Long-chain normal paraffin (C10-C13) dehydrogenation over the commercial NDC-10 catalyst (Pt-Sn-K-Mg/Al2O3): An intrinsic kinetic study

Abstract

A crucial challenge in reactor design and process optimization for long-chain normal paraffin dehydrogenation is the scarcity of reliable kinetic data. To address this gap, a comprehensive intrinsic kinetic study was performed over the industrial NDC-10 catalyst using two hydrocarbon feeds in a tubular packed-bed reactor. Experiments were conducted at 460–490 °C, 1.1–2.1 barg , hydrogen-to-hydrocarbon molar ratios of 3:1–7:1, and space velocities of 25–45 h⁻¹. The effects of operating conditions were evaluated in terms of conversion, selectivity, and yield. A detailed reaction network encompassing distinct pathways for paraffins, mono-olefins, di-olefins, and aromatics (C₁₀-C₁₃) was developed. Based on 78 experiments, kinetic and thermodynamic parameters were estimated via inverse modeling using a plug-flow reactor model and the Nelder–Mead optimization method. The enthalpy change and activation energy for paraffin dehydrogenation reactions were determined as 121.63–124.52 kJ mol⁻¹ and 137.42–144.71 kJ mol⁻¹, respectively, confirming the thermodynamic consistency of the estimated values. Higher-molecular-weight paraffins exhibited lower activation energies and higher conversions, accompanied by reduced mono-olefin selectivity due to enhanced consecutive side reactions at elevated conversions. The resulting kinetic and thermodynamic parameters enable reliable modeling, design, and optimization of radial-flow packed-bed reactors used in the paraffin dehydrogenation process.