Experimental evidence of negative linear compressibility in the MIL-53 metal–organic framework family

International audienc

Interplay of Linker Functionalization and Hydrogen Adsorption in the Metal–Organic Framework MIL-101

Functionalization of metal–organic frameworks results in higher hydrogen uptakes owing to stronger hydrogen–host interactions. However, it has not been studied whether a given functional group acts on existing adsorption sites (linker or metal) or introduces new ones. In this work, the effect of two types of functional groups on MIL-101 (Cr) is analyzed. Thermal-desorption spectroscopy reveals that the −Br ligand increases the secondary building unit’s hydrogen affinity, while the −NH2 functional group introduces new hydrogen adsorption sites. In addition, a subsequent introduction of −Br and −NH2 ligands on the linker results in the highest hydrogen-store interaction energy on the cationic nodes. The latter is attributed to a push-and-pull effect of the linkers

Development of new basic and super acid mof catalysts

Proyecto confidencialJuan Alcañiz, J. (2009). Development of new basic and super acid mof catalysts. http://hdl.handle.net/10251/34137.Archivo delegad

Synthesis of highly-uniform titania overcoats on a mesoporous alumina catalyst support by atomic layer deposition and their application in hydroprocessing

The feasibility of gas phase deposition using a Ti alkoxide precursor for precise surface modification of catalysts was demonstrated by modifying a mesoporous alumina support with a Ti oxide overcoat. Titanium tetra-isopropoxide yields a Ti oxide layer that covers homogeneously the alumina surface. Uniformity of the deposited TiO2 was verified by SEM-EDX, on both intra-particle and inter-particle levels. Only a few atomic layer deposition (ALD) cycles were required in order to obtain Ti contents with a relevance for industrial application. The pore size distribution of the overcoated catalyst support was barely affected by the coating process. Synthesized CoMo catalysts based on the Ti-alumina carrier showed up to 40% higher activity compared to a catalyst supported on pristine alumina, in hydroprocessing under industrial testing conditions. The TiO2 coating appeared to be stable, showing no agglomeration characteristics after reaction as corroborated by TEM-EDX. ALD provides a scalable route with low waste generation for the production of precisely structured TiO2-Al2O3 hydroprocessing catalyst supports.</p

The oxamate route, a versatile post-functionalization for metal incorporation in MIL-101(Cr): Catalytic applications of Cu, Pd, and Au

A new consecutive post-functionalization method has been developed for the inclusion of additional metal functionalities in Metal Organic Frameworks (MOFs) through oxamate as chelating agent. This may result in catalytic centers of metal organic complexes or in controlled formation of metal nanoparticles, demonstrated for Cu, Pd and Au, in the highly stable MIL-101(Cr) framework. In a first post-synthesis step, reduction of the NO2-MIL-101(Cr) leads to the formation of NH2-MIL-101(Cr). The second functionalization consists of a straightforward condensation of the amino groups of the ligand with ethyl chloro-oxoacetate resulting in the formation of free oxamates attached to the linker. Two different copper complexes have been coordinated through the oxamate ligand, attaining loadings as high as 9 wt.% and showing similar performance as the best reported copper MOFs (HKUST-1, [Cu(2-pymo)2] and [Cu(im)2]) in click chemistry catalysis (1,3-dipolar cycloaddition reactions) and multicomponent coupling reactions (propargylamine formation). Highly dispersed palladium and gold nanoparticles can be incorporated and stabilized in the MOF. The resultant Pd-catalysts are very active and selective in Suzuki Miyaura condensation, although palladium leaching is observed. After reduction of the Au-catalysts, immobilized gold nanoparticles are formed, which maintain a good performance in BA oxidation to benzaldehyde for at least 4 consecutive runs. No side reactions (further oxidation and esterification) are observed, which are attributed to the absence of any cationic gold species. TEM analysis and DRIFTS analysis during CO adsorption show the very uniform size (&#8764;2 nm) and metallic character of these gold particles encapsulated in the MIL-101 cages.Juan Alcañiz, J.; Ferrando-Soria, J.; Luz Minguez, I.; Serra-Crespo, P.; Skupien, E.; Santos, VP.; Pardo, E.... (2013). The oxamate route, a versatile post-functionalization for metal incorporation in MIL-101(Cr): Catalytic applications of Cu, Pd, and Au. Journal of Catalysis. 307:295-304. doi:10.1016/j.jcat.2013.08.001S29530430