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Ethylbenzene hydroperoxide temperature

Ethylbenzene Hydroperoxide Process. Figure 4 shows the process flow sheet for production of propylene oxide and styrene via the use of ethylbenzene hydroperoxide (EBHP). Liquid-phase oxidation of ethylbenzene with air or oxygen occurs at 206—275 kPa (30—40 psia) and 140—150°C, and 2—2.5 h are required for a 10—15% conversion to the hydroperoxide. Recycle of an inert gas, such as nitrogen, is used to control reactor temperature. Impurities ia the ethylbenzene, such as water, are controlled to minimize decomposition of the hydroperoxide product and are sometimes added to enhance product formation. Selectivity to by-products include 8—10% acetophenone, 5—7% 1-phenylethanol, and <1% organic acids. EBHP is concentrated to 30—35% by distillation. The overhead ethylbenzene is recycled back to the oxidation reactor (170—172). [Pg.139]

The oxidation step is similar to the oxidation of cumene to cumene hydroperoxide that was developed earlier and is widely used in the production of phenol and acetone. It is carried out with air bubbling through the Hquid reaction mixture in a series of reactors with decreasing temperatures from 150 to 130°C, approximately. The epoxidation of ethylbenzene hydroperoxide to a-phenylethanol and propylene oxide is the key development in the process. [Pg.484]

Chemical vapor deposition (CVD) using TiC was used to prepare Ti/Si02, Ti/MCM-41, and Ti/MCM-48 catalysts. These catalysts were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption, and were used to catalyze the epoxidation of propylene to propylene oxide (PO) with in situ prepared ethylbenzene hydroperoxide (EBHP). CVD time and CVD temperature affected the catalyst performance significantly. The optimum temperature range was 800-900 °C, and the optimum deposition time was 2.5-3 h. The maximum PO yields obtained in a batch reactor were 87.2, 94.3, and 88.8% for Ti/Si02, Ti/ MCM-41, and Ti/MCM-48, respectively. Ti/MCM-41 had higher titanium... [Pg.373]

FIGURE 14.4 Influence of TiCU deposition temperature on ethylbenzene hydroperoxide (EBHP) conversion and propylene oxide yield for Ti/MCM-41 catalysts. [Pg.381]

In the peroxidation reactor ethylbenzene is converted with air at 146 °C and 2 bar to form a 12-14 wt% solution of ethylbenzene hydroperoxide in ethylbenzene. The reaction takes place in the liquid phase and conversion is limited to 10% for safety reasons. The reactor is a bubble tray reactor with nine separate reaction zones. To avoid decomposition of the formed peroxide the temperature is reduced from 146 °C to 132 °C over the trays. In the epoxidation reactor the reaction solution is mixed with a homogeneous molybdenum naphthenate catalyst. Epoxidation of propylene in the liquid phase is carried out at 100-130 °C and 1-35 bar. The crude product stream (containing PO, unreacted propylene, a-phenylethanol, acetophenone, and other impurities) is sent to the recycle column to remove propylene. The catalyst can be removed by an aqueous alkali wash and phase separation. The crude PO, obtained as head stream in the crude PO column, is purified by distillations. The unconverted reactant ethylbenzene can be recycled in the second recycle column. The bottom stream containing a-phenylethanol is sent to the dehydration reactor. The vapor-phase dehydration of a-phenylethanol to styrene takes place over a titanium/alumina oxide catalyst at 200-280 °C and 0.35 bar (conversion 85%, selectivity 95%). [Pg.703]

A 9 g sample of the freshly prepared hydroperoxide decomposed after 20 min at ambient temperature, bursting the 20 ml glass container. A 30% solution of the hydroperoxide in ethylbenzene is stable. [Pg.986]

In concomitance with the displacement observed by i.r., an evolution of the catalytic activity has been observed while studying the liquid-phase epoxidation of cyclohexene in the presence of (EGDA)- Mo(VI), freshly prepared or after four months of conditioning at room temperature under inert atmosphere. As usual, the appearance of epoxide was followed by gas chromatographic analyses or by direct titration of oxirane oxygen and the disappearance of hydroperoxide was monitored by iodometric titration. In figure we report concentration-time for typical runs in ethylbenzene at 80°C obtained with the experimental procedure already described (ref. 9). It may be seen that with a freshly prepared catalyst an induction period is observed which lowers the initial catalytic activity. Our modified Michaelis-Menten type model equation (ref. 9) cannot adequately fit the kinetic curves obtained due to the absence of kinetic parameters which account for the apparent initial induction period (see Figure). [Pg.434]

An alternative method for the manufacture of styrene (the oxirane process), uses ethylbenzene that is oxidized to the hydroperoxide and reacts with propylene to give phenylmethylcarbinol (or methyl benzyl alcohol) and propylene oxide. The alcohol is then dehydrated at relatively low temperatures (180 to 400°C) by using an acidic silica gel (Si02) or titanium dioxide (Ti02) catalyst. [Pg.491]

The oxidation reactions were performed in a closed, mechanically stirred 100 ml glass batch reactor under Ar. For the epoxidation of a-isophorone, 0.2 g catalyst, 9 ml solvent, 7.2 mmol cumene (internal standard) and 77 mmol olefin were introduced into the reactor. The slurry was heated to the reaction temperature and the reaction stauted by adding 13.4 mmol t-butyl hydroperoxide (TBHP, ca. 3 M in isooctane) from a dropping funnel to the vigorously stirred slurry (n = 1000 min ). For the epoxidation of P-isophorone, 20 ml ethylbenzene solvent, 61 mmol P-isophorone, 7.2 mmol cumene and 5.6 mmol TBHP or ciunene hydroperoxide (CHP) were introduced into the reactor in this order. The solution was heated to 80 °C and... [Pg.330]

Several solvents have been tested in the epoxidation of a- isophorone with t-butyl hydroperoxide (TBHP). The best performance of the aerogel was observed in low polarity solvents such as ethylbenzene or cumene (Table 1). In these solvents 99 % selectivity related to the olefin converted was obtained at 50 % peroxide conversion, independent of the temperature. Rasing temperature resulted in increasing initial rate and decreasing selectivity related to the peroxide. The low peroxide efficiency is explained by the homol5d ic peroxide decomposition. Protic polar solvents were detrimental to the reaction due to their strong coordination to the active sites. There was no epoxide formation in water. [Pg.331]

If there is a CH2 or a CH group in a-position to an aromatic system, it is attacked preferentially by oxygen with formation of a substituted benzyl hydroperoxide, 317 examples being tetralin, ind ne, fluorene, cumene, p-xylene, and ethylbenzene. Temperatures required for autoxidation of such compounds are lower than for alkanes. [Pg.308]

Oxidation. Ethylbenzene is oxidized to hydroperoxide by air injection in the liquid phase. This takes place simultaneously in several series of reactors in parallel, each containing three elements. These are empty vessels, generally of titanium, in which a residence time of abont one hour is maintained. In each series, these units operate at. decreasing temperature as the reaction advances. The heat liberated by the reaction is... [Pg.368]

An issue which deserves further mention is the environmentally fiiendly nature of TS-l/H Oj system. It involves the use of a safe silica based catalyst, titanium silicalite, and a reagent, hydrogen peroxide, which yields water as the coproduct. This holds for the in situ route illustrated in Scheme I and also for the epoxidation of propylene with preformed hydrogen peroxide, either used as an aqueous solution (72) or extracted by means of die epoxidation solvent (Scheme 11). Hazardous chemicals, such as chlorine, performic or other organic peracids, are not required in the process. The disposal of chlorinated salts or the recycle of brine (chloroydrin process) and any possible burden resulting from the coproduction of odier chemicals (styrene and r-butanol in the hydroperoxide route) are eliminated. The liquid phase oxidation of isobutane and ethylbenzene with air under pressure and at high temperature, to produce... [Pg.67]

The main negative effect is contributed by the steps of autoinitiation (steps 10,29), due to the radical decomposition of hydroperoxide and the non-symmetric quinolide peroxide (step 29), as well as by the step of exchange of phenoxyl radicals for the peroxyl ones (27). It should be noted that the role of these steps in ethylbenzene oxidation inhibited by BHT is exclusively negative at all the studied temperatures, including the one at 37°C. [Pg.162]


See other pages where Ethylbenzene hydroperoxide temperature is mentioned: [Pg.374]    [Pg.194]    [Pg.157]   
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