Enhanced catalytic activity for toluene oxidation induced by acid-alkali synergistic treatment

Abstract

While the catalytic performance of catalysts can be improved by either acid or alkali treatment, it has not been reported hitherto that acid-alkali synergistic treatment is beneficial for enhancing catalytic activity. In this work, we synthesized a novel CoMn₂O₄-3M Aa-U400 catalyst by acetic acid and urea co-treatment. The CoMn₂O₄-3M Aa-U400 exhibits superior catalytic activity for toluene oxidation with a 90 % toluene conversion (T₉₀) at 229℃, 13°C lower than CoMn₂O₄-U400 obtained by alkali treatment, and 23°C lower than CoMn₂O₄-3M Aa obtained by acid treatment. Detailed characterizations indicate that acid-alkali synergistic treatment not only increases the specific surface area of the CoMn₂O₄, but also greatly increases the content of active lattice oxygen species, which is extremely conducive to improving the catalytic performance. Meanwhile, the acid-alkali synergistic treatment creates a high-index crystal surface (311) without altering the crystal structure, resulting in more active sites and greater surface energy. The previously unrevealed insight into the acid-alkali co-treatment would benefit future design of active catalysts.