PHOSPHORUS PROMOTED WS2 AL2O3 CATALYSTS STUDIED BY TRANSMISSION ELECTRON-MICROSCOPY/

A series of WS2/Al2O3 catalysts containing a varied amount of phosphor us (0.0, 2.5 and 6.0 wt% P2O5), sulfided at two different temperatures (873 and 1073 K), were studied by means of high-resolution transmissi on electron microscopy (HRTEM). The stacking of(002) layers in the WS2 -2H crystallites of the ''rag'' structure increases with the addition of phosphorus, whereas its length is kept almost constant. At high sul fidation temperatures phosphorus shows a stabilizing affect on the cat alysts by retarding the stacking growth of WS2 crystallites. Additiona lly, an aluminum phosphate crystalline phase is identified in the phos phorus promoted catalysts.