不同有机分子改性羟基磷灰石用于甲醛催化氧化

Formaldehyde catalytic oxidation over hydroxyapatite modified with various organic molecules

分别采用十六烷基三甲基溴化铵(CTAB)、十二烷基硫酸钠(SDS)及柠檬酸钠(SC)对羟基磷灰石(HAP)进行了有机改性.柠檬酸钠改性的羟基磷灰石对甲醛催化氧化表现出最好的催化活性,在240℃实现了甲醛完全转化.通过X射线衍射、红外光谱、N2吸附-脱附、扫描电镜和热重/差重等手段对HAP结构进行了表征.结果表明,SC改性使得HAP比表面积和孔体积增加,孔径减小,更有利于吸附及传质,从而提高了其活性.此外,SC改性的HAP中羟基含量更多,更有利于甲醛与羟基之间发生相互作用,这是该样品活性提高的另一个原因.

Hydroxyapatite （HAP） was modified by adding various organic molecules, such as cetyltrime‐thylammonium bromide, sodium dodecyl sulfate, and sodium citrate, during the precipitation of HAP. Sodium citrate‐modified HAP displayed the best activity for formaldehyde oxidation, achieving complete conversion at 240 °C. The influence of the organic modifiers on the structure of HAP was assessed by X‐ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption‐desorption, scanning electron microscopy, and thermogravimetry/derivative thermogravimetry. The higher specific surface area and pore volume, and smaller pores, owing to modification with sodium citrate, favored adsorption, mass transfer, and interaction process during formaldehyde oxidation. Fur‐thermore, the higher hydroxyl group content observed in sodium citrate‐modified HAP enhanced interactions between formaldehyde and HAP, thus resulting in higher catalytic activity.