To investigate the mechanism of the role of active center size on the selectivity of methyl mercaptan (CH 3 SH) and methane (CH 4 ) in the deep hydrogenation reaction of carbon disulfide (CS 2 ), it was first derived from DFT calculations that the Pt cluster geometries showed a decreasing and increasing pattern on the energy barriers of the two key hydrogenation steps: (I) HCSS* to HCSSH* and (II) deep hydrogenation of CH 2 S* to CH 3 SH. For further validation, we synthesized Pt NPs with varied average sizes (1.7–4.0 nm) using a reduction-agglomeration strategy to probe the source of size sensitivity at low Pt loading. It was found that the active centers of Pt NPs located in the 2.0–3.0 nm region have the highest proportion of medium-coordinated Pt sites, which can effectively promote hydrogen spillover and enhance the HCSS* pathway. Finally, with this modulation strategy, the catalytic activity and selectivity were significantly improved at 1 wt% Pt loading, which exceeded that of the fresh 4 wt% Pt/Al 2 O 3 catalyst, and the long-term stable production of CH 3 SH (selectivity was maintained at 80 %) was achieved at 250 ℃ in the high-concentration CS 2 environment.
Deep hydrogenation of dicyclopentadiene resin (DCPD resin) plays an important role in enhancing its performance and broadening its applications. However, designing suitable catalysts for promoting DCPD resin deep hydrogenation remains a challenge due to the high steric hindrance and abundant unsaturated bonds in DCPD resin, requiring strong binding to C=C double bonds. We herein propose a strategy for simultaneously constructing highly-dispersed Ni particles for hydrogen dissociation and interfacial Ni 0 /Ni(OH) + sites for C=C adsorption by controlled reduction of Ni phyllosilicate (Ni PS). The catalyst, after reduction at 400 °C, demonstrated balanced ratio between Ni 0 and interfacial Ni 0 /Ni(OH) + sites, and achieved a hydrogenation degree of 99.8% (TOF: 68.8 h −1 ) while maintaining 99.3% efficiency after seven consecutive cycles. Through in-situ DRIFTS analysis and density functional theory (DFT) calculations, it is confirmed that the introduction of Ni 0 /Ni(OH) + interfacial sites results in superior activity compared to pure Ni 0 or unreduced PS due to optimized charge transfer and electronic configuration. This work not only establishes a simple and environmentally-friendly approach to design efficient catalysts for polymer hydrogenation, but also provides insights into the mechanism of unsaturated bond hydrogenation through the synergistic effects of Ni 0 and Ni 0 /Ni(OH) + interfacial sites.
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