Catalytically cracked gasoline

Hatanaka, S. Yamada, M., and Sadakane, O., HDS of Catalytic Cracked Gasoline. 1. Inhibiting Effects of Olefins on HDS of Alkyl(Benzo)Thiophenes Contained in Catalytic Cracked Gasoline. Ind. Eng. Chem. Res, 1997. 36 p. 1519. 

The isoprene monomer is not readily available from direct cracking processes. Several routes are employed for its synthesis. One route begins with the extraction of isoamylene fractions from catalytically cracked gasoline streams. Isoprene is produced by subsequent catalytic dehydrogenation. 

Description Feed Catalytically Cracked Gasoline Product with Matrix Catalyst Product with 1% ZSM-5 in Matrix Catalyst... 

Thermal and catalytically cracked gasoline fractions can contain significant concentrations of phenols, low-molecular-weight organic acids, and alkyl and aryl mercaptans. All of these compounds can initiate gum formation in gasoline. Caustic treatment readily removes these compounds. 

Crude oil typically contains little to no olefinic compounds. Through refining and processing, however, olefins are produced and become a part of various crude oil fractions. Olefins can be found in thermally cracked and catalytically cracked gasoline fractions as well as in FCC cycle oils and coker gas oils. For this reason, it is not unusual for finished gasoline and distillate blends to contain a high-olefin-content stream. 

The application of catalysis to the production of motor fuel by cracking of less volatile petroleum oils was first investigated in France by Eugene J. Houdry in the period 1927 to 1930. The results from these investigations clearly established the superiority of catalytically cracked gasoline over that made by the thermal processes the economic possibilities were also indicated. 

The catalytic alkylation of isobutane with C3—C5 alkenes was commercialized in the US during WW II. Blending the alkylate product with catalytically cracked gasoline provided high-octane aviation fuel. The introduction of aromatic and oxygenated fuel additives, such as methyl t-butyl ether (MTBE), pushed alkylation to the sidelines. However, in the 1990s, when the environmental effects of such additives were realized, alkylation regained its importance [191]. 

Catalytically cracked gasoline has a high octane number throughout its entire boiling range. The octane number depends to only a minor... 

Fig. 46. Composition of catalytically cracked gasoline produced by fixed-bed cracking of heavy gas oil from mixed-base crude. [Bates, ei ah, Ind. Eng. Chem. 34, 147 (1942) Ardern, Dart, and Lassiat, Advances in Chem. Ser. No. 6, 13 (1951). Reprinted by permission.]...

Catalytic cracking (gasoline production) — xeolite-Y derivatives... 

Hatanaka, S., Yamada, M., and Sadakane, O. Hydrodesulfurization of catalytic cracked gasoline. 3. Selective catalytic cracked gasoline hydrodesulfurization on the Co-Mo/gamma-Al203 catalyst modified by coking pretreatment. Industrial Engineering Chemistry Research, 1998, 37, 1748. 

Hatanaka, S., Sadakane, O., and Okazaki, H. Hydrodesulfurization of catalytic cracked gasoline—Selective catalytic cracked gasoline hydrodesulfurization using C0-M0/7-AI2O3 catalyst modified by pyridine. Journal of the Japan Petroleum Institute, 2001, 44, 36. 

Any mercaptans boiling below 80°C are also readily dissolved in alkaline solutions (Eq. 18.32). A common process for the removal of dissolved mercaptans of this kind, especially from catalytically cracked gasoline and liquefied petroleum gas, is the Universal Oil Products (UOP) Merox process that also uses caustic soda for extraction. In this process, however, the mercaptans are then oxidized to disulfides using air assisted by a metal complex catalyst dissolved in the caustic soda (Eq. 18.34). 

The increased performance meant that Allied planes were better than Axis planes by a factor of 15 percent to 30 percent in engine power for take-off and climbing 25 percent in payload 10 percent in maximum speed and 12 percent in operational altitude. In the first six months of 1940, at the time of the Battle of Britain, 1.1 million barrels per month of 100-octane aviation gasoline was shipped to the Allies. Houdry plants produced 90 percent of this catalytically cracked gasoline during the first two years of the war. (12)... 

Despite the better conversion and increased yield of gasoline with REY-zeolite catalysts it was found that octane levels were lower because fewer olefins were produced. This was not really a problem for a number of years because gasoline quality could be improved by either increasing cracking severity or using antiknock compounds such as tetraethyl lead (TEL) and tetrametltyl lead (TML). About 3-ml TEL per US gallon could increase the octane number of catalytic cracked gasoline by five to six points. 

Inhibitor sweetening of catalytically cracked gasoline is successful and economical for mercaptan contents up to 0.02 to 0.03 per cent. About 6 lb of inhibitor is required per thousand bbl. The final mercaptan content is usually below 0.0015 weight per cent. 

Catalytically cracked gasolines contain more olefinic hydrocarbons than are desirable, and hence methods of hydrogenating the olefins without hydrogenating the aromatics are being studied. 

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