Ruthenium loaded moderate acidic SAPO-11 for hydrogenation of aromatic derivatives

Abstract

Hydrotreating of lignin molecules by heterogeneous catalysts has been a significant area of research in recent eras. The current study describes the hydrotreatment of lignin-derived phenol, m-cresol, over ruthenium-incorporated SAPO-11. The developed catalyst hydrogenates m-cresol completely at 160 °C and 10 bar of hydrogen pressure, yielding 22% methyl cyclohexane, 22% methyl cyclohexanol, and 55% methyl cyclohexanone. Temperature-programmed reduction (TPR) studies using hydrogen as probe molecules show that metallic-ruthenium species exist on the SAPO-11. The desorption profile at 147–215 °C reveals the formation of dispersed metallic ruthenium on SAPO-11. The above observation is consistent with the in-situ formation of metallic ruthenium as an active species during the hydrotreating process at 160 °C in a hydrogen environment. The presence of ruthenium species increases the acidity of the ruthenium-incorporated SAPO-11 system, as demonstrated by the ammonia-temperature-programmed desorption profile. The increase in surface acidity and metallic ruthenium on the surface contribute to the hydrogenation of m-cresol via a hydrogen spillover process, as evidenced by hydrogen desorption in TPR using both fresh and reduced catalysts. The catalyst works for several cycles of m-cresol hydrotreating, and the system is easily regenerated, allowing it to maintain its original activity. The ruthenium incorporated SAPO-11 catalyst is a promising system as it can hydrogenate many other model systems, including guaiacol, toluene, anisole, and cumene.