Ethene, benzene alkylation with

Benzene alkylation with ethene was studied over HY, LaY, and SK-500 between 488° and 599°K and for C6 C2 from 0.7 to 10. Ethylbenzene ethylation was also studied. For propene alkylation, conditions were similar except that the temperature range was 350° to 493°K, and the study was less complete than for the ethene system. The experimental rate data typically exhibited a maximum with respect to time and underwent extended decay (Figure 1). The location of the peak is a function of reaction conditions, particularly temperature. The propene system deactivated more rapidly than the ethene system. Data for the ethene system were reproducible to 10%. 

Styrene is manufactured by alkylating benzene with ethene followed by dehydrogenation, or from petroleum reformate coproduction with propylene oxide. Styrene is used almost exclusively for the manufacture of polymers, of which the most important are polystyrene, ABS plastics and styrene-butadiene rubber. U.S. production 1980 3 megatonnes. 

There are several other examples of ZSM-5 being used commercially to reduce waste and give high product selectivity. One of these is the alkylation of benzene with ethene to produce ethylbenzene selectively. The pore size of ZSM-5 successfully minimizes dialkylation reactions whilst the ability to regenerate the catalyst avoids waste issues associated with older catalysts such as aluminium chloride. 

The most fundamental reaction is the alkylation of benzene with ethene.38,38a-38c Arylation of inactivated alkenes with inactivated arenes proceeds with the aid of a binuclear Ir(m) catalyst, [Ir(/x-acac-0,0,C3)(acac-0,0)(acac-C3)]2, to afford anti-Markovnikov hydroarylation products (Equation (33)). The iridium-catalyzed reaction of benzene with ethene at 180 °G for 3 h gives ethylbenzene (TN = 455, TOF = 0.0421 s 1). The reaction of benzene with propene leads to the formation of /z-propylbenzene and isopropylbenzene in 61% and 39% selectivities (TN = 13, TOF = 0.0110s-1). The catalytic reaction of the dinuclear Ir complex is shown to proceed via the formation of a mononuclear bis-acac-0,0 phenyl-Ir(m) species.388 The interesting aspect is the lack of /3-hydride elimination from the aryliridium intermediates giving the olefinic products. The reaction of substituted arenes with olefins provides a mixture of regioisomers. For example, the reaction of toluene with ethene affords m- and />-isomers in 63% and 37% selectivity, respectively. 

As is outlined above (Equation 1-3), with ethene in hand the way to propene and butene/butadiene is paved. Finally, two other base chemicals which can be obtained from methanol are isoprene and toluene - the first by the reaction of methanol with 1-butene and the second by alkylation of benzene with methanol. 

Alkylation. In the field of alkylation of benzene with ethene zeolite-based catalysts are used for the past 20 years, replacing the conventional A1C13- and BF3-on-alumina based processes. Here the question in case of a new plant is not whether a zeolite-based process will be selected but rather which one to choose. The Mobil-Badger process uses ZSM-5 as the catalyst and is the most widely applied though recently other zeolites (Y, Beta and MCM-22) have come to the fore. 

De-aluminated mordenites were claimedto give more active and stable catalysts for toluene disproportionation than conventional H-mordenite. Becker, Karge, and StreubeP studied the alkylation of benzene with ethene and propene over an H-mordenite catalyst. Shape-selective catalysis was found because only ethylbenzene, w-diethylbenzene, p-diethylbenzene, cumene, p-di-isopropylbenzene, and m-di-isopropylbenzene were detected in the products neither o-diethylbenzenes nor higher alkylated products were found. The results are in agreement with earlier transalkylations over H-mordenite. Catalyst aging was caused by olefin polymerization. The selectivity of Be-mordenite... 

Supported NAFION. In order to Increase the activity of the acid sites by achieving better dispersion, NAFION has been supported on silica gel, sillca/alumina, alumina, porous glass and Chromosorb T (fluoropolymer support). These supports can have either low or high surface area and various pore diameters (50-600A). Catalysts prepared in this fashion have been used in the alkylation of benzene, isomerization of normal alkanes and disproportionation of toluene. Table XVIII summarizes the results on the alkylation of benzene with ethene for NAFION and several supported catalysts (66-68). 

Table XVIII. Alkylation of benzene with ethene...

Alkylation of benzene with ethene Mesoporous ZSM-5 Activity and selectivities toward ethylbenzene higher than those of the conventional ZSM-5 [142]... 

Alkylation of benzene with ethene Mesoporous mordenite Five to sixfold increased production of ethylbenzene compared to conventional mordenite [153]... 

Aromatic compoimds also undergo photocycloaddition reactions with alkenes, leading to 1,2-, 1,3-, and (less often) 1,4-adducts, as shown for the reaction of benzene with ethene in equation 12.70. Olefins with strongly electron-withdrawing or electron-donating substituents tend to give 1,2-photoaddition products, while olefins with alkyl substituents tend to give mostly 1,3-photoaddition. 

In [182, 183] the alkylation of benzene with ethene over H-ZSM-5 was investigated. The electronic energies and vibrational frequencies of each stationary point along the reaction coordinate were calculated for the two mechanisms presented in... 

The activity of triflic acid was similar to that found in our previous studies such as alkylation of benzene with ethene[6], isopropylation of heazsaae with propene[7], isomerization and disproportionation of diethylbenzene isomers[8], and isomerization and transalkylation of diethylbenzene isomers [9]. 

Details of two related patents for the alkylation of aromatic compounds with chloroaluminate(III) ionic or chlorogallate(III) ionic liquid catalysts have become available. The first, by Seddon and co-workers [81], describes the reaction between ethene and benzene to give ethylbenzene (Scheme 5.1-51). This is carried out in an... 

Vapor-phase alkylation of benzene by ethene and propene over HY, LaY, and REHY has been studied in a tubular flow reactor. Transient data were obtained. The observed rate of reaction passes through a maximum with time, which results from build-up of product concentration in the zeolite pores coupled with catalyst deactivation. The rate decay is related to aromatic olefin ratio temperature, and olefin type. The observed rate fits a model involving desorption of product from the zeolite crystallites into the gas phase as a rate-limiting step. The activation energy for the desorption term is 16.5 heal/mole, approximately equivalent to the heat of adsorption of ethylbenzene. For low molecular weight alkylates intracrystalline diffusion limitations do not exist. 

The activation energy for the rate decay time constant with benzene ethylation over SK-500 at C6. C2 = 8 is 13.6 1 kcal/mole. That for HY in the ethene system at Ce C2 = 2 is 11 kcal/mole. For propene alkylation over HY the activation energy for rate decay is 4 kcal/mole and is independent of C6 0 8 mole ratio. 

The gas-phase tram-alkylation reaction was performed in an automated micro-flow apparatus containing a quartz fixed-bed reactor (i d. 10 mm) at lO Pa [16 vol% benzene (1, p.a., dried on molsieve), 3.2 vol% diethylbenzene (2, consisting of 25% ortho, 73% meta, 2% para isomers, dried on molsieve), N2 balance (50 mL/min), WHSV =1.5 h ] with 2.0 mL of the tube reactor filled with catalyst particles (500-850 pm sieve fraction, typically 1.4 g). Two separate saturators were connected to the inlet of the reactor for the supply of 1 and 2. The partial vapor pressure of 1 and 2 was controlled by adjusting the temperature of the saturator-condensers and the N2 flow rate. After equilibration for 30 min at the applied reaction temperatures (473 K and 673 K, heating rate 10 K/min) within a dry N2 flow (50 mL/min), benzene (1) and diethylbenzene (2) were passed throu the reactor. To prevent condensation of both reactants and products prior to GC analysis [Hewlet Packard 5710 A, column CP-sil 5CB capillary liquid-phase siloxane polymer (100% methyl) 25 m x 0.25 mm, 323 K, carrier gas N2, FID, sample-loop volume 1.01 pL], tubes were heat-traced (398 K). FID sensitivity factors and retention times were determined using ethene (99.5 %, dried over molsieve) and standard solutions of 1, 2, and ethylbenzene (3, 99%) in methanol (p.a.). The conversion of 2 was measured as a function of time [8]. 

BP Chemicals studied the use of chloroaluminates as acidic catalysts and solvents for aromatic alkylation [43]. At present, the AICI3 existing technology (based on red oil catalyst) is still used industrially, but continues to suffer from poor catalyst separation and recycle [44]. The aim of the work was to evaluate the AlCls-based ionic liquids, with the emphasis placed on the development of a clean and recyclable system for the production of ethylbenzene (benzene/ethene alkylation) and synthetic lubricants (alkylation of benzene with 1-decene). The production of linear alkyl benzene (LAB) has also been developed by Akzo [45]. The eth)4benzene experiments were run by BP in a pilot loop reactor similar to that described for the dimerization (Fig. 5.4-8). 

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