非均相催化一步合成碳酸二苯酯的研究 Ⅷ.Ce和Sn的添加量对Pd/La_(0.62)Pb_(0.38)MnO_3催化剂性能的影响

Study on Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalyzing Reaction Ⅷ. Effect of Loaded Ce and Sn Content on Catalytic Activity of the Pd/ La_(0.62)Pb_(0.38)MnO_3 Catalyst

通过XRD对不同的Ce和Sn添加量所得催化剂的物相进行了表征,结果表明当Sn的负载量大于14 3%,Ce的添加量大于5%时,所得催化剂中主要物相仍为La0 62Pb0 38MnO3,同时也有物相CeXSn1-xO2少量存在,且其随Ce的负载量的增大而减少,x值也降低,此外存在其他杂相。由SEM、TEM及ChemBET3000比表面仪测试结果可知,当Ce的添加量为5%,Sn的负载量为14 3%时,催化剂的比表面积、空隙率较大,粒度分布较好。用DPC的合成实验对不同催化剂的活性及催化剂的寿命进行评价,结果表明无论是催化剂的活性还是催化剂的寿命当Ce的添加量为5%,Sn的负载量为14 3%时所得的催化剂的活性和寿命都较好。

Supported Pd/La_(0.62)Pb_(0.38)MnO_3 catalysts with three different loaded Ce and Sn contents were prepared for direct synthesis of diphenyl carbonate (DPC). The catalysts were characterized by XRD and the results showed that the main crystal phases in all catalysts were La_(0.62)Pb_(0.38)MnO_3. At the same time, CeO_2 and Ce_XSn_(1-x)O_2 were also detected in the catalysts and the content of crystal phase Ce_XSn_(1-x)O_2 and x value decreased with the loaded Ce content increasing when the loaded Sn content in the catalyst was greater than 14.3wt%. The specific surface areas and particle diameter distributions of the catalysts prepared with different Ce loading contents were determined by SEM, TEM and specific surface area instrument ChemBET3000 respectively, and the results showed the particle diameter distribution of the catalyst prepared with loaded Ce content 5wt% and loaded Sn content 14.3wt% was better than the others, and it's SBET was also largest. Finally, these catalysts were observed through DPC synthesis and it was found that the activity and the life of the catalyst with Sn 14.3wt% and Ce 5wt% were best. So, the crystal phase Ce_XSn_(1-x)O_2 in the catalyst might have boosted the reaction.