Highly Active and Stable P₂O₅ Catalysts Supported on Mesoporous Silica Promoted with Ce for the O‐Methylation of Catechol

P 2 O 5 has been widely used as an acid‐base catalyst for the O ‐methylation of catechol to guaiacol due to its suitable acid strength; however, its stability, which is a significant concern for industrial applications, has not seen significant breakthroughs. Herein, we developed a facile impregnation strategy to synthesize Ce promote P 2 O 5 supported on mesoporous silica (CeP/SBA). The CeP/SBA‐500 carbonized at 500 °C exhibited the highest catalytic activity with a catechol conversion of 71.5 %. The high activity stems from the addition of Ce, forming CePO 4 , which exhibits improved surface acidity compared to P 2 O 5 . Importantly, chemisorption and in situ infrared studies revealed that CePO 4 shows stronger adsorption of catechol, which then rapidly converts to guaiacol. The CeP/SBA‐500 exhibits excellent stability with no activity decrease after 10 h of continuous flow reaction, attributed to the absence of a decrease in CePO 4 surface acidity.