Hydrogenation of anhydro-mevalonolactone (aMVL) to 3-methyl-d-valerolactone (3MdVL) and 3-methyl 1,5-pentanediol (3MPD) on a nickel catalyst: effect of process conditions on conversion.

The European project NEXT-STEP aims to valorize lignocellulosic waste by producing bio-based platform molecules through sustainable and economically competitive catalytic processes. In this context, this thesis focuses on the reaction of anhydro-mevalonolactone (aMVL) to 3-methyl-d-valerolactone (3MdVL) and initiates a preliminary evaluation of the subsequent conversion to 3-methyl-1,5-pentanediol (3MPD), with particular attention to the use of non-precious catalysts operating under mild conditions. A Ni/NiO catalyst supported on silica–alumina was tested in a continuous fixed-bed reactor for the hydrogenation reaction of aMVL. The effects of temperature, pressure, and flow rate were analysed to identify the most favourable operating conditions. The catalyst, after being dried and reduced, showed high activity for hydrogenation alone, achieving complete conversion at 120 °C, 15 bar, and 0.1 mL/min. During continuous operation, it was observed a progressive deactivation of the catalyst, while regeneration treatments by reduction only partially restored its activity, highlighting the importance of pressure in the activation phase. An attempt was then made to promote hydrogenolysis towards 3MPD with the nickel-based catalyst, but the results did not show significant activity under the mild conditions explored. Furthermore, initial tests with a Cu/Ni system were carried out to evaluate the possibility of carrying out the first hydrogenation, but these too did not show significant activity under mild conditions. Overall, the results confirm the effectiveness of nickel in the hydrogenation reaction of aMVL under mild conditions, while highlighting the need for alternative catalysts to enable the selective production of 3MPD.