Synthesis of Cu1Mg3Sc2(OH)12CO3 layered double hydroxide and its derived catalyst for hydrogenation of DMCD to CHDM

Abstract

The synthesis and fabrication of new layered double hydroxide (LDH) materials are of great importance because of their versatility in catalysis, biosensors, supercapacitors, drug delivery and adsorption. In this work, Cu₁Mg₃Sc₂(OH)₁₂CO₃ LDH and its derived Cu₁/Mg₃Sc₂O₆ catalyst with Sc³⁺ as the trivalent ion were synthesized for the first time. The composition and fine structure of Cu₁Mg₃Sc₂(OH)₁₂CO₃ LDH and Cu₁/Mg₃Sc₂O₆ catalysts were characterized in detail. It was found that Cu₁Mg₃Sc₂(OH)₁₂CO₃ LDH possesses larger cell parameters a (0.3170 nm) and c (2.3073 nm) than Cu₁Mg₃Al₂(OH)₁₂CO₃. And the final Cu₁/Mg₃Sc₂O₆ catalyst possesses an enlarged surface area (260.8 m² g⁻¹), enhanced basicity (550 μmol g⁻¹) and weaken acidity compared with those of Cu₁/Mg₃Al₂O₆. Finally, the Cu₁/Mg₃Sc₂O₆ catalyst was tested in the hydrogenation of waste polyethylene terephthalate (PET) derived dimethyl 1,4-cyclohexanedicarboxylate (DMCD) to 1,4-cyclohexanedimethanol (CHDM). It was found that the Cu₁/Mg₃Sc₂O₆ catalyst was highly active and selective for the conversion of DMCD to CHDM with 96.3% yield under mild conditions (250 °C, 2 MPa and WHSV_DMCD = 0.49 h⁻¹). And it can retain its performance for 300 h.