Benzene products

In 1980, the last year for which a breakdown has been pubUshed, the amount of benzene derived from coal in the United States was 168,000 t or 2.5% of domestic benzene production. Coal-derived toluene was 0.8% of production, and xylenes from coal were only 0.1% of total chemical production (9). The amounts and proportions of BTX components derived from coal in the United States are expected to be nearly the same today as in 1980. Based on information submitted to the International Trade Commission, approximately 25 companies participated in the coal-tar industry in the United States in 1990. 

Since the 1950s, benzene production from petroleum feedstocks has been very successful and accounts for about 95% of all benzene obtained. Less than 5% of commercial benzene is derived from coke oven light oil. 

World benzene production rose to 6 x 10 t(1.8 x 10 gallons) in 1988 (63). The United States is the largest producer of benzene and accounts for about 30% of world production. The total annual U.S. production of benzene is shown in Table 4 which gives production figures from both petroleum- and coal-derived benzene. These figures show that benzene obtained from coal is steadily declining, and presendy accounts for less than 5% of the total. Many usehil statistics have been compiled (64). 

U.S. petroleum benzene prices since 1974 are Hsted in Table 6 (64). Until 1978, benzene prices were relatively stable and through 1985 they increased considerably, peaking in 1981 because of the increased demand for aromatics in the gasoline pool. At that time, there was also a large surplus of low priced imported benzene and a softening of the ethylbenzene—styrene market. The decline of cmde oil prices in 1986 caused a dramatic drop in domestic benzene prices. In 1987, U.S. benzene production increased 13.9% over 1986, and this rise was largely ascribed to a favorable export market for benzene derivatives... 

United States benzene trade data are shown in Table 7. From 1961 to 1970, the United States was a net exporter of benzene. After 1971, following a rapid growth of foreign benzene production, the amount of inexpensive benzene available from overseas sources brought the trade balance back to net imports. The trade balance was expected to fluctuate and a net import balance of 3.3ndash4.3 x 10 t (100—130 million gallons) was anticipated for 1990 (64). 

Benzene production by various foreign countries is shown in Table 8 (69—72). As of 1987, the leading foreign producers of benzene were the Federal Republic of Germany, the United Kingdom, Japan, the Nethedands, and the USSR. 

Some of the principal Japanese producers of benzene are Mitsubishi Petrochemical Co., Ltd., Nippon Steel Chemical Co., Ltd., Sanyo Petrochemical Ltd., and Idemitsu Kosan Ltd. Until 1967, the main source of Japanese benzene was coal-based. Today, approximately 40—45% of benzene production in Japan is based on pyrolysis gasoline (74), about 40% catalytic reformate, and the remainder coke oven light oil and thermal hydrodealkylation. 

Modification of the Erlenmeyer reaction has been developed using imines of the carbonyl compounds, obtained with aniline," benzylamine or n-butylamine. Ivanova has also shown that an A-methylketimine is an effective reagent in the Erlenmeyer azlactone synthesis. Quantitative yield of 19 is generated by treatment of 3 equivalents of 2-phenyl-5(4ff)-oxazolone (2) (freshly prepared in benzene) with 1 equivalent of iV-methyl-diphenylmethanimine (18) in benzene. Products resulting from aminolysis (20), alkali-catalyzed hydrolysis (21), and alcoholysis (22) were also described. 

Reaction Relative Rate toluene/ benzene Product Distribution (%) ... 

It has become clear that benzoate occupies a central position in the anaerobic degradation of both phenols and alkylated arenes such as toluene and xylenes, and that carboxylation, hydroxylation, and reductive dehydroxylation are important reactions for phenols that are discussed in Part 4 of this chapter. The simplest examples include alkylated benzenes, products from the carboxylation of napthalene and phenanthrene (Zhang and Young 1997), the decarboxylation of o-, m-, and p-phthalate under denitrifying conditions (Nozawa and Maruyama 1988), and the metabolism of phenols and anilines by carboxylation. Further illustrative examples include the following ... 

Because the content in gasoline at that time accounted for a large fraction of total benzene production, all parts of the gasoline marketing chain (Figure 8) were considered to be... 

Formation of cuprene is either by a free-radical chain reaction or by clustering around the parent ion (cluster size 20) followed by neutralization, which is not a chain process. The M /N value for decomposition of acetylene is about 20, giving the corresponding G value as 70-80, which is very large. The G value of benzene production is 5, whereas the G of conversion of monomers into the polymer is 60. 

As a consequence of the lower coke selectivity of the Cs-exchanged catalyst, the selectivity to the desired benzene product was largely increased by about 35% and remained more stable with TOS with respect to the untreated catalyst (Fig. 5). As expected from their high coke formation, the steamed catalysts displayed the lowest benzene selectivity. 

The synergism of a dual-catalyst system comprising of Pt/ZSM-12 and H-Beta aiming to improve the benzene product purity during transalkylation of aromatics has been studied. Catalyst compositions of the dual-catalyst system were optimized at various reaction temperatures in terms of benzene product purity and premium product yields. Accordingly, a notable improvement in benzene purity at 683 K that meets the industrial specification was achieved using the cascade dual-bed catalyst. 

Previously, we have developed several techniques for platinum supported zeolite catalysts to improve the benzene product purity, including on-line sulfiding [3], precoking [6], and dual-bed catalyst system [7]. We report herein an in-depth investigation on the synergism of proton zeolite and platinum supported ZSM-12 catalyst (Pt/Z12) in a cascade dual-catalyst system. 

The catalytic performances obtained during transalkylation of toluene and 1,2,4-trimethylbenzene at 50 50 wt/wt composition over a single catalyst Pt/Z12 and a dualbed catalyst Pt/Z 121 HB are shown in Table 1. As expected, the presence of Pt tends to catalyze hydrogenation of coke precursors and aromatic species to yield undesirable naphthenes (N6 and N7) side products, such as cyclohexane (CH), methylcyclopentane (MCP), methylcyclohexane (MCH), and dimethylcyclopentane (DMCP), which deteriorates the benzene product purity. The product purity of benzene separated in typical benzene distillation towers, commonly termed as simulated benzene purity , can be estimated from the compositions of reactor effluent, such that [3] ... 

The effects of Tr on benzene product purity and product yields over various dual-bed catalyst systems with different bottom bed catalyst ratios are shown in Fig. 2. As shown in Fig. 2a, over the single-bed Pt/Z12 catalyst alone (i.e., y = 0), a drastic increase in benzene purity with increasing Tr was observed, for example, the benzene purity value increased from 10.87% to 98.36% as Tr increased from 553 K to 683 K. However, upon... 

A dual-bed catalyst system has been developed to tackle the key problems in benzene product impurity during heavy aromatics transalkylation processing over metal-supported zeolite catalysts. It was found that by introducing zeolite H-Beta as a complementary component to the conventional single-bed Pt/ZSM-12 catalyst, the cascaded dual-bed catalyst shows synergistic effect not only in catalytic stability but also in adjustments of benzene product purity and product yields and hence should represent a versatile catalyst system for heavy aromatics transalkylation. 

In a pyrogram of Bisphenol A poly(formal) (6), the peak products are identified as a-methylstyrene, phenol, 4-hydroxy-a-methylstyrene, and isopropyl phenol by Py-GC/MS. These products are identical with the degradation products from Bisphenol A. In addition to the decomposition products of Bisphenol A, 4-isopropenyl anisole is also identified as a product. The pyrograms of Bisphenol AF poly(formal) (7) contain only two major species, pentafluoroisopropenyl benzene (product T) and pentafluoroisopropenyl anisole (product 2 ). They correspond to a-methylstyrene, 4-hydroxy-amethylstyrene from Bisphenol A poly(formal) (6) and are produced by the cleavage of phenylene-oxy bonds and oxy-methylene bonds according to (Scheme 6). 

After a little historical background, this chapter will cover benzene production (including the hardware) as a chemical engineer might look at it, some of the important properties from the chemists point of view, and the major benzene applications. 

Pt-KBaL catalyst than over conventional reforming catalysts. However, the advantage diminishes as carbon number increases, so these technologies are primarily of interest for benzene production. It is therefore more efficient to complement conventional reforming with the zeolitic reforming process when a broader range of aromatic products is desired. Relatively large crystal size has been claimed to be beneficial for example in CP Chem s AROMAX process. Residual acidity on the catalyst has been shown to be detrimental [86]. 

The proposed mechanism involves either path a in which initially formed ruthenium vinylidene undergoes nonpolar pericyclic reaction or path b in which a polar transition state was formed (Scheme 6.9). According to Merlic s mechanism, the cyclization is followed by aromatization of the ruthenium cyclohexadienylidene intermediate, and reductive elimination of phenylruthenium hydride to form the arene derivatives (path c). A direct transformation of ruthenium cyclohexadienylidene into benzene product (path d) is more likely to occnir through a 1,2-hydride shift of a ruthenium alkylidene intermediate. A similar catalytic transformation was later reported by Iwasawa using W(CO)5THF catalyst [14]. 

Ethylbenzene is almost exclusively (> 99%) used as an intermediate for the manufacture of styrene monomer. Styrene production, which uses ethylbenzene as a starting material, consumes approximately 50% of the world s benzene production. Less than 1% of the ethylbenzene produced is used as a paint solvent or as an intermediate for the production of diethylbenzene and acetophenone. The ethy lbenzene present in recovered mixed xylenes is largely converted to xylenes or benzene (Coty et al., 1987 Caimella, 1998). 

After styrene production, approximately 20% of benzene production is used to produce cumene (isopropylbenzene), which is converted to phenol and acetone. Benzene is also converted to cyclohexane, which is used to produce nylon and synthetic fibers. Nitrobenzene derived from benzene is used to produce aniline, which has widespread use in dye production. Besides the benzene derivatives mentioned in this section, countless other products are based on the benzene ring. Cosmetics, drugs, pesticides, and petroleum products are just a few... 

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