Toluene production figures

Primary intermediates were originally manufactured within the dyes industry. All the significant primaries, about 30 different products, are derived from ben2ene, toluene, or naphthalene. Actual production figures for primaries are not readily available, and in any event the amounts used within the dyes industry are variable. The primaries are Hsted here with a reference to the Eniyclopedia article that covers them in detail including production and consumption figures. 

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. 

A comparison of the feed and product compositions achievable by this approach is shown in Figure 16.8, which shows the depletion of multi-ring aromatics from the feed in favor of a variety of single ring aromatics with short alkyl chains. A more challenging approach that leads to a higher-value product involves optimization of the catalyst and process conditions to maximize xylene and toluene production for aromatic complex feeds [60]. 

A relatively small number of chemicals form the basis of the petrochemical industry. These are methane, ethylene, propylene, butylenes, benzene, toluene, and xylenes. These chemicals are used to derive thousands of other chemicals that are used to produce countless products. Figure 19.2 lists some of the principal chemicals and products derived from these seven basic chemicals. 

We recently built up an experimental system to further study the by-product of PCO of toluene (see Figure 4.13) (Mo, Xu and Zhang, 2008a). A PTR-MS was applied to measure the inlet and outlet pollutant concentrations. Some results are shown in Figure 4.14 (Zhang et al., 2008). It indicates that benzaldehyde, methanol, acetaldehyde, formic acid/ethanol, acetone/propionaldehyde and acetic acid... 

The GC analysis results of the liquid product (Figure 23.8) were focused on styrene, benzene, toluene, and naphthalene components, the often quoted compounds in polystyrene degradation [33, 51, 62-64,]. The run at 750°C showed 48% benzene, 18% styrene, 8% toluene. The benzene content decreased steadily with increasing operating temperatme. 

The Bureau of Mines is a source of many chemical statistics. The monthly Coke and Coal Chemicals report, part of the bureau s Mineral Industry Surveys, contains, in addition to data on oven and beehive coke production, figures on production of ammonium sulfate, ammonia liquor, naphthalene, benzene, toluene, xylene, solvent naphtha, pyridine, crude coal tar, and cresote oil. Sales and end-of-month stock figures are also shown in the report. A useful feature of the report is the year-end supplement which gives year s totals by months. 

The production of phenol by cumene oxidation is carried out in plants with a total capacity in excess of 400,000 tpa. The process is superior to the methods described below, despite the co-production of acetone, since the cycle of inorganic materials is very small and the carbon skeleton of the aromatic feed is fully utilized, unlike in toluene oxidation. Figure 5.13 shows the oxidation reactors of the 400,000 tpa phenol plant operated by Phenolchemie, Gladbeck/West Germany. 

Butylated hydroxy toluene (BHT) (Figure 9.22) is a related antioxidant food additive. It is also used as an antioxidant in cosmetics, pharmaceuticals, jet fuels, rubber and petroleum products, and embalming fluid. 

Figure 5 illustrates a typical distillation train in a styrene plant. Benzene and toluene by-products are recovered in the overhead of the benzene—toluene column. The bottoms from the benzene—toluene column are distilled in the ethylbenzene recycle column, where the separation of ethylbenzene and styrene is effected. The ethylbenzene, containing up to 3% styrene, is taken overhead and recycled to the dehydrogenation section. The bottoms, which contain styrene, by-products heavier than styrene, polymers, inhibitor, and up to 1000 ppm ethylbenzene, are pumped to the styrene finishing column. The overhead product from this column is purified styrene. The bottoms are further processed in a residue-finishing system to recover additional styrene from the residue, which consists of heavy by-products, polymers, and inhibitor. The residue is used as fuel. The residue-finishing system can be a flash evaporator or a small distillation column. This distillation sequence is used in the Fina-Badger process and the Dow process. 

The principal chemical uses of BTX are illustrated in Figure 1 and Hsted in Table 1 (2). A very wide range of consumer products from solvents to fibers, films, and plastics are based on BTX. The consumption of BTX is approximately in the proportions of 67 5 28, respectively. However, no BTX process gives BTX in these proportions. The economic value of benzene and xylenes (especially -xylene) is normally higher than that of toluene. Because of this, processes that convert toluene to benzene by hydrodealkylation (3) and disproportionate toluene to benzene and xylenes (4) have been commercialized. In addition, reforming processes that emphasize production of either benzene or -xylene [106 2-3] have been described (5). Since these are not classified as BTX processes they are not discussed in detail here. 

The main product, benzene, is represented by solute (B), and the high boiling aromatics are represented by solute (C) (toluene and xylenes). The analysis of the products they obtained are shown in Figure 12. The material stripped form the top section (section (1)) is seen to contain the alkanes, alkenes and naphthenes and very little benzene. The product stripped from the center section appears to be virtually pure benzene. The product from section (3) contained toluene, the xylenes and thiophen which elutes close to benzene. The thiophen, however, was only eliminated at the expense of some loss of benzene to the lower stripping section. Although the system works well it proved experimentally difficult to set up and maintain under constant operating conditions. The problems arose largely from the need to adjust the pressures that must prevent cross-flow. The system as described would be virtually impossible to operate with a liquid mobile phase. 

Figure 1 The gel-chromatogram of the obtained product from the alkylation reaction of toluene with EC under various reaction conditions T, K = 273 (1), 293 (2), 313 (3), 333 (4). The ratio of toluene epichlorohydrin 0.5 1 (5) 1 1 (6), 2 1 (7), and 5 1 (8). (-) refractometer detector (—) UV-detector.

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