Cu-Mg-Al类水滑石的制备及其对二苯醚合成的催化性能研究

The Production of Cu-Mg-Al Hydrotalcite Like Compounds and Their Performance for the Synthesis of Diaryl Ether

采用水热-尿素水解法制备了系列含Cu2+的类水滑石化合物Cu x Mg3-x Al1-LDHs,并考察了这些催化剂对苯酚和碘苯合成二苯醚反应的催化性能.利用X射线粉末衍射(XRD)、差热热重(TG-DTA)、H2程序升温还原(H2-TPR)和扫描电镜(SEM)等方法对催化剂进行了表征.结果表明,Cu2+含量较低时,类水滑石催化剂具有较好的结晶度和热稳定性,随Cu2+含量的增加,层板间距加大,热稳定性也随之降低.催化活性测试结果表明,适量Cu2+的掺入可使催化剂的催化活性提高,其中催化剂Cu2Mg1Al1-LDHs具有较好的催化活性,在80℃条件下二苯醚收率达到55%.

Cu-Mg-Al hydrotalcite like compounds with different Cu-Mg-A1 molar ratios were synthesized by urea hy- drolysis-hydrothermal synthetic methods. The synthesized compounds were characterized by XRD, DTA, TPR, IR and SEM. The results showed that these compounds have structure of hydrotalcite with good crystallinity and ther- mal stability when the content of Cu2＋ was low. With the increasing of the content of Cu2＋, the interlayer-spacing was enhanced and the thermal stabilities were reduced. The results demonstrated that the catalytic activity of lay- ered double hydroxides（LDHs） can be improved with the inducing of Cu2＋. Cu2MglAll-LDHs catalyst gave high activity among the studied compounds, with 55% diaryl ether yield at the reaction of 80 ℃.