Highly dispersed copper on lignin-based nitrogen-doped mesoporous carbon for selective hydrodeoxygenation of vanillin

The development of non-noble metal catalysts with high activity and selectivity in the catalytic hydrodeoxygenation (HDO) process of vanillin (VL) to produce 2-methoxy-4-methylphenol (MMP) remains a challenge. This study demonstrates the preparation of a highly efficient Cu nanoparticles catalyst, Cu/N@ALC, using alkali lignin (AL) and dicyandiamide (DCA) as the carbon source and nitrogen source of the lignin-based nitrogen-doped mesoporous carbon support, respectively. Characterization using isothermal nitrogen adsorption/desorption, SEM, EDS, FT-IR, XPS, XRD, and TEM demonstrated that DCA played the role of porogen in the preparation of lignin-based mesoporous carbon supports, and the average pore size of the mesopores could be stabilized in the range of 21–23 nm when the pyrolysis temperature was 900 °C and above, which provided a good environment for the diffusion and adsorption of the Cu salt precursors. And some N elemental residues were uniformly distributed in the mesoporous carbon, which played a key role in the anchoring of Cu species. Cu/N 8 @ALC 900 , the obtained highly dispersed copper nanoparticle catalyst, demonstrated an average particle size as low as 2.6 nm and good stability, was found to convert vanillin almost entirely to MMP at 135 °C, 2.0 MPa, and 4 h. The experimental results showed that both Cu 0 and Cu + species on the catalyst surface played a synergistic role in HDO process, thus resulting in excellent catalytic performance. This work provides valuable insights into the rational construction of efficient, non-noble metal nanoparticle catalysts based on alkali lignin for the conversion of lignin-based platform compounds.