Hydrogenation of CuBTC Framework with the Introduction of a PtC Hydrogen Spillover Catalyst

Abstract

Hydrogen uptake of a microporous metal organic framework, CuBTC, is increased 3.5-fold at 298 K and 20 bar upon the addition of a hydrogen spillover catalyst, from 0.17 to 0.61 wt %. Structural integrity upon mixing with the catalyst is important to achieve this level of uptake. Increasing the adsorption temperature to 323 K significantly reduces the rate of uptake, but 0.55 wt % uptake is observed when the experimental equilibration time is extended. The slow, pressure-independent uptake at 323 K, along with the desorption behavior is suggestive of a hydrogenation process of the CuBTC substrate. PXRD analysis suggests the hydrogenated sample remains intact and FTIR demonstrates hydrogenation of the carboxylate group of the BTC ligand but finds no evidence for hydrogenation of the carbons of the BTC ligand. Although hydrogenation of the CuBTC does not lead to readily desorbable H2, the results shed light on a possible mechanism of the hydrogen spillover process.