Stability and hydrogen adsorption of metal–organic frameworks prepared via different catalyst doping methods

Abstract

The stability of three metal–organic frameworks (MOFs), namely IRMOF-8, Cu-TDPAT, and Cu-BTC, was tested after incorporation of Pt. Stability was assessed with powder X-ray diffraction (PXRD), physical (N2 at 77K) and chemical (H2 at 300K) adsorption, and thermogravimetric analysis in H2 and N2. Introduction of Pt via wet precipitation led to MOF degradation during the H2 reduction step. Addition of pre-reduced Pt supported on activated carbon (Pt/AC) to MOFs via physical mixing also led to structural degradation. However, addition of Pt/AC via a ‘pre-bridge’ (PB) technique led to high MOF stability, with the retention of surface area, porosity, crystallinity, and thermal stability. The catalytically active surface area was assessed by hydrogen adsorption, and demonstrated extension of the catalytically active surface area to the MOF surface. High hydrogen uptake correlated with MOF particle size, due to the connectivity between Pt/AC and MOF, and the interpenetration of Pt/AC into the MOF crystal.