THE PETROLEUM INDUSTRY— Consumer of Chemicals No. 2 in α Series
Chemicals Used in Refining D. T. SHAW, Atlantic Refining Co., Philadelphia, Pa.
The varying character of crude oils, the constantly changing processes of refining, and the differing demands for products are reflected in the variety of chemicals used by this branch of the industry I V E F I K I N G is complicated, because w e are trying to make many products from a starting material of variable composition. Basically, w e are trying to separate mate rials in the crude oil according to boiling point for gasoline, kerosene, furnace oil, Diesel oil, and heavy fuels. Since there is not enough gasoline existing as such in crude oil, w e are forced to make more at the expense of other parts of crude; crack ing is the familiar term applied to those processes of breaking heavier, high boil ing parts of the crude to gasoline. Having applied this process, we again come back to the physical separation according to boiling points. •Chemicals are used in the production of crude and almost the first thing that is done to crude after it gets to the refinery is a further chemical treatment to remove inorganic salts. This takes place just be fore the crude is charged to the primary refining unit—the pipe still. This consists of a treatment witb soda ash in the amount of a pound per 5 0 0 barrels of crude, with or without the addition of proprietary com pounds like Tretolite. The lightest prod uct from the pipe still is gas, and here chemicals are used if the gas is to be processed for recovery of liquefied petro leum gases such as propane and butane. Processing is normally the removal of sul fur, which can be accomplished by scrub bing with any one of a number of com pounds, the simplest being caustic soda; more generally used are the organic amines. Consumption of such amines for hydrogen sulfide removal are in the order of a pound for every 200 pounds of hydro
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gen sulfide removed. Odier processes use potassium phosphate or sodium phenolate. The next stream from the primary separation is the naphtha stream, which contains the gasoline boiling range mate rial already in existence in the crude. Here again, chemical treatments are ap plied, but they are in the case of these straight run naphthas relatively simple. Sweetening is a process applied to naphthas and gasolines to eliminate un pleasant odor due to sulfur compounds such as hydrogen sulfide and mercaptans. Sometimes the sulfur compound is changed to a nonmalodorous form through the use of litharge. Some processes remove the sulfur from the gasoline. This not only improves the smell, but where T E L is to b e added the antiknock agent is more effective, i.e. a lesser amount has to b e used.
Since the gasolines from this primary distillation are often unsuitable for modern engines ( being of too low octane number ) they are often further processed by reform ing to alter their chemical composition. I n the past, these processes have been largely thermal, but recently a number of cata lytic processes have come into being which permit more selective operation for t h e desired compounds. These processes i n volve the use of platinized catalysts in some instances and, in others, the use of heavy metal oxides. Where platinized catalysts are used, the permanent loss of platinum may amount to 0.5 to 1.5 cents per barrel of product. We now come to the so-callod distillate fuels—kerosene and furnace oil which, t o gether with some heavier products, make up the gas oil fraction of crude. Kerosene, as taken from the fractionating column
"p\AviD TAYLOR SHAW, assistant plant manager of the Philadelphia reA ^'finery of Atlantic Refining Co. was born in Oberlin, Ohio, in 1893 and educated at Oberlin College and Brown University. His experience in the chemical industry included stints at Federal Dyestuff & Chemical Co., E . I. du Pont de Nemours & Co., National Aniline & Dye Corp., and Rubber Service Co., before he joined the Atlantic Refining Co. in 1929. He was senior engineer in the research and development department and later became general superintendent of that department, and assumed his present position in 1945. He is a member of Sigma Xi, American Institute of Chemical Engineers, the Franklin Institute, and the Philadelphia Chamber of Commerce.
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would, in almost all instances, be entirely unsuitable for wick-type burners unless considerable purification effort was expended upon it. Here, various processes are used which require chemicals in considerable amounts. Some installations exist for solvent extraction of this stream b y the use of liquid SO2 so that a highly paraffinic product will result. A more generally used processing is that of acid treating with sulfuric acid and redistillation to remove the polymerized material. Some kerosenes are prepared b y merely caustic "washing and filtration through fullers earth. The product wanted by the consumer should b e clear and water-white in appearance; incidentally, it is one of the f e w products which the consumer sees and handles personally. It must b e free of dangerous volatile substances, have no objectionable odor, and should burn with a clean, bright flame. Chemical Refining of Diesel Fuels Diesel fuel is normally a material overlapping kerosene and the next heavier product, furnace oil. In Diesel fuel, certain types of hydrocarbons appear to give preferred operating results, absence of smoke in the exhaust, low engine wear, etc. Chemical refining removes objectionable types of compounds, and additives can improve combustion characteristics in a manner not unlike the addition of tetraethyllead to gasoline. Examples are amyl nitrate and amyl nitrite. The most widely used of these distillate products is separated just above the boiling point of kerosene, and this is furnace oil, or what is often termed "fuel oil" outside the oil industry. This household fuel requires caustic washing, filtration, and often the addition of an inhibitor so that it may remain stable in storage until it reaches your home burner. The magnitude of this business has grown tremendously over the past few years. Here is a product on which the industry would welcome assistance in the form of a cheap oxidation inhibitor, which would also act to break emulsions and prevent water haze from remaining in the oil. This is a generally recognized problem in the industry, since all products of this type are produced at the refinery saturated with water at a temperature above that which it may subsequently reach after transportation through pipe lines and storage. It has been found that some excellent oxidation inhibitors are also dispersants and can, and do, maintain a stable water emulsion. There are instances of refiners going to the complete dehydration of such material before shipment, but such measures are drastic and expensive. Incidentally, a dehydrated naphtha will absorb moisture from air with which it is in contact during storage. The general gas oil fraction (which got its name many years ago when it was used to make city gas) may include furnace oil distillates as well as the heavier gas oils. It is now, since the automobile came into wide use, the chief source of the cracked
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gasolines which are responsible for much of the improvement in antiknock quality. These gas oils are charged either to thermal or catalytic cracking operations. Catalytic cracking operations u s e large quantities of catalysts, some svnthetic, others prepared by the treatment of naturally occurring earths. All o f these catalytic processes, whether fluid, moving bed, or fixed bed, lose some catalyst in the form of fines. Recovery equipment on fluid bed units will retain all but t h e finest material, but this fine material not retained may amount to two to three tons a day on a unit charging 30,000 barrels of g is oil feed. In addition, it has often been found economical to purposely withdraw and discard catalyst beyond this amount, in order to maintain the equilibrium activity at a point which gives t h e desired product distribution from the unit. This compensates for t h e gradual loss of catalytic activity which takes p l a c e in any catalyst. Gasoline produced from catalytic cracking requires only a caustic wash and
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the use of an oxidation inhibitor to make it ready for blending. Thermally cracked gasolines o n die other hand must b e more severely treated. In many instances a sulfuric acid treatment is applied, followed by redistillation, to remove the heavier ends. Heavy naphtha treating may u s e sulfuric acid followed b y caustic. Consumption of chemicals may be in the order of 3 barrels naphtha per pound acid or 1 0 barrels naphtha per pound caustic. Here w e should note that all cracking operations produce additional gas. This, unlike the gases from the primary distillation, is often highly unsaturated, i.e. olefinic. Many processes involving the use of chemicals are commercially available t o convert some of these lower boiling hydrocarbons back to higher boiling ones which can b e included in gasoline. These processes are catalytic polymerization, where the usual catalyst is phosphoric acid which produces a union of unsaturated hydrocarbons, and alkylation, where the favored catalysts are sulfuric or hydrofluoric acid
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which produce the union, of dissimilar hydrocarbons such as isobutane and butylènes. In neither of these operations are the present catalysts entirely satisfactory, since polymerization is lacking in selectivity, and yields of iso-octane from alkylation are not too good from a theoretical viewpoint because side reactions cause poor quality compounds t o b e formed. Phosphoric acid o n a clay carrier gives a yield of polymer of approximately 100 gallons per pound catalyst. Sulfuric acid is another catalyst. In alkylation, the yield of alkylate may be taken as about one gallon per pound H2SO4 and about 100 gallons per pound of HF. During World War II, the industry made over 100,000 barrels of alkylate per day. Products from catalytic cracking, thermal cracking, from the primary distillation, and from t h e recovery of light products from the gases, are blended together to make commercial gasoline. Here, the industry becomes one of the large consumers of organic chemicals because, to bring such a mixture of components t o the presently required antiknock levels, addition of tetraethyllead in amounts -up t o 3 cc. per gallon is required. Here again, the industry, though well served by the manufacturers of this compound, would b e delighted with the development of a real competitor. In addition, w e use dyes and inhibitors which, although in small concentration, amount to huge volumes in the industry. I n 1950, the United States used 114,000 tons of lead in T E L , equal to about 10% of total U . S. consumption of this metal. W e have gone over ttie three lighter streams from the primary distillation and followed t h e major ones t o a commercial product. I will omit the next streams
which are the lubricating distillates, since their processing will b e covered i n another article. The bottoms from the primary distillation, as well as the residuals from thermal cracking and some of the heavier gas oils from catalytic cracking, make up commercial Bunker C or No. 6 Fuel. This material d o e s not receive further processing. Future Trends There is little question that t h e u s e of catalytic cracking is increasing and that demands for cracking catalysts will continue and grow. There is at present an upsurge in t h e use of catalytic reforming and here it is probable that t h e demand for platinized catalysts will increase with considerable rapidity. Solvent extraction processes for finishing gasolines are increasing, as is the use of solvents i n production of waxes. These trends lead to a reduction in the use of sulfuric acid, but as fast as w e reduce use of acid i n o n e part of the refinery, w e seem to pick it up in another. Here are some problems w h i c h m a y i n dicate fields that should b e explored for chemicals to help the petroleum refiner. W e need to understand h o w fuel burns. Give us a plentiful, cheap equivalent o f tetraethyllead for automobile fuel and o f amyl nitrate for Diesel engines. Examine the applications of sulfuric acid and possibly y o u can come up w i t h some other chemical which will d o t h e same job cheaper and better. Much of the industry's alkali consumption is a direct result of the use of acid. Find us a cheap chemical which will reduce t h e viscosity o f heavy fuel oil without changing the other
characteristics of the fuel. D e v e l o p for us catalysts which can do a more selective and better controlled job of the conversion of normal paraffins t o isoparaffins and of naphthenes t o aromatics cheaply and w i t h high yields. A problem that, if solved, would produce almost inestimable savings is the economical removal of sulfur and sulfur compounds from crude oil. This would be a tremendous boon to the refiner, as it w o u l d reduce t h e use of alloys, reduce maintenance costs, and eliminate many treating processes' which are n o w required o n finished products to remove sulfur w h i c h has followed through all of the preliminary processing steps. A list of the principal chemicals used in refining is shown in the accompanying table. It would b e misleading to place an absolute figure o n t h e importance or volu m e usage on them. As was explained, the varying character of crude oils availto the refiner, the constantly changing processes of refining, and the differing demands for products will cause each refiner to compile his o w n list each year. It is more enlightening to look at the magnitude of the total outlet for the chemical industry w h i c h is afforded b y petroleum refining. Taking my o w n c o m pany as a proportionate part, I h a v e estimated that the part of t h e petroleum refining industry which I have briefly covered consumes $241 million worth annually of chemicals, catalysts, etc. Naturally, w e would like to lessen this amount, a n d you would like to increase it. Perhaps w e can agree on the common ground where the chemical industry can give u s t h e means of making better petroleum products. Principal Chemicals Used in Petroleum Refining A c i d hydrofluoric Acid phosphoric Acid sulfuric Alcohol, ethyl Alcohol, methyl Alcohol, isopropyl Alpha naphthol AlCIa AlaOa Al 2 (S04)s Ammonia, anhyd Ammonia, aqua BaO a H a Bauxite Benzene CaCOa CaCIa C a hypochlorite C a O - f CaO*Ha CO* CS8 CCI4 Cl2 Chloronaphthalene Clay Copper chloride Copper oxide Copper sulfate Cresol Dibutyl phthalate
Diethylene glycol Dyes, miscellaneous Ethanol amine Ethyl acetate Ethylene dichloride Ferric sulfate Ferrous sulfate Inhibitors, miscellaneous, gasoline Inhibitors, miscellaneous, oil Lead oxide Methyl ethyl ketone Phenol KOH KNO* K 3 PO* Na aluminate NaHCO. NaaCO* NaCI NasCrsOi NaOH Na meta phosphate N a phosphate N a silicate Na 2 SO* Na 2 S Na 2 SO a Sulfur SOa Talc Tetraethyllead
T H I S is the second of a series of articles on t h e consumption of chemicals b y the petroleum i n dustry. T h e symposium was presented b y the Commercial Chemical Development Association a t a meeting in Philadelphia on Jan. 2 3 .
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Employers and Applicants
800 r
Employers
^Applicants
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cm ployment Trends As O b s e r v e d Through ACS Employment Aids
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Figure 1
B. R. STANERSON, American X H E A M E R I C A N C H E M I C A L SOCIETY
several employment aids including the National Employment Clearing House operated at national meetings, the Regional Employment Clearing House with three offices, t h e advertising section of C H E M I C A L AND ENGINEERING N E W S ,
em-
ployment committees ,and services operated by local sections, and the ever-present assistance of o n e member for another. Some of these are informal and others are highly organized. Only those which are w e l l organized and have been in operation for some time provide data in the discussion of employment trends. Much has b e e n said about the shortage of chemists a n d chemical engineers during the past year or more, and various statistics from Society operations have been investigated t o determine the severity of the situation. National Employment Clearing House One of the oldest employment activities of the Society and one on which most statistical information is available is the Na-
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Chemical Society, Washington, O. C.
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N o w h e r e have economic trends b e e n more sharply observed than in the records of the A C S Employment Clearing House tional Employment Clearing House. This has operated at each of the national m e e t ings since 1937 and summary statements of operating statistics have appeared from time to time, most recently in the Aug. 2 1 , 1950, C&EN, pages 2887-9. At that time it was pointed out that it is difficult to draw many conclusions from the data because of the number of variables involved. The statement is still true but as additional statistics are accumulated it is possible to eliminate or determine the effect of certain variables.
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In the summer of 1950 when the previous report on NECH operating statistics was written, the statement was made that the current buyers' market was evident from the relative number of applicants and employers. For several years preceding 1949 w h e n there was a strong sellers' market there had been approximately the same number of employers and applicants registered at Clearing Houses. Since almost every employer was looking for more than one employee, obviously there "was a shortage of technical manpower. This
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