Effective and Stable Zeolite Imidazole Framework-Supported Copper Nanoparticles (Cu/ZIF-8) for Glycerol to Lactic Acid

The dehydrogenation and isomerization of glycerol to produce lactic acid is an important way to realize the effective utilization of biodiesel by-products. Currently, precious metal catalysts have been widely used in the preparation of lactic acid from glycerol. In this paper, Cu-supported zeolitic imidazolate framework (ZIF-8) crystals of different loadings were synthesized by the reaction of zinc nitrate, copper nitrate and 2-aminobenzophenone at room temperature, and were applied to the reaction of glycerol to lactic acid. Characterizations including XRD, XPS, SEM, TEM, BET, FT-IR, UV–vis DRS, CO2-TPD and TG were carried out to evaluate the morphology and properties of the catalysts. The results showed that the lattice structure of body centered cubic of the materials was successfully formed, and nano-copper was distributed uniformly on the supports, which provided abundant active alkaline sites. In addition, the catalytic reactions achieved good results under optimum copper loading and reaction conditions, which the glycerol conversion and lactic acid yield can reach 97.5% and 84.2%, respectively.