Role of Interfacial Silica in the Local Structure, Strain, and Propane Dehydrogenation Activity of Dispersed Ga3+ Sites
Year: 2026
Type: preprint
Abstract: Understanding the structure of the active sites in supported Ga-based propane dehydrogenation (PDH) catalysts is essential, as the Ga–O coordination environment and the nature of neighboring atoms (e.g., Al or Si from SiO2 or Al2O3 supports) strongly influence the catalytic properties. Here, we prepared Ga3+ sites dispersed on Al2O3 and SiOx-Al2O3 supports using atomic layer deposition, tailoring the thickness of the grown SiOx layer and the acidity at the Ga-SiOx-Al2O3 interface. Comparing the propene selectivity and Ga-normalized propene formation rates of the prepared materials reveals that, for the Al2O3 and SiOx-Al2O3 supports, catalytic activity decreases as Si content increases, which correlates with a decrease in the relative abundance of weakly Lewis acidic tetracoordinate Ga3+ sites in the local coordination environment with Al3+ atoms ([4]Ga(Al) and [4]Ga(Al/Si) sites), driving the PDH activity of those catalysts. In comparison, a reference catalyst with Ga3+ sites dispersed on SiO2 is more active and features the highest abundance of strongly Lewis acidic tetracoordinate Ga3+ sites in the local coordination environment of Si4+ atoms ([4]Ga(Si) sites), which drive its PDH activity. Solid-state 71Ga nuclear magnetic resonance studies at ultra-high field (28.2 T) highlight that the distorted coordination geometry of [4]Ga(Si) sites is characteristic of the silica support, and notably less frequent for dispersed [4]Ga(Al) and [4]Ga(Al/Si) sites on alumina and SiOx-Al2O3.
Source: ChemRxiv
Language: English
Subfield: Catalysis
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214573413