Jin Yuan,Jinxing Mi,Weitao Zhao,Ke Zheng,Shaoqi Zhou,Jianjun Chen
Although ceria-based catalysts have been proven to be a promising alternative to conventional vanadyl catalysts for the selective catalytic reduction of NOx with NH3 (NH3–SCR), whether the interaction between tungsten (W) and CeO2 could be well established for enhancing SCR performance is still unclear. Herein, W/CeO2 catalysts with different CeO2 morphologies for SCR are fully investigated. Systematic characterization results confirmed that the crystalline WO3 phase was formed on W-loaded CeO2 nanocubes, nanospindles, and nanospheres. Intriguingly, the W/CeO2 nanorods exhibited exclusively polymeric tungstate species. This divergence originates from the distinct W-CeO2 interaction mediated by preferentially exposed {110} lattice planes, endowing the nanorod catalyst with stronger reducibility, more surface-active oxygen species, and acid sites. Consequently, the NH3–SCR activity followed the order W/CeO2 nanorods > W/CeO2 nanospindles > W/CeO2 nanocubes > W/CeO2 nanospheres. This work reveals the significant role of the CeO2 morphology in the dispersion and interaction of W species, which directly influences the NH3–SCR performance. The insight offers a valuable opportunity for the design of a more efficient SCR catalyst.
Cassava residue was proposed as a raw material for the production of ethylene glycol (EG) via a one-pot hydrothermal reaction in the present study. Various mixed catalysts consisting of activated carbon supported Ru (Ru/AC) and a tungsten species were used for the conversion of cassava residues, and the effects of various reaction conditions on the catalytic performance were investigated. When the reaction was carried out at 245 °C for 60 min, the Ru/AC–H 2 WO 4 mixed catalyst showed a EG yield of 53.1 % with a total polyols yield of 80 %, which was confirmed to be the most active among the prepared catalysts. The excellent catalytic performance using cassava residue as the feedstock mainly resulted from a high content of carbohydrates and a low amount of lignin in cassava residues. Furthermore, the Ru/AC–H 2 WO 4 catalyst also showed reasonable stability during the hydrothermal conversion of cassava residues for EG production.
The photocatalytic conversion of methane into valuable liquid oxygenates presents a promising strategy for advancing a sustainable chemical industry. However, achieving both high conversion efficiency and high selectivity using non-precious metal catalysts under ambient conditions remains a significant challenge. Inspired by the functional characteristics of natural enzymatic catalytic systems, this study has constructed a multicomponent synergistic catalytic system with ZnMn₂O₄ as the support. Through the defective engineering design of fluorine doping and in situ growth of tungsten species, it achieves efficient construction of the microenvironment of active centers and precise regulation of free radical intermediates. The optimized 3W20F-ZnMn₂O₄ catalyst achieved a liquid-phase product yield (including methanol and ethanol, etc.) of 442.02 μmol·g⁻¹ ·h⁻¹ with a selectivity of 98.6 % under ambient temperature and pressure—surpassing the performance of most reported non-precious metal-based catalytic systems. Studies have demonstrated that catalysts doped with the two elements exhibit significant differences in the oxygen sources of products, which reflects the distinct pathways they follow in catalyzing methane oxidation. Specifically, the oxygen vacancy (FVo) sites formed by F doping primarily adhere to a single reaction pathway using water as the oxygen source, where the active oxygen species are mainly dominated by ·OH generated from the dissociation of water molecules, ultimately yielding ethanol and small amount of methanol. In contrast, the active sites formed by W doping involve multiple reaction pathways. The production of ethanol relies more on ·OH from water molecule dissociation, while the generation of methanol and methyl hydroperoxide is more dependent on active oxygen species derived from oxygen activation. This study deepens the understanding of the multi-element synergistic catalytic mechanism and lays a foundation for the development of sustainable and efficient catalytic systems.
Novel heterogeneous tungsten species in mesoporous silica SBA-16 catalysts based on ship-in-a-bottle methodology are originally reported for oxidizing cyclopentene (CPE) to glutaric acid (GAC) using hydrogen peroxide (H 2 O 2 ). For all W-SBA-16 catalysts, isolated tungsten species and octahedrally coordinated tungsten oxide species are observed while WO 3 crystallites are detected for the W-SBA-16 catalysts with Si/ W = 5, 10, and 20. The specific surface areas and the corresponding total pore volumes decrease significantly as increasing amounts of tungsten incorporated into the pores of SBA-16. Using tungsten-substituted mesoporous SBA-16 heterogeneous catalysts, high yield of GAC (55%) is achieved with low tungsten loading (for Si/W = 30, ~13 wt%) for oxidation of CPE. The W-SBA-16 catalysts with Si/W = 30 can be reused five times without dramatic deactivation. In fact, low catalytic activity provided by bulk WO 3 implies that the highly distributed tungsten species in SBA-16 and the steric confinement effect of SBA-16 are key elements for the outstanding catalytic performance.
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