On the mechanism of the side reactions in the dehydrocyclization of n-octane
Coke deposition during an experiment on the aromatization of n-octane on an aluminum-chromium-potassium catalyst at 528° and a volume velocity of 0.3 h−1 causes a change in the selectivity of the action of the catalyst: dealkylation of the hydrocarbons is intensified, isomerization is reduced, and the ratio of the yield of o-xylene to the total yield of ethylbenzene and styrene decreases from 1.4 to 1.0.
Preliminary poisoning of the catalyst by nitrogen compounds (aniline, pyridine, quinoline) and by water during the period of development causes the same change in the selectivity of the catalyst that was observed during a prolonged experiment on aromatization of n-octane, i.e., during the poisoning of the catalyst with coke.
It was hypothesized that m- and p-xylenes are formed during the dehydrocyclization of n-octane from intermediate compounds, which arise during the dehydrocyclization before the formation of the aromatic hydrocarbons; moreover, the reactions of dehydrocyclization and isomerization proceed on different active centers.
KeywordsHydrocarbon Pyridine Styrene Aniline Aromatic Hydrocarbon
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- 1.M. I Rozengart, V. L. Polinin, and B. A. Kazanskii, Izv. AN SSSR, Ser. Khim.,1966, 1323.Google Scholar
- 2.E. F. Herington and E. K. Rideal, Proc. Roy. Soc.,184A, 434 (1945).Google Scholar
- 3.H. Pines and Chao-Tung Chen, J. Amer. Chem. Soc.,82, 3562 (1960).Google Scholar
- 4.M. I. Rozengart, E. S. Mortikov, and B. A. Kazanskii, Dokl. AN SSSR,166, 619 (1966).Google Scholar
- 5.H. Pines and G. Benoy, J. Amer. Chem. Soc.,82, 2483 (1960).Google Scholar
- 6.B. L. Evering and R. C. Waugh, Industr. and Engng Chem.,43, 1820 (1951).Google Scholar
- 7.N. L. Cull and H. H. Brenner, Industr. and Engng. Chem.,53, 833 (1961).Google Scholar
- 8.M. I. Rozengart and B. A. Kazanskii, Dokl. AN SSSR,119, 716 (1958).Google Scholar