Highly active and green mesostructured titanosilicate catalysts synthesized for selective synthesis of benzoquinones

Abstract

Two-dimensional hexagonal thick-walled mesoporous titanosilicate catalysts synthesized using various amounts of titanium were used for the synthesis of 2,3,5-trimethyl-1,4-benzoquinone (TMBO) by liquid-phase oxidation of 2,3,6-trimethylphenol (TMP–OH). These catalysts were also used for the oxidation of di-/tri-substituted phenols to produce 2,6-disubstituted p-benzoquinones (DSBQs). A promising chemical treatment method, for the preparation of green mesoporous TiSBA-15(6) or Washed TiSBA-15(6), was used for removal of non-framework TiO₂ nanoparticle species from the active surface, and the catalytic activity of the recovered mesoporous TiSBA-15(6) catalyst has been evaluated. To confirm the green aspects, recyclability and hot-catalytic filtration experiments were performed. Based on the experimental results, it was found that the green mesoporous TiSBA-15(6) is a highly active, recyclable, and promising heterogeneous catalyst for the selective synthesis of TMBO and DSBQs and produces >99% TMBO selectivity with 100% TMP–OH conversion at 353 K for 60 min and 90–100% DSBQs selectivity with 83–99% phenol conversion at 330 K for 1–5 h.