Carbon nanofiber-supported ReO_x catalysts for the hydrodeoxygenation of lignin-derived compounds

Abstract

The effect of ReOx loading (2–13 wt%) and H2 pressure (0–5 MPa) for the hydrodeoxygenation of phenol has been studied for carbon nanofiber-supported ReOx catalysts in a batch reactor at 573 K.

Hydrodeoxygenation of Lignin-Derived Phenols: From Fundamental Studies towards Industrial Applications

“…Reactivity of anisole higher than guaiacol reported in [39] similarly to the work of Prasomsri et al [36], can be explained by a higher bond dissociation energy required for the aromatic hydroxyl compared to methoxyl (Table 3). For o-cresol the preferred route is demethoxylation followed by ring hydrogenation [37]. Only when HDO was performed at 400 °C over Pt-Sn/CNF/Inconel nickel-(Inconel is chromium-based superalloy), guaiacol reactivity was higher than for anisole probably due to a very high temperature [48].…”

“…It was also observed that when the other hydroxyl was in the meta position, degree of HDO was much higher (Table 1, entry 7). The products in the HDO of guaiacol, phenol and anisole are mainly aromatic compounds, such as benzene and toluene at high temperatures, whereas cyclohexane can be formed below 340 °C over catalysts exhibiting hydrogenation activity, such as supported Ni, Rh, ReOx, CoNx and MoO3 [36,37,43,62,63].…”

“…From HDO of different model compounds, comprising guaiacol, anisole, phenol and o-cresol with a single reactant over the same catalyst it is possible to compare their relative reactivity, which is of high interest for industrial applications (Table 2) [36,37,39,48]. Results over ReOx/CNF catalyst at elevated temperature, 300 • C and pressure of 50 bar showed that conversion of four different model molecules decreased in the following order: guaiacol = anisole > phenol > cresol ( Figure 5) [37].…”

“…MoO3, 1 bar, benzene [36], for anisole 6. ReOx/CNFox, 50 bar, cyclohexane [37], 7. MoO3, 1 bar, benzene [36], 8.…”

An Overview on Catalytic Hydrodeoxygenation of Pyrolysis Oil and Its Model Compounds

“…It was found that large BET surface area and acidity of supports were conducive to improving the catalytic efficiency. Ghampson et al investigated ReO x supported on oxidized carbon nanofiber (ReO x -CNFox) to catalyze phenol HDO at 573 K, finding that phenol was completely converted at 10% ReO x loading [99]. The coordinatively unsaturated Re 4+ , which acts as a Lewis acid, interacts with the oxygen lone pair on phenol.…”