Regulating the Spatial Distribution of Ru Nanoparticles on CeO₂ Support for Enhanced Propane Oxidation

Abstract

Developing efficient catalysts for the total oxidation of propane at low temperatures is challenging; however, it is crucial for the purification of automotive exhaust and volatile organic compounds emitted in industrial processes. We report a highly stable and active Ru-based catalyst for propane oxidation by tuning Ru loading to achieve the balance between RuO x species in the CeO2 bulk and on the surface via a facile coprecipitation approach (Ru–CeO2). Compared to the Ru catalyst prepared through wet impregnation on a CeO2 support (Ru/CeO2), the prepared Ru–CeO2 catalyst allows for the formation of RuO x species with smaller particle sizes and lower oxidation states, as well as an increased number of oxygen vacancies on the catalyst surface, leading to a greater ability to adsorb and activate propane and oxygen. As a result, the Ru–CeO2 catalyst presents a substantially improved activity and durability toward propane oxidation, which can maintain 90% propane conversion at 220 °C for 50 h. This work highlights the synthetic tuning of the spatial distribution of Ru active sites within catalysts through a coprecipitation strategy for improved catalytic alkane oxidation, and the prepared Ru–CeO2 catalyst is a promising candidate material for industrial applications.

Highly Efficient Oxidation of Propane at Low Temperature over a Pt-Based Catalyst by Optimization Support

“…To clarify the mechanism of propane oxidation on the Pt/CeO 2 , Pt/ZrO 2 , Pt/Nb 2 O 5 and Pt/SnO 2 catalysts, in situ DRIFT experiments of propane adsorption, reaction, and desorption on the Pt/MO x catalysts and corresponding supports were conducted at 220 °C. As shown in Figure S19, strong bands assigned to carboxylate (1457, 1525 cm –1 ) and carbonate species (1546, 1426 cm –1 ) were observed in the spectra of C 3 H 8 adsorption and reaction on CeO 2 support, revealing that propane was activated and oxidized by reactive oxygen species on the CeO 2 surface at 220 °C, consistent with our previous works. ,, However, Nb 2 O 5 , ZrO 2 , and SnO 2 hardly have the ability to activate C 3 H 8 at 220 °C.…”

“…As shown in Figure S19, strong bands assigned to carboxylate (1457, 1525 cm −1 ) and carbonate species (1546, 1426 cm −1 ) were observed in the spectra of C 3 H 8 adsorption and reaction on CeO 2 support, revealing that propane was activated and oxidized by reactive oxygen species on the CeO 2 surface at 220 °C, consistent with our previous works. 7,9,11 However, Nb 2 O 5 , ZrO 2 , and SnO 2 hardly have the ability to activate C 3 H 8 at 220 °C.…”

“…Supported noble metal catalysts, especially Pt, are deemed particularly enticing catalysts in oxidizing propane, the most typical light alkane widely produced in petroleum processing, the coal industry, and automobile exhaust. − In most cases, the support for supported noble metal catalysts generally plays a decisive role in determining catalytic activity. The support can affect the dispersity and valence state of active noble metals due to the interaction between them and can participate directly in the oxidation reaction by providing oxygen species. , Additionally, the acid sites on the support can prompt C–H bond scission as the rate-limiting step due to the synergistic action of dipolar catalytic sites. − Despite the immense effort that has been dedicated to the development of the catalysts with efficient propane oxidation, optimizing the activity, water resistance, and practical suitability for operating conditions simultaneously is still a tough task due to the mutual exclusivity of these qualities.…”

“…Supported noble metal catalysts, especially Pt, are deemed particularly enticing catalysts in oxidizing propane, the most typical light alkane widely produced in petroleum processing, the coal industry, and automobile exhaust. − In most cases, the support for supported noble metal catalysts generally plays a decisive role in determining catalytic activity. The support can affect the dispersity and valence state of active noble metals due to the interaction between them and can participate directly in the oxidation reaction by providing oxygen species. , Additionally, the acid sites on the support can prompt C–H bond scission as the rate-limiting step due to the synergistic action of dipolar catalytic sites. − Despite the immense effort that has been dedicated to the development of the catalysts with efficient propane oxidation, optimizing the activity, water resistance, and practical suitability for operating conditions simultaneously is still a tough task due to the mutual exclusivity of these qualities. For example, the introduction of acid sites generally causes significant deactivation of the catalyst in the wet reactant gas, owing to the strengthened adsorption and coverage of H 2 O on active sites. , On the other hand, the superior redox properties of supports such as CeO 2 and SnO 2 lead to Pt in a highly oxidized state, resulting in decreased propane oxidation activity of the Pt-based catalyst, as the metallic Pt or the synergism of Pt 0 /Pt δ+ sites are more active. ,− Therefore, there are still several limitations associated with supported Pt catalysts with respect to the oxidation of propane under varied conditions, and a key aspect of developmental adaptations is efficiently constructing stable and highly active Pt species (such as metallic Pt).…”

“…The support can affect the dispersity and valence state of active noble metals due to the interaction between them and can participate directly in the oxidation reaction by providing oxygen species. 7,9 Additionally, the acid sites on the support can prompt C−H bond scission as the rate-limiting step due to the synergistic action of dipolar catalytic sites. 10−13 Despite the immense effort that has been dedicated to the development of the catalysts with efficient propane oxidation, optimizing the activity, water resistance, and practical suitability for operating conditions simultaneously is still a tough task due to the mutual exclusivity of these qualities.…”