In Situ Polymerization Of The Metal-organic Framework 5 (MOF-5) By The Use Of Maghnite-H+ As A Green Solid Catalyst

Laboratory of Polymer Chemistry, Department of Chemistry, Faculty of Science, University of Oran, BP 1524 El M'Naouar, 31000 Oran, Algeria

Adv. Mater. Lett., 2015, 6 (3), pp 271-277

DOI: 10.5185/amlett.2015.5660

Publication Date (Web): Feb 22, 2015

Copyright © IAAM-VBRI Press

E-mail: Souad_bennabi02@yahoo.fr

Abstract

Metal-organic framework MOF-5 [Zn4O(BDC)₃, BDC : 1,4 benzenedicarboxylic] is a microporous material with a large specific surface area and high porosity formed by benzenedicaroboxylic acid as organic ligand and zinc nitrate hexahydrate as metal ion . This material is mainly used in the field of automobile industry as a container for storing hydrogen (alternative fuel) and for the environmental preservation by trapping CO₂ (greenhouse gas emissions). The present study shows the synthesis of this material using a clay called Maghnite-H+ as catalytic support in order to enhance the yield which increases from 35% to 63% and improve the thermal stability of MOF-5. Maghnite-H+ is a montmorillonite sheet silicate clay, exchanged with protons, it is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers. The structure of resulting products is characterized and established by Magic Angle Spinning Nuclear Magnetic Resonance (¹³C MAS NMR). ²⁷Al MAS NMR and ²⁹Si MAS NMR results show that there are interactions between the chains of MOF-5 and the silicate surface or aluminum of Maghnite-H⁺. Fourier Transform Infrared spectroscopy (FTIR) is also used to confirm the structure of these products showing that there is a complete deprotonation of benzenedicaroboxylic acid. The X-Ray Diffraction (XRD) allows to study the morphology of the obtained compounds and reveals the formation of a partially exfoliated/partially intercalated structure. Thermal stability is studied by Thermogravimetric Analysis (TGA) and shows an enhanced thermal stability for MOF-5/Mag-H⁺ with a gain of 40°C.

Keywords

Maghnite-H+, green catalyst, MOF-5, in situ polymerization, thermal properties.