Y-Y Liu

Synthesis, characterization and sorption properties of NH2-MIL-47

K. Leus, S. Couck, M. Vandichel, G. Vanhaelewyn, Y-Y Liu, G.B. Marin, I. Van Driessche, D. Depla, M. Waroquier, V. Van Speybroeck, J.F.M. Denayer, P. Van der Voort

Physical Chemistry Chemical Physics (PCCP)

14, 15562–15570

2012

A1

Abstract

An amino functionalized vanadium-containing Metal Organic Framework, NH₂-MIL-47 has been synthesized by a hydrothermal reaction in an autoclave. Alternatively, a synthesis route via microwave enhanced irradiation has been optimized to accelerate the synthesis. The NH₂-MIL-47 exhibits the same topology as MIL-47, in which the V center is octahedrally coordinated. After an exchange procedure in DMF the V+III center is oxidized to V+IV, which is confirmed by EPR and XPS measurements. The CO² and CH₄ adsorption properties have been evaluated and compared to MIL-47, showing that both MOFs have an almost similar adsorption capacity and affinity for CO². DFT- based molecular modeling calculations were performed to obtain more insight into the adsorption positions for CO² in NH₂-MIL-47. Furthermore our calculated adsorption enthalpies agree well with the experimental values.

DOI

http://dx.doi.org/10.1039/C2CP42137B

The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene

K. Leus, M. Vandichel, Y-Y Liu, I. Muylaert, J. Musschoot, H. Vrielinck, F. Callens, G.B. Marin, C. Detavernier, Y.Z. Khimyak, M. Waroquier, V. Van Speybroeck, P. Van der Voort

Journal of Catalysis

285 (1) 196-207

2012

A1

Abstract

A Metal Organic Framework, containing coordinatively saturated V+IV sites linked together by terephthalic linkers (V-MIL-47), is evaluated as a catalyst in the epoxidation of cyclohexene. Different solvents and conditions are tested and compared. If the oxidant TBHP is dissolved in water, a significant leaching of V-species into the solution is observed, and also radical pathways are prominently operative leading to the formation of an adduct between the peroxide and cyclohexene. If, however, the oxidant is dissolved in decane, leaching is negligible and the structural integrity of the V-MIL-47 is maintained during successive runs. The selectivity toward the epoxide is very high in these circumstances. Extensive computational modeling is performed to show that several reaction cycles are possible. EPR and NMR measurements confirm that at least two parallel catalytic cycles are co-existing: one with V+IV sites and one with pre-oxidized V+V sites, and this is in complete agreement with the theoretical predictions.