Over 40 billion gallons of gasoline are now used to power American au omobiles each year. TO produce the high quality fuels required for these engines, the petroleum industry makes extensive use of catalytic processing. The bulk of the high octane components i s provided by some 2,300,000 barrels per day of catalytic cracking capacity. In the treatment of naphtha catalytic reforming i s rapidly replacing thermal reforming, since the chemical reactions which naphtha will undergo are carried out more efficiently in the presence of catalysts. Hydroforming, the first catalytic naphtha-upgrading process, became a commercial reality in 1939. Eight hydroforming plants were built during World War I I for production of premium-grade motor gasoline and/or toluene. One of these plants alone produced more than half the toluene used in TNT for the U.S. Armed Forces. Since the war at least nine new catalytic reforming processes have been disclosed. Most of them operate with a fixed-bed platinum catalyst under nonregenerative conditions, yielding both high octane gasoline and a romatics. The existing requirements for high octane gasoline make it necessary to continue extensive research and development in catalytic processing. A fruitful way of studying these processes has been to investigate the reactions of pure hydrocarbons over the commercial catalysts. Examination of the product composition has yielded further valuable information on the reaction mechanisms. In addition, studies of processes such as polymerization and alkylation are adding more to our knowledge of hydrocarbon reactions. One of the major improvements in development work has been a reduction of the pilot plant size necessary to guide commercial design of a full scale process. At present, emphasis i s increasing on gasoline properties other than octane number, particularly on the tendencies to form deposits in combustion chambers and crankcases. The method of selective hydrogenation i s continually improved through studies of gasoline fractions and of pure compounds. Treating of cracked gosolines with boron trifluoride has been proposed for removing undesirable components. The information contained in the symposium is evidence of continuing progress in the field of catalytic processing. E. C. HUGHES, Chairman
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The Symposium on Catalytic Processing of Gasoline Fractions was a presentation o f the ACS Division of Petroleum Chemistry at the 726th Meeting of the American Chemical Society, New York, N. Y. SELECTIVE HYDROTREATING OVER TUNGSTEN NICKEL SULFIDE CATALYST:
HYDROFORMING REACTIONS AND EFFECT OF CERTAIN CATA-
LYST PROPERTIES AND POISONS
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W. P. Hettinger, Jr., C. D. Keith, J. L. Gring, and J. W . Teter. DEHYDRO CY CLlZATlON IN PLATFORMlN G G. R. Donaldson, 1. F. Pasik, and Vladirnir Haensel
HOUDRIFORMING OF HYDROCRACKED NAPHTHAS Heinz Heinemann, J. 8. Hattrnan, and J. W. Schall HOUDRIFORMING FOR AROMATICS Dudley Beyler, D. H. Stevenson, and F. R. Shuman
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735
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740
OLYMERIZATION OF LIGHT OLEFINS OVER NICKEL OXIDESILICA-ALUMINA J. P. Hogan, R. L. Banks, W. C. Lanning, and Alfred Clark
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TREATMENT OF CRACKED GASOLINES R. M. Casagrande, W. K. Meerbatt, A. F. Sartor, and R. P. Trainer.
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REACTION STUDIES WITH MIXTURES OF PURE COMPOUNDS W. K. Meerbott and G. P. Hinds, Jr.
749
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DEHYDROALKYLATION OF AROMATICS WITH ISOPARAFFINS Joe T. Kelly and Robert J. Lee
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BORON TRIFLUORIDE TREATMENT OF CRACKED GASOLINES H. Beuther and R. G. Goldthwait
764
ISOMFRIZATION OF ALKYL AROMATIC HYDROCARBONS P. M. Pitts, Jr., J. E. Connor, Jr., and L. N. Leum
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Hydroforming Reactions Effect of Certain Catalyst Properties and Poisons W.
P. HETTINGER, Jr., C.
D. KEITH, J. L. GRING, AND J. W. TETER
Sinclair Research Laboratories, fnc., Harvey, 111.
n-Heptane, methylcyclohexane, an enriched d'methylcyclopentane feed stock, as well as several other pure hydrocarbons, have been used to study the pertinent Hydroforming reactions which occur over RD-150 platinum on alumina catalyst. The rates of dehydrogenation, isomerization, dehydrocyclization, and hydrocracking have been investigated over a range of temperatures and pressures of interest commercially. Data are presented to show the effect of catalyst particle size and platinum concentration, as well as the specific effects of such temporary poisons as water, sulfur, and nitrogen on Hydroforming reactions. Studies of the effect of arsenic demonstrate the catalyst's considerable tolerance for this potential poison.
R
ECENT articles (3, 1 2 ) have described in some detail the reactions involved and the yield and octanes obtained when hydroforming various virgin naphthas with the Sinclair-Baker RD-150 platinum on alumina catalyst. This catalyst was developed for both continuous and regenerative Hydroforming operations. T h e various Hydroforming reactions have been described in considerable detail, including the reaction mechanisms involved. Of interest here are articles describing the results obtained on recently developed catalysts utilizing an alumina or silica-alumina base containing i n particular a small amount of nickel or precious metals of group VI11 (2, 8) and in one case incorporating halide (6). Historically, platinum and nickel on alumina have been used much earlier in hydrocarbon studies (15, 14). Hydroforming reactions include dehydrogenation, isomerization, hydrocracking, and dehydrocyclization. Dehydrogenation of alkyl substituted cyclohexanes is rapidly accomplished b y the RD-150 catalyst. Dehydrogenation of these naphthenes results in a wide variety of aromatics, all of which have blending research octane numbers well above 100. Because cyclohexane derivatives are essentially paraffinic in nature, and under conditions of commercial Hydroforming are April 1955
subject to hydrocracking as are members of the aliphatic group the more rapidly they are converted to aromatics, the less possibility there is for opening the naphthene ring, and therefore the better is the aromatization selectivity. Isomerization activity in a Hydroforming catalyst is important for two reasons. 1. Isomerization of cyclopentane derivatives to cyclohexane derivatives must be accomplished rapidly and selectively in order to maximize naphthene aromatization. 2. Isomerization is also essential for achieving equilibrium distribution of paraffin isomers. Figure 1 shows the octane number which should result when any given molecular weight paraffin is isomerized t o equilibrium distribution a t 900" F. (10, 11). Isomerization of C?to C ~parafZ fins alone could never meet present octane requirements. Hydrocracking achieves octane improvement by decreasing the average molecular weight of the paraffins (Figure 1). For a paraffin C, at equilibrium with regard to isomerization there is an octane improvement of 14 t o 15 units when going to C, -1 and an accompanying volume loss of some 8 t o 10%. In addition t o reducing molecular weight, the end result of hydrocracking is t o increase the concentration of the aromatic fraction relative to the
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