Catalytic fast pyrolysis of beech wood lignin isolated by different biomass (pre)treatment processes: Organosolv, hydrothermal and enzymatic hydrolysis

Lignin is one of the three main structural components lignocellulosic biomass and considered as most abundant source aromatic phenolic compounds. produced side-stream in pulp/paper industry or residue production second-generation bioethanol. More recently, novel fractionation processes biorefineries have been developed aiming at high quality/purity lignin towards its more efficient down-stream catalytic conversion to chemicals, monomers, fuels. Within this context, work, we studied thermal (non-catalytic) fast pyrolysis on a Py/GC–MS system fixed-bed reactor unit types lignin, all originating from same (beech wood sawdust) but with different isolation processes: organosolv derived by pretreatment/fractionation biomass, surface extracted mild Soxhlet extraction (with ethanol acetone) hydrothermally (HT) pure water pretreated enzymatic hydrolysis lignin-rich solid HT biomass. Conventional microporous ZSM-5 mesoporous zeolites intracrystal mesopores, ˜ 9 nm) were used catalysts experiments. Both very active converting initially via methoxy-substituted phenols, benzenes benzaldehydes mainly BTX mono-aromatics, such 1,3-dimethylbenzene/p- o-xylenes, toluene trimethylbenzenes, well polycyclic hydrocarbons (PAHs, naphthalenes). The induced higher dealkoxylation reactivity compared leading concentration aromatics without consequent increase PAHs. pronounced dealkoxylation/aromatization both resulted lower yields (but highly aromatic) organic bio-oils (e.g. 32−35 wt.% 15−22 wt.%) pyrolysis, increased non-condensable gases (mainly CO, CO2, methane, ethylene propylene) formation relatively low amounts coke 3−5 lignin) addition char. observed moderate variations characteristics beech i.e. molecular weight (GPC), S/G ratio, inter-unit linkages (2D HSQC NMR) elemental composition, did not induce systematic/substantial differentiation product composition.