Zhe Wang,Yuzhuo Chen,Shanjun Mao,Kejun Wu,Kaichao Zhang,Qichuan Li,Yong Wang
Propane dehydrogenation (PDH) catalyzed by PtSn/Al 2 O 3 is a vital industrial process for producing propylene, a significant building block in the chemical industry. However, coke produced in the process deactivates the catalyst and the energy-intensive regeneration procedures can produce considerable CO 2 emission. In this work, coke on the spent catalysts is analyzed by thermogravimetric-mass spectra, Raman spectra, 1 H solid NMR spectra, and infrared spectra. Several C 3 species, including propyl, propylidene and propylidyne are found on the surface of the PtSn alloy. Several reaction pathways are investigated by density functional theory (DFT) calculations. It is also found that this coke can be hydrogenated to propylene in the PDH process. These results could provide theoretical guidance for optimizing process parameters in industry.
Regulating catalyst component is necessary to improve the catalytic efficiency of selective hydrogenation for 5-hydroxymethylfurfural (HMF). Here, we precisely construct PtSn bimetallic alloy catalysts with different Pt/Sn atomic ratios by a deposition–precipitation strategy. Importantly, a volcano-type relationship between the PtSn alloy component and catalytic activity is disclosed during the selective hydrogenation of HMF. Remarkably, the Pt3Sn1 alloy catalyst exhibits the highest catalytic activity compared to that of other samples, which could achieve 99.1% HMF conversion and 98.1% 2,5-bis (hydroxymethyl) furan selectivity. Moreover, the turnover frequency of Pt3Sn1 catalyst is 1952 h–1, which is about 6 times as high as that of pure Pt catalyst. Further studies reveal that the introduction of Sn could change the electronic structure of Pt atoms. Different Pt/Sn atomic ratios result in different extents of charge transfer from Sn to Pt. The Pt sites in Pt3Sn1 show moderate changes in electronic structure, which enhance the adsorption of the reactants and thus boost the intrinsic catalytic activity. This work provides a novel insight to optimize the component of catalysts in various reactions.
Tao Xiao,Peijian Yan,Kaijie Li,Caoping Yang,Hongbo Yu,Junyou Wang,Hongfeng Yin,Shenghu Zhou
Hollow mesoporous nanoreactors with encaged functional nanoparticles are promising heterogeneous catalysts due to the advantages related to their hollow cavities. In this study, we employ metal ion-bound polymer micelles to synthesize PtSn alloy nanoparticle-encaged hollow mesoporous nanoreactors (PtSn@HMSNs), which contain ∼4 nm PtSn alloy NPs located in ∼13 nm hollow cavities and relatively large (∼9 nm) mesoporous channels in silica shells. Relative to monometallic Pt@HMSNs and supported Pt1Sn0.3/SiO2, Pt1Sn0.3@HMSNs exhibit greatly enhanced activity and selectivity for hydrogenation of furfural to furfuryl alcohol. At 1.0 MPa H2, 100 °C, and a furfural/Pt molar ratio of 1884:1, 97.5% of furfuryl alcohol yield was achieved in 5.0 h. The dramatically promoted catalytic performance of Pt1Sn0.3@HMSNs can be assigned to the confinement effect that the location of active NPs inside hollow cavities increases the collision rates between reactants and active NPs to promote catalytic activity, as well as the synergistic effect between Pt and Sn.
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