13 research outputs found
Noncatalytic Direct Liquefaction of Biorefinery Lignin by Ethanol
There
is a growing interest in lignin valorization to biofuels
and chemicals. Here, we propose a novel and simple noncatalytic process
to directly liquefy lignin rich solid residual from second generation
bioethanol production by solvolysis with ethanol. Through an extensive
parameter study in batch autoclaves assessing the effects of varying
reaction temperature, reaction time, and solvent:lignin ratio, it
is shown that hydrothermally pretreated enzymatic hydrolysis lignin
solvolysis in supercritical ethanol can produce a heptane soluble
bio-oil without the need for exhaustive deoxygenation. The process
does not require addition of catalyst or a reducing agent such as
hydrogen. The process is advantageously carried out with a low reaction
period (<1 h) and with a reduced amount of solvent to lignin feedstock
(ethanol:lignin (w/w) ratio of 2:1) which is a previously unexplored
domain for lignin solvolysis. The resulting bio-oil product is mainly
a mixture of di- and monomeric lignin species where the original lignin
unit linkages have been broken. The oxygen content is lowered to <10
wt % (corresponding to an HHV of 36 MJ/kg) and the bio-oil is stable
and acid free (verified by NMR), and due to the use of sulfur free
lignin rich residual as feedstock, the resulting oil product is equally
sulfur free. The residual solid product (char) has a reduced oxygen
content relative to the lignin feed and equally increased higher heating
value, making it a candidate for use as a biochar