Catalytic Advantages of SO₃H-Modified UiO-66(Zr) Materials Obtained via Microwave Synthesis in Friedel–Crafts Acylation Reaction

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 (H₂BDC) and monosodium 2-sulfoterephthalic acid (H₂BDC-SO₃Na), were used for the synthesis to modulate the sulfonic content. The sulfonic-based UiO-66(Zr) material synthesized with a H₂BDC/H₂BDC-SO₃Na 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.