物理化学学报 >> 1996, Vol. 12 >> Issue (07): 609-614.doi: 10.3866/PKU.WHXB19960707

研究论文 上一篇    下一篇

嵌入Y型分子筛中钯簇合成与结构的研究

张婉静,稽天浩,孟宪平,刘英骏,林炳雄   

  1. 北京大学物理化学研究所,北京 100871
  • 收稿日期:1995-12-09 修回日期:1996-02-08 发布日期:1996-07-15
  • 通讯作者: 张婉静

Studies on the Synthesis and structure of Pd Clusters Encaged in Y-zeolite

Zhang Wan-Jing,Ji Tian-Hao,Meng Xian-Ping,Liu Ying-Jun,Lin Bing-Xiong   

  1. Institute of Physical Chemistry,Peking University,Beijing 100871
  • Received:1995-12-09 Revised:1996-02-08 Published:1996-07-15
  • Contact: Zhang Wan-Jing

摘要:

经微波交换-焙烧-氢还原等过程制备了嵌入Y型分子筛中的钯簇化合物(Pd0Y)应用径向电子分布函数法(Redial Electron Distribution Function),就其钯原子簇化合物进行了结构的研究.结果说明,嵌入Y型分子筛中的钯原子以A1型密堆积方式排列,聚集成约12Å大小的原子簇,嵌在Y型分子筛超笼之中.分子筛骨架的作用使族之间分立存在.它在超笼之中的占有率仅为0.06. 因此Pd0Y化合物既有纳米级金属钯的性能,又有分子筛固有的孔道结构特征.
如此含有钯簇的分子筛化合物对一氧化碳完全氧化的反应具有超常的催化活性.

关键词: Y型分子筛, Pd原子簇, 径向分布函数, 合成, 结构

Abstract:

Pd clusters encaged in Y-zeolite (Pd0Y) have been prepared by means of exchanging zeolite HY with [Pd(NH3)4]2+ under microwave radiation. The product formed was deaminized by heating, washed sufficiently with de-ionized water and reduced with hydrogen. The crystal phase diffraction of Pd was not found in the XRD spectrogram of Pd0y. According to polycrystal X-ray diffraction data. Radial Electron Distribution Function (REDF) of Pd0Y was calculated to elucidate the structure of Pd cluster. The results show that the Pd clusters are of the Al type closely packed arrangement. The dimension of them is about 12 Å. They are encaged in the supercage of zeolite Y. Their occupancy on the supercage is as small as 0.06 so that the framework structure of zeolite Y is unchanged. Therefore, the high dispersing Pd cluster aggregating in supercage exhibit strong catalytic effect. The CO-conversion of Pd0Y with Pd 0.72% and 6.13% (in mass fraction) is 67 % and 100 % (in volume fraction) respectively. Evaluation conditions:
mixed gas containing 0.02% CO and air,
space velocity 3000 h-1,
reaction temperature 0 ℃.

Key words: Y-zeolite, Synthesis;Structure, Pd cluster, Radial Electron Distribution Function