Green-synthesized MIL-100(Fe) modified with palladium as a selective catalyst in the hydrogenation of citronellal to citronellol

Abstract

Abstract The influence of palladium embedded into green-synthesized MIL-100(Fe) and its role as a selective catalyst in the hydrogenation of citronellal into citronellol were investigated. MIL-100(Fe) was synthesized in water at 95 °C without addition of hydrofluoric acid (HF). The loading of Pd was carried out using wet impregnation method with Pd loadings of 1 and 3 wt%. The obtained materials were then tested as catalyst in hydrogenation of citronellal in a batch reactor. XRD analysis confirmed the high crystallinity of the synthesized MIL-100(Fe). FTIR analysis indicated the deprotonation of carboxylic ligand and its coordination with Fe3+ metal ions. The materials had thermal stability up to 287 °C according to TG/DTA analysis. The modification with palladium changed the morphology and decreased the crystallinity, surface area, and porosity as shown by XRD, SEM, TEM and nitrogen sorption isotherm analysis. The presence of Pd successfully increased the catalytic performance and selectivity to convert the citronellal into citronellol through a hydrogenation reaction, and an optimum 63.7% conversion and 22.2% selectivity to citronellol was attained over 3% Pd/MIL-100(Fe).