Reductive Hydroprocessing of Hydrolysis Lignin over Efficient Bimetallic Catalyst MoRu/AC

The fast-growing demand for renewable fuels and chemicals, together with environmental concern, has inspired the study of lignin. However, the valorization of lignin is challenged by its large molecular structure and oxygen content. Catalytic hydroprocessing of lignin is the effective depolymerization for producing fuels and chemicals. The aims of this work were the implementation and study of the role of a novel and inexpensive bimetallic catalyst, MoRu/AC, in the reductive depolymerization (hydroprocessing) of hydrolysis lignin. The increase in the reaction temperature, between 200 and 340 °C, dramatically enhanced the hydrogen content of the bio-oils relative to the feed. The MoRu/AC catalyst exhibited excellent activity in the hydrogenation and produced bio-oils with a substantially increased H/C ratio, suggesting enhanced hydrodeoxygenation activity of the MoRu/AC. The catalyst at optimum temperature, 340 °C, significantly promoted the hydrogenation, and the H content in the bio-oil was 1.5 times of that in the feed. The results demonstrated that the phenolic compounds were the main component in all the produced bio-oils. This confirms that hydrolysis lignin can be easily depolymerized at the temperature range of 200–340 °C in the presence of the MoRu/AC catalyst.