TEXTURE AND STRUCTURE OF NICKEL-MOLYBDENUM CATALYSTS SUPPORTED ON ALUMINA MODIFIED WITH SULFATE AND PHOSPHATE IONS

A series of nicker-molibdenum catalysts supported on alumina modified with sulfate and phosphate ions was studied. The studies involved text ure evaluation measurements through Na adsorption isotherms. Besides, IR spectroscopic and derivatographic studies were carried out. Results of the studies enable us to conclude that modification of the alumina support with the above ions leads to a significant decrease in its su rface area and pore volume. Modification does not result in a change o f the type of pores of the support, but in the change of their size di mention. The pores present on the surface of the catalyst have the sha pe of ''ink-bottles''. Modification with phosphate ions improves the t hermal stability of the catalyst, whereas sulfate ions present on the surface of the catalyst undergo decomposition upon heating of the samp le. Phosphate ions inhibit formation of aluminum molybdate, and instea d form polymeric layer structures of phosphate on the surface of catal ysts. Sulfate ions occur in the form of surface aluminum sulfate.