Styrene, catalytic cracking

The ethylene feedstock used in most plants is of high purity and contains 200—2000 ppm of ethane as the only significant impurity. Ethane is inert in the reactor and is rejected from the plant in the vent gas for use as fuel. Dilute gas streams, such as treated fluid-catalytic cracking (FCC) off-gas from refineries with ethylene concentrations as low as 10%, have also been used as the ethylene feedstock. The refinery FCC off-gas, which is otherwise used as fuel, can be an attractive source of ethylene even with the added costs of the treatments needed to remove undesirable impurities such as acetylene and higher olefins. Its use for ethylbenzene production, however, is limited by the quantity available. Only large refineries are capable of deUvering sufficient FCC off-gas to support an ethylbenzene—styrene plant of an economical scale. 

A mixture of monolauryl phosphate sodium salt and triethylamine in H20 was treated with glycidol at 80°C for 8 h to give 98% lauryl 2,3-dihydro-xypropyl phosphate sodium salt [304]. Dyeing aids for polyester fibers exist of triethanolamine salts of ethoxylated phenol-styrene adduct phosphate esters [294], Fatty ethanolamide phosphate surfactant are obtained from the reaction of fatty alcohols and fatty ethanolamides with phosphorus pentoxide and neutralization of the product [295]. A double bond in the alkyl group of phosphoric acid esters alter the properties of the molecule. Diethylethanolamine salt of oleyl phosphate is effectively used as a dispersant for antimony oxide in a mixture of xylene-type solvent and water. The composition is useful as an additive for preventing functional deterioration of fluid catalytic cracking catalysts for heavy petroleum fractions. When it was allowed to stand at room temperature for 1 month it shows almost no precipitation [241]. 

It is noted that Mo/DM is the best performing catalyst with the highest steady state activity and lowest deactivation rate. The deactivation rate is the lowest even under the influence of intense acid-catalyzed side reactions known to produce coke, i.e. oligomerization of styrene and cracking of ethylbenzene. Obviously, the high surface area and high connectivity of the support have played a determining role in the catalytic reaction. The effects they exert can be looked at in two ways ... 

Chapter 7 is the climax of the book Here the educated student is asked to apply all that he/she has learned thus far to deal with many common practical industrial units. In Chapter 7 we start with a simple illustrative example in Section 7.1 and introduce five important industrial processes, namely fluid catalytic cracking in FCC units in Section 7.2, the UNIPOL process in Section 7.3, industrial steam reformers and methanators in Section 7.4, the production of styrene in Section 7.5, and the production of bioethanol in Section 7.6. 

Bittles et al. ° carried out a detailed kinetic and mechanistic study of the polymerisation of styrene by commercial catalytic-cracking acid clays (Filtrol). Thisheter-c eneous process gave low DP s and displayed all the typical features of a cationic (or pseudocationic) polymerisation. 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

However, other authors have proposed that the primary product of the PS catalytic cracking is styrene, as in thermal cracking, which is further converted into ethylbenzene, toluene, benzene, etc. on the acid sites of the catalyst. De la... 

Puente et al.33 have studied the conversion of PS dissolved in benzene in a fluidized bed reactor over a commercial FCC catalyst. The product distribution obtained in the catalytic degradation of PS was compared to that obtained in styrene conversion (Figure 5.15). The same relationship between the conversion and the selectivity towards the different products was observed in both PS and styrene catalytic conversion at 550 °C, suggesting that styrene is also the primary product in the catalytic PS cracking. The authors proposed a mechanism to explain the formation of the main products from styrene. 

Figure 2 shows the carbon specific C-GCxGC chromatogram of a fluidized catalytic cracking (FCC) gasoline. Note that the compounds present were resolved into distinctive bands for nonaromatics, mono-aromatics, and di-aromatics. This can also be seen in Fig. 3, which shows the C-GCxGC separation of a steam-cracked naphtha (SCN). Because of the process used to produce this gasoline, additional aromatic compound classes such as styrenes and indenes were identified. 

Butadiene is a petroleum product obtained by catalytic cracking of naphtha or light oil or by dehydrogenation of butene or butane. It is used to produce butadiene-styrene elastomer (for tires), synthetic rubber, thermoplastic elastomers, food wrapping materials, and in the manufacture of adiponitrile. It is also used for the synthesis of organics by Diels-Alder condensation. 

Styrene. All commercial processes use the catalytic dehydrogenation of ethylbenzene for the manufacture of styrene.189 A mixture of steam and ethylbenzene is reacted on a catalyst at about 600°C and usually below atmospheric pressure. These operating conditions are chosen to prevent cracking processes. Side reactions are further suppressed by running the reaction at relatively low conversion levels (50-70%) to obtain styrene yields about 90%. The preferred catalyst is iron oxide and chromia promoted with KzO, the so-called Shell 015 catalyst.190... 

Chemical intermediates are listed first in Table 1.1. These are the chemicals that are used to synthesize other chemicals, and are generally not sold to the public. For example, ethlyene is an intermediate produced from hydrocarbons by cracking natural gas derived ethane or petroleum derived gas oil, either thermally using steam or catalytically. Ethlyene is then used to produce polyethylene (45%), a polymer and ethlyene oxide (10%), vinyl chloride (15%), styrene (10%), and... 

Figure 5.15 Selectivities of benzene (O), toluene ( ), ethylbenzene (A), and cracking products (V) as a function of conversion at 550 °C in the catalytic treatment of PS (dashed line and open symbols) and styrene (filled line and closed symbols) over a commercial FCC catalystP...

Butadiene is first recovered by extractive distillation, employing furfural or an amide, such as dimethylformamide. Some l 5Mt and 0-8 Mt per annum of butadiene are obtained in western Europe and Japan respectively. With less naphtha and gas oil cracking in the U.S.A., over 20% of the l 7Mt demand for butadiene in 1993 was met by imports. Butadiene can also be made by catalytic or oxidative dehydrogenation of w-butenes, or even -butane. The major outlets (approx. 65%) are for tyre rubbers, as polybutadiene or co-polymers with styrene or acrylonitrile. Some 15% is used for adiponitrile in the U.S.A. Chloroprene and co-polymer resins account for the remainder. 

Ethylene from cracking of the alkane gas mixtures or the naphtha fraction can be directly polymerized or converted into useful monomers. (Alternatively, the ethane fraction in natural gas can also be converted to ethylene for that purpose). These include ethylene oxide (which in turn can be used to make ethylene glycol), vinyl acetate, and vinyl chloride. The same is true of the propylene fi action, which can be converted into vinyl chloride and to ethyl benzene (used to make styrene). The catalytic reformate has a high aromatic fi action, usually referred to as BTX because it is rich in benzene, toluene, and xylene, that provides key raw materials for the synthesis of aromatic polymers. These include p-xylene for polyesters, o-xylene for phthalic anhydride, and benzene for the manufacture of styrene and polystyrene. When coal is used as the feedstock, it can be converted into water gas (carbon monoxide and hydrogen), which can in turn be used as a raw material in monomer synthesis. Alternatively, acetylene derived from the coal via the carbide route can also be used to synthesize the monomers. Commonly used feedstock and a simplified diagram of the possible conversion routes to the common plastics are shown in Figure 2.1. 

Today, benzene is one of the most important commercial organic chemicals. Approximately 17 billion pounds are produced annually in the United States alone. Benzene is obtained mostly from petroleum by catalytic reforming of alkanes and cycloalkanes or by cracking certain gasoline fractions. It is used to make styrene, phenol, acetone, cyclohexane, and other industrial chemicals. 

The term PR refers to hydrocarbon resins obtained by the catalytic oligomerization of deeply cracked petroleum stocks. These petroleum stocks generally contain mixtures of resin formers such as styrene, methyl styrene, vinyl toluene, indene, methyl indene, butadiene, isoprene, piperylene, and pentylenes. The so-called polyalkylaromatic resins fall into this classification. 

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