Paul Emmett, ca. 1970s.
When, after the war, I resigned from my position on the Manhattan Project and joined the multiple petroleum fellowship sponsored by the Gulf Oil Company at The Mellon Institute, a great deal of interest existed in the production of synthetic gasoline. The cause of concern in those days was the possibility of submarine warfare in some emergency cutting off our petroleum supply. Today it is OPEC and the Middle East that causes us to look for substitutes for imported petroleum. Both periods have directed attention toward synthesizing gasoline from carbon monoxide and hydrogen over metallic catalysts according to the Fischer-Tropsch process. The carbon monoxide and hydrogen would of course come from the gasification of some of our ample supply of coal. Accordingly in 1945, a major effort was directed by the U. S. Bureau of Mines and a number of petroleum companies toward the study of catalysts for the synthesis of such hydrocarbons. We elected to make use of the newly available supply of carbon-14, the radioactive isotope of carbon, as a tracer in studying the mechanism of the synthesis reaction over iron and cobalt catalysts. I believe this was the first such tracer work undertaken on this system.
The results have been described in a number of papers. In brief they seemed to indicate that the reaction takes place through the formation of oxygen complexes between carbon monoxide and hydrogen on the catalyst surface and not through the formation of an intermediate carbide such as Fe3C or Fe2C. The use of radioactive ketene as a tracer seemed to indicate that the ketene, CH2CO dissociates on the surface to CH2 and CO. The CH2 can then start a reaction chain that builds up the higher hydrocarbons. In actual synthesis the CH2 is probably produced by the hydrogenation of carbon atoms formed by the dissociative adsorption of carbon monoxide on the surface of the iron catalyst. As in the case of ammonia synthesis we made a thorough study of the thermodynamic properties of the solid phases that might be involved, including Fe2C or Fe3C. We never reached the point of making a better catalyst but we hope our work has proved of some help to those who are again attacking the gasoline synthesis problem in connection with our most recent energy crisis. Incidentally, our work was given headline recognition in an article on the front page of the Financial Section of the New York Times under the heading "Gulf Oil Company produces Radioactive Gasoline." I never did find out who was responsible for the release - I only know our "radioactive gasoline" at the time consisted of a few cubic centimeters of gaseous radioactive propane and butane hydrocarbons - roughly a thimbleful of gas (not liquid gasoline).