Designing versatile nanocatalysts based on PdNPs decorated on metal oxides for selective hydrogenolysis of biomass derived γ-valerolactone and reduction of nitro aromatics

In this work, we designed versatile heterogeneous nanocatalysts based on palladium nanoparticles (PdNPs) decorated on metal oxides supports (i.e., PdNPs/gamma-Al2O3, PdNPs/WO3 and PdNPs/Nb2O5) by step-wise controlled synthesis of novel monodispersed similar to 2 nm PdNPs at room temperature and then impregnated over metal oxides. PdNPs supported catalysts were characterised by powder XRD, TEM, HRTEM, NH3-TPD, N-2-BET, H-2-TPR, and XPS techniques. PdNPs based catalysts studied in two different model reactions were presented i.e., biomass platform chemical intermediate gamma-valerolactone (GVL) conversion into pentanoic acid (PA) studied in vapor phase hydrogenolysis and 4-Nitrophenol (4-NP) reduction to 4-Aminophenol (4-AP) in liquid phase using NaBH4 as reducing agent over 0.5 wt% Pd nanoparticles -based nanocatalysts. The relationship between the active sites and the catalytic performance was evaluated. The Under optimized reaction conditions, over 0.5 wt% PdNPs/gamma-Al2O3 catalyst exhibited the highest PA yield of 100%, and over 0.5 wt% PdNPs/WO3, 0.5 wt% PdNPs/Nb2O5 exhibited PA yields of 98% and 96% respectively. Over PdNPs/gamma-Al2O3, PdNPs/WO3, and PdNPs/Nb2O5, the reduction reaction rates in the 4-NP to 4-AP are 5.40 x 10(-3) s(-1), 2.55 x 10(-3) s(-1) and 2.30 x 10(-3) s(-1) respectively. The calculated thermodynamic parameters of the Ea values for 4-NP to 4-AP reaction were 25.30, 26.75, and 27.81 KJ/mol for the PdNPs/gamma-Al2O3, PdNPs/WO3 and PdNPs/Nb2O5, respectively.

Automated summary

Versatile heterogeneous nanocatalysts based on PdNPs decorated on metal oxides supports were designed and characterized. The catalysts showed high yields in the conversion of GVL to PA and the reduction of 4-NP to 4-AP. The relationship between the active sites and the catalytic performance was evaluated through various techniques. The thermodynamic parameters of the activation energy for the reduction reaction were calculated for different catalysts.