磁性水滑石负载纳米钯催化剂的制备及催化Suzuki反应的研究

采用化学沉淀法将磁性基质与二维层状水滑石组装制备了磁性的水滑石，再利用浸渍法和滴加吸附的负载方法制备了磁性水滑石负载纳米钯催化剂。通过XRD、ICP—AES、TG、氢气脉冲吸附等分析手段对磁性催化剂晶型结构、形貌及金属分散度进行了表征，考察了用磁性水滑石负载纳米钯催化剂对不同碱、溶剂、溶剂与水比例、时间、温度、催化剂用量等条件对Suzuki反应的影响。实验结果表明，水滑石赋予磁性后结构并没有改变，仍然具有较高的催化活性。反应的最佳条件为：碳酸钾作碱、溶剂为乙醇、与水比例为1：5、反应温度为60℃、反应1h、催化剂用量分别为3．6×10^-3mmol和4．8×10^-3mmol，催化剂重复三次产物收率仍可保持在90％以上。

Preparation of Magnetic Hydrotalcite Supported Nanopalladium Catalyst and Its research on Suzuki Coupling Reaction

The magnetic hydrotalcite has been prepared by chemical co-precipitation method. Then two kinds of catalysts of magnetic hydrotalcite supported nanopalladium are synthesized by impregnation and adding adsorption method. The crystal structure, morphology and metal dispemity of above-prepared catalysts are characterized by X-ray diffraction （XRD）, inductively coupled plasma-atomic emission spectrometry （ICP- AES）, thermo-gravimetry （TG）, and hydrogen pulse adsorption. The influences of different bases, solvents, ratio of solvent to water, time, temperature and catalyst amount on the catalytic activity of magnetic hydrotalcite supported nanopalladium catalyst applied in Suzuki reaction are investigated. The results of Suzuki coupling reaction demonstrated that the structure of hydrotalcite is not changed after being magnetized and it retains high catalytic activity. The product yield of the Suzuki coupling reaction after the third recycled reaction can reach more than 90% when using ethanol / H20 and K2CO3 as the solvent and base and the adding amount of catalysts is 3.6×10-3 mmol and 4.8×10-3 mmol respectively within lh at 60℃.