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. A high reactivity with 40% ethylbenzene conversion and 92% styrene selectivity was obtained over the nanodiamond catalyst under oxygen-lean conditions even after a 240 h test, demonstrating the potential of this procedure for application as a promising industrial process for the ethylbenzene dehydrogenation to styrene without steam protection. World-wide capacity of styrene was reported to be 17*10. The relations for the calculation of exergy of convective flow.32. To improve the exergetic efficiency of the preheater, an Liquified Natural Gas (LNG) type of HX is coupled with the furnace. SM is the valuable product of EB dehydrogenation; however, some materials are produced as byproducts. 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. Therefore, the exergy analysis of reactors is performed by three aspects: Decreasing the inlet temperature and pressure of reactors, Replacement the steam with other suitable gas. Sluiten. During the process, vaporized EB, recycled EB, and superheated steam are fed to the first catalytic reactor. Crude styrene from the reactors is then fed into a distillation train. The second effective factor in the selection of catalyst is the temperature of feed. This product could help you, Accessing resources off campus can be a challenge. 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. The dehydrogenation reactions are as follows, The heat of reaction is provided by steam injection. Kinetic parameters of dehydrogenation of ethylbenzene to styrene monomer.29, Table 3. The purpose of the study is to decrease the work loss in the process. Find out about Lean Library here, If you have access to journal via a society or associations, read the instructions below. Several catalysts are generated for SM production. EB: ethylbenzene; SM: styrene monomer. of ethylbenzene to styrene by TEOM C. Nederlof,a P. Vijfhuizen,a V. Zarubina,b I. Melián-Cabrera,b F. Kapteijn,a and M. Makkee*a A packed bed microbalance reactor setup (TEOM-GC) is used to investigate the formation of coke as a function of time-on-stream on γ-Al 2O 3 and 3P/SiO 2 catalyst samples under different conditions for the de Araujo, JCS, Sousa Ch, BA, Oliveira, AC. EB: ethylbenzene. studied the catalytic activities of various metal oxides and phosphates for the oxidative dehydrogenation of ethylbenzene to styrene. Therefore, by considering T > T0, the exergy of heat transfer is given as follows32, Dividing the exergy by transferred heat is named exergy coefficient, The exergy of work is defined as follows32, Exergy of convective flow of a system consists of four components: kinetic exergy of the stream (EXK), potential exergy (EXP), physical exergy (EXPh), and chemical exergy (EXCh), so we have, Relations for the calculation of exergy of convective flow are given in Table 5. Figure 8. The majority of industrial production of styrene follows from the dehydrogenation of ethylbenzene. Thus, an exergy analysis specifies the source, the magnitude, and the location of thermodynamic inefficiencies in processes, especially in the thermal system.31. The styrene monomer is polymerized using free-radical initiators primarily in bulk and suspension… Styrene was first isolated in 1786 from liquidambar with steam distillation on the laboratory scale. The catalytic dehydrogenation of ethylbenzene to styrene was studied in a tubular palladium membrane reactor using a commercial styrene catalyst. Table 1. The styrene production by dehydrogenation of EB takes place in radial fixed bed reactor at 885–920 K over the potassium-promoted iron catalyst. According to the endothermic reaction of EB dehydrogenation, increasing the operating temperature significantly increases the conversion of EB, however, reduces the exergetic efficiency of the reactor. A mechanism is described indicating the role of the O2−–Fe 2019 Catalysis Science & Technology HOT Articles Thus, the CO2 injection is canceled. This reaction path produces water as a byproduct as opposed to hydrogen and is therefore an exothermic reaction. ethylbenzene to styrene. The preparation of modern catalysts involves the addition of a small amount of water to a potassium and iron oxide mixture. / Kovacevic, M.; Lefferts, Leonardus. Comparison of different catalyst employed in the styrene monomer production process. Please read and accept the terms and conditions and check the box to generate a sharing link. The exergy method of thermal plant analysis. who studied spinel oxides containing Ni, Cr, Zn, Cu, Fe, and Al. Dimopoulos, GG, Stefanatos, IC, Kakalis, NMP. Login failed. Despite the fact that they have identical building schemes, the reason for preferential adsorption of styrene compared to ethylbenzene is very different for the two frameworks. It is used primarily as an intermediate for styrene production and is also a … She did BSc and MSc from Mohaghegh Ardabili University (2005) and University of Sistan and Baluchestan (2007) respectively. If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. To lower the energy consumption of Tol/Bez column, the operating pressure of column is reduced, and the oxygen injection rate to the second reactor was optimized. It is easy. Figure 6(a) and (b) illustrates the pressure variation effects on energy consumption and toluene and benzene mole fraction. Thus, it is expected to modify the equipment with little exergetic efficiency. In fact, exergy is related to the irreversibility of the process that is the measure of performance loss. Increasing the energy consumption of industrial processes imposes a high cost of the process as well as the worldwide crisis by pollutants emission. An Fe2O3 (10 wt%)/Al2O3 (90 wt%) catalyst prepared by a coprecipitation method was found to be effective for dehydrogenation of ethylbenzene to produce styrene in the presence of CO2 instead of steam used in commercial processes. The dehydrogenation of ethylbenzene to styrene over a potassium-promoted iron oxide-based catalyst: a transient kinetic study. 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. Visitdumrongkul, N, Tippawan, P, Authayanun, S. Zhu XM, Schön M, Bartmann U, et al. For more information view the SAGE Journals Sharing page. For example, zeolite catalysts such as ZSM-5 can have reaction conditions of 1.4 to 2.7 MPa and 370 C.7, Steam is an integral part of the activation and regeneration of the catalyst. Ethylbenzene is converted to styrene at high selectivity in a multistage process in which ethylbenzene is oxidized to ethylbenzene hydroperoxide which is reacted with ethylene or propylene to produce a mixture of 1-phenylethanol and acetophenone which are converted to styrene. Members of _ can log in with their society credentials below, Ahmad Taghizadeh Damanabi and Fatemeh Bahadori, Faculty of Chemical Engineering, Urmia University of Technology, Urmia, Iran. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. In practice, 10 reactions occur during styrene production. The steam reacts with surface carbon to produce carbon dioxide and hydrogen.4, Because of the large worldwide demand for styrene, a number of alternative catalysts are being actively investigated. Kotas, TJ. Rijksuniversiteit Groningen founded in 1614 - top 100 university. In addition, the oxidation reaction between a part of the produced hydrogen and injected oxygen provides the main part of the consumed energy in the second reactor. A furnace supplies the heat of reaction for the first reactor as a preheater. As it can be seen from Table 7, the highest exergetic efficiency is obtained for the HX, compressor, and SM Tower, respectively. View or download all content the institution has subscribed to. 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. The overhead gaseous stream is sent to flare. It is a highly flammable, colorless liquid with an odor similar to that of gasoline. This monocyclic aromatic hydrocarbon is important in the petrochemical industry as an intermediate in the production of styrene, the precursor to polystyrene, a common plastic material. 5% of styrene is produced by oxidation. The purpose of the … Their findings include the fact that basic sites and acidic sites on the catalyst surface influence ethylbenzene conversion.3. Expired - Lifetime Application number Inventor Harry M Van Tassell Pressure variation effects on (a) reboiler and condenser duty, (b) toluene and benzene purity at the top of the column. This site uses cookies. Catalytic performance of Al‐MCM‐41‐supported vanadia catalysts (V/Al‐MCM‐41) with different V loading was investigated for oxidative dehydrogenation of ethylbenzene to styrene (ST) with CO 2 (CO 2 ‐ODEB). “Ethylbenzene (CAS 100-41-4) is a low molecular weight, highly flammable liquid with moderate volatility and an aromatic odor. The mentioned columns consist of EB/SM tower, SM tower, EB tower, and toluene/benzene tower (Tol/Bez tower). Minor ethylbenzene applications also include the production of chemicals other than styrene or as a solvent, as well as some agricultural and home insecticide sprays, dyes, household degreasers, rubber adhesives, and rust preventives. 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. Samir CN, Rajubhai KM and Marc AR. It is seen that, at first, increasing the oxygen injection rate increases the mole fraction of SM; however, more injection of oxygen slightly decreases SM production. Table 6 illustrates the exergy relations for each equipment. This produces water as a byproduct as is therefore an exothermic reaction. It is clear that the efficiency of Tol/Bez column is increased from 77.45 to 90.86. 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 reducing the pressure increases the exergetic efficiency of the column, while the purity reduction of products is negligible. Oxidative dehydrogenation of ethylbenzene to styrene: staged O2 feeding F Kapteijn , C Nederlof, M Makkee , V Zarubina, IV Melian-Cabrera, HJ Heeres ChemE/Catalysis Engineering In 1938 Dow chemical began using the cracking of ethylbenzene with zinc oxide as the catalyst. In thermodynamics, the exergy of a system is the maximum useful work obtained during a thermal or chemicals process from a specific energy.18 An important purpose of energy and exergy analysis is computing input and output of several possible designs before building a factory. Thus, it is important to select the most efficient process. Applied Catalysis A: General 2004 , 266 (1) , 99-108. Figure 7. He completed his BSc studies at Urmia University of Technology (2016). (1) conversion of reaction, (2) energy supplying of reactors (feed temperature), and (3) operating pressure of reactors.33 Energy supply for the first reactor is provided by latent heat of feed and superheated steam injection. Effects of (a) operating temperature and (b) pressure on ethylbenzene conversion and exergetic efficiency of first reactor (Tref=650°C). Figures 3(a) and 4(a) illustrate effects of feed temperature of reactors on conversion and exergetic efficiency. Also, decreasing the pressure of benzene–toluene column from 220 kPa to 60 kPa increases the exergetic efficiency from 77.45 to 90.86, while by optimizing the oxygen injection rate to the second reactor, the exergetic efficiency increased from 25.76 to 38.07. In the case of reactors, the conversion of dehydrogenation process is sensitive to the variation in operating conditions. A large proportion of modern day styrene is produced with an unsupported iron(III) oxide catalyst promoted with a potassium compound. “Ethylbenzene (CAS 100-41-4) is a low molecular weight, highly flammable liquid with moderate volatility and an aromatic odor. 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