Ethylbenzene styrene synthesis from

Ethjlben ne Synthesis. The synthesis of ethylbenzene for styrene production is another process in which ZSM-5 catalysts are employed. Although some ethylbenzene is obtained direcdy from petroleum, about 90% is synthetic. In earlier processes, benzene was alkylated with high purity ethylene in liquid-phase slurry reactors with promoted AlCl catalysts or the vapor-phase reaction of benzene with a dilute ethylene-containing feedstock with a BF catalyst supported on alumina. Both of these catalysts are corrosive and their handling presents problems. 

The ODH of ethylbenzene to styrene is a highly promising alternative to the industrial process of non-oxidative dehydrogenation (DH). The main advantages are lower reaction temperatures of only 300 500 °C and the absence of a thermodynamic equilibrium. Coke formation is effectively reduced by working in an oxidative atmosphere, thus the presence of excess steam, which is the most expensive factor in industrial styrene synthesis, can be avoided. However, this process is still not commercialized so far due to insufficient styrene yields on the cost of unwanted hydrocarbon combustion to CO and C02, as well as the formation of styrene oxide, which is difficult to remove from the raw product. 

Example 2 Synthesis of a styrene process. Styrene, the monomer of polystyrene, has enjoyed strong market growth over the past two decades. It is prepared starting with benzene and ethylene which react to form ethylbenzene the ethylbenzene is dehydrogenated to yield styrene. Further information about styrene manufacture, properties, and uses is available. 3 In this example, the steps involved in synthesizing a process to produce styrene from ethylbenzene will be illustrated. The procedure followed is analogous to that followed by the PIP program. 

Sample Problem 18.7 Design a synthesis of styrene from ethylbenzene. 

Flowsheet analysis and HEN synthesis problem. A material balance has been completed for a process to manufacture styrene and an ethylbenzene byproduct from reactions involving methanol and toluene. See Figure 10.61 for a block flow diagram of the process with the results of material balance calculations. You are to develop an optimal heat exchanger network for this process. Note that ... 

Sales demand for acetophenone is largely satisfied through distikative by-product recovery from residues produced in the Hock process for phenol (qv) manufacture. Acetophenone is produced in the Hock process by decomposition of cumene hydroperoxide. A more selective synthesis of acetophenone, by cleavage of cumene hydroperoxide over a cupric catalyst, has been patented (341). Acetophenone can also be produced by oxidizing the methylphenylcarbinol intermediate which is formed in styrene (qv) production processes using ethylbenzene oxidation, such as the ARCO and Halcon process and older technologies (342,343). 

There are nine chemicals in the top 50 that are manufactured from benzene. These are listed in Table 11.1. Two of these, ethylbenzene and styrene, have already been discussed in Chapter 9, Sections 5 and 6, since they are also derivatives of ethylene. Three others—cumene, acetone, and bisphenol A— were covered in Chapter 10, Sections 3-5, when propylene derivatives were studied. Although the three carbons of acetone do not formally come from benzene, its primary manufacturing method is from cumene, which is made by reaction of benzene and propylene. These compounds need not be discussed further at this point. That leaves phenol, cyclohexane, adipic acid, and nitrobenzene. Figure 11.1 summarizes the synthesis of important chemicals made from benzene. Caprolactam is the monomer for nylon 6 and is included because of it importance. 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

The base-catalyzed reactions were carried out over Na, K, Cs modified Y zeolites for example the conversion of toluene to ethylbenzene and styrene in presence of methanol over CsY zeolite. Also the side chain alkylation of picolines with methanol was carried out over CsY. CsY is also used in the synthesis of 4-methylthiazole from acetone, methylamine and SO2... 

Since no synthetic chemistiy infrastructure was available at the Department (or, indeed, the Institute) before 2008, polyciystalline samples of catalysts had to be obtained from external, often industrial, partners. In order to produce model systems in house, researchers in the Department of Inorganic Chemistry developed a suite of instruments allowing the synthesis of metal oxides by physical vapor deposition of elements and by annealing procedures at ambient pressure. They chose the dehydrogenation of ethylbenzene to styrene on iron oxides as the subject of their first major study. Figure 6.6 summarizes the main results. The technical catalyst (A) is a complex convolution of phases, with the active sites located at the solid-solid interface. It was possible to synthesize well-ordered thin films (D) of the relevant ternary potassium iron oxide and to determine their chemical structure and reactivity. In parallel. Department members developed a micro-reactor device (B) allowing them to measure kinetic data (C) on such thin films. In this way, they were able to obtain experimental data needed for kinetic modeling under well-defined reaction conditions, which they could use to prove that the model reaction occurs in the same way as the reaction in the real-life system. Thin oxide... 

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