Ab initio investigation of the adsorption of phenolic compounds, CO, and H2O over metallic cluster/silica catalysts for hydrodeoxygenation process

The catalytic hydrodeoxygenation (HDO) of lignin is an important route to produce green aromatics. Herein we study the adsorption of key phenolic molecules (phenol, catechol, guaiacol, anisole) over various metallic nanoparticles (NP) (Ni, Cu, Co, Fe) supported over amorphous silica, by the periodic spin polarized density functional theory (DFT). CO and water are potential inhibiting molecules present in the lignin pyrolysis gas. Therefore their competing adsorption is also studied in details. Our calculations show that the oxygenated compounds have a stronger interaction at the interface between the NP cluster and the silica for all the studied metals. By comparing the resulting adsorption energies, we found that the Ni-13@silica catalyst is the most attractive one for oxygenated molecules. The most stable configuration is a phenol adsorption at the interface through the OH group with the silica surface and the aromatic ring with the transition metal cluster. In addition, we show that the adsorption of the oxygenated compounds is not impacted by the presence of inhibiting molecules on Fe-13@silica, Co-13@silica and Ni-13@silica catalysts. This type of DFT investigation appears to be useful to suggest suitable formulations for an optimal HDO of lignin.

Automated summary

This study investigated the adsorption of key phenolic molecules on various metal nanoparticles supported on amorphous silica using periodic spin polarized density functional theory (DFT). The results suggested that Ni nanoparticles exhibited the strongest interaction with oxygenated compounds. Furthermore, the adsorption of oxygenated compounds was found to be unaffected by the presence of inhibiting molecules on Fe, Co, and Ni catalysts.