ZIF-67-derived Co@NC catalyst for hydrodeoxygenation of 4-ethylphenol to cycloalkanes/cycloalkanols

Hydrodeoxygenation (HDO) of lignin-derived phenolic compounds plays a crucial role in the production of renewable biofuels. In this regard, a series of different Co@NC catalysts were prepared with ZIF-67 as a sacrificial template by modulating the catalyst pyrolysis temperature and used for the catalytic hydrodeoxygenation of lignin-derived phenolic model compound 4-ethylphenol for the preparation of cyclohexanols/ cyclohexanes. The results showed that the low-temperature pyrolysis will retain a large number of CoO x compounds, which led to a high dispersion of Co. For Co@NC catalysts, the uniformly dispersed Co component facilitated the adsorption and transfer of hydrogen, and the exposed surface of the carrier promoted the adsorption of reactants. The pyrolysis temperature also played a crucial role in the differences in catalyst crystal surface, specific surface area, acid strength distribution and oxygen vacancies. Co@NC catalyst prepared at 600 °C has a stronger hydrogen absorption capacity, the largest specific surface area and a higher number of oxygen vacancies. Therefore, the Co@NC-600 catalyst showed the best HDO activity. Under the mild conditions (220 °C, 2.5 h and 3 MPa H 2 ), the conversion of 4-ethylphenol was close to 100 %, and the selectivities of 4-ethylcyclohexanol and ethylcyclohexane were 62.7 % and 10.8 %, respectively.