Reaction Pathways of Gamma-Valerolactone Hydroconversion over Co/SiO 2 Catalyst.

The hydroconversion of γ-valerolactone (GVL) over Co/SiO₂ catalyst proceeds in a complex reaction network, resulting in 2-methyltetrahydrofuran (2-MTHF) as the main product, and C₄–C₅ alcohol and alkane side-products. The catalyst was shown to contain Co⁰ sites and Lewis acid (Co²⁺ ion)/Lewis base (O²⁻ ion) pair sites, active for hydrogenation/dehydrogenation and dehydration reactions, respectively. The initial reaction step was confirmed to be the hydrogenation of GVL to key intermediate 1,4-pentanediol (1,4-PD). Cyclodehydration of 1,4-PD led to the main product 2-MTHF, whereas its dehydration/hydrogenation gave 1-pentanol and 2-pentanol side-products, with about the same yield. In contrast, 2-pentanol was the favored alcohol product of 2-MTHF hydrogenolysis. 2-Butanol was formed by decarbonylation of 4-hydroxypentanal intermediate. The latter was the product of 1,4-PD dehydrogenation. Alkanes were formed from the alcohol side-products via dehydration/hydrogenation reactions. [ABSTRACT FROM AUTHOR]