Catalytic Advantages of SO<sub>3</sub>H-Modified UiO-66(Zr) Materials Obtained via Microwave Synthesis in Friedel–Crafts Acylation Reaction
Marta Bauzà, Pedro Leo, Carlos Palomino Cabello, Antonio Martín, Gisela Orcajo, Gemma Turnes Palomino, Fernando Martı́nez
Abstract
High Resolution Image Download MS PowerPoint Slide The catalytic activity and stability of sulfonic-based UiO-66(Zr) materials were tested in the Friedel–Crafts acylation of anisole with acetic anhydride. The materials were prepared using microwave-assisted synthesis, producing microporous materials with remarkable crystallinity and physicochemical features as acid catalysts. Different ratios between both organic ligands, terephthalic acid (H 2 BDC) and monosodium 2-sulfoterephthalic acid (H 2 BDC–SO 3 Na), were used for the synthesis to modulate the sulfonic content. The sulfonic-based UiO-66(Zr) material synthesized with a H 2 BDC/H 2 BDC–SO 3 Na molar ratio of 40/60 exhibited the best catalytic performance in the acidic-catalyzed Friedel–Crafts acylation reaction. This ratio balanced the number of sulfonic acid sites and their accessibility within the UiO-66 microporous structure. The catalytic performance of this material increased remarkably at 200 °C, outperforming reference acids and commercial heterogeneous catalysts such as Nafion-SAC-13 and Amberlyst-70. Additionally, the best sulfonic-based UiO-66(Zr) material proved to be stable in four successive reaction cycles, maintaining both its catalytic activity and its structural integrity.