Selective C–O bond cleavage in diphenyl ether via catalytic transfer hydrogenolysis over Ru-decorated nanocrystalline H-ZSM-5

Abstract

Abstract: Renewable lignocellulosic biomass holds the potential to cater to the escalating energy requirements of the expanding global population. The intricate task of creating a durable catalyst capable of selectively breaking C–O bonds of model compounds of lignin, specifically diphenyl ether (DPE), presents a substantial hurdle due to their formidable bond energy. In this study, we accomplished the conversion of diphenyl ether (DPE) into hydrogenated derivatives (cyclohexanol and cyclohexane) via a sustainable catalytic transfer hydrogenolysis (CTH) route, facilitated by ruthenium nanoparticle (NP) decorated nanocrystalline HZSM-5 (N-HZSM-5), while employing isopropanol (IPA) as the hydrogen source. The catalyst synthesis involved the integration of ruthenium into N-HZSM-5 through impregnation and chemical reduction techniques. The catalyst acidity and reducibility, evaluated using NH3-TPD and H2-TPR analyses, facilitated the CTH process. Remarkably, a full transformation of DPE was achieved at 170 °C with nearly 100% selectivity towards hydrogenated (HYD) products over Ru(3%)/N-HZSM-5. Furthermore, the Ru(3%)/N-HZSM-5 catalyst exhibited exceptional robustness and reusability during the CTH of DPE, thereby facilitating the conversion of diverse lignin model compounds into HYD products via the CTH mechanism.