Applied Catalysis A: General, 90 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFE (1992) 35-49 Elsevier Science Publishers B.V., Amsterdam 35 APCAT A2344 Influence of vanadium on the physicochemical and catalytic properties of USHY zeolite and FCC catalyst M. Torrealba and M.R. Goldwasser Universidad Central de Venezuela, FacuMad de Ciencias, Escula de Quimica, 47102, Caracas (Venezuela) and G. Perot and M. Guisnet Universitt? de Poitiers, URA CNRS 350, Catalyse en Chimie Organique, 40 Avenue du Recteur Pineau, 86022 Poitiers CXdex (France) (Received zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 15 June 1992, revisedmanuscriptreceived30 July 1992) Abstract The effect of a deposit of 1 wt.-% vanadium on the physicochemical and catalytic properties of a USHY zeolite and of a FCC catalyst has been determined by various techniques: X-ray diffraction, transmissionelectron microscopy, X-ray photoelectron spectroscopyand methylcyclohexane transfor- mation. With USHY and whatever the pretreatment: calcination underdry air flow at 546’ C or hydro- thermal treatmentat 750’ C, vanadium is well dispersedwhile in the FCC catalyst it is in the form of large aggregates (6 to 12 nm). The hydrothermal treatment causes a partial elimination of vanadium from the sample and a decrease of the surface concentration of vanadium. The matrix of the FCC catalystlimits the formationor/and the migrationof the volatilevanadiumspecies.Vanadium decreases the stability of the zeolite (decrease in crystallinityand increase of the deal~ination rate during the hydrothermal treatment) and consequentlythe activity of the zeolite and FCC catalyst samples.How- ever this decreasein activity seems to be due partly to other phenomena,particularlyto the exchange of the protonic sites by cationic vanadium species. Keywords: fluid catalytic cracking, hydrothermaltreatment,model reaction, USHY, vanadium, X-ray photoelectron spectroscopy,zeolites. INTRODUCTION Heavy crudes can contain large quantities of metals such as nickel and va- nadium [l-5]. While nickel has little effect on the activity of FCC catalysts, vanadium can have a detrimental effect as soon as its concentration is greater than 0.5% [5]. In a FCC unit, vanadium is deposited during gasoil cracking in the riser zone. Correspondence to: Prof. M. G&met, Universit4 de Poitiers, URA CNRS 350, Catalyse en Chimie Organique, 40, av. du Recteur Pineau, 36022 Poitiers C&lex, France. Tel. (+33) 49453905, fax. ( + 33 ) 49453499. 0926-3373/92/$05.00 0 1992 Elsevier Science Publishers B.V. All rights reserved.