Uses Depending on Chemical Properties

Furfural is an amber-colored liquid. It has been manufactured for more than 20 years at a plant in Cedar Rapids, Iowa, by treating oat hulls with dilute sulfuric acid and steam. The residue from this treatment is used as fuel or sold as fertilizer filler. Important uses for furfural have been found in making plastics, refining wood rosin, making lubricating oils from petroleum, and in producing other important chemicals derived from it. When it was found that furfural was one of the best chemicals for purifying butadiene used in making synthetic rubber, the production requirements were so great that the Government built a plant at Memphis, Tenn., that produces 12,000 tons of furfural a year and uses 100,000 tons of cottonseed hulls or corncobs as raw material.

Although cottonseed hulls were available to the Memphis plant and oat hulls to the Cedar Rapids plant, the value of these raw materials during the war for augmenting the supply of scarce livestock feeds caused attention to be turned to cobs, since cobs had long been known as a good source of furfural. Vast quantities of cobs, therefore, ground to pass a 1-mesh screen, were bought by both furfural plants.

The prospects are bright for an expanding market for furfural. Many large chemical companies here and in other countries have carried on extensive research to find new uses for it. We, too, have been actively engaged in such research since the founding of the Regional Laboratories. It is now known that many new and important uses are possible. For example, fibers like nylon can be made from chemicals prepared from furfural.

More than 100 years ago chemists learned that when starch or cellulose was treated with sulfuric acid under right conditions glucose, also known as 'corn sugar, resulted. The sugar, glucose, is the raw material used in the fermentation process for making alcohol. In the present process for making furfural the cellulose of the hulls and cobs is destroyed and appears in the residue. We believed that if the right conditions Could be found, it should be possible to produce furfural from corncobs on the one hand and glucose on the other, both from the same material and at the same time. The smaller amount of residue resulting should be just as valuable as the present furfural residue.

Our research confirmed this idea, with the result that this laboratory has been able to develop a process that gives promise of producing both furfural and glucose at lower costs than was possible before. We are now studying this process in a semicommercial plant at the Northern Laboratory, built under a special appropriation by Congress for the production of synthetic liquid fuels from nonpetroleum sources. If our expectations can be realized, a greatly expanded market not only for corncobs but also for other agricultural residues such as peanut shells, rice hulls, cottonseed hulls, flax shives, and the like will exist.

Although thousands of bushels of ear corn are ground whole and fed to cattle with good success, ground cobs have not been considered desirable for addition to mixed feeds. Indeed, many States prohibit such use in commercially prepared feeds. During the time of feed shortage, however, cobs ground to pass a one-eighth screen were moving in carload quantities into this market. Cobs may have some value, also, in feeds of high molasses content, but they contain very little protein and their vitamin content is very low.

Corncob processing will be found to be just like any other business markets must be established, and sales and managerial ability will be even more important than ability to process the product. Careful investigation should be completed before investments in processing plants are made. Cob prices, it should be realized, can never be high but a small return to the farm per ton will result in a good percentage return on net farm income. A market should be found for all fractions resulting in cob grinding. Furfural plants can use any of the fractions, coarse or fine. With the start made, and with intelligent effort, there should be an industrial market for cobs and hulls, whether we consider the raw material either in its physical or its chemical composition.

THE AUTHOR

Elbert C. Lathrop, chemical engineer in the Bureau of Agricultural and Industrial Chemistry, organized and has directed the research work of the Agricultural Residues Division at the Northern Regional Research Laboratory since 1939. From 1909 to 1918 he did research on soil fertility in the Bureau of Plant Industry, was with E. I. du Pont de Nemours and Co., in the development of the dye industry from 1918 to 1922, and was director of research and later vice president of The Celotex Corporation for some 12 years. He was technical director of the Crown-Zellerbach Corporation from 1934 to 1938. Dr. Lathrop was awarded the Edward Longstreth medal by the Franklin Institute in 1912.