FUEL FROM COAL

Hawera Star, Volume L, 7 February 1931, Page 13

FUEL FROM COAL

THE PROSPECT REVIEWED. Two world events next year will emphasise the activities of the industrial chemist—the British Industries 1* air in England in February and the jubilee meeting of the Society of Chemical Industry in duly, in the following article Professor A. W. Nash, of the university of Birmingham, reviews the activities of the chemist as they affect the motorist of the future. "me possible augmentation of the world's petrol supply oy the production of synthetic ’petrol is a subject which has received considerable attention during the last I few years. Tne world's petroleum de--1 posits are by no means as evenly distributed as, for example, coal or oil shale; and large and important countries and continents such as England, trance, Germany, Africa, and Australia, appear, as far as is known at present, to be devoid of large oil fields, this uneven distribution of the world’s petroleum deposits at once raises the interest .of synthetic petrol on purely economic grounds. “The handling and distribution of petroleum and its products is considerably more costly in, say, Australia or ■south Africa than in England. With these considerations in mind, it is obvious that the possibility of turning other fuels or raw materials into petrol or petrol substitutes has warranted the interest displayed. The allied problem to that of synthetic petrol—namely, that of power alcohol —cannot j tie considered here, although it is closely related, especially* in the case of countries where large supplies of readily fermentable vegetable produets can be raised. )

“it is well known that on heating coal in retorts either to high temperatures (high temperature carbonisation) or to somewhat lower temperatures (low temperature carbonisation) tars are formed, but only in relatively small proportion to the gas and coke products. A yield of 18 gallons of tar per ton is a high one by such carbonisation process. Dr. Bergius, however, found that if coal is heated up to temperatures of 800-900 deg. F. in the presence of hydrogen gas, at pressures of 2100-880010 per square inch, the coking reaction of coal is largely suppressed and hydrogen is absorbed, giving rise to a very much increased yield of tar. A typical yield of products by the treatment of one ton of coal by the original process of Bergius is: 45 gallons petrol, 50 gallons Diesel oil, 30 gallons heavy oil. This process, which may be looked upon as a distillation of coal under high hydrogen pressure thus requires specialised plant 'to withstand the high pressure necessary. The cost of the process will depend largely upon the price of the raw material and the hydrogen. The crude product from coal will then he gas, some coke, and 00-70 per cent, of heavy tarry oil, of which something under one-third its bulk is petrol. “The next important step in the production jot synthetic petrol by this process was made when certain metallic oxides were found to further hydrogenation of coal under the conditions of temperature and hydrogen pressure discovered by Bergius, and an 85 per cent, yield of crude petrol is ] claimed from coal and heavy tarry oil.; Many experiments on a large scale have j been carried out, and many hundreds | of patents filed, chiefly by the large) German and English chemical concerns. From this patent literature it is obvious that great difficulties are experienced when powdered coal is the material to be treated, and it would appear that the use of heavy tar is perhaps a simpler problem. This crude oil would yield the petrol by the usual distillation and refining processes. As regards the value of this petrol, when compared with the petroleum product, there can be no doubt that it is quite good. “The possibility of obtaining such synthetic petrol by the treatment of heavy oil residues by means of this catalytic hydrogenation process has been investigated, especially in America, and it has been found that heavy asphaltic oils are readily amenable to the process, and high yields of petrol are obtained. In some cases very high yields of petrol are recorded, and this is due to the fact that the original material is already largely hydrocarbon, which is not the case with, say, brown coal. “The whole question of whether synthetic petrol will take its place side by side with the natural product from petroleum is one of economics. The petrol from these synthetic sources appears to be of good quality, and the previous technical difficulties of the large-scale plant, both on the chemical and engineering sides, appear to be solved; but the process involving high pressures is costly and dangerous. There can be no doubt that this process can only be run with hope of success in conjunction with larger chemical concerns who already have staffs skilled in high-pressure technique. “Any process devised by Dr Fischer depends on the reaction of the two gaseous constituents of water gas, namely, carbon monoxide and hydrogen, by passage over heated metallic oxides, but this has been evolved so far only on a small scale, and there are many difficulties in its exploitation on a commercial scale, even though it does not require high pressure.”