Improving the Efficiency of Hydrogen Spillover by an Organic Molecular Decoration Strategy for Enhanced Catalytic Hydrogenation Performance

Abstract

Hydrogen migration from metal particles to the support, known as hydrogen spillover, has provided insights for designing highly efficient catalysts in catalytic processes involving hydrogen. A facile and controllable strategy is highly desired to achieve an effective hydrogen spillover effect on nonreducible oxides for catalytic performance optimization and clarifying the catalytic function of hydrogen spillover. Here, we provide an organic molecular decoration (OMD) strategy obtained by the molecular layer deposition-like pulse method for facilitating hydrogen spillover over the nonreducible silica support. After decorating with the fluoroalkylsilane (FAS) molecular layer, the hydrogen spillover effect over the catalysts (xFAS-Pt/SBA-15) is greatly enhanced due to the presence of carbonaceous species compared with the original Pt/SBA-15. The amount of hydrogen spillover can also be precisely regulated by controlling the FAS pulse number. For cinnamaldehyde hydrogenation, xFAS-Pt/SBA-15 presents superior catalytic performance versus its untreated counterpart and the sample decorated via the traditional method. Also, the catalytic activity varies based on the FAS pulse number, showing a linear correlation with the amount of hydrogen spillover. The altered adsorption behavior of the reactant plays an important role in the hydrogenation selectivity. This facile OMD strategy for efficient hydrogen spillover is general and may have potential applications in many heterogeneous reactions.

Key Role of Metal Oxide Support in Tuning Active Surface Components of Fe-Based Catalysts for CO2 Hydrogenation

“…Consequently, the increased desorption of H 2 on spent Fe/ZrO 2 and Fe/Al 2 O 3 at higher temperatures suggests that oxygen vacancies may enhance the hydrogen spillover capacity, thereby facilitating the migration of surface H species and thus CO 2 hydrogenation. , For spent Fe/CeO 2 , however, the above two peaks are weakened and shift toward higher temperatures, which is unfavorable for the dissociation of hydrogen molecule and subsequent transfer of active hydrogen species, likely due to the absence or inadequacy of the surface FeO x component, as supported by the XPS and subsequent 57 Fe Mössbauer results. Therefore, the appropriately strong adsorption of CO 2 and enhanced hydrogen spillover through the formation of more surface FeO x component with oxygen defects on spent Fe/ZrO 2 and Fe/Al 2 O 3 catalysts, as confirmed by the above CO 2 -TPD and H 2 -TPD results, are conductive to CO 2 hydrogenation. − …”

Mechanism of Hydrogen Spillover on Metal-Doped Carbon Materials: Surface Carboxylic Groups Are Key

“…These results emphasize the importance of rational surface modification of carbon materials to regulate the H-spillover. Precise syntheses should be developed to go in that direction, to be able to regulate H-spillover strength for enhanced catalytic performance. , This study also shows how surface chemistry affects and is affected by H-spillover. Consideration of these different elements should allow significant advances in the field of catalytic reactions involving hydrogen and, in a broader context, in the hydrogen-based economy.…”

Operando Mobile Catalysis for Reverse Water Gas Shift Reaction

“…To illustrate the critical role of hydrogen spillover, MeCpPt/SiO 2 was prepared by bonding MeCpPt‐ species on SiO 2 , and the performance of both MeCpPt/SiO 2 and a physical mixture of MeCpPt/SiO 2 +CeO 2 was tested. First, we employed a color‐changing reaction to confirm the existence of H spillover [17] . The hydrogen spillover from the catalyst will induce color change from WO 3 reduction.…”

“…First, we employed a color-changing reaction to confirm the existence of H spillover. [17] The hydrogen spillover from the catalyst will induce color change from WO 3 reduction. As shown in Figure S24, after treatment with H 2 /Ar at 25 °C, both the MeCpPt/SiO 2 + WO 3 mixture and the MeCpPt/ SiO 2 + CeO 2 + WO 3 mixture changed from yellow to blue, providing evidence for H spillover on both Pt/SiO 2 and Pt/ SiO 2 + CeO 2 mixture.…”