PVDF/PAA@Pd催化膜的制备及性能表征

Preparation and property characterization of PVDF/PAA@Pd catalytic membrane

为了使聚偏氟乙烯(PVDF)膜具有良好的催化性能,对PVDF进行改性.采用自由基聚合反应合成聚丙烯酸(PAA)微凝胶,通过共混法制备PVDF/PAA共混膜,再利用原位还原法将Pd纳米粒子负载到共混膜中,制备了PVDF/PAA@Pd催化膜.采用FTIR、SEM及EDX对PVDF/PAA@Pd催化膜的结构及元素组成进行表征,并通过NaBH_4对4-硝基苯酚的还原反应对PVDF/PAA@Pd催化膜的催化性能进行研究.结果表明:PAA和Pd纳米粒子成功固定在催化膜内;催化反应速率受发生在Pd纳米粒子表面的化学反应控制,随Pd含量的增加而增大,同时随操作压力的增大呈先增大(≤0.3 MPa)后减小(≥0.3 MPa)的趋势;对催化膜进行循环催化反应,1~5次转化率均为100%,6~10次均保持在96%以上,表明催化膜具有良好的催化稳定性.

In order to provide the PVDF membrane with good catalytic performance, the PVDF was modified. PAA microspheres were synthesized through free radical polymerization. Then, PVDF/PAA blend membrane was prepared by blending PAA microspheres with PVDF powders. Finally, PVDF/PAA@Pd catalytic membrane was prepared by loading the Pd nanoparticles in blend membrane via in-situ reduction method. The catalytic membranes were characterized through FTIR, SEM and EDX. The catalytic performance of PVDF/PAA@Pd catalytic membrane was studied through the reduction reaction of 4-nitrophenol by NaBH4. The results indicated that the PAA and Pd nanoparticles were successfully immobilized in PVDF membrane. The reaction rate is controlled by the chemical reation occurring on the surface of Pd nanoparticles, and increases with increasing the amount of Pd nanoparticles in catalytic membrane. Meanwhile, with the operating pressure increasing, the reaction rate firstly increases （≤0.3 MPa） and then decreases （≥0.3 MPa）. In the recycle test, the conversion rates of 1-5 times are 100%, and those of 6-10 times are more than 96%, and this indicates that the catalyticmembrane has good catalytic stability.