Preparation of Ce - Zr - O Solid Solution

摘要

The application of Ce-Zr-O solid solution is a break through for auto-gas purification catalyst. Generally, the auto - catalyst containing Ce-Zr-O are in the composition of active component (noble metals) / Ce-Zr-O solid solution /Al_2O_3 / ceramic monolith support, in which Ce-Zr-O plays a key role. Supported catalysts can be made by impregnation, but for this auto-catalyst, Ce-Zr-O solid solution is hardly to be formed with impregnation method, because Ce and Zr can not be well mixed after drying. For example, when monolith support is impregnated with the solution of nitrate of cerium and zirconium, the compounds supported on monolith after drying should be cerium nitrate and zirconium nitrite, and the supported material should be changed to particles of CeO_2 and ZrO_2 after calcination. It is difficult for the two kinds of particles to form solid solution because of the much high diffuse energy. Ce-Zr-O solid solution can be easily produced and well dispersed on the support, if a kind of compound that contains both Ce and Zr elements can be made and if this kind of compound can be well dispersed on the ceramic support. The reason is that because Ce and Zr atoms are in one molecule and thus the diffuse energy in solid phase reaction for formation of Ce-Zr-O solid solution should be much lower. In this work, we found an interesting phenomenon it is just as stated in the above paragraph, and based on this phenomenon Ce-Zr-O solid solution may be dispersed on the monolith support.