Catalytic Depolymerization of Lignin into Aromatic Monomers over Ru-Ni/TiO2 Catalysts

This title has been presented on Thursday, December 14, 2023 at 14.00-14.10 GMT+7.

Abstract

This title has been presented on Thursday, December 14, 2023 at 14.00-14.10 GMT+7.

Lignin, a natural hydrocarbon polymer with both aliphatic and aromatic structures, can be converted into aromatic monomers through catalytic depolymerization. This research aims to depolymerize lignin through hydrogenolysis reaction over bimetallic Ru-Ni supported on TiO₂. TiO₂ was prepared by hydrolysis of titanium alkoxide, followed by modification using a mixture of acids (H₃PO₄ and HNO₃). TiO₂ was then impregnated with Ru and Ni with ratios of 5:0, 4:1, 2.5:2.5, 1:4, and 0:5. The prepared catalysts were thoroughly characterized using NH₃ – TPD, N₂ physisorption, XRF, XRD, H₂-TPR, and SEM analyses. The XRD results showed the formation of the anatase phase of TiO₂ at 2θ = 25.28°, 38.02°, and 38.33°, Ru at 2θ = 38.5°and 44.0°, and Ni at 2θ = 44.5° and 51.7° dispersed in TiO₂, which was corroborated by the SEM and XRF characterization results. N₂ physisorption results indicated that impregnation with Ru and Ni metals reduced the surface area of the catalyst by 20.1–40.3 m²/g with a catalyst pore size of 1.7-24.4 nm (mesoporous). The characterization results with TPD-NH3 revealed that the ratio of Ru and Ni to TiO₂ affected the acidity of the catalyst. The depolymerization reaction involving an aromatic monomer was analyzed by GC-MS. The best results were obtained using the 4:1 Ru-Ni/TiO₂ catalyst, which exhibited selectivities and yields of 42.2% and 71 mg/g, respectively.