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Acetylacetone Covalent Triazine Framework: An Efficient Carbon Capture and Storage Material and a Highly Stable Heterogeneous Catalyst

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journal contribution
posted on 03.06.2018, 00:00 by Himanshu Sekhar Jena, Chidharth Krishnaraj, Guangbo Wang, Karen Leus, Johannes Schmidt, Nicolas Chaoui, Pascal Van Der Voort
We present, for the first time, covalent triazine frameworks functionalized with acetylacetonate group (acac-CTFs). They are obtained from the polymerization of 4,4′-malonyl­dibenzonitrile under ionothermal conditions and exhibit BET surface areas up to 1626 m2/g. The materials show excellent CO2 uptake (3.30 mmol/g at 273 K and 1 bar), H2 storage capacity (1.53 wt % at 77 K and 1 bar), and a good CO2/N2 selectivity (up to 46 at 298 K). The enhanced CO2 uptake value and good selectivity are due to the presence of dual polar sites (N and O) throughout the material. In addition, acac-CTF was used to anchor VO­(acac)2 as a heterogeneous catalyst. The V@acacCTF showed outstanding reactivity and reusability for the modified Mannich-type reaction with a higher turnover number than the homogeneous catalyst. The higher reactivity and reusability of the catalyst come from the coordination of the vanadyl ions to the acetyl acetonate groups present in the material. The strong metalation is confirmed from Fourier transform infrared analysis, 13C MAS NMR spectral analysis, and X-ray photoelectron spectroscopy measurement. Detailed characterization of the V@acac-CTF reveals that electron donation from O∧O of the acetylacetonate group to VO­(acac)2, combined with the very high surface area of acac-CTF, is responsible for the stabilization of the catalyst. Overall, this contribution highlights the necessity of stable catalytic binding sites on heterogeneous supports to fabricate greener catalysts for sustainable chemistry.