The kinetics of decalin ring opening over a Ir/H-Beta catalyst

The selective ring opening of decalin over Pd/H-Y-30, Ir/H-Beta-300 and Ir/H-Beta-25 catalysts, measured in a stirred, batch reactor at 350 °C and 3 MPa H2, showed that Ir/H-Beta-25 (SiO2/Al2O3 = 25) had the highest activity and yield of ring-opened products. The effect of temperature (275–350 °C) and pressure (3–6 MPa) on the activity and product selectivity was further investigated over the Ir/H-Beta-25 catalyst. The highest ring-opened product yield (53 mol%) was obtained at a decalin conversion of 90 mol% at 325 °C and 6 MPa H2. A Langmuir–Hinshelwood kinetic model, that assumed a bifunctional catalytic process in which hydrogenation and dehydrogenation reactions occurred on metal sites and isomerization, ring-opening and cracking occurred on acid sites, was successfully applied to the data. The model included the effect of catalyst deactivation associated with the catalyst acid sites. Activation energies estimated from the model parameters showed that the ring opening of isomers had the lowest activation energy (141 kJ/mol), whereas cracking had the highest (159 kJ/mol).

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► Ring opening of decalin over Pd/H-Y-30, Ir/H-Beta-300 and Ir/H-Beta-25 is reported.
► Ir/H-Beta-25 (SiO2/Al2O3 = 25) had the highest activity and ring opening yield.
► Kinetic data described by Langmuir–Hinshelwood model with catalyst deactivation.
► Decalin isomerization and isomer ring opening had the lowest activation energies.