METHOD FOR DISPERSION OR REDISPERSION OF GROUP VIII ELEMENT ON INORGANIC POROUS CARRIER

摘要

PURPOSE: To disperse average crystallite sizes to about 1/10 and to facilitate dispersion by depositing group VIII noble metal species of an average crystallite diameter of >=25Åon a porous inorg. support, then bringing the support into contact with nitrogen oxide and dispersing the noble metal species. CONSTITUTION: The group VIII noble metal species having the average crystallite diameter of at least 25 or are deposited on the porous inorg. support and if a carbonaceous material exists on the support, at least the major parts of the carbonaceous material are previously removed and thereafter, the noble metal species are brought into contact with the nitrogen oxide. The nitrogen oxide is then removed from the deposited noble metals subjected to dispersion/ redispersion. The oxides and sulfides of palladium, iridium, osmium, rhodium and ruthenium are used as the noble metal species. One or more kinds of the basic metals selected from the group IB, IVB, VIIA and VIIII of the element periodic table may be additively deposited on the support, in addition to the noble metal species.