Hydrocracking of <i>n</i>‐heptane. Study of NiO—MoO₃ catalysts supported on a HY ultrastable zeolite

The hydrocracking of n ‐heptane in the temperature range of 573 to 623 K and at 2.45 × 10 6 Pa pressure has been employed as a test reaction for the study of Ni—Mo bifunctional catalysts supported on a HY ultrastable zeolite. Two groups of catalysts containing 8 and 12 wt% of MoO 3 and different amounts of NiO have been studied. In both series a maximum in the activity has been obtained for catalysts with a Ni/Mo atomic ratio of 0.8‐1.0. The order of the impregnation of the oxides can have little influence on the activity. The most active catalyst has been obtained when the zeolite is exchanged with NH + 4 ions until the Na + level is less than 2% of the original and calcined at 823 K to obtain a HY ultrastable zeolite. Using this catalyst the rate controlling step could be the transformation of the carbonium ion on the acid sites.