Formic acid assisted hydrogenation of levulinic acid to $\gamma$-valerolactone over ordered mesoporous ${\text{Cu/Fe}}_2{\text{O}}_3$ catalyst prepared by hard template method

Vapor phase hydrogenation of levulinic acid using formic acid as a hydrogen source has been conducted over ordered mesoporous ${\text{Cu/Fe}}_2{\text{O}}_3$ catalysts prepared by hard template method using mesoporous silica, SBA-15. X-ray diffraction result reveals the absence of copper peaks because of either highly dispersed state, or formation of a solid solution with iron oxides. The ${\text{N}}_2$ sorption analysis and TEM results indicate the retainment of mesoporous nature in the samples. Among the catalysts tested, 10 (wt%) ${\text{Cu/Fe}}_2{\text{O}}_3$ seems to be an efficient catalyst to yield higher amounts of $\gamma$-valerolactone under hydrogen-free conditions. The results reveal the formation of spinel species, which gets reduced easily at a lower temperature (as evidenced from TPR studies), and as a consequence of this synergism, significant improvement in the catalytic performance for the synthesis of $\gamma$-valerolactone from levulinic acid and formic acid in presence of water has been achieved. The presence of water plays a crucial role in obtaining a higher yield of $\gamma$-valerolactone. This makes the catalytic system a viable methodology for hydrogenation of levulinic acid to get $\gamma$-valerolactone.

Graphical Abstract 

SYNOPSIS: Cu (10wt%) deposited on mesoporous ${\text{Fe}}_2{\text{O}}_3$ prepared by hard template method exhibits good activity in the hydrogenation hydrogenation of levulunic acid with formic acid as ${\text{H}}_2$ source in vapour phase conditions. .