物理化学学报 >> 1994, Vol. 10 >> Issue (02): 114-120.doi: 10.3866/PKU.WHXB19940205

研究论文 上一篇    下一篇

ZrO2酸碱性质的TPD表征 II. NH3和CO2共吸附研究

徐柏庆, 山口力, 田部浩三, 梁娟, 郑禄彬   

  1. 大连理工大学化工学院化学系,大连 116012| 日本国北海道大学理学院化学系;中国科学院大连化学物理研究所,大连 116023
  • 收稿日期:1992-05-18 修回日期:1993-04-23 发布日期:1994-02-15
  • 通讯作者: 徐柏庆

Characterization of Acid-Base Property of ZrO2 by Thermal Desorption: II. Dual Adsorption of NH3 and CO2

Xu Bai-Qing, Yamaguchi Tsutomu, Tanabe Kozo,  Liang Juan, Zheng Lu-Bin   

  1. Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian 116012| Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060, Japan; Dalian Institute of Chemical Physics, Academia Sincia, Dalian 116023
  • Received:1992-05-18 Revised:1993-04-23 Published:1994-02-15
  • Contact: Xu Bai-Qing

摘要:

用NH_3和CO_2双组分并吸附TPD-MS和IR技术对ZrO_2催化剂表面酸中心和碱中心的相互关系进行了表征. 先吸附NH_3(或CO_2)对在其后吸附的CO_2(或NH_3)不仅无阻碍,反而导致后吸附CO_2(或NH_3)在最高程脱峰温区(>510 K)的脱附量增加.这种双组分并吸附效应在IR谱图上表现为NH_3共吸附诱发生成了一种新的CO_2吸附态,即在碱中心上形成单齿碳酸根物种.同时CO_2共吸附又强化NH_3与Zr~(4+)(Lewis酸中心)的配位键合.这表明ZrO_2表面存在相互邻接的酸中心和碱中心,它们通过表面键诱导极化而令酸-碱相互作用加强.这类双组分共吸附效应可归结为表面键诱导酸-碱相互作用.

关键词: 氧化锆, 酸-碱作用, 表面键诱导作用, TPD, IR, NH3, CO2

Abstract:

Dual adsorption of NH_3 and CO_2 has been used to study the acid property of ZrO_2 in relation to its base property by TPD and IR spectroscopy. It is found that preadsorbed NH_3 (or CO_2) has no inhibitory but a promotive effect to a postadsorption of CO2 (or NH_3). The increased adsorption of the postadsorbed moecules is most pronounced in the TPD curves at above 510 K. In the IR observation, the dual adsorption effect is characterized by a formation, on one hand, of a monodentate carbonate species which can not be formed in the single adsorption of CO_2, and by a strengthened bonding of NH_3 to surface acid site (Zr~(4+)) on the other hand. These results suggest that there exists not only independently located acid and base sites, responsible for the adsorption of NH_3 and CO_2, but some sites located closely (i.e acid-base pair sites). A surface induced through-bond acid-base interaction seems to be the nature of the dual adsorption effect.

Key words: Zirconium dioxide, Acid-base interaction, Surface induced interaction, TPD, IR, NH3, CO2