Ni (20 wt%) supported on SiO₂, γ-Al₂O₃ and ZrO₂ catalysts was examined for hydrogenation of aqueous levulinic acid (LA) to γ-valerolactone (GVL) at 270 °C and ambient pressure. The band intensities of Brønsted (BAS: 1540 cm⁻¹) and Lewis acid sites (LAS: 1450 cm⁻¹) estimated by pyridine adsorbed DRIFT spectra revealed a lower ratio of BAS/LAS over the Ni/SiO₂ catalyst than over the Ni/ZrO₂ and Ni/γ-Al₂O₃ catalysts. The rate of angelica lactone (AL) formation was lower than the rate of AL hydrogenation over the Ni/SiO₂ catalyst. The poisoning and regeneration of the Ni/SiO₂ catalyst using pyridine and 2,6-dimethylpyridine demonstrated that Lewis acid sites influenced the conversion of LA to AL and subsequent hydrogenation of AL to GVL occurred on surface Ni sites. In contrast, Brønsted acid sites were responsible for the ring opening of GVL to valeric acid (VA). Kinetic data emphasized that the hydrogenation activity and product distribution were dependent on the type of acid site, and the Ni sites in close proximity to Brønsted acid sites are prone to hydrogenolysis of GVL to valeric acid and hydrocarbons.

A Cu-BTC (MOF-199) [copper(II)-benzene-1,3,5-tricarboxylate] catalyst has been synthesized and evaluated for imine synthesis from amine compounds under neat conditions. The performance of the Cu-BTC MOF was significantly higher than that of the CuO supported on Al₂O₃, TiO₂ and SiO₂ catalysts. The role of surface Lewis acid sites on the catalyst in the formation of imine products was illustrated by the pyridine-IR studies. The recovered Cu-BTC catalyst demonstrated consistent activity for five cycles under similar experimental conditions. The physicochemical properties of the catalysts were analyzed by XRD, BET-SA, FT-IR, UV-DRS, SEM, TEM, XPS and pyridine adsorbed DRIFT spectroscopy.