Hydroconversion of γ-valerolactone over Co/γ-Al2O3 and Co/H-Beta zeolite catalysts: Acidity and selectivity

Hydroconversion is an obvious way to convert γ-valerolactone (GVL) into value-added products. Co/γ-Al2O3 and Co/H-Beta catalysts were found to direct the reaction to get selectively 2-methyltetrahydrofuran (2-MTHF) and pentanoic acid (PA), respectively, at 200–250 °C. The activity difference were related to the difference of acid-base properties of the catalysts. Acid sites of the catalysts initiated opening of the [CH3CH-O] bond of GVL well below 100 °C resulting in surface pentanoates (POAs). POA, strongly bound to Co/γ-Al2O3 was not converted to PA up to about 250 °C, but at ≥150 °C formation of 2-MTHF was initiated by reduction of the carbonyl group, hydrogenolysis of the obtained [O-COH] bond to 1,4-pentanediol, and dehydrocyclization. Formation of 2-MTHF prevailed up to about 250 °C, where conversion of POA to PA became accelerated. Over Co/H-Beta the reactions bringing about 2-MTHF could not compete with the facile conversion of GVL to PA.