Selective oxidation of glycerol to dihydroxyacetone over layer double hydroxide intercalated with sulfonato-salen metal complexes

A series of sulfonato-salen metal complexes were intercalated into Mg-Al layer double hydroxide (LDH) and used for selective oxidation of glycerol to dihydroxyacetone (DHA). The X-ray diffraction, Fourier transform infrared spectroscopy and elemental analysis results of the as-prepared catalysts demonstrated that the metal ions were combined with sulfonato-salen ligands to form metal complexes that intercalated in the LDH. The Cr(III) and Cu(II) sulfonato-salen complex-intercalated LDH catalysts were favorable for activation of H₂O₂, promoting the oxidation of glycerol to DHA. It was found that the Cu(II) sulfonato-salen-intercalated LDH catalyst was also beneficial for the dehydrogenation of glycerol, resulting in a high selectivity to DHA. The glycerol conversion and DHA selectivity obtained over the Cu(II) sulfonato-salen-intercalated LDH catalyst reached 40.3% and 52.9% respectively under the optimum reaction conditions of 60 ℃, 4 h and pH value 7.