Multifunctional Pd@UiO-66 Catalysts for Continuous Catalytic Upgrading of Ethanol to n-Butanol

UiO-66-encapsulated nanopalladium (Pd@UiO-66) catalysts were used as highly efficient and stable catalysts for continuous catalytic upgrading of ethanol to n-butanol. The best Pd@UiO-66 catalyst exhibited 49.8% of ethanol conversion, 48.6% of selectivity toward n-butanol, and thereby 24.2% of n-butanol yield at relatively low temperature (523 K) and pressure (2 MPa) during a 200 h long-term evaluation. The high catalytic activity and selectivity of Pd@UiO-66 catalyst are primarily ascribed to the close synergy of highly dispersed Pd nanoparticles and coordinatively unsaturated Zr sites on Zr-6 nodes of UiO-66, as active centers for dehydrogenation/hydrogenation and aldol condensation, respectively; however, the high stability of the catalyst is mainly attributed to the electrostatic attraction of Pd nanoparticles with Zr-6 nodes and the confinement effect of the cavities of UiO-66.