• Ionic liquid [Bmim]BF4 enables fluorination of hydroxyapatite, tuning its surface acidity/basicity and morphology for enhanced catalytic performance.
• Fluoridized hydroxyapatite achieves 54.7% methacrylic acid yield from itaconic acid under mild conditions (250 °C, 2 MPa N2) without precious metals or corrosive alkalis.
• Optimal synthesis parameters: [Bmim]BF4:calcium salt mass ratio 0.2:1, hydrothermal time 12 h, temperature 130 °C.
• Excessive fluoride ion concentration leads to CaF2 formation, which significantly reduces catalytic activity.