Boosting catalytic activity of Ni/ZrO2 by introducing MoO3 on selective hydrogenolysis of lignin

Abstract

Conversion of renewable lignin to value-added aromatic chemicals presents a broad prospect to achieve the goals of “carbon neutrality”. In this work, an efficient approach is proposed for selective hydrogenolysis of lignin to valuable 4-propyl syringol in the presence of cost-effective catalyst of yNi/ZrO2-xMoO3. When the lignin hydrogenolysis is performed with 15Ni/ZrO2-10MoO3, 15.4% yield of monophenols is achieved, which is approximately twice as that from the 15Ni/ZrO2 catalytic system (7.8%). Importantly, 33.1% of these monophenols are identified as 4-propyl syringol (4-PS), a versatile fine chemical. An extensive characterization of the modified catalysts by means of XRD, nitrogen adsorption–desorption isotherm, SEM, TEM, XPS, NH3-TPD, CO2-TPD, and H2-TPR, confirms that the introduction of MoO3 changes the primary phase of ZrO2 and the acidity/basicity properties of catalyst. As a result, an enhanced cleavage of the C-O linkage between S-lignin and other units is demonstrated, which consequently contributes to the good selectivity of 4-propyl syringol. Therefore, this work provides a new insight for producing bulk aromatic chemicals via a sustainable route.