SPIRITUS AUS CELLULOSE UND HOLZ.
E. Simonsen (Ztschr. angew. Chem., 1898, 3).
PRODUCTION OF ALCOHOL FROM CELLULOSE AND WOOD.
(pp. 50, 209) This investigation was undertaken with one main object—to determine the optimum conditions of treatment of wood-cellulose and of wood itself for conversion into 'fermentable sugar.' The process of 'inversion' or hydrolysis, by digestion with dilute acid at high temperature, involves the four main factors: pressure (i.e. temperature), concentration of acid, ratio of liquid to cellulose and duration of digestion. Each of these was varied in definite gradations, and the effect measured. The degree of action was measured in terms of 'reducing sugar,' calculated from the results of estimation by Fehling solution, as 'glucose' per cent. of original cellulose (or wood).
(a) Cellulose. [Wood-cellulose obtained by bisulphite process.]—With a proportion of total liquid to cellulose of 27:1, and using sulphuric acid as the hydrolysing agent, the optimum results were obtained with acids of 0.45-0.60 p.ct. (H2SO4) and pressures of 6-8 atm. The maximum yield of 'sugar' was 45 p.ct. of the cellulose.
Under the above conditions the maximum of conversion is attained in 2 hours.
Having now regard to the production of a solution of maximum concentration of dissolved solids, the following conditions were asertained to fulfil the requirement, and, in fact, may be regarded as the economic optimum:
| Proportion of total liquid | 6 times wt. of cellulose |
| Concentration of acid | 0.5 p.ct. H2SO4 |
| Pressure | 10 atm. |
| Duration of digestion | 1.5 hour |
giving a yield of 41 p.ct. 'reducing sugar' calculated to the original cellulose (dry).
Alcoholic Fermentation of Neutralised Extract.—The liquors were found to ferment freely, and on distillation to yield a quantity of alcohol equal to 70 p.ct. of the theoretical—i.e. on the basis of the numbers for copper oxide reduction.
(b) Hydrolytic 'Conversion' of Wood (Lignocellulose).—A similarly systematic investigation carried out upon pine sawdust established the following as optimum conditions:
| Proportion of total liquid | 5 times wt. of wood |
| Concentration of acid | 0.5 p.ct. H2SO4 |
| Pressure | 9 atm. |
| Duration of digestion | 15 minutes |
giving a yield of 20 p.ct. 'reducing sugar,' calculated from the 'Fehling' test.
Fermentation of the neutralised extracts gave variable results. The highest yields obtained were 60 p.ct. of theoretical, the author finally concluding that under properly controlled conditions of inversion and fermentation 100 kg. wood yield 6.5 l. absolute alcohol.