Bio-derived fuels have garnered significant interest within the energy sector as the aviation industry aims to halve carbon emissions by 2050. Upgrading ethanol from corn stover to n-butene rich olefins, a precursor for jet fuel, offers a promising bio-renewable alternative to conventional aviation fuel. Recent innovations have demonstrated that ethanol can be directly converted to n-butene in a single step process using metallic Cu particles deposited on a ZrO₂/SBA-16 mixed oxide support. However, this catalyst is prone to deactivation through sintering due to the high amount of steam and H₂ generated during reaction, hindering the commercial viability of this process. Thermally stable single atom catalyst synthesis has been shown to slow down or prevent sintering in similar reactions due to the improved thermal stability of the single atom active sites. We demonstrate that using a sol-gel synthesis to deposit Cu in the form of ionic single atoms on the ZrO₂/SBA-16 mixed oxide support the Cu is more thermally stable than its metallic counterpart. Using TEM and CO oxidation as a probe reaction, we characterize and compare the growth of the Cu species and their activity before and after aging in the presence of steam and H₂. However, TEM has limitations in characterizing the Cu particles due the morphology of the mesoporous SBA-16. To account for this we utilize a spherical non-porous silica support to offer an edge on view of the Cu particle growth during TEM analysis providing clear images of the metallic Cu particle growth. Using this method, we demonstrate that the metallic Cu catalyst shows significant particle growth after aging while the ionic single atom Cu remains highly dispersed and loses no loss of activity for CO oxidation indicating improved thermal stability of the catalyst. Implementing the thermally stable single atom Cu synthesis to control Cu particle growth in the ethanol upgrading reaction can slow deactivation, helping the process reach industry scale furthering the aviation industry’s emission reduction goals.

Andrew DeLaRiva

Appearances