Repurposing fluid catalytic cracking catalysts for methanol conversion: route selection and deactivation of fingerprints

Abstract

The rapid global shift toward low-carbon technologies necessitates the development of cost-effective and sustainable catalytic systems to support the emerging methanol economy. At the same time, large volumes of spent refinery catalysts (aka fluid catalytic cracking (FCC) catalysts) are routinely discarded, posing both environmental and economic challenges. We benchmark fresh and equilibrium FCC catalysts in methanol-to-hydrocarbons (MTH) reactions and demonstrate that industrial aging alters textural properties, acid-site distribution, and methanol-activation pathways. Integrated advanced characterization, including operando measurements and solid-state NMR studies, links regeneration-induced structural degradation to altered catalytic behavior and mechanism. Both catalysts show high initial methanol conversion, but the spent FCC catalyst (Ecat) deactivates quickly and produces more methane due to leftover metals and lower acidity. The fresh FCC catalyst is (expectedly) more stable, makes relatively more light olefins and paraffins, and forms less coke. Mechanistic studies show that the fresh catalyst forms more useful reaction intermediates, while Ecat traps heavier, less reactive species, leading to faster deactivation. This study shows how industrial aging reshapes catalytic routes and deactivation, enabling the reuse or retuning of spent (equilibrium) catalysts for low-carbon MTH and guiding the design of efficient, waste-derived catalysts for a circular C1 economy.