Benzene production figures

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). 

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... 

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. 

The Z-substituted benzene (benzaldehyde, Figure 11.2) is not activated toward electrophilic attack since the HOMO of benzene is scarcely affected. No preferred site for attack of the electrophile can be deduced from inspection of the HOMOs. The interaction diagram for a Z-substituted pentadienyl cation, substituted in the 1-, 2-, and 3-positions, as models of the transition states for the ortho, meta, and para channels are too complex to draw simple conclusions. The HOMO and LUMO of the three pentadienyl cations with a formyl substituent are shown in Figure 11.4. The stabilities of the transition states should be in the order of the Hiickel n energies. These are 6a — 9.204 / , 6a — 9.2031/ , and 6a -9.1291/ , respectively. Thus, by SHMO, the ortho and meta channels are favored over the para channel, with no distinction between the ortho and meta pathways. Experimentally, meta substitution products are usually the major ones, contrary to the SHMO predictions. Either the SHMO method fails in this case or the predominance of meta products may be attributed to steric effects. 

The rate of benzene production from neat benzaldehyde solution was measured as a function of [Rh(dppp)2]+ concentration at 135°C. The reaction is first order in catalyst concentration as shown in Figure 1 (21). The rate of benzene production also was monitored as a function... 

Figure 1. Rate of benzene production from neat benzaldehyde at 135 °C as a function of Rh(dppp)2+ concentration...

Figure 2. Rate of benzene production vs. benzaldehyde concentration at 158°C for [Rh(dppp)2]+ = 6.7 x I0"3M (22). The curved line was calculated from the plot in Figure 3 (see Equation 4).

Figure 9.20(b) illustrates the use of pervaporation with two distillation columns to break a binary azeotrope such as benzene/cyclohexane. The feed is supplied at the azeotropic composition and is split into two streams by the pervaporation unit. The residue stream, rich in cyclohexane, is fed to a distillation column that produces a pure bottom product and an azeotropic top stream, which is recycled to the pervaporation unit. Similarly, the other distillation column treats the benzene-rich stream to produce a pure benzene product and an azeotropic mixture that is returned to the pervaporation unit. 

Figure 4 shows the temperature dependences of cyclohexane conversion (curve 1) and benzene yield (curve 2). The maximal benzene productivity was 1.76 mol/m2h at 673 K with the catalyst containing 5 % Re. The usual Re/C catalysts require Re loading as much as 30% for achievement the similar activity at such operation conditions [8], This may be explained by the membrane form of catalyst, used in this work, in spite of the absence of absolute permselectivity of the membrane. 

Figure 10.1 shows the nine basic unit operations of the HDA process as described in Douglas (1988) reactor, furnace, vapor-liquid separator, recycle compressor, two heat exchangers, and three distillation columns, Two raw materials, hydrogen and toluene, are converted into the benzene product, with methane and diphenyl produced as by-products. The two vapor-phase reactions are... 

In Figure 10.3a the flowrates of the fresh feed streams of hydrogen and toluene are shown. An 18°F decrease in reactor inlet temperature is made at time equals 10 minutes, and then the temperature is returned to its normal value at time equals 125 minutes. The drop in temperature reduces reaction rates, so the flowrates of the fresh reactant feed streams are reduced. After a fairly short time lag, the benzene product rate also drops as shown in Figure 10.36. The lower inlet temperature produces a lower reactor exit temperature, so less quench flow is required to maintain quench temperature (1150°F). Less heat-exchanger bypassing is required to maintain the furnace inlet temperature (1082°F) because the flowrate of the hot stream entering the FEHE has dropped. 

Figure 10.3c shows how the disturbance affects benzene product quality. The maximum deviation in the control tray temperature is about 2°F. Notice that- a constant tray temperature does not give constant benzene purity, which changes by 0.015 mole %. Reflux flowrate is constant in the product column, so product purity improves as the feed rate to the column decreases. 

Figure 10.4 gives results for 20 percent changes in the toluene recycle flowrate. The change in benzene production is the same as with the 18CF decrease in reactor inlet temperature. Now, however, the control tray temperature in the product column is disturbed about 53F, compared to 2 when reactor inlet temperature was changed. 

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. 

During almost all tests it has been general practice to measure not only the main gas constituents, but also benzene and light tars. An interesting correlation between the amount of light tars and benzene in the product gas has been noticed, which can be seen in Figure 5 below. A correlation also exists between methane and benzene, see Figure 6. 

To effectively utilize the information obtained from the experimental work, it is advantageous to re-evaluate the same data based on the normalized benzene selectivity as described by Equation (5). A more useful trends can be seen as given in Table 1, in which the benzene production and normalized benzene selectivity are listed with respect to the cumene conversion for the same two values of Cp as in the Figure 6. From columns 2 and 4, the maximum benzene production are clearly shown for Cp = 5 and 50 respectively. The best production at low Cp is when the cumene conversion is at 60%, while at high Cp, this is at 75% conversion. These conversion levels are typical in the FCC unit operation. 

Figure 5. Optimization process to maximize benzene production the flow of fluidized gas vs. feed...

The rate at which the complex phase changes from one AO Xn to the next AO is proportional to k. It jumps from one vertex of the phase polygon to the -th, counterclockwise for t and clockwise for 0 i. This procedure is illustrated for the HOMOs and LUMOs of benzene in Figure 2.12a. The products of AO coefficients needed for evaluating the overlap densities are easily obtained from these diagrams by simply adding the complex phases. Thus,... 

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. 

In Figure 4 the fractional conversion of toluene to benzene is reported versus irradiation time for the same runs reported in Fig. 3. The presence of water was beneficial for benzene production, but benzene virtually disappeared after 3-4 h of irradiation, independent of the presence of water. 

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