Catalytic cracking process conditions

Catalytic Cracking. This is a refinery process that produces a mixture of butylenes and butanes with very small amounts of butadiene. The specific composition of the mixture depends on the catalyst and process conditions. Most catalytic cracking processes employ temperatures about... 

The most dominant catalytic process in the United States is the fluid catalytic cracking process. In this process, partially vaporized medium-cut petroleum fractions called gas oils are brought in contact with a hot, moving, freshly regenerated catalyst stream for a short period of time at process conditions noted above. Spent catalyst moves continuously into a regenerator where deposited coke on the catalyst is burnt off. The hot, freshly regenerated catalyst moves back to the reactor to contact the hot gas oil (see Catalysts, regeneration). 

It is no exaggeration to say that without catalysts Germany would have been in no condition to pursue its war effort until November 1918. Likewise, if Houdry had not developed in the early days of World War II its catalytic cracking process, the United States would have found it very hard to provide its bombers with light fuel. It was also through catalytic reforming that the United States managed to obtain from petroleum the toluene needed to produce TNT between 1941 and 1945. 

Typical operating conditions for the several commercial catalytic cracking processes are shown in Table XVI. 

Operating Conditions in Commercial Catalytic Cracking Processes ... 

In reforming and catalytic cracking processes, in contrast, there is an increase in aromatization, since isomerization reactions occur under the reaction conditions and cycloaliphatic hydrocarbons are converted into aromatics. 

The performance analysis and product analysis results confirm previous findings (3,8) that hydrotreating improves the quality of catalytic cracker feedstock and the resultant products. In addition, it was shown that the quality of the liquid products and the yields of the coke and the heavy cycle oil (HCO) from cracking of the severely hydrotreated feedstock (WM-2-9) were independent of the conditions of the cracking process. These results imply that there exists a degree of pretreatment hydrotreating above which... 

Deep catalytic cracking (DCC) is a commercially proven FCC process for selectively cracking a wide variety of feedstocks to light olefins, particularly propylene. Innovations in catalyst development, operational severity, and anticoking conditions. 

The first reaction provides a route for the reduction of alkyl halides since the carbo-cation (isopropyl, in Rl) may be prepared from action of AICI3 on the corresponding alkyl halide. Reactions of the type Rl are also important in the process, catalytic cracking, in the manufacture of gasoline. They have also been studied in mass spectro-metric experiments [235]. Reaction R2 is one route to the preparation of carbocations under stable ion conditions. Reaction R3 is employed in the laboratory synthesis of the tropylium cation. Reaction R4, the (crossed) Cannizzaro reaction, is unusual in that it takes place under strongly basic conditions. The oxy dianion is an intermediate in the reaction of concentrated hydroxide with the aldehyde, R HO. None of R1, R2, or R3 may have hydrogen atoms a to the carbonyl groups. Formaldehyde (R1 = H) is readily... 

The preferential release of C3 and C4 as the smallest fragments is a relative matter ethylene, ethane, and methane can be produced under more drastic experimental conditions, and are produced in small amounts in ordinary catalytic cracking. The conventional process operates under conditions which maximize the desired type of splitting to the more useful gaseous products. To demonstrate the application of theory to practice, the predicted and experimental curves for the cracking of cetane (7) are shown in Figure 3. 

Cracking is effected by one of three general methods thermal cracking, catalytic cracking, or hydrocracking. Each process has its own characteristics concerning operating conditions and product compositions. 

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... 

C at pressures of about 250—400 kPa (36—58 psi). The two types of catalysts, the amorphous silica—alumina (52) and the crystalline aluminosilicates called molecular sieves or zeolites (53), exhibit strong carboniumion activity. Although there are natural zeolites, over 100 synthetic zeolites have been synthesized and characterized (54). Many of these synthetic zeolites have replaced alumina with other metal oxides to vary catalyst acidity to effect different type catalytic reactions, for example, isomerization. Zeolite catalysts strongly promote carboniumion cracking along with isomerization, disproportionation, cyclization, and proton transfer reactions. Because butylene yields depend on the catalyst and process conditions, Table 7 shows only approximations. 

Tphe rate-limiting processes in catalytic reaction over zeolites remain A largely undefined, mainly because of the lack of information on counterdiffusion rates at reaction conditions. Thomas and Barmby (7), Chen et al. (2, 3), and Nace (4) speculate on possible diffusional limitations in catalytic cracking over zeolites, and Katzer (5) has shown that intracrystalline diffusional limitations do not exist in liquid-phase benzene alkylation with propene. Tan and Fuller (6) propose internal mass transfer limitations and rapid fouling in benzene alkylation with cyclohexene over Y zeolite, based on the occurrence of a maximum in the reaction rate at about 100 min in flow reaction studies. Venuto et al (7, 8, 9) report similar rate maxima for vapor- and liquid-phase alkylation of benzene and dehydro-... 

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