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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.

The conversion of light hydrocarbons with solid catalysts is an important class of reactions in the chemical and energy industries. Our knowledge on the exceedingly complex reaction kinetics of these catalytic reactions, especially the inter-influence between the reactions on catalyst and those in the gas phase, lags behind the requirement of technology development to improve efficiency and reduce emissions.The purpose of this study was to investigate the significance of surface-generated radicals in influencing the kinetics and mechanisms of gas-solid catalytic reactions. The results indicate that desorption is an important fate of the surface-generated radicals. The presence/absence of significant mass transfer resistance for radicals, which is different from that for the mass transfer of molecular species, determines the successful desorption/diffusion of radicals into the bulk gas phase.When a non-porous nickel mesh was used to catalyse the reactions between ethane and oxygen, it was found that the desorption/diffusion of radicals into the bulk gas phase could be facilitated by decreasing the mass transfer of radicals across the gas film around the nickel wires through increasing the gas flow rate traversing the mesh. The desorption of radicals increases the rate of chain reactions in the gas phase, resulting in the positive catalytic effects of nickel mesh. The nickel mesh can also have negative catalytic effects by quenching the gas-phase radicals by providing a surface to catalyse radical termination reactions.Many Ni-catalysed hydrocarbon oxidation reactions involve the reduction and oxidation (redox) of nickel catalyst itself. Results of this study show that the migration/diffusion of radicals on the surface, from the surface into the NiO bulk and from the surface into the gas phase can all have significant effects on the reduction kinetics. These in turn depend on the size of NiO crystallite, the presence/absence of rigid pore structure and the type of rad

Xu, D., Yang, L., Ding, K., Zhang, Y., Gao, W., Huang, Y., ... & Zhang, H. (2019). Mini-Review on Char Catalysts for Tar Reforming during Biomass Gasification: The Importance of Char Structure. Energy & Fuels, 34(2), 1219-1229. https://doi.org/10.1021/acs.energyfuels.9b03725

Xu, D., Yang, L., Zhao, M., Zhang, J., Syed-Hassan, S. S. A., Sun, H., ... Zhang, S. (2021). Conversion and transformation of N species during pyrolysis of wood-based panels: A review. Environmental Pollution, 270, article 116120. https://doi.org/10.1016/j.envpol.2020.116120