Improvement on the catalytic performances of butyl levulinate hydrogenation to γ-valerolactone over self-regenerated CuNiCoB/Palygorskite catalyst

The acid-activated Palygorskite (H+-PAL) was applied to support Cu(M)NiCoB amorphous alloy catalysts with high-activity and self-regeneration ability for selective hydrogenation of butyl levulinate (BL) to γ-valerolactone (GVL). The catalysts were characterized by ICP-OES, nitrogen physisorption, XRD, FE-SEM, TEM, XPS, H2-TPD, NH3-TPD and FTIR-pyridine adsorption techniques. Compared to the unsupported Cu0.5Ni1Co1B catalyst, the Cu0.5Ni1Co1B/H+-PAL catalyst showed the highest GVL yield of 96.3 % with BL conversion of 99.7 % at 200 °C. When Mo was doped into the Cu0.5Ni1Co1B/H+-PAL catalyst, the GVL yield showed gradually increase to 95.7 % with BL conversion of 100 % after five times run. The high activity and self-regeneration ability was attributed to the Mo doping effect and the synthetic effect between Cu hydrogenation active species and H+-PAL support. Various characterization results indicated that Mo acted as both structural promoter to improve the dispersion of metallic Cu and CuMoNiCoB amorphous alloy and electronic promoter to enhance the formation and increase the fraction of Cu+ species. In addition, the incorporation of Mo provided more Lewis acid sites to promote BL conversion to GVL and GVL conversion to 1,4-PDO and n-PeOH. On the basis of characterization and catalytic performance testing results, the synergistic effect between CuMoNiCoB amorphous alloy and Cu2O/Cu hydrogenation sites and Lewis/Brønsted acid site of H+-PAL support is considered to be the key to produce GVL.