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JAMES L. VAUGHAN Air Reduction Co., Murray Hill, N. J.
Manufactured Petroleum Chemical Intermediates Large-scale syntheses of petrolem chemical intermediates has essentially eliminated supply restrictions which existed with natural resources
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ox PROCESS DETAIL: raw material and utilities requirements, and manufacturing costs of manufactured petroleum chemical intermediates may be found in the literature ( 7 : 2 ) . Representative materials in this field have been chosen to illustrate some important economic and market factors in the gro\vth of large volume petroleum chemical intermediates.
Ethyl Alcohol Synthetic ethyl alcohol is from many standpoints the classic petroleum chemical, and its development illustrates many of the basic economic and growth characteristics of the petroleum chemical industry. At the present time, industrial ethyl alcohol is made in the quantity of close to 200,000,000 gallons per year. IVhere in 1935 only 10% of the production (then 100,000,000 gallons) was made synthetically, today about SO%> is made from ethylene. This represents a growth of the synthetic product of nearly 16-fold in 25 years, with essentially a complete reversal of the relative positions of fermentation and petroleum synthesis. ‘There was never a question as to the products’ end uses and markets, but there were difficult technical and market problems to overcome, as well as the competition of the fermentation process using low-cost molasses. 7 h e conditions needed to provide for the expansion of the synthetic alcohol industry were : reasonably stable prices and an assured market picture on Irhich to base the investment of very large capital expenditures; the solution 10 very difficult technical problems, parricularly those of processing sulfuric acid; and an economical method of providing ethvlene of high concentration. IYhile all these factors were developing before 1940, the war greatly accelerated the need for synthetic alcohol. With the necessity for expansion of the synthetic rubber industry, huge quantities of ethyl alcohol were used to make butadiene. The quantities of alcohol were so tremendous-reaching close to 700,000,000 gallons per yearthat fermentation from grain as well as molasses was used.
After the war, the availability of surplus molasses a t low prices disappeared and the market conditions for synthetic alcohol improved greatly. In entering this market, however, the pattern of synthetic alcohol producers has been to contract for long term delivery of alcohol a t a stable price. In this manner, the petroleum chemical companies were able to underwrite their huge investments on a sound basis. At the same time, increasing dominance of synthetic alcohol provided the users with assurances of price stability and essentially unlimited supply. This illustrates one of the very important characteristics of petroleum chemicals-Le., the supply and price picture is such that they eliminate uncertainty and permit markets to be developed to the limits of their acceptance. The technical problems were solved in several ways. Greatly improved sulfuric acid restoring and concentrating processes were developed. Improved materials of construction and equipment developments contributed a great deal along with improved control and instrumentation equipment to permitting larger units with their greatly improved economy. The largest units built are designed for the production of 40,000,000 gallons per year, a quantity nearly half the total industrial alcohol production only 30 years ago. .\ v e q important technical development made 10 years ago was that of the direct hydration process by Shell Chemical. This system recycles ethylene with a large excess of steam over a phosphoric acid on Celite catalyst. This process eliminates the need for handling large quantities of sulfuric acid but requires higher capital cost for the circulation of large quantities of gas a t high pressure with the simultaneous input and removal of heat. The problem of developing low cost ethylene was essentially an outgrowth of the search for oil cracking processes to produce higher octane gasoline. This search led to low-pressure, high-temperature processes particularly suited to ethylene production from light feeds, such as ethane and propane. Combined with the development of separating techniques involving low temperature sepa-
ration and absorption systems, pure ethylene has been provided a t prices as l o x as 5 to 6 cents a pound. As the ethylene cost is about half of the price of the synthetic alcohol, this has been very basic. At the same time, the availability of low-priced ethylene has had a major effect on the development of such products as polyethylene and ethylene glycol. Further. the availability of cheap ethylene on a pipeline delivery basis has had the effect of opening large segments of the petroleum chemical industry to companies with no petroleum raw material pojition. The future growth of synthetic ethyl alcohol cannot possibly duplicate the past 25 years. ‘The displacement of fermentation alcohol is largely complete and the markets it serves are in general matured. In spite of this, it still provides an interesting area for research because of the huge volume made and the potential for an improved process. -4 major development will probably come fxom research directed toward other goals as only minor research efforr is directed toward this process.
Ethylene Oxide and Glycol I n contrast to ethyl alcohol, ethylene glycol was not produced from natural sources. Consequently, in its early consideration, assured markets could not be projected on the basis of lower cost production. lVhile glycol obviously had properties which could be related to the lower aliphatic alcohols and was promoted for similar uses, ethylene oxide’s chemical and physical properties had no natural equivalents. The tremendous growth of glycol for use in the specialized application as an automobile anti-freeze is well known with its essentiallv complete domination of this market. The exploitation of its properties as a dihydric alcohol and polymers has been much slower. Similarly, the development of such applications for ethylene oxide as uses in nonionic surface active agents and for production of other intermediates such as ethyl alcohol and ethanolamines have been a slower process. However, these newer uses are expected to have rapid growth curves and VOL. 51, NO. 9
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have been the basis for recent capacity expansions. Ethylene oxide and glycol are interesting from both the process development and marketing standpoints. The first commercial process waS the chlorhydrin process. This involves the reaction of ethylene and hypochlorous acid formed from chlorine to the chlorhydrin followed by hydrolysis with lime to yield ethylene oxide which is hydrolyzed to glycol. While characterized by high yields, the limitation to a lower cost process was imposed by the relatively high cost of chlorine, xvhich ended up as calcium chloride having little by-product value. In comparison with ethyl alcohol, for example, utilizing the same ethylene feed, and having substantially the same molecular weight, ethylene oxide generally costs about twice as much. The opportunity for a lower cost process stimulated a great deal of effort which developed into the direct oxidation processes based on the use of silver catalyst. The variations in this process include the use of air or oxygen, and fixed and fluid bed operations. While eliminating the need for chlorine and lime, the primary disadvantage in the oxidation process is the relatively low yield on ethylene, probably about 707%. Economically, lost ethylene yield is being exchanged for chlorine and lime utilization. This in turn points up the importance of the development of low cost ethylene in affecting the course of this, as well as ethyl alcohol, development as it thus favors this route. While the development of the direct oxidation process gave better economics on the basis of present conditions than the chlorhydrin process, the chlorhydrin plants are still operating, presumably economically. However, all the new plants built in the past 10 years have utilized the oxidation process, including those built by producers already having chlorhydrin plants. This tends to refute the often stated remarks regarding rapid process obsolescence in the chemical industry. I n general, capacity obsolescence is more common than process obsolescence. One compelling economic reason for this is that in the last analysis, a plant is shut down when it cannot return what are essentially out-of-pocket costs. T h a t is, once a plant is built its displacement must be on a depreciation free basis. .4s an unusually large improvement is necessary to displace a n existing plant on this basis because of the high proportion of capital cost in such intermediate plants, this is not often done. As is the case with glycol, the less economical operation can continue to be attractive in a rising market. In a contracting market, however, these plants and particularly the smaller units could become obsolete because of the high out-of-pocket costs. The market aspects of ethylene glycol
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offer some contrasts to synthetic alcohol. .4s an anti-freeze agent, it would be highly desirable from the low volatility standpoint as compared to methanol or ethyl alcohol. The primary problem was that of selling the advantages of the premium priced material for this use, which has been done with notable success. However, the continuing trend to larger automobiles has probably been as important a contributor to the increasing market for glycol as any other single factor. At the same time, the promotion of the material as a permanent anti-freeze is giving distributors problems. Another point in the economic and market pattern is that the growth of glycol and ethylene oxide to large size markets and low cost: has stimulated further developments in their use as intermediates for other uses. Ethy-lene oxide has found considerable use in nonionic surfactants and polyethers, \vhile ethylene glycol is used in Dacron polyester fiber and Mylar film. These uses are, in fact, expected to shois much greater grobvth than for anti-freeze use. Glycerine LYhile glycerine is far smaller in scale than either ethyl alcohol or glycol, its development from synthetic sources represents a classic case from a number of viewpoints. In 1937, when Shell Development Co. published the results of their work on the production of synthetic glycerine from propylene, it represented an extremely impressive research and development effort. One of the primary discoveries upon which the process was based was that by operating a t sufficiently high temperature, chlorine substituted for hydrogen rather than adding across the double bond, thus making it possible to add the three hydroxyl groups. With the use of this process, Shell calculated that glycerine could be made profitably for considerably less than the prevailing market price. The fact that glycerine was supplied entirely as a soap by-product and was not in short supply, dropped glycerine prices to levels such that the synthetic process became relatively unattractive. This represents a n excellent example of the inability of synthetics to compete with a by-product, where the cost of recovery of the latter is far below market cost. The price of a by-product can decrease if necessary to only recovery and selling expenses so long as the market can be satisfied by the by-product. This situation changed shortly after LVorld War I 1 when the continuing gro\sth of alkyd resins and other outlets for glycerine resulted in sharp price increases because of short supply. Following the pattern of synthetic ethyl alcohol, Shell was able to ensure the economics of a synthetic plant through
INDUSTRIAL AND ENGINEERING CHEMISTRY
long term contracts, in turn providing the assurance of essentially unlimited supply a t stable prices to those companies utilizing it for further processing. The position of synthetic glycerine became even further established when the synthetic detergents began their phenomenal growth, decreasing the supply of by-product glycerine. By 1955, 35% of the total glycerine production was from synthetic sources. Conclusions One of the primary contributions made by the syntheses of petroleum chemical intermediates on a large scale has been to eliminate the supply restrictions existing with materials from natural sources. The petroleum chemical industry utilizes only a n extremely small fraction of the available materials, being itself a by-product of the huge fuel industry. The synthesis of petroleum chemical intermediates on a large scale has provided a price stability permitting far better long range planning and greater reliance and assurance for developments dependent upon such materials. The establishment of the large volume intermediates has to a gredt degree been dependent upon the development of relatively stable, large markets to provide the economic basis to justify the very large capital requirements. The use of long-term purchase contracts has been a very important tool in this growth. The developments in technology, particularly in materials of construction, and in equipment developments permitting larger and more economical units, have ail been extremely important in permitting the low cost production of these large quantities of intermediates and the products depending upon them. Acknowledgment The author wishes to express his appreciation to the Air Reduction Co. for permission to publish this article which was prepared prior to association with them. literature Cited (1) Encyclopedia of Chemical Technology, Vol. VII, 988 pp., Frances-Jute, R. E. Kirk, D. F. Othmer, et al., eds., Interscience, New York, 1951. (2) Faith, L., Keyes, D. B., Clark, R. L., Industrial Chemistry,” 652 pp., FViIey, Xew York, 1950.
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RECEIVED for review April 17, 1959 ACCEPTEDApril 27, 1959 Division of Industrial and En ineering Chemistry, Symposium on Plant 8osts and Economics in the Chemical Process Industry, 135th Meeting, ACS, Boston, hlass., April 1959.
