January 2 0 , 1933
I N D U S T R I A L
A N D
E N G I N E E R I N G
C H E M I S T R Y
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Britain Agitates for Home-Produced Motor Fuels Hydrogenation of T a r s and T a r Oils Being Investigated C. H. S. TUPHOLME, 32 Russell Hill, Purley, Surrey, England T H E BRITISH public has long been agitating for home-produced motor spirit, and all sections of t h e press have been asking for years wny British chemists cannot do something about i t ; the motor press in particular has pointed to the success of the NewJersey plant of the Standard Oil Co. and has inquired why Britain, too, cannot hydrogenate her coal. T h e lead in t h i s matter has been taken by chemists in the manufactured-gas and coke-oven industries, and, as a result of their investigations, both at the expense of private concerns and of t h e government, there is a general opinion slowly crystallizing t h a t hydrogénation of tar and tar oils is a better commercial proposition for Britain than is the hydrogénation of coal. The general argument is that, where a tar or tar oil is used, a liquid would be handled in place of a paste of coal and tar, and also that, hydrogen being a n important factor in the cost of the process, tar oil requires o n l y half as much hydrogen as coal. As matters now stand, Britain has available vast quantities of high-temperature tars for which adequate markets cannot be found, and a rich source of hydrogen is available in t h e large quantities of coke-oven gas which are at present blown to waste.
FIGUBB 1.
REACTION VESSELS
A t the Fulham laboratories of the Gas Light and Coke Co., the largest manufactured-gas utility in the world, a motor spirit of a value intermediate between petrol and benzol has been produced on a laboratory scale, the yield being 56 per cent of spirit boiling below 180° C. o n distillation of a crude product obtained by treating creosote with hydrogen at 200 atmospheres and 400° C. The residue from the distillation, some 40 per cent by volume of the original creosote, can be used as Diesel fuel, or it can be mixed w i t h fresh creosote and resubmitted to hydrogénation. E X P E R I M E N T S AT GOVERNMENT F U E L RESEARCH STATION
These experiments have been confirmed by J. S. G. King, working a t the Government Fuel Research Station, who has found that it is possible to hydrogenate creosote under pressure w i t h about 2.5 per cent by weight of hydrogen, and to obtain 97 per cent by weight of the original creosote. This spirit, however, contains about 40 per cent of saturated hydrocarbons, as against the 17 per cent obtained at Fulham. B o t h spirits contain a high percentage of aromatics. The possibilities of commercial-scale operation of coal-tar hydrogénation were recently discussed by King and M. A. Matthews before the Institute of Fuel, when the practice to date was reviewed. These t w o workers reported that, on the Dubbs plant installed a t the Langerbrugge Power Station in Belgium, good work has been done on tar obtained from Salermo a n d Thyssen carbonization plants, and t h a t only that part boiling above 220° C. is subject to cracking. This yields 28 per cent by volume of acidfree motor spirit (specific gravity 0.78), of which 35 per cent distils below 100° C. and 95 per cent below 200° C. T h e unit at Langerbrugge produces from one ton of coal:
Motor spirit for carbonization and cracking g a s . Motor spirit b y distillation of t a r Motor spirit b y cracking of residue
Imperial Gallons 3.0 2.5 4.5
TOTAL 5 t o 6 cwt.
10.0 2 9
T h e cracking pressure used is 23.5 atmospheres and the t e m perature 480° C. The plant can also be operated t o give a pitch residue, though the yields of spirit are then lower. Under the supervision of Doctor King, experiments have b e e n carried out at the Government Fuel Research Station, and t h e plant used was described to the Institute of Fuel by that worker, in conjunction with M. A. Matthews. Experiments were started on a laboratory scale using highpressure converters of 2 liters capacity. These reaction vessels (Figure 1) were similar t o those used b y Bergius in his pioneer work on coal, and were arranged for heating b y manufactured gas. With these converters t h e conditions of temperature, pressure, and hydrogen concentration were determined, under which cracking and hydrogénation could take place without the formation of carbon residue. Further experiments were carried o u t in which the effect of catalysts was studied. T h e method of treatment is to charge a 2-liter converter with 250 grams of tar and 5 per cent of catalyst, secure the head and charge t o a predetermined pressure with hydrogen, discharge this hydrogen, and then recharge t o 100 atmospheres. T h e converter is heated to about 450° C. during 2 hours and maintained a t this temperature for another 2 hours. During this time the pressure rises from 200 t o 250 atmospheres owing to g a s expansion, and, if hydrogénation takes place at all extensively, the pressure at the end of the heating period drops t o about 160 atmospheres when hot, or 40 atmospheres when cold. After a thorough examination of various catalysts, it was found that some catalysts h a v e an adverse effect on the reactions and accelerate coke formation ( e . g . , calcium oxide and hydride); some convert tar acids into neutral oil (e. g., iodine, hydriodic acid, molybdic acid, molybdic acid and sulfur, tungstic acid and sulfur); and some convert pitch into neutral oil (e. g., molybdic acid, molybdic acid and sulfur, tungstic acid and sulfur, tin oxide, chlorine, bromine, and iodine). Molybdic acid was found to be the best general catalyst, and it was found that the addition of sulfur increased its hydrogenating power, the catalyst then being in the form of MoSj, with hydrogen sulfide present in the gaseous phase.
16
NEWS
The crude product obtained from the experiment, using the catalyst, was an amber colored oil, containing only a trace of sulfur, and completely soluble in petroleum, indicating that it contained no pitch. The yield of spirit boiling below 200° C. was 43.3 per cent by weight of the original tar. This represents a volume yield of 56 per cent (or 11 gallons) from 20 gallons of lowtemperature tar—i. e., from one ton of coal. The remainder (9 gallons) is an oil which can be reprocessed t o produce further quantities of spirit. An apparatus was then designed for continuous operation. Figure 2 is a diagram of the plant erected for the continuous treatment of 5 gallons of low-temperature tar per day at 200 atmospheres and 450° to 460° C , and 480° to 490° C. in the liquid and vapor phases, respectively. T h e converter is heated externally by an electric furnace. Tar and hydrogen under pressure are fed in at the top of the converter and pass down through an internal pipe to the bottom. The tar and hydrogen are thus preheated before contact with the catalyst. The catalyst is contained in a cage which just fits the reaction vessel, the vapor and liquid phases being separated by a perforated plate. In the liquid-phase compartment there is a baffle plate about one inch from the bottom, which prevents the formation of a stagnant layer of liquid at the bottom of the converter and thus avoids unnecessary coke formation. The preheated tar and hydrogen pass from the bottom through t h e liquid and liquid-phase catalyst. The liquid in the reaction vessel is maintained at a constant level by a standpipe, from which the heavy product is withdrawn intermittently. From the liquid phase the low-boiling part of the tar vaporizes, together with the fresh low-boiling material formed. The mixture of vapors and residual hydrogen passes upward through the bed of vapor-phase catalyst. The products then pass through a condenser to a receiver where permanent gas and liquid ("light product") are separated. With this apparatus it is found that, where a ton of coal will produce 20 gallons of low-temperature tar, hydrogenationcracking of this tar in one stage will produce: Imperial Gallons 11.6 8.6 20.2
Motor spirit to 200° C TOTAL
with an expenditure of 240C cu. ft. of hydrogen. Further experiments were then carried out on the creosote from a horizontal retort tar in another apparatus. In these experiments an ammonium molybdate on charcoal catalyst was used, and temperatures of 495° and 510° C. were employed. A t both temperatures the product obtained was a water-white mobile oil. The increase in temperature from 495° to 510° C. increased the amount of gaseous hydrocarbons formed and reduced the yield of dry oils from 92.4 to 83.1 per cent. In these tests the volume yields per 100 cc. of creosote were: Dry product Spirit to 200° C.
495° C. 109.0 44.5
510° C 102.0 64.0
The high-volume yield of dry product is a result of the large decrease of specific gravity from 1.07 for creosote to 0.906 and 0.870, respectively, for the two products. Solid matter did not separate from either product, showing complete conversion to liquids of naphthalene, anthracene, etc. The yields of spirit (0° to 200° C.) obtained, including one stage of reprocessing the high-boiling fraction, were 75 and 84.5 per cent by volume of the creosote treated a t 495° and 510° C , respectively.
R O T E N O N E F O U N D I N COMMON AMERICAN W E E D
THE DEVIL'S SHOESTRING, a common weed in the eastern half of the United States, contains rotenone, a U. S. Department of Agriculture chemist has found. The discovery is significant for farmers, both as potential growers of the plant and as users of the insecticide, to insecticide manufacturers, and to importers who carry on international trade in rotenone and other insecticides. W. W . Skinner, assistant chief of the Chemical and Technological Research Unit of the Bureau of Chemistry and Soils, first called attention to the probable insecticidal value of devil's shoestring, following his observation that bees and other insects fed on nearby plants but avoided the blooms of this toxic weed. Doctor Skinner later instigated the research which led to the recent discovery of this weed's rotenone content by E . P. Clark of the bureau's Insecticide Division. Although the insecticidal value of devil's shoestring was demonstrated about two years ago by V. A. Little, of the Texas Agricultural College, who found it effective against various species of insects, its value as a source of rotenone was not known until proved b y the department's research.
E D I T I O N
Vol. 11, N o . 2
Rotenone, which is used for much the same purposes as pyrethrum and nicotine insecticides, has been extracted chiefly from derris, a vine from the East Indies and from the root of cubé, a South American shrub. It is deadly to many insects, but it does not poison man or animals. The devil's shoestring, Cracca virginiana, is the first North American plant found to contain rotenone. This plant is also known as the wild pea. Related species are found in tropical countries. The discovery of rotenone in this American plant promises to make the United States independent of foreign sources for insecticides made of rotenone. The rotenone is found chiefly in the root of the plant. Rotenone and other constituents of an insecticidal rature make up 4 or 5 per cent of the roots. Department scientists believe this could be increased by selection and breeding, much as the sugar content of sugar beets has been increased. Rotenone now costs about the same as the pyrethrins, the active principles of pyrethrum flowers, but the department scientists believe that as its use increases it will become cheaper. It is rapidly coming into use in greenhouses, for truck crops, and for combating fleas and other external parasites on animals. Spray material, containing about 5 per cent rotenone, has recently sold for about $10.00 a gallon. A gallon of this material is diluted to make about 800 gallons of spray.
T H E COVERED W A G O N — 1 9 3 3 M O D E L SOME TIME AGO we called attention to success in the use of Dowmetal in constructing trailers weighing so much less than other equipment of this kind as to effect very substantial saving in operating cost. A new trailer has now been designed and manufactured which is 20 feet shorter than t h e older model and weighs a little more than half that of other comparable vehicles. The main feature of the new trailer is the 1000 cubic feet of weatherproof loading space inside the body, which can be used to carry a profitable freight load o n the return trip. The new trailer will carry four automobiles of medium size or two large and two small cars. The body is enclosed and it is in this compartment that two of the cars are carried. The other two are accommodated on top of this compartment. The weight is 2400 pounds, whereas its nearest comparable competitor weighs 7600 pounds. The light weight of the trailer means lower cost in motive power to move it, and its shorter length is a great advantage on the highway, making it much safer for other cars to pass the unit when en route. The trailers are equipped with a system of vacuum brakes which work automatically with the regular truck brakes. It is an interesting application of this new magnesium alloy and is the covered wagon, 1933 model.
INDUSTRIAL R E S E A R C H LABORATORIES T H E RESEARCH INFORMATION* SERVICE of the
National
Re-
search Council is preparing a revision of its "Industrial Research Laboratories of the United States, Including Consulting Research Laboratories," the fourth edition of which was published in 1931 and contained over 1600 such laboratories. This bulletin is the only list of research laboratories known to the compilers (Clarence J. West and Callie Hull) and is undoubtedly used by many persons, not only as a source of information concerning such laboratories, but also as a mailing list for important announcements about new apparatus and processes and for compilations of interest t o research workers in industrial fields. In addition to the 1600 laboratories already known, it is very desirable that additional laboratories be listed, if such are in existence. While every effort will be made to locate such firms, it is felt that many will be overlooked unless these laboratories will make themselves known to t h e compilers. If the reader of this note is a member of a firm maintaining a research laboratory and if it is n o t known whether the firm in question is already listed in the previous bulletin, it is hoped that a request will be forwarded immediately t o the Research Information Service, National Research Council, Washington, D. C , requesting a questionnaire, in order that the forthcoming bulletin may be made as complete as possible. The listing involves no financial obligations on the part of any firm and may be of considerable value, since this publication is recognized by all familiar with it as a valuable source of information regarding industrial research activities in the United States. The data included in the bulletin are made up of the name and address of the firms, the research directors, and the research problems engaging the attention of the laboratories. There are also included an alphabetical list of research directors, a subject index of research interests, and a geographical index of firms. In order to avoid inquiries regarding the appearance of the bulletin, it m a y be stated that t h e bulletin will not be available for distribution before September, 1933.
