This study is concerned with the conversion of biomass to
higher value products. The medium to long term
possibility of substituting oil-derived fuels and
chemicals as well as developing compact and low capital
investment technologies is the main reason for this work.
One of routes being explored is direct liquefaction,
which consists of mixing wood with a recycle liquid and
converting the slurry under the action of temperature,
pressure and often catalysts.
The study is composed of two parts: (1) a literature
review of same basic aspects of wood liquefaction and (2)
an experimental investigation of the initial
solubilization of wood under liquefaction conditions.
The rationale behind this study is based on concepts put
forward by the Sherbrooke liquefaction group. The key
concept is that, to achieve a controlled and selective
conversion of wood to liquids, a well designed
pretreatment is needed to solubilize the wood components
(or major families) under conditions in which little or
nochemical degradation other than depolymerization takes
place. Under these circumstances the primary products can
be subsequently upgraded via selective catalytic
processes. In this study, the swelling, the dissolution
and the depolymerization of wood and wood components are
reviewed together with the effects of the important
physiochemical parameters on wood solubilization.
In the experimental study, poplar wood was treated with
water as well as with five potentially wood-derivable
solvent systems (methanol, methanol/water,
diethyleneglygol, phenol/water, toluene) using a 250 ml
autoclave and at temperatures between170 and 235 °C.
Heating rates of ant 10 °C/min were used and the time at
reaction temperature was typically 10 minutes. The yields
of ethanol solubles ranged between10 and 63 % of m.a.f.
wood at 235 °C.
A correlation between the swelling power of the solvent
and the hemicellulose solubilization was found. This
result is also of significance for lignin removal since
hemicellulose solubilization and hydrolysis (i.e.
autohydrolysis presumably) precedes lignin
solubilization. The highest lignin conversion to ethanol
solubles was found to be 90 %. No cellulose was converted
to ethanol solubles below 235 °C except in the presence
of water and phenol/water mixtures where the amorphous
cellulose could be partially solubilized.
|Place of Publication||Espoo|
|Publisher||VTT Technical Research Centre of Finland|
|Number of pages||91|
|Publication status||Published - 1985|
|MoE publication type||D4 Published development or research report or study|
|Series||Valtion teknillinen tutkimuskeskus. Tutkimuksia - Research Reports|
- liquid phases
- transition temperature