I N D U S T R I A L and Vol.31 Consecutive No· 44
PUBLISHED
ENGINEERING
CHEMISTRY
ID NEWS EDITION BY
THE
AMERICAN
CHEMICAL
NOVEMBER 20, 1939
VOLUME 17
HARRISON E. HOWΒ Editor
SOCIETY NUMBER 22
Wilson Receives Chemical Industry Medal N ACCEPTING the Chemical Industry Ipresident Medal for 1939, Robert E. Wilson, of the Pan-American Petroleum
and Transport Co., predicted that ex ploitation of veritable chemical mines in oil refiners' back yards will in the next 20 years yield developments of an im portance far exceeding the dramatic growth of this industry in itsfirsttwo dec ades. The medal was presented by James G. Vail, Philadelphia Quartz Co., at a joint meeting of the American Section of the Society of Chemical Industry and the New
York Sections of the AMERICAN CHEMICAL
SOCIETY and the American Institute of Chemical Engineers, held at The Chemists' Club of New York on November 10. Wal lace P. Cohoe presided, Thomas Midgley, Ethyl Gasoline Corp., spoke on the per sonal side of the medalist's life, and Bruce K. Brown. Standard Oil Co. of Indiana, described his technical achieve ments. In his address, under the title, "Refinery Gas: A Raw Material of Growing Im portance", Dr. Wilson remarked that 940,000,000 cubic feet a day, or 14,000,000 tone per year, of cracked gases are avail able from oil refinery operations and classified their uses into three general categories: direct utilization of compounds separated out of refinery gas; refinery gases as raw materials for the chemical industry; and the conversion of refinery gases into motor fuel and other products primarily useful within the petroleum in dustry. The following items are from Dr. Wilson's address: While a substantial percentage of butanes and butènes are almost always present in refinery gas, in an up-to-date refinery about three fourths of the total C4 hydrocarbons and probably over 80 per cent of the η-butane are put into gasoline, and there is an increasing trend in this direction. Although the C4 hydrocarbons boil between 14° and 39° F., they are quite soluble in gasoline, and average gasoline contains in the neighborhood of 9 per cent of C4 hydrocar bons. Since butanes are desirable from both the volatility and antiknock stand points, a good refiner recovers and puts into gasoline all that he reasonably can without danger of too high vapor pressure, which is likely to cause vapor lock in the gasoline feed systems of motor vehicles, particularly in hot weather. As a re finery produces butane at a fairly uniform rate, it is possible to separate out and store during the summer enough to make the best winter motor fuel without buying casinghead gasoline. The liquid is stored during the summer in spherical tanks under high pressure, or in what is known as refrigerated storage, where the liquid (containing considerable pentane) is main tained approximately at its boiling point
and color bodies, which decrease the marketability of the oils. For the past 15 years, refinery laboratories have searched Beilstein tofindselective solvents which would do a better job than sulfuric acid and other refining agents in removing undesirable constituents, but they have not been able tofindone which was of real value for removing more than two or three of those constituents. However, all the while, in their own backyards, were thousands of tons of the neglected gas propane which, when liquefied under pressure, has the amazing property of acting as an antisolvent tending to remove everyone of the five undesirable constituents. In addition to its being the most efficient known solvent for the removal of wax, asphalt, and heavy ends, it has the further advantage of removing each of Robert E. Wilson these three types of constituents separately from the others, thus greatly facilitating by-product utilization. For the removal (below 40° F.) in large insulated tanks, of naphthenic constituents and color the temperature being kept down by bodies, it is very helpful, particularly steady boiling off of butane vapors which when used with other refining agents such are compressed, liquefied, ana returned as selective solvents, sulfuric acid, or clay. to the tank to maintain this cycle. Propane owes its versatility as a preFour principal factors make possible cipitant largely to the fact that its solvent the inclusion of more and more of the bu properties change rapidly over the contanes in gasoline rather than in gas: the venient temperature range between its general use of stabilizers and closer boiling point ( - 4 4 ° F.) and its critical fractionation, which permits the better temperature (212° F.). For example, its recovery of the butanes and the substan density drops from 0.5 to> 0.25 in this temtial elimination of propane; the develop perature range, and it really possesses the ment of methods for separating out and properties of a whole series of different storing butane during the summer months solvents, any one of which can be obtained for use in winter; the elimination of the by raising or lowering the temperature and butylènes (which can readily be poly- using enough pressure to keep it liquid. merized into high antiknock gasoline), Important from a vo>lume standpoint which makes room for the inclusion of are the growing usee of liquid propane. It most of the butanes in gasoline; and the is used as bottled gas for cooking and heatbetter design of the fuel systems for motor ing where city gas is not available; as vehicles to minimize the danger of vapor industrial fuel where accurate control and lock and permit the use of more volatile low sulfur content are important; as an gasoline. A liquefied butane cut is also enriching agent for city gas -and even as used to some extent, particularly in the oil- city gas itself, by mixing it with air in producing states, as a substitute for gaso- quantities too small to make an explosive line, and this has the advantage for use in mixture. The total consumption in these refrigerated trucks that its evaporation fields amounts to approximately 150,000,from liquid form produces considerable 000 gallons yearly. I t is shipped in refrigeration. special tank cars and by pipe line as well One of the most important new uses as in cylinders. The use of refinery gases as raw mafor compounds present in refinery gas is the employment of propane as a refining terials in the American chemical industry agent in the manufacture of lubricating had its real inception only about 18 years oils. The various crude cuts of lubricating ago, when propylene in cracked gases was oil, as obtained from crude oils, contain converted into isopropyl alcohol. This four or five kinds of undesirable constitu- product was then selling at prices up to ents which must be removed in order to $7.00 per gallon and enjoyed a modest make high-quality lubricating oils: paraf- demand as a substitute for ethyl alcohol fin wax, which must be removed to obtain because of the legal restrictions surrounda low pour point; asphaltic compounds, ing the use of the latter. This synthesis which nave excessive sludge- and carbon- brought the price down very rapidly, until forming tendencies; the heavy ends of its price today is about one twentieth of lubricating cuts, which have high carbon- what it was and its uses have multiplied forming tendencies; the naphthenic com- accordingly. Ethylene dichloride and pounds, which are responsible for poor ethylene chlorohydrin, made by chloviscosity and low resistance to oxidation; rinating ethylene, followed closely after 697
INDUSTRIAL AND ENGINEERING CHEMISTRY
isopropyl alcohol and again resulted in greatly cheapening these reagents. The next important product to be made synthetically from cracked gas was ethylene glycol, about 1022. At that time glycol was a chemical rarity practically unknown in industry and the development of uses for it was a major problem. However, its outstanding merit as an antifreeze much less volatile than alcohol and less viscous than glycerol, coupled with aggressive sales work, soon developed a mass market and other uses were found. Nitroglycol is now largely used in conjunction with nitroglycerin, particularly to make lowfreezing explosives, and the related compound, diethylene glycol ether, is increasingly used as a substitute for glycerol for the moistening of cigaret tobacco. While ethyl alcohol, glycol, and isopropyl alcohol are the three most important primary products synthesized from cracked gas, one company is making commercially more than 100 synthetic chemicals starting from ethylene, propylene, and the butylènes, and including some 24 alcohols and alcohol ethers, 4 ketones, 23 esters, 14 amines, 8 ethers, and 7 chlorinated compounds. The olefins in refinery gases are by far the most reactive and hence the most important raw materials for chemical synthesis. The simplest reaction is the formation of various alcohols from the corresponding olefins by absorbing in sulfuric acid and then hydrolyzing. Starting with a complex mixture of refinery gases, it is possible by increasing stepwise the temperature and concentration of the acid to react, first, with the butylènes, next with the propylene, and last with the ethylene, to secure reasonably good separation of the resultant alcohols. Each of the principal olefins in refinery gas is being used commercially for the production of the corresponding alcohol and the synthetic plant capacity for making ethyl alcohol is about equal to half of the total industrial alcohol production of the country. Practically all of the commercial isopropyl alcohol and secondary and tertiary butyl alcohols on the market today are made from petroleum gases. Most of the acetone is made by the catalytic dehydrogenation of isopropyl alcohol, and acetone is, in turn, converted into acetic anhydride by pyrolysis to ketene and ab-
sorption in glacial acetic acid. The latter is of large and growing importance in the manufacture of cellulose acetate. In fact, the primary reason for the rapidly increasing importance of cellulose acetate in this country is the availability of this very cheap acetic anhydride. An equally important general reaction of the olefins is that with chlorine with and without the presence of water. Ethylene dichloride, in particular, is finding increasing use as one of the two principal raw materials in the making of the rubber substitute, Thiokol. Vinyl chloride is generally made by treating ethylene dichloride with alkali and is of great importance as the starting point in making the polyvinyl resins used widely as insulating compounds and rubber substitutes. The copolymer of vinyl chloride and the vinyl acetate is widely marketed as a plastic under the trade name Vinylite. Incidentally, acrylate and methacrylate resins can also be made, starting with petroleum gases, ethylene chlorohydrin and acetone being the respective starting points for cyaniding. Ethylene dichloride can also be made to react with ammonia to produce a series of amines which are now available commercially. Similar reactions for the higher olefins have all been worked out and only wait a satisfactory market to become commercial. Allyl chloride and methallyl chloride and the corresponding alcohols and propylene glycol are all being made commercially from refinery gases. An interesting and important synthesis recently found to be possible from petroleum is that of glycerol, which can be made by the regulated chlorination of propylene followed by hydrolysis under certain special conditions. While the synthesis is not yet commercial, it is a real possibility in case the price of glycerol should skyrocket because of war demands. The paraffin hydrocarbons, of course, are less reactive than the olefins and are less widely used as chemical raw materials. For this reason the most important chemical use of the paraffinic gases has been to convert them into olefinic gases, either by cracking or by catalytic dehydrogenation. Thus, most of the chemical compounds synthesized from refinery gas are actually made by cracking propane to give a cracked gas with nigh concentrations of
VOL. 17, NO. 22
propylene and ethylene. Catalytic dehydrogenation can be made to give even better yields of the desired olefins. Butylène can also be dehydrogenated to butadiene, and this, in turn, polymerized into the familiar Buna rubber. Chlorination can, of course, be applied to the paraffinic hydrocarbone and it is possible to make methyl chloride, chloroform, and carbon tetrachloride by this method, but none of these processes are commercial today» partly because of the difficulty in controlling the reactions to obtain products of high purity. Propane is commercially chlorinated to form a moderate yield of the 1,3-dichloropropane, which is separated and converted into the important new anesthetic cyclopropane by the use of zinc dust. Butane can also be chlorinated to make butyl chlorides. The direct oxidation of petroleum hydrocarbons to make useful products has received much attention in the literature, but actually the complexity of the mixtures made by most of the oxidation processes is so great as to make them of doubtful commercial importance. However, some methyl alcohol and formaldehyde are made by the controlled oxidation of methane. Ethylene can be oxidized to ethylene oxide and this converted into glycol and other related products. An interesting new development is the vapor phase nitration of the gaseous paraffin hydrocarbons with the oxides of nitrogen to form the nitroparaffins. It is understood that a commercial plant is being built to carry out some of these reactions, though details are lacking as to the precise products to be made and their uses. While these processes are of great importance to the chemical industry, they are less significant in the economics of the petroleum industry. The total amount of refinery gases available is hundreds of times as large as the chemical industry is likely to need for some time. Far more important to the petroleum industry are certain new processes, principally polymerization, which convert refinery gases into gasoline of unusually high quality. In a sense these processes are the reverse of cracking, as they cause the relatively small gas molecules to recombine into medium-sized molecules suitable for gasoline. Commercial polymerization processes are of two types: catalytic processes which polymerize the propylene and butylènes into higher olefins (generally with phosphoric acid as a catalyst at temperatures between 400° and 500° F.): and thermal processes which crack tne saturated hydrocarbons and then polymerize the increased quantities of olefins at much higher temperatures and pressures. Since the demand for these polymer gasolines is almost unlimited, such processes are bound to be adopted rather generally. Approximately 600,000 gallons of such gasoline are being synthesized every day by polymerization plants now operating. Possibly even more significant, from the standpoint of our national welfare, is a series of related processes which start by separating out certain relatively pure hydrocarbons from the refinery gases and causing them to* combine to make other hydrocarbons of a composition especially suited for use in aviation gasoline. Present plant capacity for such products is in excess of 300,000 gallons daily. Dr. Wilson described in some detail the process used and results obtained.
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