Hydroconversion of n-heptane on platinum/H-Mordenite catalysts prepared via different routes

Two Pt/H-mordenite catalysts were prepared via different routes: (a) by impregnating H₂PtCl₆ in H-mordenite (HM) (catalyst 1) and (b) in NH₄HM (catalyst II), followed by drying, calcination and reduction. Catalyst I was found (i) to be more active for n-heptane hydroconversion, (ii) to be more selective for its isomerisation, (iii) to encounter more diffusion limitation as it yields a larger Thiele modulus, (iv) to give a lower effectiveness factor and (v) to give lower activation energy, E_a, values than catalyst II. A study of the pressure effect between 1·5 and 5·5 MNm^?2 showed an increase of the catalytic activities to a maximum at 3·0 MNm^?2, followed by a decrease. A compensation effect plot gave a linear relationship between In A (pre-exponential factor in the Arrhenius equation) and E_a at various pressures for n-heptane hydroconversion and its hydrocracking. High selectivities for central hydrocracking of heptane components and high iso-butane to n-butane ratios were obtained on both catalysts.