Volatile–char interactions during biomass pyrolysis: Cleavage of C–C bond in a β–5 lignin model dimer by amino-modified graphitized carbon nanotube

This study investigated the interactions between volatile and char during biomass pyrolysis at 400 °C, employing a β–5 lignin dimer and amino-modified graphitized carbon nanotube (CNT–NH2) as their models, respectively. The results demonstrated that both –NH2 and its carrier (CNT) facilitated the conversion of the β–5 dimer, which significantly increased from 9.7% (blank run), to 61.6% (with CNT), and to 96.6% (with CNT–NH2). CNT mainly favored the breakage of C–O bond in the feedstock to produce dimers with a yield of 55.5%, while CNT–NH2 promoted the cleavage of both C–O and C–C bonds to yield monomers with a yield up to 63.4%. Such significant changes in the pyrolysis behaviors of the β–5 lignin dimer after the introduction of CNT–NH2 were considered to be mainly caused by hydrogen-bond formations between –NH2 and the dimeric feedstock/products, in addition to the π–π stacking between CNT and aromatic rings.