Alkylation toluene

Synthesis ofp-Ethyltoluene. j )i7n7-Ethyltoluene, the feedstock for j )-methylstyrene, is difficult to separate from the products of toluene alkylation with ethane using conventional acidic catalysts. The unique configurational diffusion effect of ZSM-5 permits -dialkylbenzenes to be produced in one step. In the alkylation of toluene with ethene over a chemically modified ZSM-5, -ethyltoluene is obtained at 97% purity (58). 

Laminates. Laminate manufacture involves the impregnation of a web with a Hquid phenoHc resin in a dip-coating operation. Solvent type, resin concentration, and viscosity determine the degree of fiber penetration. The treated web is dried in an oven and the resin cures, sometimes to the B-stage (semicured). Final resin content is between 30 and 70%. The dry sheet is cut and stacked, ready for lamination. In the curing step, multilayers of laminate are stacked or laid up in a press and cured at 150—175°C for several hours. The resins are generally low molecular weight resoles, which have been neutralized with the salt removed. Common carrier solvents for the varnish include acetone, alcohol, and toluene. Alkylated phenols such as cresols improve flexibiUty and moisture resistance in the fused products. 

Fig. 13 Synthesis of oxazoles on JandaJel. Reagents and conditions a toluene, alkyl acetoacetate (R0(C0)CH2C0R R =t-Bu), reflux, 6h or alkyl acetoacetate (R = Me, Et), toluene, LiC104, reflux, 6h fc dodecylbenzenesulfonyl azide, EtsN, toluene, rt, 16 h c benzamide, Rh2(oct)4, toluene, 65 °C, Ih rf Burgess reagent, pyridine, chlorobenzene, MW 100 °C, 15 min (or 80 °C, 4 h with conventional heating) e AICI3, piperidine, CH2CI2, rt, 16 h...

Since their development in 1974 ZSM-5 zeolites have had considerable commercial success. ZSM-5 has a 10-membered ring-pore aperture of 0.55 nm (hence the 5 in ZSM-5), which is an ideal dimension for carrying out selective transformations on small aromatic substrates. Being the feedstock for PET, / -xylene is the most useful of the xylene isomers. The Bronsted acid form of ZSM-5, H-ZSM-5, is used to produce p-xylene selectively through toluene alkylation with methanol, xylene isomerization and toluene disproportionation (Figure 4.4). This is an example of a product selective reaction in which the reactant (toluene) is small enough to enter the pore but some of the initial products formed (o and w-xylene) are too large to diffuse rapidly out of the pore. /7-Xylene can, however. 

Keywords SSZ-33, SSZ-35, zeolites, acidity, toluene, alkylation, disproportionation... 

The objective of this contribution is to investigate catalytic properties of zeolites differing in their channel systems in transformation of aromatics, i.e. toluene alkylation with isopropyl alcohol and toluene disproportionation. In the former case zeolite structure and acidity is related to the toluene conversion, selectivity to p-cymene, sum of cymenes, and isopropyl/n-propyl toluene ratio. In the latter one zeolite properties are... 

Both catalytic reactions were investigated in the gas phase under atmospheric pressure using a glass fixed bed micro-reactor Prior to the reaction given amount of the catalyst (fraction 0.5-0.71 mm) was in situ activated at 500 °C for 2 h (N2 stream 40 ml min"1) In the case of toluene disproportionation the reaction temperature was 500 °C, WHSV 2-20 h"1, concentration of toluene in a stream was 18.5 mol%. Toluene alkylation was studied at the reaction temperature 250 °C. WHSV related to toluene was 10 h"1, concentration of toluene was 18.5 mol% and toluene to isopropyl alcohol molar ratio was 9.6. 

The reaction products were analyzed using an on-line gas chromatograph (HP 6890) equipped by a FID detector and a capillary column DB-5 for toluene alkylation while HP-INNOWax, was used for toluene disproportionation. 

The catalytic activity of SSZ-33 and SSZ-35 was compared with those of ZSM-5 and Beta in toluene disproportionation and toluene alkylation with isopropyl alcohol. The crystals size of SSZ-33 and Beta is about 0.2-0.3 pm while crystals of ZSM-5 and SSZ-35 are larger - around 1 pm. Thus, the size of all crystals provides a nice opportunity to compare the catalytic behavior of zeolites in toluene transformations. 

Figure 2 Dependence of toluene conversion and selectivity to p-cymene in toluene alkylation with isopropyl alcohol.

Toluene alkylation with isopropyl alcohol was chosen as the test reaction as we can follow in a detail the effect of zeolite structural parameters on the toluene conversion, selectivity to cymenes, selectivity to para-cymene, and isopropyl/n-propyl ratio. It should be stressed that toluene/isopropyl alcohol molar ratio used in the feed was 9.6, which indicates the theoretical toluene conversion around 10.4 %. As you can see from Fig. 2 conversion of toluene over SSZ-33 after 15 min of T-O-S is 21 %, which is almost two times higher than the theoretical toluene conversion for alkylation reaction. The value of toluene conversion over SSZ-33 is influenced by a high rate of toluene disproportionation. About 50 % of toluene converted is transformed into benzene and xylenes. Toluene conversion over zeolites Beta and SSZ-35 is around 12 %, which is due to a much smaller contribution of toluene disproportionation to the overall toluene conversion. A slight increase in toluene conversion over ZSM-5 zeolite is connected with the fact that desorption and transport of products in toluene alkylation with isopropyl alcohol is the rate controlling step of this reaction [9]... 

The pyrolysis of diethyl mercury has been studied using a nitrogen carrier flow system87 both in the presence and absence of toluene. The experimental conditions used were total pressure = 10+1 torr with 0.4 torr partial pressure of toluene, alkyl pressure 1-10 x 10 2 torr, decomposition 10-75 % and contact time 0.1-0.3 sec. The presence of toluene had no effect on the rate coefficient, the observed ethane/ethylene ratio ( 1) or the C4/C2 ratio ( 4). These ratios were essentially independent of temperature. 

Other examples of systems that are likely to be governed by product shape selectivity effects include toluene disproportionation to para-xylene -i- benzene in favor of other xylenes r- benzene [61]. Toluene alkylation by methanol to give para-xylene in favor of other xylenes is yet another such example [76],... 

In the case of toluene alkylation with methanol an opportunity exists for para selectivity. Para-xylene ortho-xylene ratio was 3.1 over MFl and 0.6 over BEA framework types. 

The acidic/basic properties of zeolites can be changed by introdnction of B, In, Ga elements into the crystal framework. For example, a coincorporation of alnminnm and boron in the zeolite lattice has revealed weak acidity for boron-associated sites [246] in boron-snbstitnted ZSM5 and ZSMll zeolites. Ammonia adsorption microcalorimetry gave initial heats of adsorption of abont 65 kJ/mol for H-B-ZSMll and showed that B-substituted pentasils have only very weak acidity [247]. Calcination at 800°C increased the heats of NH3 adsorption to about 170 kJ/mol by creation of strong Lewis acid sites as it can be seen in Figure 13.13. The lack of strong Brpnsted acid sites in H-B-ZSMll was confirmed by poor catalytic activity in methanol conversion and in toluene alkylation with methanol. 

In this work acidic and catalytic properties of ZSM-5 type zeolites containing polyvalent cations in exchange positions wera Investigated. Toluene alkylation by ethylene and ethylbenzene transalkylation were studied as model reactions. 

Toluene alkylation by ethylene temperature inside catalyst bed... 

Pig. 1 Scheme of main reaction routes of toluene alkylation by ethylene. (ET= ethyltoluene XYL=xylene S = selectivity to the product on converted toluene)... 

The experimental results of investigation of catalytic activity of samples (Table 1) in toluene alkylation by ethylene are presented in Pig. 3. Taking into account the literature [1], one could... 

Table 2. Values of para-seleotivlty (pS) to different dialkyl-benzenes in reactions of toluene alkylation by ethylene and transalkylation of ethylbenzene.

A comparative study with various types of zeolite showed that Cs-exchanged X and Y zeolites were active for toluene alkylation but primarily catalyzed the decomposition of methanol to CO.431 L and Beta zeolites, in turn, were less active and required higher reaction temperature but were much more selective, providing only very little CO. Adding boron to Cs-exchanged zeolites promotes the alkylation reaction 432 It appears that boron reduces the decomposition of methanol to CO without inhibiting active sites for side-chain alkylation. 

However, there are some contradictory reports on the composition of the products of toluene alkylation or benzene dialkylation at high conversions. In some cases, compositions corresponding to the thermodynamic equilibrium between ortho, meta and para isomers were found, and in other cases, kinetic control of orientation, giving mostly the ortho + para substitution, prevailed. Consecutive isomerisation of the ortho and para isomers to the more stable meta isomer seems to be the cause of the disagreement. More active catalysts gave more meta derivatives than the less active ones [343] and increasing the temperature has the same effect [351]. 

PROP A by-product of isopropyl alcohol manufacture composed of trimeric and tetrameric polypropylene -I- small amounts of benzene, toluene, alkyl benzenes, polyaromatic ring compounds, hexane, heptane, acetone, ethanol, isopropyl ether, and isopropyl alcohol (lARC 15,225,77). CONSENSUS REPORTS lARC Cancer Review Animal Inadequate Evidence IMEMDT 15,223,77 Human Limited Evidence IMEMDT 15,223,77. 

The majority of the carbon in the Murchison macromolecular material is present within aromatic ring systems. This aromatic nature has been revealed by a series of pyrolysis studies of meteorites such as OrgueU (CIl), Murchison (CM2), Murray (CM2), and Allende (CV3) in which the macromolecular material was thermally fragmented to produce benzene, toluene, alkyl-benzenes, naphthalene, alkylnaphthalenes, and PAHs with molecular weights up to around 200-300 amu (Simmonds et al, 1969 Studier et al, 1972 Levy et al, 1973 Bandurski and Nagy, 1976 Holtzer and Oro, 1977 Murae, 1995 Kitajima et al, 2002). Further identification of the aromatic units in the Murchison macromolecular material was achieved by Hayatsu et al (1977),... 

Haag (25) has examined the kinetics of toluene isopropylation and ethylation in the presence of REY catalyst. At 1 atm (total pressure) in the liquid phase, toluene alkylation with propylene is uncontrollably fast near 25°C, and decreases in rate with increasing temperature up to the toluene boiling point (110°C) because of decreasing partial pressure... 

External acid sites can be eliminated by building an inert iso-structural silica shell around the zeolite by continuing the synthesis in an Al-fi ee synthesis gel This increases the crystal size and the effective divisional pathway and is an effective method to enhance the para-selectivity in toluene alkylation but reduces the converaon over the catalyst [101]. 

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