Solvolysis and hydrotreatment of wood to provide fuel

The objective of this study is to describe a liquefaction process of wood in two successive steps. The wood is first dissolved in an organic solvent, acidified with small amounts of H2SO4, in mild conditions of temperature and pressure. The solvolytic oil is then subjected to a catalytic hydrotreatment at about 350°C. In the first step, whatever the tested solvent, simple alcohol, phenol or ethylene glycol, the best experimental conditions prevail when the amount of H2SO4 is not higher than 1% (with respect to dry wood) and the temperature is not over 250°C. A mixture of phenol-tetralin (50/50 by mass) is a good solvent media and can be recycled several times in batch tests. The solvolytic oil is upgraded under H2 pressure in the presence of tetralin. The tetralin/solvolytic oil ratio is one of the tested parameters. A ratio as low as 1 results in a good hydrotreatment and avoids the processing of too large quantities of tetralin, difficult to separate from the other compounds. The effectiveness of the hydrotreatment is evaluated from the viscosity and the oxygen content of the upgraded oil. The best deoxygenation is obtained with NiMo as catalyst.