Symposium on Wood as a Chemical R a w Material' 0
SUMMARY OF SYMPOSIUM" HARRY F. LEWIS The Institute of Paper Chemistry, Appleton, Wisconsin
THIS Symposium on Wood as a Chemical Raw Material has been directed toward the problems involved in the chemical utilization of one form of plant life, that of our forests. Chemical utilization of other plants would follow many of the same paths. This is the aim of the Farm Chemurgic Council. The primary product of the forest is lumber. The conversion of the tree into logs and the logs into lumber is wasteful in terms of the per cent of wood substance in the tree recovered in the form of lumber. Vast amounts of wood residues are currently available for secondary conversion in spite of the efforts being put forth by the up-to-date logger and lumberman. The complete utilization of this wood substance mould yield (and does yield) many other products in addition to lumber and plywood, including pulp, paper, and paperboard-particle and other hardboards-iusulation boards, itc., and directly or indirectly, a whole host of compounds of present and future importance to our chemical economy. I'ractically the entire organic chemical industry of the Scandanavian countries is now wood-derived. The aim of the scientists and engineers of our ow11 wood-consuming industries is the establishment of a competitive chemical industry based upon the utilization of our own wood residues. Availability of Wood for Chemical Utilization
Earlier, the term "vast amounts" wasused to describe the volume of wood residues in the United States. How much is a vast amount? To answer this and other questions about our wood residues, we called upon E. G. Locke (U. S. Forest Products Laboratory, Madison, Wisconsin) and E. E. Matsou (Pacific Northwest Forest aud Range Experiment Station, U. S. Forest Service, Portland, Oregon). They reported that more than 100 million tons of wond residues are Presented before the Divisions of Chemical Education and Cellulose Chemistry a t the 133rd Meeting of the Amerioan Chemical Society, San Francisco, April, 1958. EDITOR'S NOTE: The press of material scheduled for puhlication made it impossible for the complete text of all papers read a t this symposium to be printed in these pages. Recognizing the value of having a complete story, the Editor asks Dr. Lewis to provide this aummary of the day-long program. For readers of this article who are interested in the chemistry of wood and its utilization, there is a two-volume work, "Wood Chemistry," by Wim and Jahn, 2nd ed., published by Reinhold Publishing Co. as the A.C.S. monograph No. 97. These two volr~meswill provide adequate background far an understanding of the chemistry involved in the papers on this symposium.
produced annually from commercial logging and lumber manufacture, and by the pulp mills of the United States. Logging operators aloue leave better than 50 million tons of mood substance in the forest to rot or be consumed by slash fires. Lumber and plywood mills converting the logs by the logger, produce another 45 million tons of waste. Finally t,he pulp mills remove some 9 million tons of unused wood substance in their digesters; these are largely found iu the spent liquors with smaller amounts in the stack gases. Of the total volume, not all is equally available. The cheapest materials are the wastes of primary and secondary processing (the lumber and plywo3d residues) for the costs of collectiou and transportation have already been met. Locke and Matson are careful t o point out that almost two-thirds of this is currently being used as fuel and if converted chemically, would have t o be replaced by other fuels. Chippable slabs, edgings, and trim may be sold to pulp and fiberboard plants; this practice is increasing particularly in those lumber mills where hydraulic barkers produce a barkfree slab. Unfortunately the waste left in the woods (cull t.rees and logging residues) is expensive t o collect and its effective use calls for a processing plant able t o make an integrated multiple use of the material. Plants of this type are expensive and would be of no interest to the small logger of the "peckerwood variety." They are of much greater interest to those companies operating their forests on a sustained yield basis. Composition a n d Structure of Wood
In order to understand the problems faced by those who seek to establish commercially stable operations from the utiliiation of wood residues, it seemed desirable to describe the biological and chemical components of wood substance, for these determine the value of the material in terms of utilization. This was done by Professor A. B. Anderson of the Forest Products Laboratory of the Univerbity of California. In the complete paper (page 487) will be found a classification of trees iuto hardwoods and softwoods, a discussion of the anatomy of the tree in terms of tracheids, fibers, vessels, ray cells and resin ducts and of the chemistry of the tree with particular reference to the important chemical const~ituents-cellulose, hemicelluloses, and lignin. The reader is urged to read the Anderson paper before continuing with this review. JOURNAL OF CHEMICAL EDUCATION
Dwadative Conversion of Wood Waste by Destructive Distillation
One of the earliest wood converting operations was that based upon the pyrolysis of hardwood, whereby the organic constituents are decomposed by heat into charcoal and a variety of volatile hyproducts, many of which may he recovered when the retort gases are cooled. A. W. Coos of Clis-Dow Chemical Company of Marquette, Michigan, told the symposium of the ups and downs of the "hardwood distillation industry." He pointed out that not only is charcoal a convenient fuel but it is also a chemical of some worth in the manufacture of carbon hisulfide, carbon tetrachloride, sodium cyanide, and silicon. I n earlier times it was widely used in metallurgy; presently it has been largely replaced by coke. I n addition to the manufacture of charcoal, the larger byproduct plants of today recover certain pure chemicals together with useful oil and tar fractions. One major product, wood alcohol (methanol), is an important alcohol denaturant. A second, acetic acid, has all the uses of synthetic acetic acid. These two substances cannot compete by themselves with their synthetic analogues, hut as byproducts of charcoal production they find a good market. Hardwood tars are distilled to yield antioxidant fractions and are refined for pharmaceutical grade creosote, guaiacol, creosol, maltol, and methylcyclopentenolone. Unfortunately the markets for such products are somewhat limited. Some two hundred compounds are found in wood distillates, hut only a few have commercial outlet. Softwood distillation, Goos continued, has been confined to the southeastern part of the United States where pine heartwood is available. With the exception of the charcoal, the products are quite different from those obtained from the distillation of hardwood, running largely to pine tar, turpentine, and pine oils. At the present time, wood distillation is enjoying an upward trend, thanks to the rediscovery of the pleasures of outdoor cookery. Glowing charcoal, Goos contended, enhances the flavor and savory quality of many foods. This recent trend has increased the demand for charcoal briquets which are more compact and uniform than lump charcoal. The mood carhonization industry provides a useful outlet for thinnings, undesirable wood species, and trees unfit for lumher. Inexpensive carbonization retorts have been developed by the Forest Products Laboratory, and even the small operators can use their residues for the manufacture of charcoal. Chemicals from Wood Residues by Treatment with Catalytic Quantities of Acid
While the pyrolytic reaction alters the chemical nature of the major wood constituents t o a significant degree, other forms of chemical conversion may react either with lignin on the one hand or with the carhohydrates on the other. The fourth paper in the symposium described the use of acids iu catalytic amounts to hydrolyze the polysaccharides in wood into simple sugars and/or their degradation products. The authors, J. F. Saeman, J. F. Harris, and E. G. Locke, are all on the staff of the U. S. Forest Products Laboratory. Dr. Saeman first reviewed the history VOLUME 35, NO. 10, OCTOBER, 1958
of wood conversion by straight acid hydrolysis followed by fermentation of the sugars into alcohol. Many millions of dollars have been invested in this process in research and plant development in the United States and other countries. Under the present state of our basic knowledge of wood chemistry, alcohol from the fermentation of wood hydrolyzates cannot compete with synthetic alcohol largely because of our inability to convert lignin into dollars. Because of this, the Forest Products Laboratory has revised its program for the chemical utilization of wood. Although various routes are available, the Forest Products Laboratory has concentrated on a series of hydrolytic reactions brought about by catalytic quantities of dilute acids. In such a process chemical costs are kept low and the recovery of processing chemicals is unnecessary. I n addition, a large portion of the wood substance can potentially be put t o use. The studies in process include: prehydrolysis to liberate acetic acid and the hemicellulose constituents; conversion of the cellulose t o glucose; conversion of pentoses t o furfural; conversion of the hexnses to hydroxymethyl furfural, levulinic acid and formic acid; and separation of the lignin from the carbohydrates of wood. Saeman reported on conditions which favor a maximum yield of sugars. Prehydrolysis studies indicate a correlation between the extent of hydrolysis and the residual xylan and mannan in the insoluble portion of the wood. The maximum yield of glucose from cellulose is favored by an increase in temperature and acidity and by treatment of the cellulose with ionizing radiations and by grinding. Maximum yield of furfural from the pentoses improves with increased temperature and dilution of the pentoses. Hexoses by an analagous reaction are converted to hydroxymethyl furfural. At low temperatures the yield of these products is low; they increase markedly with increase in temperature. Hydroxymethyl furfural as it is formed is converted into levulinic acid and formic acid. The profitable conversion of wood residues into chemicals by these steps requires efficient use of all the wood constituents. The key point in the over-all program is based upon the utilization of lignin. Up t o date, the greatest amount of effort to utilize lignin has been put on lignin from the pulping process. The authors believe that this limits the evaluation of the true potential of this chemical as a tonnage industrial material. Consequently the separation of the lignin from the carbohydrates of the wood by means of unconventional lignin solvents is being studied. Their hope is to isolate a more reactive form of lignin than is now available from pulping spent liquors. Separation of the Components of Wood by the Pulping Proc-
At the present time, the most profitable method for using wood unfit for lumher or plywood would seem to be t o convert it into pulp where this is feasible. J. L. McCarthy (University of Washington) told the symposium via his colleague, Vincent Felicetta, of the chemical reactions involved when wood is pulped. Using the gymnosperms (softwoods) as an illustration, McCarthy referred t o the longitudinal cells for
fibers in these woods as being of particular interest t o the papermaker. The walls of the fibers are predominantly cellulose whiie the middle layer between the fibers is predominantly lignin. The essential process of pulping comprises acting on this middle layer so as to break down the cellular structure of the wood to yield individual cells or pulp fibers consisting principally of cellulose. In practice today, the lignin may be largely removed during cooking so that relatively little effort will be required to separate the fibers, or less lignin is removed by cooking for shorter times or with milder conditions, substituting mechanical energy for the fiber separation. Very little if any ligniu is removed in the groundmood process which is based upon the mechanical grinding of wood in the presence of steam. The resultant pulp is a mixture of lignified fibers, fiber fragments, and fiber bundles. Groundwood pulp is used in the manufacture of newsprint. The three major chemical methods for delignifying wood are based upon the reaction of wood chips with an aqueous solution of a pulping agent at elevated temperatures and pressures. McCarthy suggested that the lignin is thereby broken down into smaller units which are water soluble while some of the hemicelluloses are either hydrolyzed t o monomeric hexoses and pentoses and/or converted t o sugar degradation products. The "acid sulfite" process uses for its pulping agent a mixture of sulfurous acid and bisulfite, with calcium ion usually as the basic ion, although in certain cases this may be ammonium, magnesium, or sodium. Appropriate salts of lignosulfonic acids are formed and these are found in the spent sulfite liquor together with the hydrolyzed sugars and the degradation products of the sugars. The most widely used pulping process en~ploysan alkaline solution of nonsodium sulfide and sodium hydroxide. Lignin in this case is solubilized probably through the formation of alkali-soluble thiolignins; the sugars from whatever hemicellulose is dissolved, together with a part of the dissolved cellulose, form large amounts of saccharinic acids. This is the "kraft" or "sulfate process." The "neutral sulfite" process, which is developing in interest as a means of converting hardwoods into quite useful pulps, is based on a solution of sodium sulfite and sodium carbonate. Much work is still necessary before we can speak about the chemical reactions taking place: normally, however, much larger amounts of lignin remain in the neutral sulfite pulps. I t should be pointed out that both sulfite and sulfate pulps have t o havetheresidual lignin removed by bleaching before they can be used in the manufacture of fine papers. Unbleached pulps are bleached in stages. As an example, they may be first treated with chlorine in acid solution, followed by treatment with an alkaline hypochlorite solution, then they are washed thoroughly t o remove bleaching residues. For pulps of high brightness, sodium peroxide or chlorine dioxide solutions may be employed in a final step. Chemical Cellulose from Wood
Bleached pulps contain varying amounts of resistant cellulose (or-cellulose), together with the lower molec-
nlar-weight cellulose, hemicelluloses, and undesirable extractives. Before these pulps can be converted t o such products as cellophane and viscose, cellulose esters and ethers, etc., they must be further purified. Berwyn Thomas (Rayonier, Inc., Shelton, Washington) outlined the steps necessary for the manufacture of chemical cellulose and its various derivatives (page 493). Utilization of Pulping Spent Liquors
The presentations of McCarthy and Thomas have geuerally covered the processes involved in isolating cellulose from wood. Up t o this point, very little has beeu said about the half of the wood substance which has gone into solution during pulping. The liquor coming from the digester after the cook is called 8' spent liquor." That from the sulfite process is known as "spent sulfite liquor," although in earlieryearsit was "waste sulfite liquor." No longer is it essentially a waste product. The spent liquor from the sulfate process is called "kraft black liquor." This has never been considered a waste product in the strict sense, for the recovery of inorganic chemicals from kraft black liquor is an essential part of the process; the organic constituents of the black liquor are burned in the recovery process. M. N. Hearon (Crown Zellerbach Corporation, Camas, Washington) stressed the potential value of the organic constituents of both spent liquors in his discussion of "Utilization of Pulping Spent Liquor" (page 498). Much work remains to be done before the wood substance dissolved in pulping is completely utilized. Millions of dollars have already gone into such research and additional millions will be spent before these substances are profitably used as chemicals. Again an important stumbling block is our inability to convert lignin to dollars. Production of Pure Chemicals from Lignin
A somewhat different approach t o the liguin problem is that of producing pure organic chemicals from lignin, the dream of liguin chemists for many years. This was described by Irwin Pearl (The Institute of Paper Chemistry, Appleton, Wisconsin). Pearl referred first t o the conversion of the lignin derivatives in "spent sulfite liquor" into vanillin. He pointed out that substantially all the vanillin used in the United States comes from this source. Unfortunately, the market will take the vanillin from about 1% of the available lignin, and so the conversion of lignin into other chenlicals has been extensively studied (page 502). Processes have been developed for preparing many other organic compounds from lignin, some of which appear t o have properties of commercial importance. Utilization of Spent Sulfite Liquo~Ca~bohyd~ates
Lignin represents only one of the important classes of wood components which dissolves during pulping; a second would be those substances which may be generally classified as carbohydrates. I n sulfite pulping, some hemicelluloses are hydrolyzed t o component pentoses and hexoses. The lower weight celluloses likewise yield glucose. Included with the sugars in bhe spent liquor would be the acid-induced degradation products of these sugars and possibly small amounts of related oligosaccharides. Free wood sugars are the predominant carbohydrates in most spent sulfite liquors IOUANAL OF CHEMICAL EDUCATION
and make up from 15% t o 20% of the total dissolved solids, says Whitmore who gave the paper on the spent sulfite liquor carbohydrates prepared by A. J. Wiley, L. M. Whitmore, Jr., and L. A. Boggs (Sulfite Pulp Manufacturers' Research League, at Appleton, Wisconsin). The substance of this paper follows. I n the past, utilization of the carbohydrates in speut, sulfite liquor has been based on methods of fermentation. For many years, ethyl alcohol from such fermentable sugars has been an important source of this material, especially in certain European countries. Three alcohol plants are currently operating in connection with North American sulfite pulp mills. Competition from synthetic ethyl alcohol has limited the wide-spread adoption of the process although the sales of the desugared lignin derivatives at a reasonable profit would make the process more attractive. A second fermentation method involves the production of yeast; of particular interest is the manufacture of torula yeast. Although torula yeast has to compete with other products entering animal feed and human food, the more complete use of the sugars by the yeast upgrades desugared lignin sulfonates for their ultimate utilization and reduces the stream pollution effect of the residual effluent. Two pulp mills in Wisconsin manufacture torula yeast from spent sulfite liquor and operate without government subsidies. Other fermentive processes have also been tested. One which yields lactic acid, acetone, and.'butyl alcohol is technically feasible, but is not of commercial interest because of the cost of recovery of these chemicals from dilute solutions. Butyric, propionic, and acetic acids, methane and antibiotics have also been produced by the fermentation of wood sugars. Attention has also been given toward finding methods for isolating purified wood sugars with unique properties, hut it does not seem probable that sufficient large scale uses will be developed for sugars like xylose, arabinose, mannose, and galactose to warrant large plant expenditures and high processing costs. Whitmore did describe one process in advanced state of evaluation in which the sugars in dry spent liquor solids react with solvents t o yield soluble sugar derivatives which are susceptible t o separation into individual sugars and their derivatives. Diacetone sugars and glycosides can be thus prepared. No attempt was made by Whitmore t o follow t,he fate of the dissolved hemicelluloses in the kraft process. Reference has already been made by Hearon to the fact that these are converted t o saccharinic acid. John Green at The Institute of Paper Chemistry has shown that a variety of acids are formed, running from three to six carbon atoms. These are present in the black liquor as sodium salts in amounts up to 15% or more of the weight of the wood pulped. Unfortunately no significant uses have yet been found for large amounts of such acids which might be available to the extent of a million or more tons of crude salts per year as byproducts of kraft pulping. Naval Stores end Tall Oil Industries
Hearon (loc. eit.) in discussing the materials removed from wood by pulping liquors called attention briefly t o tall oil which is recovered as a byproduct in the kraft pulping of the resinous pines of the South. E. 0. VOLUME 35, NO. 10, OCTOBER, 1958
Barnes and M. L. Taylor (Union Bag-Camp Corporation, Savannah, Georgia) told the symposium in somewhat greater detail about tall oil, and also the naval stores industries. For centuries, the gummy substance termed oleoresin which exudes from the bark of certain trees when the outer bark is wounded has been used as a calking compound for waterproofing the timbers and rigging of early sea-going vessels-hence the name "naval stores." The oleoresin from southern pines is easily separated by steam distillation into gum rosin and gum turpentine, the two important components of the naval stores industry. The industry also has available as a source of oleoresin the heartwood of older pine stumps. Usually in ten years the sapwood of the stump decays leaving resinrich heartwood. I n addition t o the recovery of turpentine and rosin from "turpentining" living tree and dead stump, Barnes also described the processes which occur in the sulfate pulping of southern pine whereby the soaps of resin and fatty acid are recovered from "black liquor." These form during pulping as the result of saponification of the acids and related derivatives in the wood. During the earlier stages of pulping, turpentine vaporizes and together with other gases leaves the digester during venting t o be recovered from the condensate as highly odorous crude sulfate turpentine. On refining, much of the objectionable odor is removed. As the digester black liquor is later concentrated in the evaporators, the crude soaps rise to the surface and are skimmed off; a t this stage they are known as "black liquor skimmings." Further purification converts them t o rather pure free fatty and resin acids, together with an unsaponifiable fraction. Tall oil is the mixture of acids and unsaponif5ables which result from the acidification of the skimmings. Barnes reviewed in some detail the composition of the gum oleoresin harvested from slash and longleaf pine in this country. Somewhat less than 2.5% t o 3.5% of oleoresin is recovered based on the weight of the dry wood. As collected it contains approximately 18% turpentine, 65% resin acids, 7% neutral materials, and 10% moisture and trash. The turpentine portion contains from 60% to 65y0 a-pinene, 25% t o 35% @-pinene,and 5% t o 8% minor constituents such as dipentene, paracymeue, terrene alcohols, and ketones. The resin acids include palustric, levopimaric, abietic, neoabietic, dehydroabietic, dihydroabietic, dextropimaric, and isodextropimaric acid. Levopimaric acid is so sensitive t o heat that in processing t o gum rosin, it is isomerized t o palustric, abietic, and neoabietic acids. Almost two-thirds of the neutral materials are esters of resin and fatty acids; the fatty acids are a mixture of oleic, liuoleic, linolenic, and stearic acids. The resinous portion of the stumps and taproots used in the wood naval stores industry contains 15% t o 25% oleoresin analyzing 14% turpentine, 71% resin acids, 7% pine oil, and 8% neutrals. The turpentine portion contains more a-pinene, very little @-pinene, some camphene, and more terpenes and p-cymene, and the resin acids portion is similar to the resin acids portion of gum rosin. Crude tall oil, made from the "black liquor skim-
mings" by acidifying the latter with sulfuric acid, is a mixture of resin acids, fatty acids, and unsaponifiables. Much of the crude oil contains from 35% to 65% resin acids and 6% t o 8% unsaponifiables, with the rest fatty acid. The composition varies with the locality where the trees were grown. The resin portion is a mixture much like the mixture in gum and wood rosin. The fatty acids contain 6% to 8% saturated acids, largely palmitic acid with small amounts of stearic acid. The unsaturated acids run about 46% to 48% oleic, 43% t o 45% linoleic, and 1%to 2% linolenic acids, the unsaponifiables are 25% t o 35% phytosterols, 5% t o 15% higher alcohols, and the remainder hydrocarbons. The crude oil may be refined by acid refining or by distillation. I n this country there are now eight major distillation plants in operation with a capacity of about 316,000 tons of crude tall oil annually. Bark as a Chemical Raw Material
The final paper on the symposium dealt with the utilization of waste bark. Although the relative amount of bark varies between trees and species, the over-all figure of 10% is not much out of line. While the composition of various commercial woods has been rather thoroughly looked into a t least by empirical methods, the same cannot be said for their barks. Cellulose and the hemicelluloses as they exist in wood have meaning. It is unfortunate that by now we cannot define lignin from wood with the same degree of comprehension. But in spite of this uncertainty there is some significance to the term "lignin" as it refers t o the lignin from the softwoods. Since these analytical methods even as they relate t o wood are empirical, they need interpretation based upon experience and supplemental testing. The application of the same procedures t o the estimation of bark components is hazardous and not always convincing. A number of barks appear t o contain significant amounts of material which appear in the lignin fraction and for which we have no counterpart in wood. This material behaves much as a polyphenolic acid, evolving carbon dioxide on heating; it differs also from lignin in that it is almost free of methoxyl groups. In the lignin fraction from redwood bark, there is also isolated a smaller amount of material which is much like the lignin in the wood. Nor is the structure of bark the same as the structure of the wood. This is t o be expected for bark has a function of its own. It is on the tree t o protect the living cambial tissue upon which the growth of the tree is dependent. It protects the tree from insect attack. It helps t o regulate and conserve the water content of the tree, thus making possible the flow of sap and the translocation of the products of photosynthesis. Much research needs t o be done before we can elucidate the chemical nature of the bark components. Much of this will be pioneering; new techniques may be required for the estimation of these components. A lot of what has been done will need t o be r e d o n e or reinterpreted-before we can speak with assurance about the chemistry of bark. Such work is currently under way in a number of laboratories. William G. Van Beckum and Robert W. Miller of the Pacific Lumber Company closed the symposium
with a review of the present commercial practices in the field of bark utilization. They first referred to the operations based upon the extraction of some unusual constituents from a specific bark. As illustrations they cited the production of quinine from cinchona bark, of cascara from the cascara tree, and of tannin from the tan oak. They next pointed out an important advantage of any scheme involving the utilization of bark, namely its availability. I n general, the logging operations leave the bark on the log from which it is not removed until the log reaches the lumber or pulp mill. There it either goes through a hydraulic barker, or the barking drums of a pulp mill operation, or is sawed off as a slab together with some sapwood or, in the case of redwood, it may be taken off with a spud. At the present time, the most obvious use for bark is as a fuel a t the mill and as such it is used in many operations. While this may be considered as a low form of chemical utilization, it would appear that the chemical potential of bark is not being fully utilized. During recent years, basic researches have expanded somewhat our knowledge of the composition of some of the more important barks, and as a result, it would seem that compounds of commercial importance might be produced. Among these constituents are dihydroquercetin, quercetin, certain waxes, myrocitin, and reducing sugars. The barks of western hemlock and tan oak are a source of tannin for the processing of hides and for other chemical uses of tannin. Commercial processes for the recovery of useful chemicals from Douglas fir, western hemlock, and redwood are based upon extraction with organicsolvents,ormithhotcaustic, soda ash, and sodium sulfite solutions. Current annual production of millions of pounds of such extracts are used in oil well drilling, ore flotation, water treatment, ceramics, and other fields. As the structures of other bark contituents are elucidated, me should be able t o expand the market for bark products. SUMMARY
In summary it may be said that in the United States wood wastes provide a potential source for a number of important chemicals, principally cellulose fibers, chemical cellulose and its derivatives, methyl alcohol, acetic acid, saccharinic acids,acetone, ethyl alcohol,charcoal, various pentose and dextrose sugars, fnrfural and hydroxymethyl furfural, tall oil, rosin acids, fatty acids, sterols, turpentine, a-and p-pinene, dipentene, dimethyl sulfide, methyl mercaptan, lignin sulfonates, vanillin, vanillic acid, esters of vanillic acid, syringaldehyde syringic acid and its esters, torula yeast, tannin, quercetin, dehydroquercetin, 8-conidendrin, bark waxes, myracitin, etc. From ethyl alcohol obtained through the fermentation of spent snlfite liquors, the Scandanavians have established an important organic chemical industry analogous in part t o the commercial operations set up in the United States based on ethylene from petroleum processing. Unfortunately, the raw materials are spread out all over the country, and one of the principal chemicals available in larger amounts, lignin, has failed to develop an industrial potential of sufficient size and value t o carry its proportion of costs. It is said that alcohol JOURNAL OF CHEMICAL EDUCATION
from the fermentation of wood sugars several years ago cost about 256 a gallon t o produce. This cost is not competitive with other alcohol sources. Along with the gallon of alcohol, 13 pounds of lignin are formed which brought in no financial returns. It does not take a financial wizard to realize that a couple of cents a pound return on the lignin, F.O.B. point of manufacture, would make alcohol manufacture from this source a going business. The future of wood as a chemical raw material depends upon our ability t o set up wood utilization on a sound basis of integrated operation in which all types of mood components and
VOLUME 35, NO. 10, OCTOBER, 1958
fractions are utilized. Fundamental research on lignin on a broad front would seem t o be the first step. One hundred million tons of wood residue mould yield from twenty to twenty-five million tons of lignin, fifty to sixty million tons of cellulose, ten to twenty million tons of hemicellulose, and ten million tons of bark, together with lesser amounts of extractives and their derivatives related t o tannin, the terpenes, etc. A large percentage of the vast amount of raw material is currently not being utilized; it should soon begin to carry its weight in the chemical economy of the United States.
