Applied Catalysis zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA A: General, 107 (1994) 1333145 Elsevier Science B.V., Amsterdam 133 APCAT A2456 Deactivation of industrial hydrotreating catalyst for middle petroleum fractions processing Radmila Marinkovic-NeduEin, Goran Bo6kovic, Erne KiEC and Gizela Lomii: University of Novi Sad, Faculty of Technology, Bul-AVNOJ-a I,21000 Novi Sad (Yugoslavia) Harold Hantsche Bundesanstalt fiir Materialforschung und Prufung, Unten den Eichen 87, D-1000 Berlin 45 (Germany) and Radosav Micii: and Pavle Pavlovii: NIS-Refinery Novi Sad, Put sajk&kog odreda bb, 21000 Novi Sad (Yugoslavia) (Received 21 May 1992, mvised manuscript received 11 December 1992) zyxwvutsrqponmlkjihgfedcbaZY Abstract Representative samples of regenerated hydrotreating NiO-Mo0,/A1,03 catalyst were investigated in order to define the main reasons for activity decline, observed after restarting the industrial reactor. By complex structural and textural characterization, followed by surface chemical analysis, it was shown that pronounced sintering and structural changes take place in a fraction of catalyst bed, particularly in the upper layer. The intermediary presence of MOO, in the liquid phase was assumed to be the cause of the intensive sintering during regeneration, which was followed by loss of active component. Restruc- turing and segregation of the active phase in hot spots, resulting from blocking of a part of the catalyst bed, are supposed to be the main causes for changes taking place later on during regeneration. Key words: deactivation; hydrotreating catalyst; loss of active component; mechanism of deactivation; sintering INTRODUCTION Catalysts for hydrodesulphurization/hydrodenitrogenation (HDS/HDN) of petroleum fractilons are known as robust and highly resistant to classical catalyst poisons, which are normal constituents of the process feed. In pro- cessing of light petroleum fractions the normal catalyst life is several years, with stable activity even at relatively high metal poison level [l-3]. The in- creased interest for heavy fraction and residue processing, characterized by Correspondence to: Dr. R. MarinkoviE-Ned&n, University of Novi Sad, Faculty of Technology, Bul.AVNOJ-a I,21000 Novi Sad, Yugoslavia. Fax. (+381-21)611102. 0926-860X/94/$07.00 @ 1994 Elsevier Science B.V. All rights reserved. SSDZO926-86OX(93)1~0165-7