Enhanced stability and coke resistance in methanol to olefins reaction using fibrous silica-wrapped silicoaluminophosphate zeolite

The conversion of biomethanol into olefins is a sustainable alternative to fossil fuels, yet this reaction is limited by the deactivation of the silicoaluminophosphate zeolite catalysts due to its microporosity, which promotes coke deposition. Here we synthesized a fibrous silica-wrapped silicoaluminophosphate catalyst by microemulsion and seed-assisted hydrothermal method. This catalyst was characterized by X-ray diffractometer, Fourier transform infrared spectroscopy, nitrogen physisorption, field emission scanning electron microscopy, transmission electron microscopy, and ammonia temperature-programmed desorption. The catalytic performance was evaluated from 300 to 500 °C, followed by a stability test conducted at 500 °C for 30 h. Coke deposition on spent catalysts was analyzed using thermal gravimetric analysis, oxygen temperature-programmed oxidation, ultraviolet–visible, and Raman spectroscopy. Results show a 54% extension of the catalyst lifetime, and a 31.4%w reduction in coke formation. These findings are explained by the fibrous silica wrapping that creates a surplus mesoporosity beyond conventional hierarchical structure, enabling improved accessibility, reduced diffusion resistance, and suppressed coke formation.