• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>RSC Advances >Insightful understanding of the correlations of the microstructure and catalytic performances of Pd@chitosan membrane catalysts studied by positron annihilation spectroscopy
【24h】

Insightful understanding of the correlations of the microstructure and catalytic performances of Pd@chitosan membrane catalysts studied by positron annihilation spectroscopy

机译：对正电子hil没光谱法研究的Pd @壳聚糖膜催化剂的微观结构与催化性能的相关性的深刻理解

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In this study, the catalytic performances of palladium supported on chitosan (Pd@CS) membrane heterogeneous catalysts have been studied from the aspects of free volume by positron annihilation lifetime spectroscopy (PALS). The results showed that the variation in free volume hole size of the Pd@CS membrane catalyst was closely associated with microstructure evolutions, such as increase of Pd content, valence transition of Pd by reduction treatment, solvent swelling, physical aging during catalyst recycling, and so on. The PALS results showed that both the mean free volume hole size of the Pd0@CS membrane in the dry or swollen state (analyzed by the LT program) and its distribution (analyzed by the MELT program) are smaller than the molecule size of the reactants and products in the catalysis reaction. However, the results showed that the Pd0@CS membrane catalyst has excellent catalytic activity for the Heck coupling reaction of all the reactants with different molecule size. It was revealed that the molecule transport channels of the Pd0@CS membrane catalyst in the reaction at high temperature was through a number of instantaneously connected free volume holes rather than a single free volume hole. This hypothesis was powerfully supported by the catalytic activity assessment results of the CS layer sealed Pd0@CS membrane catalyst. Meanwhile, it was confirmed that the leaching of Pd0 nanoparticles of the reused Pd0@CS membrane catalyst during the recycling process was also through such instantaneously connected free volume holes.
机译：本研究从正电子have没寿命谱（PALS）的自由体积方面研究了壳聚糖（Pd @ CS）膜多相催化剂上负载的钯的催化性能。结果表明，Pd @ CS膜催化剂的自由体积孔尺寸的变化与微观结构的演变密切相关，例如，Pd含量的增加，还原处理后Pd的价态转变，溶剂溶胀，催化剂回收期间的物理老化以及以此类推。 PALS结果显示，Pd 0 @CS膜在干燥或溶胀状态（通过LT程序分析）的平均自由体积孔尺寸及其分布（通过MELT程序分析）小于催化反应中反应物和产物的分子大小。然而，结果表明，Pd 0 @CS膜催化剂对不同分子大小的所有反应物的Heck偶联反应均具有优异的催化活性。结果表明，高温反应中Pd 0 @CS膜催化剂的分子传输通道是通过多个瞬时连接的自由体积孔而不是单个自由体积孔。 CS层密封的Pd 0 @CS膜催化剂的CS活性评估结果有力地支持了这一假设。同时，证实了在重复使用的Pd 0 @CS膜催化剂中Pd 0 纳米颗粒的浸出过程回收过程也是通过这样的瞬时连接的自由容积孔进行的。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号