Multiscale kinetic model of ethylene oligomerization in Ni-NU-1000 metal-organic framework

Abstract Single-atom catalysts (SACs) provide isolated, well-defined metal sites that are suited for mechanistic modeling in porous materials such as metal-organic frameworks (MOFs). However, the influence of framework topology and mass transport on catalytic outcomes remains poorly understood. Here we develop a multiscale kinetic model for ethylene oligomerization in Ni-grafted NU-1000 that combines density functional theory (DFT)-derived free-energy barriers with adsorption and diffusion descriptors. The framework predicts product distributions under realistic reaction conditions. The simulations show that flow -mode operation favors selective C 4 H 8 formation across a temperature range. This selectivity window progressively narrows with increasing effective diffusion length and catalytic-site density, as longer residence times enhance chain growth beyond dimerization. In contrast, batch -mode operation shifts the product distribution toward heavier olefins. These trends provide practical guidance for tuning operating conditions and material properties to achieve desired selective Ni-MOF catalysts.