2.6 Lignin Hydrogenolysis
The hydrogenolysis of birch organosolv lignin was carried out in 100 mL
stainless steel autoclave (Beijing Shijisenlang Chemical Machinery Co.,
Ltd., China). Typically, 0.3 g birch organosolv lignin 0.06 g catalyst
and 20 mL water/ethanol (1:1) were added into the autoclave vessel. The
vessel was purged three times with nitrogen before sealed and pressured
to 1 MPa with hydrogen. The reaction was carried out at 280 ºC for 2 h.
After reaction, the reaction vessel was cooled to room temperature. The
reaction mixture was filtered to remove catalyst and the filtrate was
extracted with ethyl acetate to obtain lignin oil. And then, the lignin
oil was analyzed by GC-MS, gel permeation chromatography (GPC) and
two-dimensional heteronuclear single quantum correlation (2D HSQC). The
yield of the aromatic monomers
was calculated using the following Eq. (3):
Yield of the aromatic monomers (%) =
WA/WF×100% (3)
Where WA is the weight of aromatic monomers after the
hydrogenolysis of lignin; WF is the weight of feed
lignin.