Applied Catalysis, 70 (1991) 197-212 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH Elsevier Science Publishers B.V., Amsterdam 197 Hydrocracking and isomerization of n-octane and 2,2,4_trimethylpentane over a platinum/alumina-pillared clay Christian Doblin and Joseph F. Mathews Department of Chemical Engineering, Monash University, Clayton, Vie. 3136 (Australia) and Terence W. Turney* CSIRO Diuision zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Materials Science and Technology, Locked Bag 33, Clayton, Vie. 3168 (Australia), fax. (+ 61-3) 544 1128 (Received 13 June 1990, revised manuscript received 1 November 1990) zyxwvutsrqponmlkjihgfedcba Abstract The hydrocracking and isomerization of n-octane and 2,2,4_trimethylpentane over an alumina-pil- lared clay, containing 0.16% Pt was investigated in a microreactor operating at atmospheric pressure with varying temperature (175-325°C ) weight hourly space velocity and (0.48-7.5 hh’). The structure of the catalyst changed during the first 30 h of use before becoming stable, as shown by X-ray diffraction. Hydrocracking of n-octane produced significant but diminishing quantities of methane and ethane dur- ing the first 30 h on stream. During this time the dominant classical bifunctional reaction mechanism was accompanied by a second reaction mechanism, possibly hydrogenolysis or cleavage by a non-clas- sical pentacoordinated carbonium ion. After the initial period, the catalyst performed as an ideal hydro- cracking catalyst, as characterized by high isomerization yields up to medium conversions, and showed product distributions very similar to those found in platinum loaded large pore zeolites. Keywords: Hydrocracking, pillared clay, platmum, bifunctional catalyst, octane isomerization. INTRODUCTION Ion-exchange of interlayer alkali metal ions in swelling clays, with large po- lyhydroxycations of various metals, such as aluminium [1,2], zirconium [3] and chromium [ 41, affords a class of materials commonly called pillared clays (PILCs). PILCs are microporous solids with high surface areas (200 to 500 m’/g) and behave as acid catalysts for a range of organic reactions, including cracking of hydrocarbons [ 51. Previous studies [S] have shown that, although PILCs give comparable or even higher yields of gasoline for Light Cycle Gas Oil cracking than zeolites, they generate two to three times more coke and lack thermal and hydrothermal stability to withstand continued high temperatures and the rigors of repeated regeneration. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 0166-9834/91/$03.50 0 1991 Elsevier Science Publishers B.V.