Pyrolysis of lignin, derived from lignocellulosic biomass, produces bio-oils with high oxygen content (20-45 wt.%). These bio-oils can be upgraded by hydrodeoxygenation (HDO), a thermal catalytic process under H2 pressure, to obtain more valuable oxygen-free products. Thus, we combine theoretical and experimental techniques to elaborate, characterize, and test innovative HDO catalysts. Among different catalysts and supports, iron supported on silica proves an optimal selectivity/activity with low deactivation rate . Different amorphous silica surfaces having various silanol densities (7.2, 5.9, 4.6, 3.3, 2, 1.1 OH/nm2) have been considered . DFT calculations show negligible CO competition on phenol adsorption over those surfaces , which make them more favorable than conventionally used CoMoS supports. Among them, the one with 3.3 OH/nm2 appears to exhibit the highest selectivity for the direct C-O bond cleavage with less water competition effect.
Then single iron atom catalysts (SACs) supported on mesoporous silica were elaborated following the Sol-gel mechanism using non-ionic (P123) and metallic (CTAF) surfactants as porogens [4,5]. Tuning the P123/CTAF molar ratio enables to control the iron loading, as well as the silica structural properties, Fe-impregnated and Fe/Cu impregnated catalysts were tested for guaiacol HDO conversion and results proved that Fe-Cu have a better performance (90% conversion, 70% phenol selectivity) than pure Fe catalysts since incorporation of Cu facilitates the reduction of Fe(III) species.
We will also show how protonated zeolites [6,7] and mesoporous silica  with optimized silanol density can be used to purify the bio-oils obtained by selectively remove the residual phenol from the feed.