Effect of Mesopore Structural Parameters in Alumina Supports on Catalytic Hydrodeoxygenation of Guaiacol to Cycloalkanes via Ni-Supported Al2O3 Catalysts

Abstract

The elevated oxygen content in lignin-derived oil restricts its direct application as a liquid fuel. Ni-based Al2O3 catalysts are commonly employed to enhance the quality of lignin-derived oil via the hydrodeoxygenation (HDO) process. In this study, we successfully synthesized Ni-supported Al2O3 catalysts with diverse mesopore structural parameters of the Al2O3 support. Subsequently, we investigated the impacts of mesoporous size and volume on the HDO of guaiacol, a representative model compound of lignin-derived oil. The results indicate that optimizing the mesoporous size can enhance catalyst stability and significantly boost selectivity for cyclohexane. Moreover, an increase in the mesoporous volume can further improve the selectivity of cycloalkanes in the products. When the Ni/meso-Al2O3-F-100 catalyst was utilized, the cycloalkane selectivity reached 98.8%. During the upgrading of lignin-derived oil, the Ni/meso-Al2O3-F-200 catalyst, featuring a mesopore size of 4.07 nm and a mesopore volume of 0.286 cm3/g, exhibited outstanding performance. Notably, its selectivity for alkanes reached 65.9%, significantly higher than that of the commercial Ni/c-Al2O3 catalyst, which has a mesopore size of 3.83 nm and a mesopore volume of 0.184 cm3/g. This work offers valuable insights into the design of efficient and stable Ni-based Al2O3 catalysts for upgrading lignin-derived oil.