Description:
<jats:p>
Heterogeneous continuous transformation of methyl levulinate (ML) and ethyl levulinate (EL) to
<jats:italic>γ</jats:italic>
-valerolactone (GVL), as a promising C
<jats:sub>5</jats:sub>
-platform molecule was studied at 100°C. It was proved that the H-Cube
<jats:sup>®</jats:sup>
continuous hydrogenation system equipped with 5% Ru/C CatCart
<jats:sup>®</jats:sup>
is suitable for the reduction of both levulinate esters. While excellent conversion rates (greater than 99.9%) of ML and EL could be achieved in water and corresponding alcohols, the selectivities of GVL were primarily affected by the solvent used. In water, 100% conversion and
<jats:italic>ca</jats:italic>
50% selectivity that represent
<jats:italic>ca</jats:italic>
0.45 mol
<jats:sub>GVL</jats:sub>
g
<jats:sub arrange="stack">metal</jats:sub>
<jats:sup arrange="stack">−1</jats:sup>
h
<jats:sup>−1</jats:sup>
productivity towards GVL, were obtained under 100 bar of total system pressure. The application of alcohols as a solvent, which maintained high conversion rates up to 1 ml min
<jats:sup>–1</jats:sup>
flow rate, resulted in lower productivities (less than 0.2 mol
<jats:sub>GVL</jats:sub>
g
<jats:sub arrange="stack">metal</jats:sub>
<jats:sup arrange="stack">−1</jats:sup>
h
<jats:sup>−1</jats:sup>
) of GVL. Therefore, from a synthesis point of view, the corresponding 4-hydroxyvalerate esters could be obtained even at a higher reaction rate. The addition of sulfonated triphenylphosphine ligand (TPPTS) allowed reduction of the system pressure and resulted in the higher selectivity towards GVL.
</jats:p>