Base catalytic activity of alkaline earth MOFs: a (micro)spectroscopic study of active site formation by the controlled transformation of structural anions

michel — Tue, 20 May 2014 12:44:05 +0000

P. Valvekens, D. Jonckheere, T. De Baerdemaeker, A. Kubarev, M. Vandichel, K. Hemelsoet, M. Waroquier, V. Van Speybroeck, E. Smolders, D. Depla, D. Roeffaers, D. De Vos

Chemical Science

5 (11), 4517-4524

2014

Abstract

A new concept has been developed for generating highly dispersed base sites on metal-organic framework (MOF) lattices. The base catalytic activity of two alkaline earth MOFs, M2(BTC)(NO3)(DMF) (M = Ba or Sr, H3BTC = 1,3,5-benzenetricarboxylic acid, DMF = N,N-dimethylformamide) was studied as a function of their activation procedure. The catalytic activity in Knoevenagel condensation and Michael addition reactions was found to increase strongly with activation temperature. Physicochemical characterization using FTIR, 13C CP MAS NMR, PXRD, XPS, TGA-MS, SEM, EPR, N2 physisorption and nitrate content analysis shows that during activation, up to 85 % of the nitrate anions are selectively removed from the structure and replaced with other charge compensating anions such as O2-. The defect sites generated via this activation act as new strong basic sites within the catalyst structure. A fluorescence microscopic visualization of the activity convincingly proves that the activity is exclusively associated with the hexagonal crystals, and that reaction proceeds inside the crystal’s interior. Theoretical analysis of the Ba-material shows that the basicity of the proposed Ba2+-O2--Ba2+ motives is close to that of edge sites in BaO.

DOI

http://dx.doi.org/10.1039/C4SC01731E

Private attachment

14_ChemScience_5(11)4524_Valvekens.pdf

Enhanced base catalytic activity of M2(BTC)(NO3)(DMF) via controlled structure modification

mat — Wed, 05 Nov 2014 10:11:33 +0000

D. Jonckheere, P. Valvekens, T. De Baerdemaeker, A. Kubarev, M. Vandichel, K. Hemelsoet, M. Waroquier, V. Van Speybroeck, M. Roeffaers, D. De Vos

P19

ISBN/ISSN:

Poster

Conference / event / venue

DZA2014

Ghent, Belgium

Tuesday, 7 October, 2014

Center for Molecular Modeling - D. Jonckheere

Base catalytic activity of alkaline earth MOFs: a (micro)spectroscopic study of active site formation by the controlled transformation of structural anions

Abstract

DOI

Private attachment

Enhanced base catalytic activity of M2(BTC)(NO3)(DMF) via controlled structure modification

Conference / event / venue