (Tol/Bez tower). Potassium-promoted iron oxide catalyst (SM5) is used for styrene production in the reactors. The injected steam prevents from carbon formation on the active surface of the catalyst and increases the conversion of dehydrogenation of EB;10 however, energy loss in the steam injection is high. Emad Ali, Mohamed Hadj-Kali, Energy efficiency analysis of styrene production by adiabatic ethylbenzene dehydrogenation using exergy analysis and heat integration, Polish Journal of Chemical Technology, 10.2478/pjct-2018-0006, 20, 1, (35-46), (2018). Styrenics 9 Direct Heating Unit technology Direct Heating Unit (DHU) Technology is a groundbreaking improvement to the styrene industry. The feed is mixed by recycled EB, and after passing a furnace, it enters to the first reactor. Ethylbenzene is an organic compound with the formula C6H5CH2CH3. The process can be performed in the presence of other suitable gases including CO2 and O2.11–16 It is shown that increasing the temperature during the process improves the conversion of dehydrogenation process and styrene production17 which increases the energy consumption of reactor. Exergy and exergoeconomic analyses of thermally coupled reactors for methanol synthesis. / Kovacevic, M.; Lefferts, Leonardus. Also, in the absence of steam, the probability of coke formation increases. Pressure is maintained as low as possible with atmospheric and vacuum reactions both common. Also, by more injection of oxygen, the production of hydrogen as an important byproduct decreases, while the temperature of products increases. Styrene monomer (SM) is a valuable material and extensively used in the petrochemical industry to produce polystyrene, styrene–butadiene rubber, acrylonitrile butadiene styrene, and styrene–acrylonitrile copolymers.1–7 Several processes are proposed for styrene production. Its rate of industrial production is the fourth highest after monomers such as vinyl chloride.Consider the endothermic dehydrogenation of ethylbenzene (EB) to produce styrene … If you have access to a journal via a society or association membership, please browse to your society journal, select an article to view, and follow the instructions in this box. I have read and accept the terms and conditions, View permissions information for this article. Login failed. The crude ethylbenzene/styrene product is … For the first reactor, the heat of reaction is supplied by steam injection and for the second reactor by steam and O2 injection. the site you are agreeing to our use of cookies. These plastics are commonly used in toys, television shells, and insulation foam. The output stream of the second reactor is cooled and divided into two gaseous and liquefied streams in a flash tank. Thus, an exergy analysis specifies the source, the magnitude, and the location of thermodynamic inefficiencies in processes, especially in the thermal system.31. The temperature of the reaction train can be lowered when newer catalysts are utilized. Operating conditions and geometrical parameters of reactors. Due to the high energy consumption of the unit, exergy analysis was used to optimize the energy consumption of styrene production unit and associated fractionation unit. If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. It is evident that by the addition of LNG, the duty of furnace decreases and the exergetic efficiency of furnace increases. The activity of a V2O5/TiO2–Al2O3 catalyst for oxidative dehydrogenation of ethylbenzene to styrene with various V2O5 loadings in the presence of CO2 and N2 was studied. The schematic of modified dehydrogenation of EB is illustrated in Figure 2. The catalytic dehydrogenation of ethylbenzene to styrene was studied in a tubular palladium membrane reactor using a commercial styrene catalyst. EB: ethylbenzene; SM: styrene monomer. The other suitable gas is oxygen. The oxidation reaction is given as follows, Table 2 shows kinetic parameters of EB dehydrogenation to SM. This produces water as a byproduct as is therefore an exothermic reaction. Contact us if you experience any difficulty logging in. For this purpose, an LNG HX that has high exergetic efficiency is added to reduce the duty of preheater. Styrene, also known as vinyl benzene as well as many other names (see table), is an organic compound with the chemical formula C 6 H 5 CH=CH 2.Under normal conditions, this aromatic hydrocarbon is an oily liquid.It evaporates easily and has a sweet smell, although common impurities confer a less pleasant odor. Access to society journal content varies across our titles. The iron oxide mixture is then extruded to form 4 to 6 mm diameter pellets. Simply select your manager software from the list below and click on download. The unit consists of three reactors (one of the reactors is a bypass reactor), four towers, a compressor, a heat exchanger (HX), and a flash tank. The liquefied stream is sent to a set of four distillation columns in order to separate styrene from unreacted EB and the byproducts of reaction mainly toluene and benzene. It is observed that coupling of an Liquified Natural Gas (LNG) type of heat exchanger with preheater improves the exergetic efficiency of the preheater. As it can be seen from Table 7, the highest exergetic efficiency is obtained for the HX, compressor, and SM Tower, respectively. Also, exergetic efficiency of the second reactor is increased from 25.76 to 38.07. Since methanol synthesis is an exothermic reaction, the produced heat can be used for supplying energy for endothermic reactions like styrene production. who studied spinel oxides containing Ni, Cr, Zn, Cu, Fe, and Al. Visitdumrongkul, N, Tippawan, P, Authayanun, S. Zhu XM, Schön M, Bartmann U, et al. Heat capacity parameters for each piece in the gas mixture.30. EB: ethylbenzene. In fact, exergy is related to the irreversibility of the process that is the measure of performance loss. By continuing to browse The energy required for producing styrene in the presence of CO 2 is 1.5 × 10 8 cal per t -styrene, which is 20% lower than that via one-step pathway estimated in our previous study. Lean Library can solve it. The second effective factor in the selection of catalyst is the temperature of feed. In addition, the output exergy/input exergy of the second reactor increases from 0.23 to 0.51 and Tol/Bez column increases from 0.82 to 0.96. 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