RESEARCH
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Wood as Source of Furfural Rate and yield d a t a developed f o r processing xylose from w o o d t o furfural with acid catalyst
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tained experimentally in making furfural from xylose. J A n d as the reaction proceeds, maximum yield results in the time region of four xylose half-lives, says Donald F. Root, now with Weyerhaeuser Timber, who carried out research on this process at the Forest Products Laboratory. This data was determined as part of efforts to gather information for speculative economic calculations on processing material which contains pentosans to yield furfural. As nylon manufacture continues to expand, demand for furfural to make nylon intermediates is expected to increase. Thus, this may be another step in efforts to utilize the half of standing timber which is cut in lumbering a n d lost. A wide range of conditions was used in this work of Root and his coworkers at the Forest Products Laboratory and the University of Wisconsin. Initial concentration of xylose, amount of sulfuric acid catalyst, and temperature were varied so t h a t the half-life of xylose ranged from one second to five hours. In general, yield of furfural inCellulose Chemistry
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creased with increased reaction temperature and decreased as initial xylose concentration increased, Root told t h e Division of Cellulose Chemistry. • Data Correlation. On the basis of yield, rate, and conditions data, Root and coworkers made a mathematical correlation to select optimum reacting conditions for making furfural. This correlation would permit designers to select optimum conditions accurately and to predict results of changes in plant operating variables of time, temperature, and concentrations of reactants and products. The reaction goes from xylose through unknown intermediates to furfural a n d then, depending on conditions, t h e furfural goes to destruction products. Some evidence exists t h a t furfural forms condensation products with t h e intermediates. Previous work showed that this condensation reaction caused unusually low yields of furfural. Root's experiments with furfural added to xylose at the start confirmed this result. Yields lowered as initial furfural concentration increased. However, efforts to separate and identify suspected intermediates were not completed. They probably never accumulate in quantity, Root and his coworkers believe. • Faster Reaction. T h e answer to the problem of how to prevent product furfural from reacting with intermediates would b e to speed the reaction rate. Experiments made by the group showed that higher initial sulfuric acid concentration would cause higher yields of furfural u p to a given acid concentration. While increased initial acid concentration increased reaction rate in a direct ratio, above 0.1N acid furfural yield did not increase. As temperature increased, so did maximum furfural production for a fixed sulfuric acid catalyst concentration. However, increases in yield with increased temperature become very slight above about 300° C. Other data developed by Root and coworkers confirmed that yield of furfural decreases with initial xylose concentration. They also found the decreased yield greatest at lower reaction temperatures. On the basis of experimental work and data correlations, Root expects that favorable yields can be obtained by processing at a relatively high temperature in dilute solution without simultaneous removal of furfural.
Key to Monolayer Structure Graphite-wetting technique gives entropy values—may e x p l a i n specificity of surfactants
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t% rt^CS Sizable and un4 / N A T I O N A L expected differ„ .„ entropy = w ™ m L t i i n u ences in changes call for a Colloid new look at interChemiltry action calculations in surface chemistry, say A. C. Zettlemoyer a n d coworkers at Lehigh University. They feel that these entropy changes h e l p depict .the w a y in which, for example, surfactants g o down upon a surface. • Special Apparatus. Surface chemists frequently consider heat a n d free energy terms as somewhat parallel. T o check this, as well as to calculate a c curately entropies of adsorption, YungFang Yu, Zettlemoyer, and J. J. Chessick told the Division of Colloid C h e m istry that they have developed a special adsorption apparatus-basically a Bourdon spoon gage. One side of t h e gage is connected to t h e adsorption system —sample, organic-vapor source with calibrated volume doser, Teflon plug, stopcock, a n d glass seals. The other side leads t o the pressure-measuring system—oil manometer and volume compensator. Small deflections a n d null-point are observed through a traveling microscope. • Further Work Indicated. These studies, Zettlemoyer says, show surprising results. Heat determinations alone, he explains, are n o t a true measure of energy changes. The "ordering" of monolayers varies significantly. Apparently the manner in which surfactants adsorb onto surfaces is a prime factor. Unexpected effects which point u p the need for further studies include observations that: • Toluene yields a much higher energy change when adsorbed on graphite (is arranged in a more organized manner) t h a n its 7-carbon counterpart, h e p t a n e . • T h e h e a t of interaction is less for graphite in propanol than for t h e graphite previously covered with a monolayer of that alcohol.
