Interaction of alkali salt promoters and silicon impurities in Rochow contact masses
✍ Scribed by H. Ehrich; D. Born; J. Richter-Mendau; H. Lieske
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 191 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0268-2605
No coin nor oath required. For personal study only.
✦ Synopsis
Cesium chloride-and rubidium chloride-promoted Rochow contact masses based on both technical-grade and highly pure silicon have been investigated in the Rochow reaction and by REM/EDX surface analysis. The alkali-salt promoters seem to act analogously to the wellknown zinc promoter, by localizing the reaction to distinct reactive areas and keeping free the surface area for the reaction, probably for the formation of catalytically active Cu-Si surface species. The alkali salts exhibited their promoting action only in combination with the impurities within the technical-grade silicon. Otherwise, they acted as blocking poisons. The promoter action of alkali chlorides in contact masses based on technical-grade silicon is possibly connected with the formation of salt melts, containing alkali chlorides and impurities. These melts, analogously to zinc chloride, could dissolve oxidic impurities from the silicon surface which otherwise would enhance the blocking of potentially active surface by extensive copper deposition.