A Facile and General Coating Approach to Moisture/Water-Resistant Metal–Organic Frameworks with Intact Porosity

The moisture sensitivity of many metal–organic frameworks (MOFs) poses a critical issue for their large-scale real application. One of the most effective methods to solve this problem is to convert the surface of MOFs from hydrophilic to hydrophobic. Herein, we develop a general strategy to modify hydrophobic polydimethysiloxane (PDMS) on the surface of MOF materials to significantly enhance their moisture or water resistance by a facile vapor deposition technique. MOF-5, HKUST-1, and ZnBT as representative vulnerable MOFs were successfully coated by PDMS, and these coated samples well inherited their original crystalline nature and pore characteristics. Strikingly, the surface areas of these MOFs were nearly 100% retained upon PDMS-coating. Such a coating process might render MOFs applicable in the presence of water or humidity in extended fields such as gas sorption and catalysis

Precisely Controlled Porous Alumina Overcoating on Pd Catalyst by Atomic Layer Deposition: Enhanced Selectivity and Durability in Hydrogenation of 1,3-Butadiene

Metal catalyst in selective hydrogenation reactions often suffers from low selectivity and especially poor durability due to heavy coke formation. Here we report that precisely controlled porous alumina overcoating on a Pd catalyst using atomic layer deposition (ALD) not only remarkably enhances the selectivity to butenes, especially to 1-butene, but also achieves the best ever durability against deactivation in selective hydrogenation of 1,3-butadiene in the absence (or presence) of propene. Therein no visible activity declines or selectivity changes were observed during a total 124 h of reaction time on stream

Hollow Metal–Organic Framework Nanospheres via Emulsion-Based Interfacial Synthesis and Their Application in Size-Selective Catalysis

Metal–organic frameworks (MOFs) represent an emerging class of crystalline materials with well-defined pore structures and hold great potentials in a wide range of important applications. The functionality of MOFs can be further extended by integration with other functional materials, e.g., encapsulating metal nanoparticles, to form hybrid materials with novel properties. In spite of various synthetic approaches that have been developed recently, a facile method to prepare hierarchical hollow MOF nanostructures still remains a challenge. Here we describe a facile emulsion-based interfacial reaction method for the large-scale synthesis of hollow zeolitic imidazolate framework 8 (ZIF-8) nanospheres with controllable shell thickness. We further demonstrate that functional metal nanoparticles such as Pd nanocubes can be encapsulated during the emulsification process and used for heterogeneous catalysis. The inherently porous structure of ZIF-8 shells enables encapsulated catalysts to show size-selective hydrogenation reactions