Unraveling the Role of Cu⁰ and Cu⁺ Sites in Cu/SiO₂ Catalysts for Water‐Gas Shift Reaction

Abstract

CuO x /SiO 2 precursor was successfully fabricated by an ammonia evaporation hydrothermal method. Upon reduction in 5 vol % H 2 /N 2 at 250, 300, 350, 400, or 450°C, CuO and copper phyllosilicate species in the precursor bring about the formation of highly dispersed Cu 0 and Cu + species, respectively. The Cu + / Cu 0 ratios were studied by XAES technique, while the particle sizes were estimated on the basis of HRTEM images. It is disclosed that the ratios and particle sizes varied with CuO x /SiO 2 reduction temperatures. The results of in situ DRIFTS and XAES characterization reveal that both Cu 0 and Cu + are active for CO adsorption and water dissociation, especially so with Cu 0 and Cu + particles of small sizes. It was also observed that the adsorption of CO on Cu + is stronger than that on Cu 0 , and Cu 0 is more active than Cu + for water dissociation. Among the prepared Cu/SiO 2 catalysts, the one resulted from precursor reduction at 300°C shows the highest CO conversion in WGS reaction, which is attributed to the small size of Cu 0 (2.45 nm) and the large amount of Cu + .

Dynamic Structural Evolution of CeO2 in CuO−CeO2 Catalyst Revealed by In Situ Spectroscopy

“…In fact, due to the strong interaction with the metal and oxides, it was difficult for the metal to exist in a fully metallic state on the catalytic interface. Therefore, there might be rich Cu + sites at the catalyst surface which could facilitate the adsorption and activation of CO [35–37] . In order to detect the surface states of Cu species in the reaction process, the quasi in situ XPS measurement was measured.…”

“…[34] In fact, due to the strong interaction with the metal and oxides, it was difficult for the metal to exist in a fully metallic state on the catalytic interface. Therefore, there might be rich Cu + sites at the catalyst surface which could facilitate the adsorption and activation of CO. [35][36][37] In order to detect the surface states of Cu species in the reaction process, the quasi in situ XPS measurement was measured. After the H 2 pretreatment, the reaction gas flow was injected into the sample room for 1 hour at 300 °C, and then the experiment was conducted by directly vacuuming at 300 °C from the sample preparation chamber.…”

Cu/CuxO@C nanocomposites as efficient electrodes for high-performance supercapacitor devices

“…1c), it can be seen that the Auger peak position of Cu + is near 916.8 eV, the peak of Cu 2+ is about 917.4 eV, and the peak of Cu 0 is around 918.2 eV, which are in good agreement with peer references. 50 Besides, it is notable that the carbon element is still maintained due to the lowtemperature oxidation process. As shown in Table S1, † the result indicates that the carbon content increases with increasing temperature up to 900 °C while the oxygen content decreases in the meantime, which is in good agreement with the EDS results.…”

Copper Phyllosilicates-Derived Catalysts in the Production of Alcohols from Hydrogenation of Carboxylates, Carboxylic Acids, Carbonates, Formyls, and CO2: A Review

“…Burgeoning research of CuPS-cats in the hydrogenation of other carbonyls such as carbonate [105,108,169,203,205], carboxylic acid [111,119,175], and aldehyde [104,106,160,172] have shown their potentials recently. Alternative applications of CuPScats, should be explored such steam reforming of DME [109,114,166], water-gas-shift reaction [206,207], dehydrogenation ethanol [98,202], dry reforming CH4 [136], ethynylation of formaldehyde [117]. Moreover, process design for large scale, continuous processing by using CuPS-cat as the catalyst is needed.…”