• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Inelastic Neutron Scattering Study of the Activation of Molecular Hydrogen in Silver-Exchanged A Zeolite: First Step in the Reduction to Metallic Silver at Low Temperature
【24h】

Inelastic Neutron Scattering Study of the Activation of Molecular Hydrogen in Silver-Exchanged A Zeolite: First Step in the Reduction to Metallic Silver at Low Temperature

机译：银交换沸石中分子氢活化的非弹性中子散射研究：低温还原为金属银的第一步

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The initial steps in the reduction of Ag~+ ions by H2 to produce metallic silver nanoparticles in silver cation-exchanged type A zeolite has been investigated in a novel way using inelastic neutron scattering (INS) to follow the reaction. The rotational tunneling excitations of the hydrogen adsorbed at low temperature were measured. The neutron scattering spectra show rotational tunneling peaks from the librational ground states of the adsorbed hydrogen. A transition at 0.3 meV is the lowest energy excitation ever observed for hydrogen adsorbed in a zeolite, and is characteristic of a σ-bond complex between a metal center and molecular hydrogen. The transition is assigned to a chemisorption complex between molecular hydrogen and the Ag_3~(2+) linear complex cation that has been proposed in X-ray diffraction studies of dehydrated Ag-A. Rotational tunneling peaks from H_2 molecules physisorbed on individual Ag~+ ions located at different sites in the zeolite are also observed. Warming the sample allows the reduction reaction to proceed, causing the rotational tunneling peaks to decrease and disappear irreversibly. New INS features appear that are attributed to H_2 physisorbed on neutral Ag clusters. The results clearly demonstrate that the first step in the reduction of the silver is the formation of an intermediate [Ag_3~(2+)…H_2] complex rather than a dissociative adsorption of hydrogen, and that the reduction reaction proceeds via this complex.
机译：已经用非弹性中子散射（INS）以一种新颖的方式研究了用H2还原Ag〜+离子以生成银阳离子交换的A型沸石中的金属银纳米颗粒的初始步骤。测量了在低温下吸附的氢的旋转隧穿激发。中子散射光谱从吸附氢的自由基态显示出旋转隧穿峰。在0.3 meV处的跃迁是有史以来观察到的沸石中吸附的氢的最低能量激发，并且是金属中心与分子氢之间σ键络合物的特征。过渡过程被赋予了分子氢与Ag_3〜（2+）线性络合阳离子之间的化学吸附络合物，这是在脱水Ag-A的X射线衍射研究中提出的。还观察到了H_2分子在分子筛中不同位点上个别吸附的Ag〜+离子上的旋转隧穿峰。加热样品可使还原反应继续进行，从而导致旋转隧穿峰减少并不可逆地消失。出现了新的INS特征，这些特征归因于在中性Ag团簇上物理吸附的H_2。结果清楚地表明，还原银的第一步是形成中间[Ag_3〜（2+）…H_2]配合物，而不是氢的解离吸附，并且还原反应通过该配合物进行。

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