THE SIMULTANEOUS PRODUCTION OF FURFURAL AND LEVULINIC

ACID FROM BAGASSE

Emiliano Ranios, Luis A. Carlo and Rafael Vgzquez Romero

(Presented by C. I . Nee)

Economics Develo$wtent Administration of Puerto Rico, X i o Piedras, Puerto Rico

SUMMARY

The production of furfural from bagasse illdustrially yields 9-10%. This is collsidered a low degree of conversion into chemicals. The concomitallt production of furfural and levulinic acid was attempted, using sulfuric acid as the catalyst. A total yield of these two chemicals of 25%, based upon the dry weight of bagasse, was obtained. As the potential yield of furfural and levuliilic acid is 45.50%, this indicates an efficiency of conversion of 55.87% for these two chemicals.

A copper-clad reactor with agitation and cooling coil, electrically heated, was used for the experiments. 90% of the total furlural distillati011 was carried out at-170' C wit11 agitation, while the main productioil of levulillic acid and the rest of the furfural was obtained from 170' C to . 1 9 5 ~ C. Some experiments were carried out with cotton for comparision.

A linear relationship was found between the levulinic acid yield and a factor defined as

roo x conc. 13, SO, (gll) r =

dry weight of bagasse (g)

when the bagasse quantity was kept constant. When the concentration of acid was constant and the bagasse quantity was varied, there was linear relationship between yield and log r. The yield of furfural was seen to depend on the rate of distillation at optimum r values. This optimum is different for furfural and levulinic acid. Details of the experiments are given in several tables.

By studying the econoinic impact of the production of both furfural and levulinic acid upon the gross income of the sugar mill, it is shown that such incoine could be increased by 117%. A 30% yield of humin, not considered in this paper, was also obtained in a condition that could be easily treated to yield a good activated carbon. The value of same is not taken into account in estimating the econoinic influence on gross income.

INTRODUCTION

Interest in the production of furfural froin bagasse is shown by early papers on the subject. Industrially an average yield of 9-10% is realized, which is at best a rather poor degree of conversion into chemicals. But bagasse contains about 52% of cellulose

E. RAMOS et al. 1901

compared to 6nly 27% of pentosans. In producing furfural this cellulose is modified and made unsuitable for pulp. Together with the residual lignin it is actually burned simply for its fuel value. The present paper deals with attempts to increase the production of chemicals from bagasse, namely: furfural from the pentosans and levulinic acid from the cellulosic fraction, in an integrated way. Dilute sulfuric acid is used as the catalyst and about 30% of a huinic material results as a by-product.

Tlle rate of hydrolysis of pentose and heoxse polynlers has been well studied in connection wit11 wood saccharification. The hemicellulosic part is known to hydrolyze under milder conditions than the resistant cellulosic fraction which corresponds to alpha-cellulose4. This is called the stable cellulose. As shown by Saelnans the saccharification of wood involves two consecutive first-order reactions

Cellulose \ reducing sugars

sugar decomposition products.

The energy of activation using Douglas fir was found to be 42900 calories. Values of the same order are assumed for bagasse. I t is also known that the second hydrogen in sulfuric acid does not contribute to the hydrolysis of cellulose5. The rates of decomposition of xylose, the main constituent of bagasse pentosails and of cellulose have also been determined5 and it has been shown that above 170' C the rate of hydrolysis increases faster than the rate of decomposition, as the concen- tration of the catalytic acid is increased. SaeinanQ determined the half-life of stable cellulose from different woods hydrolyzed with 0.75% sulfuric acid at 185" C, and found it to lie between 17.7 and 22.1 minutes.

In hydrolyzing bagasse under conditions that bring about the decoinposition of the sugars we have two different steps (Fig. I) . A first one where pentoses and hemicelluloses are hydrolyzed to produce mainly xylose and some arabiilose and glucuronic acid (which are immediately decomposed into furfural) and glucose from the cellulose, found in the an~orphous or hemicellulosic part whic11 deco~nposes more slowly at the teinperature of the distillation of furfural (170" C). In a second step,

PENTOSAN UNIT PEN rOSE

1st STEP

FURFURAL

2nd STEP

LEVULlNlC ACID

FORMIC

FURFURAL

I C 6 H 6 0 3 I L--,--J

HEXOSAN UNIT HEXOSE

Fig. I. Steps of the transforlllatioll of bagasse into furfural and levuliillc acid.

BY-PRODUCTS

preferably at 195" C, the hydrolysis of stable cellulose and the decomposition of glucose through hydroxymethyl furfural into levulinic acid is mainly carried out. The kinetics of the formation of hydroxymethyl furfural have been studied recentlylO. As is shown in Table I, we should theoretically be able to obtain a 76.97% conversion into chemicals such as furfural, levulinic acid, formic acid and lignin. But under

TABLE I

AVERAGE BAGASSE COMPOSITION, POTENTIAL SUGAR AND POTENTIAL CHEMICALS (percent 0.d. bagasse)

Conlpos~t~on Potentla1 sugar P o t e l ~ t ~ a l chemicals --

Cellulose 51.81 Glucose 46.63 Levulin~c acid 30.05 Peiltosails 26.88 Formic acid 11.91 Lignin 19.56 Xylose 23.65 Furfural 15.45 Ash 1.75 Lignin 19 56 - - -

1oo.00 70.28 76.97

our actual conditions most of the formic acid is lost and some of the furfural and hydroxymethyl furfural are decoinposed into humic substances which together with the more or less modified lignin residue make up a 30% percent of humus on the 0.d. weight of bagasse. The potential yield of furfural and levulinic acid is 45.50%. Our highest yield of both products is 25.42% indicating an efficiency of conversion for ,

these chemicals of 55.87%. When making levulinic acid from wood chips containing 60% of cellulose, using

hydrochloric acid as the catalyst, yields as high as 23% based on the weight of wood have been reported1 equivalent to 38.33% based on cellulose. We have obtained up to 34.74% on the same basis from bagasse using sulfuric acid. In a previous work by Frost and Kurthz, the possibility of an integrated levulinic acid-furfural process is mentioned. Levulinic acid yields of 43.27 and 37.42% on cellulose content of Douglas fir are reported, together with 0.85 and 1.50% of furfural, based on dry weight of wood. I t should be pointed out that the method used for the estimation of levulinic acid in many previous technical papers is based on Ploetz-Bartels volumetric determination with iodine7, which gives errors as large as 5%, while the method used by us, developed in this laboratory by other colleagues is accurate to within 0.4% when run by different operators. Much higher yields-above 30% of levulinic acid-have been obtained from sugars by means of hydrobroinic acid*. This acid is too expensive for industrial use and we have adhered to sulfuric acid because it is best adapted to a new method of extraction of levulinic acid, developed by one of us*, which will be published elsewhere.

EQUIPMENT

In running these experiments we used a (Fig, 2) copper-clad pressure digester, heated electrically, and equipped with an agitator set for 36 rev./min and a cooling coil through which cold water could circulate to cool the reaction products rapidly.

* by Dr. Emiliano Ramos.

I E. RAMOS et al.

Fig. 2. Diagram of reactor. I, Motor. 2, Pressure gauge. 3, Pyrometer. 4, Insulation. 5 , Heating strips. 0, Agitator. 7, Cooling coil. 8, Thermocouple. 9, Condenser. 10, Graduated cylinder.

An outlet 0.30' id . , was provided for the furfural distillation, leading to a condenser for the collection of the distillate. The temperature was measured with a chroinel- Aluillel thermocouple inserted into the mass of liquor.

MATERIAL AND METHODS

The charge consisted of bagasse briquettes (6-7% moisture) which were previously ground in a hammer mill and run through a Wiley mill. The largest fibers were only 113'' long. The ground bagasse was impregnated for 18 h at room temperature with a solution of sulfuric acid (technical grade sp. gr. 1.84) of variable concentration to suit the particular experiment.

The general procedure followed in the cooks was as follows: The pre-impreg- nated bagasse was charged into the digester. This was closed and heated without agitation until the temperature reached 170° C which required 60-66 min. The agitator was then started and simultaneously the furfural distillation was begun for a period of time from 30 to 40 min. In some experiments, after the collection of the first distillate, the outlet was closed and the reactor heated to 190-195O C in 5 min and kept at this temperature for 10 min more. This procedure was followed for experiments 273-289.

In order to improve the yield of furfural in most of the experiments reported, a second fraction of distillate, and sometimes a third one, was collected froin 170° C up to 195' C , usually in 15 to 18 min.

In the experiments M-671 to M-673 the digester contents were cooled below 100" C after the first distillation and water added, sometimes containing sulfuric acid (M-672-M-673). In such cases it took about 37 min to heat the digester back to 170" C.

After the last distillation the digester was cooled down rapidly and distillate ahd liquor analyzed, the latter after removing humus by filtration.

Ig04 BY-PRODUCTS

Analytical

The furfural was determined spectropl~otoinetrically using a Beckinan D.U. spectro- photoineter and reading optical density at 172 m,~s (Ref. 3). A modified Icullgren- TydenG method was also used to check on the purity of the distillate. This will be reported elsewllere? The levulinic acid was analyzed by making the dinitrophenyl hydrazone, extracting same and reading optical density at 490 mp (Ref. 11).

EXPERIMENTAL RESULTS

For convenience the experiments have been suininarized in Tables 2-6. The values shown are the average for the number of runs indicated in each experiment. Runs 273-289 were conducted to study the influence of the concentration of sulfuric acid

Flg. 3 . Linear dependeilce of the levulinic acid yields on r, a t a bath ratio of 12.7.

in the yield of both levulinic acid and furfural. I t was found that the yield of the latter remained below 78% but that of the former increased linearly (Fig. 3) with the average value, r,, of the "r factor" defined as follows:

above r, = 2. I t should be noted that in the experiments just referred to the quantity of bagasse was kept constant at 353 g.

Experiments S661 and S663 were run to iinprove the yield of total product when using a inore dilute sulfuric acid (25 g/l). The best result achieved was 23% of levulinic acid and furfural by means of two distillations, one at 170° C and another from 17oO to 195O C which served to iinprove the yield of furfural. In this dilute catalyst region we wanted to study the influence of the quantity of bagasse upon the total yield. This is covered by experiments 1R67-4R67.

I t is shown in Table z that an improvement in the yield of both furfural and levulinic acid was obtained as the concentration of bagasse diminished. The yield

* Dr. E. Ramos.

E. RAMOS et al. 1905

TABLE 2

TOTAL YIELDS ON O.D. BAGASSE A N D DISTILLATES VOLUMES

(initial liquor volume 4500 ml)

Experi- Number Bagasse Sulfuric Distillate volume Yielcl percent on 0.13. bagasse ment of (g) acid First Second Third Furfural Levulinic Total

runs (9) acid

1 2000 in1 water added after the first distillation. 2 Same as I but containing 41 g HzSO,. 3 Same as but containing 20 g HISO,.

of levulinic acid was most adversely affected when the quantity of bagasse was such as to give a bath ratio, liquor (ml)/bagasse (g) of 10. No linear dependence on r, was found for the levulinic acid yield, but a plot against log r, restored linearity

(Fig. 4). For the sake of colnparison some experiments were run using bleached cotton

(Tables 3 and 5) instead of bagasse and 25 g sulfuric acid as the catalyst. I t was

Log r,

Fig. 4. Linear dependence of lcvulinic acid yields on log r, a t variable bagasse quantity.

TABLE 3

TOTAL YIELDS ON O.D. COTTON AND DISTILLATES VOLUMES

(~nltial liquor volume : 4500 inl) -

Experlnlerlt Number Cottoil Sulfuric Distillate volunle Yield peicent on o d cotton of (9) First Second Third Furfural Levulinic Total runs (g) acid

1906 BY-PRODUCTS

again shown that a low concentration of cellulosic material improved the yield of levulinic acid. This is in line with well known experiments using sugarx2.

Finally we ran experiments M671-M673 designed to improve the yield of both levulinic acid and furfural in the neighborhood of an initial bath ratio 10. Here we added a third range of distillation and stopped the reaction to add 2000 n ~ l of water to the reactor after the first distillation. The best yield total was 22.54% or 2.73% inore than in experiment 1R67. As shown in Table 2, we added 41 g and 20 g respect- ively of sulfuric acid together with the zoo0 in1 of water after the first distillation in experiments M672 and M673.

Table 4 shows the proportion of furfural distilled after-the first distillation. I t ran from 8 to 26% depending upon the particular conditions of the experiments.

In the same tables we indicate the initial and final concentration of sulfuric

TABLE 4

VALUES O F I FACTOR AND RATES O F DISTILLATION

C = Conc. H,SO, r = factor C, = average coilcentratioll r, = average factor

Experi- First distillatioll Secolld and third distillatiol~ Furfural Yield ~ercei l t Ba- initial final rate initial fulal rate in & furfural levulinic gaSSe conc. g/l conc. g/l ml/min conc. g/l conc. g/l ml/min 31d disk acid (g)

% of total

I I E. RAMOS et al.

4

1.64 2.79

9.26 9.26 18.52 45.0 13.89 48.1 17.1 9.82 13.60 353

2.62 2.62 5.25 2.09 3.93

5.55 9 32 9.32 16.30

3R67 Cm 7.43 45.5 12.81 41.1 18.3 10.46 14.10 300

2.48 3 11 3.11 5.43

4.27

5.55 9.32 9 32 16.44 7.33 45.5 12.88

2.77 41.4 19.30 10.52 14.90 200

4.66 4.66 8..22 rm 3.71 6.44

2.22 4.54 - --

273 Cm 3.38 43.3 - 4.7 5.4 353 1.29 - -

[rm 0'63 0.96

4.44 9.09 -

6.76 43.3 - 7.0 13.8 353 2.58 - -

1.92 -

6.67 13.64 - -

281 (rl I,89 0 ' 15 3.86 43.3 - - 6.9 15.4 353

rm 2.87 -

8.89 18.18 - - 13.53 43.3 - 7.3 16.4 353

5.15 - -

11.11 22.73 16.92 43.3 - 7.0 18.0 353

6.44 - - -

acid, C, in each distillation as well as the average value, C m . Values for r and rm are also given together with the rate of distillation for all the experiments. In Table 6 we indicate the average value of 5 runs using 453 g of bagasse and taking one distillate at 170" (2000 ml) and another from 170° to 195" (2300). The rate of distillation was hyre increased to test its effect on the yield of furfural and levulinic acid.

TABLE 4 (continued) .

Expert- Ftrst dlstlllatlon Second and third dlstlllation Fulfural Yleld percent Ba- -- ment lnltial final rate inltlal final rate In 2nd & furfural levulinlc g"SSe

conc g/l conc. g/l ml/rnin conc g/l conc g / l ml/rnln 3rd actd (g ) % of total

1 --

5.55 9.32 9.32 16.30 3R67 (rl "I3 45.5 12.81 41.1 18.3 10.46 14.10 300

1.65 3.11 1 3.11 5.43 rm 2.38 4.27

1908 BY-PRODUCTS

TABLE 5

r FACTOR* AND RATES OF DISTILLATION USING COTTON

Expen- First distillation Secoild and third distillation Furfural Yield percent Cot- lnent initial final rate initial final rate 2nd & fu~fural levnl~nic ton

conc g/l conc g/l ml/min coilc g/l conc. g/l inl/inin 31ddist. acid (g) % of total

*I = roo x conc. SO,H, (g/l)

dry weight of cotton

TABLE 6

BAGASSE COOIZED WITH RAPID DISTILLATION

(initial liquor volunle : 4500 1111) * Bagasse Nuinber Yield Yield Rate ol distillatioll (9) of of of inl/inin -

runs furf. lev. Total acid Yleld first second

453 5 10.59 11.29 21.98 56.6 62.2

* With the initial 4500 in1 it was added 25 g SO,H,. After the first distillation zoo0 in1 water were addscl together with 10 g SO,H,.

I DISCUSSION

The linear dependence of the yield of levulinic acid upon the r, factor, wllen the quantity of bagasse remains constant, corroborates a long established fact, i.e. the dependence of the disappearance of cellulose and the decomposition of glucose on pH. In our usual work conditions the rate of hydrolysis was practically equal to the rate of decomposition, and Harris and Lang4 have shown the linear dependence of the half-life of hydrolysis and decomposition on pH.

The linear relationship between levulinic acid yield and the log r,, when the quantity of bagasse is varied at constant acid concentration, also finds explanation in the fact that a plot of the yield of levulinic acid froin sugar vs. logarithin of the percent concentration of sugar is a straight line, as can be verified from data presented by WigginsI2.

I t inight be thought that the low yields of levulinic acid in the experinients with rapid distillation shown in Table 6 were due to losses of hydroxymethyl furfural cluring the distillation. To ascertain the amount of the former lost with the distillate an aliquot was analyzed spectropl~otonietrically and volumetrically. I t was then submitted to distillation with salt and hydrochloric acid according to a technique given by Kullgren and Tyden6 to destroy the hydroxymethyl furfural. After correct-

E. RAMOS et al.

ing for the furfural lost in the distillation we found that only 0.35% of hydroxymethyl furfural based on the o.d. weight of bagasse passed into the distillate.

For best results in the production of furfural the r, factor should Lie between 1.7 and 3.7. Experiment M671 supports this conclusion, for the r, factor equals 4.34 and the yield of furfural is lower than in M67z-M673, despite the fact that in this experiment the distillation was run faster than in the other two. Best values for the rm factor in the production of levulinic acid run froin 3 to 6.4. The values for this factor in the cotton runs should be at least divided by 2 for comparison with bagasse. The appearance of some furfural in this distillation coines inost probably from the presence of oxycellulose.

Finally we want to make the observation that reading the optical density for furfural at 272 nip, instead of at 277 mp as recorninended by Fuchs3, was made in order to get away from a close lnaximum in the absorption spectrum of hydroxy- methyl furfural located at 284 mp.

These experiments prove the feasibility oi producing both furfural and levulinic acid from bagasse siinultaneously and in the same cook with good yields. I t is apparent that better results can be achieved by controlling the r factor in the course of the digestion. This is the subject of new experiments already under way in our laboratories.

ECONOMICS

The importance of levulinic acid as a valuable inaterial for a large range of organic industries have been given sufficient einphasis13 while the applications of furfural are already extensively known. But we want to give an idea of the econoinic impact that these two productions could have upon the sugar inill gross income, assuming for sugar, furfural and molasses their international unit value and for levulinic acid a price wliich is our present goal. In the calculations summarized in Table 7 we have not talcen into account the potential value of the hun~us, which can be easily transformed into active carbon of high quality. Even so it looks as though these two chemicals from bagasse could econoinically be as important as sugar and molasses.

TABLE 7

VALUE OF THE CHEMICAL PRODUCTS (FURFURAL AND LEVULINIC ACID)

COMPARED WITH THE VALUE O F THE SUGAR AND MOLASSES

from 1000 tolls of cane.

Product Basls Production Unit value Total value U.S. centsllb. U.S.$

- Sugar 10% 100 tons 3 G.ooo.oo Molasses d.5 gal./ton 6500 gals. 0.8 585.00 Bagasse 0.d. 15% 150 tons - -

li‘urfural 10% 15 tons 10 3.000.00 Levul~nic acid 13% 19.5 toils 12 4.680.00

Total gross incollle from sugar and molasses = $6,585.00 Total gross lllcome froin chemical products = $7,680.00 Percent Increase In gross income = 117%

1910 BY-PRODUCTS

ACKNOWLEDGEMENT

For all the conveniences and administrative support we want to express our sincere appreciation to Mr. Carlos Vicenty, Director of the Industrial Research Department (EDA), Puerto Rico, and to Mr. Felix H. Prieto, Assistant Director. Our gratitude goes also to Mrs. Carmelita Bou de Rivera and Mrs. Heb6 D. de Guardiola for the analytical assistance.

REFERENCES

I CARLSON, L. J. (1962) U.S. Pat . 3,065 263. 2 FROST, T. R. AND E. F. KURTH (1951) Levulmic Acid from Wood Cellulose. T A P P I , 34 (2) 80. 3 FUCHS, L. (1950) Detern~instion of furfural in the distillat~on of pentoses and uronic acids with

hydrochlorlc and hydrobroinic ac~ds. Un~v. of Vienna, Monatsh., 81. 70. 4 HARRIS, E. E. AND H. G. LANG (1947) Hydrolys~s of wood cellulose and decoinposition of sugar

dilute phosphoric acid. J . Phys. Collozd Chem. 51 1430. 5 HARRIS, E. E. AND A. KLINE (1949) Hydrolysis of wood cellulose w ~ t h hydrochlor~c acid and

sulfur dioxide and the decomposition of its hydrolytic products. J. Phys. Collozd Chem., 53 : 344.

6 RULLGREN, C. AND I f . TYDEN (1929) Determination of pentosanes. Ingenzovvetensk Handl . No . 94.

7 PLOETZ, J. AND H. BARTELS (1941) Quantitative determination of levulinic acid. Ber., 7 4 B : 1456.

8 PLOETZ T. (1946) Gev. Pat . 732 890. g SAEMAN J . F. (1945) Kinet~cs of wood saccharificarion. I n d . Eng . Chenz., 37. 43.

10 TOICAREV B. I. AND V. I. SHARIZOV (1963) A study of hydroxyinethyl fhrfural formation dur- ing hydrolysis of cellulose. Trans . Leningrad Lesotekhn. Akad . 102 : 153-165.

11 TORRES J. R., F. ROMAN, S. GOODMAN AND N. F. DE CARBALLO (1962) A new method for ana- lyzing for levul~nic acid in bagasse hydrolyzates. Rev. Coleg. de Quzm. de Puevto Rzco, 20 (2): 38.

12 WIG GIN^ L. F. (1949) The utilization of sucrose. Advances zn Cavbohydrate Chem., Vol. 4. Acadein~c Press, New Work, p. 308.

13 SHILLING W. L. (1965) Levulinic acid from wood residues. T A P P I , 48 (10) : 1o5A.

Discussion

T. R MCHALE. At the present t ~ m e market prices of furfural and levul~nic acid are cons~derably lowel than those used In the paper, t h ~ s dlstorts the economics of the process C I NEE I am not fam~llar w~tl l Puerto Rlcail prlces, but t h ~ s paper states that a better result should be obta~ned from these by-products than from sugar and molasses J P SANTO DOMINGO What would be the pentosan content In the bagasse from which a yield of g 82% furfural was obtained as mdicated In the paper C I NEE The pentosan content is about 30%. The effic~ency of conversion IS about 50% low C. W DAVIS Does anyone know the market for levul~il~c a c ~ d ? Can it be sold m quant~ties ? C I NEE The market is not presently reported The raw materials froin petioleum sources for the chemical ~ndustry may become scarce and expensive m the future The development of agri- cultural sources for these chemicals may be important for the return. J. M PATURAU Would the author agree that a prlce lower than 12 cents per pound would in- crease the use of levulmlc a c ~ d ? C. I NEE The prlce est~mated in the paper IS opt~m~stic. W ~ t h volume production some improve- inent should be possible The market~ng problem would certainly be a d~fficult one a t present T G CLEASBY IS ~t possible to use a b~ological process, such as Ritter's, to store bagasse for par- t~cle board production ?

C. I NEE We have been offe~ed such a system but have not t r ~ e d it. J E ATCHISON HOW extensive were the tests on br~quettmg 7

C I NEE The testing was done by our consultants in Europe who have board experience.

W Y ZICICMAN It is grat~fylng to know that a superlor board can be made from bagasse. L ~ g h t dens~ty can also be made from bagasse I feel moisture control is critical and I believe belt

E. RAMOS et al. 1911

conveying is preferable to pneumatic for this reason and because of loss of fines in pneumatic conveying. C. W. DAVIS : IS there a inarlret for board with rough surfaces ? C. I. NEE : There is a small diminishing market. RUCI~STUHL: High quality boards can be made from briquetted bagasse. Previous briquetting machines damaged. fibre due to excessive pressure. STAI~ER: Our experience as regards setting of cement shows that sucrose has a retarding effect when added to a mix. , B. B. PAUL: Do YOU haveany comment on the quality of particle board prepared from diffuser bagasse ? C. I. NEE: There is a diffusion plant in our area but we have not tried its bagasse for board ma- chining. RUCKSTUHL: Tests indicate lime effect is small compared with effect of dirt in diffuser bagasse, and the bagasse can be used for board malring provided there is thorough depithing. M. F. GLORIA: We find pneumatic conveying preferable for handling dry bagasse but have found that cyclones do not recover particles below 10 microns. H U G ~ T : The amount cost is very small. A. C. REICHARDT: What is the capital cost of the plant described ? C. I. NEE: Total capital cost is U.S. $750,000 altogether. A. C. REICHARDT: What are the critical parts of the process from the operational point of view. C. I. NEE: The forming machine requires a great deal of attention to secure uniform fiber distribu- tion. This is essential for good board quality, also the press must be controlled a t proper condi- tions for each type of board to be made. T. G. CLESSBY: Would anybody like to comment on the future of a glueless fiberboard from ba- gasse ? This has been investigated in South Africa and has shown very proinising results. C. I. NEE: We have not tried this although we are studying malring our own resin using barlr of an Acacia tree. J . E. ATCHISON: I doubt if there is sufficient lignin in bagasse to provide binder for a dry process of boards. C. RUCI~STUHL: I have made laboratory board of this type but the curing time is very long and for the reason the economics are not satisfactory.