Operando study of palladium nanoparticles inside UiO-67 MOF for catalytic hydrogenation of hydrocarbons $(document).ready(function() { if (!$("html").hasClass("ie8")) { $.ajax({ url: "https://crossmark-cdn.crossref.org/widget/v2.0/widget.js", dataType: "script", cache: true }).done(function() { $(".crossmark-button").addClass("visible"); }); } });

Abstract

Functionalization of metal-organic frameworks with metal nanoparticles (NPs) is a promising way for producing advanced materials for catalytic applications. We present synthesis and in situ characterization of palladium NPs encapsulated inside functionalized UiO-67 metal-organic framework. The initial structure was synthesized with 10% of PdCl₂bpydc moieties with grafted Pd ions replacing standard 4,4'-biphenyldicarboxylate linkers. This material exhibits the same high crystallinity and thermal stability of standard UiO-67. Formation of palladium NPs was initiated by sample activation in hydrogen and monitored by in situ X-ray powder diffraction and X-ray absorption spectroscopy (XAS). The reduction of Pd^II ions to Pd⁰ occurs above 200 °C in 6% H₂/He flow. The formed palladium NPs have the average size of 2.1 nm as limited by the cavities of UiO-67 structure. The resulting material showed high activity towards ethylene hydrogenation. In reaction conditions, palladium was found to form carbide structure indicated by operando XAS, while formation of ethane was monitored by mass spectroscopy and infra-red spectroscopy.