NiMo catalysts supported on zeolite type Y modified with various anions wer
e investigated. The structural properties and catalytic HDS activity of obt
ained samples were measured. It has been shown that change in zeolite cryst
al structure as a result of impregnation with anions was small. However, du
e to these anions considerably higher HDS activity of NiMo/NaY catalysts co
mpared to samples without anions was observed. NiMo catalysts containing fl
uoride anions exhibited the highest activity. An explanation of the influen
ce of anions on the HDS activity is also presented. (C) 2001 Elsevier Scien
ce B.V. All rights reserved.