A Systematic Comparison of Monometallic and NiCu Bimetallic Catalysts for Isopropyl Alcohol Production via Acetone Hydrogenation

Isopropyl alcohol (IPA) was synthesized via the acetone hydrogenation over silica-supported monometallic catalysts using Ni, Cu, Fe, Co, Ru, Rh, Pd, and Pt. The catalysts were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR), and CO pulse chemisorption. Screening of the metal species revealed that the Ni/SiO2 catalyst achieved the highest IPA yield, whereas the Cu/SiO2 catalyst exhibited the highest turnover frequency for IPA formation (TOFIPA). The NiCu bimetallic catalysts exhibited higher IPA yields and TOFIPA values than the monometallic Ni and Cu catalysts and the physically mixed catalysts, respectively, indicating a synergistic effect arising from the use of NiCu bimetallic particles. TPR results showed that the reduction temperature of the NiCu bimetallic catalysts was lower than that of the individual monometallic catalysts, suggesting that, in the acetone hydrogenation reaction, Cu within NiCu bimetallic particles can dissociate H2 at relatively lower temperatures and provide active hydrogen to the acetone adsorbate. Among the metal species investigated, NiCu bimetallic particles with loadings of 1.5 wt.% Ni and 0.5 wt.% Cu provided the most efficient active sites for converting acetone to IPA. A model for IPA synthesis via acetone hydrogenation was proposed, and the synergistic effect observed with NiCu bimetallic particles was discussed.