Unsolved
Λ Ε STAFF REPORT Ν
Problems In the Petroleum Industry T>
in the petroleum industry, from the initial work in exploration for oil to the time w h e n the products finally I ave the refinery, are finding the anomaly that the more they know, the less they know. As the business of looking for oil, pro ducing it, and making new and improved products has grown in staggering complexity, technically trained persons of all de scriptions have provided literally hundreds of thousands of answers to questions. Yet, like the magic pitcher of the fairy tale of our younger days, every time one question is answered it seems that several arise in its place; even the answer itself may lead to more intriguing questions hitherto completely unsuspected. The symposium on Unsolved Problems in the Petroleum Industry, presented before the Division of Petroleum Chemistry at the 122nd National ACS Meeting at Atlantic City, left everyone wondering whether the things w e don't know about the oil industry amounted to more than the things we do know. EOPLE
A
JL w o of t h e most brksome problems are the lack of a complete picture of what petroleum is and how it was formed, and the question of how much there is and how much can be recovered. Organic chemistry textbooks o f half a century ago reveal just how far w e have come in our knowledge of t h e composition of petro leum. H e r e are two typical quotations from t h e m : American petroleum consists almost ex clusively of normal paraffins; yet minute quantities of some of trie benzene hy drocarbons ( cumeme and mesitylene ) appear to be present and T h e following para-ffins h a v e been ob tained from crude petroleum: n- and iso-pentane, η-hexa-ne and an isomer, and η-heptane, all these being present in t h e so-called "ga_soline" which is ob tained b y the distillatioo of petroleum and is used for carbxuretting coal-gas O u r knowledge of jDetroleum's composi tion has increased in the s a m e degree as the use of gasoline h a s increased, b u t w e still h a v e many glaring gaps in spite of the work of many individuals a n d the pro ductive API projects. Definite isolations o f specific hydrocar bons are confined almost entirely to those of low molecular weight. E x c e p t for nor mal paraffins, the only individual hydro carbon beyond t h e C12 range which has 2758
been isolated and identified is 4-methyl biphenyl. W e cannot depend on extrap olation into high molecular weight ranges by hydrocarbon-type analysis. Typical of the questions t h a t arise is that of branched chain paraffins. Are they absent in the high molecular weight fractions, or is their presence simply obscured for some reason? Among the ring compounds we have a reasonable amount of information on ben zene derivatives, and data indicate that short chains are in greater prevalence than long. Where more than one aromatic ring is present evidence indicates that perhaps condensed rings are the prevalent struc ture, b u t some evidence points to t h e pres ence of biphenyl derivatives, or even CHEMICAL
totally discrete rings. W e need to estab lish this point and to know what condensed structures there are beyond two rings. If biphenyls are present, w e need to know more about the quantitative picture a n d the relationships between biphenyls, mono cyclic aromatics, naphthenes, and polycylic aromatics. G r e a t e s t Ignorance on Naphthenes
As far as the composition of petroleum is concerned we probably know less about the naphthene hydrocarbons than any of t h e other components. They are rather well known up through C 8 compounds, only a few Co's h a v e been isolated a n d identified, and almost none beyond that. AND
ENGINEERING
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N o w that w e h a v e found cycloheptane derivatives, n o t suspected until recently, w e might even expect cyclooctane or even spiropentane compounds. T h e five-carbon ring, which we have assumed important in large molecules, may actually just fade out as we think the branched-chain paraffins do. Trans-decalin is "the only condensed ring naphthene which has b e e n isolated and identified. H o w far can w e reason b y analogy from t h e aromatic hydrocarbons into the naphthenes? Answers to all these high-molecular weight problems will help us in elucidat ing the structure of lubricating oil mole cules. A C30 lubricating oil with two aro matic a n d t w o n a p h t h e n e rings might look like any one of the pictures in the accompanying illustration, or any one of a great variety of other combinations. T h e answering of questions like this will b e long and tedious and may be possible only through isolation and identification of compounds in a sufficiently higher range to make extrapolations more plausible, by correlations b e t w e e n physical properties and constitution, spectroscopic data, and synthesis of possible structures and com parison of properties with those of isolated fractions. Still dealing with high molecular weight
compounds, b u t in t h e very high range, about all w e know even at this time aJbout t h e composition of asphalts and its rather arbitrary separation into asphaltenes, p^trolenes a n d t h e like is that the molecular weight a n d t h e carbon-hydrogen ratio are very high. W e are not even sure whether these materials should b e classed as hydro carbons, sulfur compounds, or oxygen compounds. Ceresins and waxes are also high molecular weight compounds -which can bear further identification work. Sulfur, Nitrogen, and Oxygen Compounds United States petroleum averages 0.65% sulfur, with t h e amounts varying in individual crudes from 0.1 to T.5%. Foul odors and instability of the STilfur compounds has made research on -them unpopular. API Project 48A is now doing some concentrated work on the subject. Much of the sulfur in fractions w h e r e we know most about it is still characterized as "unidentified," and although we have identified some thiols and sulfides in low molecular weight fractions, we know noth ing about the higher ones. Knowledge of nitrogen compounds is pretty well confined to the heterocyclic bases of the pyridine, quinoline, a n d isoquinoline series. This accounts for less
than one third of t h e nitrogen present, however, t h e remainder being nonbasic. A s far as oxygen compounds are con cerned, w e have information on t h e phenols a n d sketchy data on t h e naphthenic acids. Otherwise the field is prac tically untouched, because w e h a v e had no good analytical m e t h o d for direct deter mination of oxygen until recently. Indi cations are that oxygen compounds in crudes may be more important t h a n p r e viously realized. T h e r e is some evidence now t h a t some of t h e metallic constituents which poison catalysts are present as volatile compounds and actually distill with the oil. If we can find out more about the type of com pounds, w e may be able to work out easier separations. Finally, increasing knowledge of t h e composition of petroleum, and per haps thereby of its origin, may lead to some interesting discoveries about its re lation to life processes. Greater Oil Recovery S o m e o n e wondered in a facetious w a y at t h e symposium whether, by t h e t i m e all the problems of t h e petroleum industry were solved, there would be any petroleum left. Certainly there is a limit to t h e amount available, b u t estimates of re-
U.S. PETROLEUM PROCESSING - • NATURAL GAS
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- * SULFUR - * CARBON BLACK - * L.P.G.
NATURAL GAS
- * PARAFFIN PETROCHEMICAL
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