Production of Environmentally Friendly Polyester by Hydrogenation of Poly(butylene terephthalate) over Rh–Pt Catalysts Supported on Carbon Black and Recovery by a Compressed CO2 Antisolvent Technique

The direct hydrogenation of poly­(butylene terephthalate) (PBT) using 1,1,1,3,3,3-hexafluro-2-propanol (HFIP) as the solvent to environmentally friendly polyester poly­(butylene-1,4-cyclohexanedicarboxylate) (PBC) using a VulcanXC72-supported 2.5 wt % rhodium (Rh) and 2.5 wt % platinum (Pt) catalyst synthesized via the polyol method was studied. The pathway for the complete hydrogenation of PBT was suggested by observing the effects of temperature, H2 pressure, and reaction time on conversion and selectivity. Rh–Pt bimetallic catalysts were found to be superior to monometallic Rh catalysts for the hydrogenation of PBT, owing to the stronger aromatic ring adsorption ability of Rh coupled with Pt, assisting effective H2 spillover. At 50 °C and a H2 pressure of 6.89 MPa, PBT could be completely hydrogenated to PBC in 60 min, and PBC could be effectively recovered using a compressed CO2 antisolvent technique at room temperature after hydrogenation.