Influência de métodos de síntese na regeneração de catalisadores de Ni/Al2O3 na reforma a seco de metano

Abstract

Hydrogen production via dry methane reforming (DRM) represents a promising advance in the energy transition, offering a route to reducing greenhouse gas emissions through the use of methane and CO2. Although challenging due to the need for high temperatures and coking risks, process efficiency is significantly improved by alumina-supported nickel catalysts (Ni/Al2O3), due to their high activity and economy compared to other catalysts. Alumina directly influences the activity of nickel due to its intrinsic properties. This study focuses on the influence of different alumina synthesis methods on the properties and efficiency of these catalysts in RSM, in addition to examining regeneration after deactivation by coking. Four synthesis methods were explored: sol-gel (SG), Pechini (PC), hydrothermal (HT) and microwave combustion (CM), followed by impregnation via incipient humidity with nickel at 10% by mass. Using characterization techniques such as DRX, FTIR and TG, three catalysts (CSG, CHT and CCM) were selected for RSM tests at 700ºC, at a space velocity (GHSV) equal to 96 L/g.h, for 4 hours, with a subsequent step of regeneration using synthetic air. The CCM catalyst demonstrated superior activity, efficient regeneration and lower deactivation rate, while the CHT showed significant deactivation, and the CSG intermediate performance. Variations in performance are attributed to the properties of alumina, influenced by synthesis methods, such as nickel distribution, surface area, crystallinity and accessibility of active sites. To improve RSM and extend the useful life of catalysts, it is recommended to continue investigating synthesis variables and explore regeneration strategies that maximize coke removal and recovery of catalytic activity. These guidelines are essential for advances in the area of catalysis and the development of more efficient and economically viable hydrogen production processes.