Understanding the influence of the composition of the Ag Pd catalysts on the selective formic acid decomposition and subsequent levulinic acid hydrogenation

Abstract

Formic acid is obtained in equimolar amount with levulinic acid during the hydrolysis of cellulose and thus can be used as a sustainable hydrogen source in the direct levulinic acid hydrogenation towards gamma-valerolactone (biofuel additive). Ag-Pd catalysts prepared by various methods and containing different Ag:Pd ratio were investigated in this context. By combining activity tests, characterization of the main physicochemical properties of the catalysts and DFT study of formic acid decomposition, the key factors responsible for the activity of Ag-Pd catalysts in both the formic acid decomposition and the subsequent hydrogenation of levulinic acid were specified. Pd is shown to be active, but prone to poisoning by CO, while the CO poisoning remains limited on diluted Ag-Pd alloy with strong intermetallic interaction, where its adsorption is very weak thanks to the isolation of Pd atoms.Therefore, the catalyst containing 4%Ag-1%Pd/AlOOH showed the highest selectivity in formic acid decomposition as well as the highest activity in levulinic acid hydrogenation (34% conversion in 5 h at 190°C).

Electrodeposited Ni-Rich Ni–Pt Mesoporous Nanowires for Selective and Efficient Formic Acid-Assisted Hydrogenation of Levulinic Acid to γ-Valerolactone

“…The high energy consumption required to vaporize LA makes this approach less attractive compared to the liquid-phase hydrogenation. Typically, the conversion of LA to GVL can be performed using three different hydrogen sources: (i) molecular hydrogen from an external source, (ii) hydrogen generated in situ from the decomposition of formic acid (FA), or (iii) by the Meerwein–Ponndorf–Verley reaction using alcohols. − Further, to exploit the facile separation of the liquid products upon hydrogenation, the conversion of LA to GVL has been extensively studied using molecular hydrogen under heterogeneous catalysis. − …”

The Influence of Carbon Nature on the Catalytic Performance of Ru/C in Levulinic Acid Hydrogenation with Internal Hydrogen Source

“…In the case of the decomposition of formic acid, a strong adsorption of hydrogen can poison the catalyst [ 61 ]. Higher hydrogen mobility on the catalyst surface reduces certainly the effect of catalyst poisoning and simultaneously increases its activity in the FA decomposition reaction.…”

Catalytic valorisation of biomass levulinic acid into gamma valerolactone using formic acid as a H2 donor: a critical review

“…52 Sneka-Płatek O. et al used another approach to inhibit CO poisoning in which tuning the alloy ratio of Ag : Pd at 4% Ag–1% Pd resulted in isolated Pd atoms and thereby in the highest conversion of HCOOH at 34%. 53…”