Hierarchical Porous Activated Carbon-Supported Ruthenium Catalysts for Catalytic Cleavage of Lignin Model Compounds

Abstract

The catalytic conversion of lignin model compounds was performed using Ru/C catalysts and an autoclave reactor. The Ru/C catalysts were prepared by the impregnation method using highly porous homemade activated carbon and characterized by XRD, SEM, and specific surface area. The catalytic reactions were performed in a high pressure/temperature reactor at different temperatures and with different solvents. The results showed that the novel Ru/C catalysts prepared from carbon supports activated by the KOH agent showed higher catalytic activity than the commercial catalyst. Ethanol and 2-propanol were suitable solvents for the cleavage of the β–O–4 ether bond of 2-phenoxy-1-phenyl ethanol (~65–70% conversion) over a Ru/C-KOH-2 catalyst at 220 °C in comparison to tert-butanol and 1-propanol solvents (~43–47% conversion of 2-phenoxy-1-phenyl ethanol). Also, the increase in reaction temperature from 200 °C to 240 °C enhanced the cleavage of the ether bond with an increase in phenol selectivity from 9.4% to 19.5% and improved the catalytic conversion of 2-phenoxy-1-phenyl ethanol from 46.6% to 98.5% over the Ru/C-KOH-2 catalyst and ethanol solvent. The Ru/C-KOH-2 catalyst showed outstanding conversion (98.5%) of 2-phenoxy-1-phenylethanol at 240 °C, 1h, ethanol solvent. This novel hierarchical porous activated carbon-supported ruthenium catalyst (Ru/C-KOH-2) can be applied for the further conversion of the lignin compound.

Boosting the catalytic performance of Ru nanoparticles in the cleavage of β-O-4 linkages in lignin by doping Mo

“…21,22,25,26 For instance, AC supported Pt/AC, Ru/AC, and Ni/AC catalysts were used for lignin hydrogenolysis in which AC played a key role in the dispersion of active metal nanoparticles and clusters. 27–30 Meanwhile, CNT supported Ru/CNT, MoO x /CNT and Ni/CNT catalysts exhibited also considerable recyclability and stability during the lignin depolymerization process. 31–33 Compared with AC and CNTs, reduced graphene oxide (rGO) shows a unique single atomic layer morphology, outstanding flexibility, a large surface area, and high charge carrier mobility, all of which are essential for a catalyst supporting substrate.…”