Jian-Lei Qi,Dan Zhou,Qin-Qin Xu,Jian-Zhong Yin,Kun-Peng Yu,Hai-Xin Sun
In recent years, single-atom catalysts (SAC) have emerged as a new frontier in the field of heterogeneous catalysis owing to their unique properties and minimized metal dosage. Herein, the Pd-ZIF-8 single-atom catalyst was successfully fabricated using ZIF-8 as support, and Pd(hfac) 2 as the precursor using the supercritical CO 2 deposition method. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) images confirmed the formation of uniformly dispersed Pd atoms. Supercritical CO 2 has the advantage of zero-surface tension and high diffusibility, it can carry the molecules of Pd precursor into the micropores of ZIF-8. The dissolution and diffusion of precursor were observed by a visual view cell and the mechanism of the preparation was analyzed. Finally, semi-hydrogenation of phenylacetylene to styrene was performed to evaluate the catalytic activity of the prepared Pd-ZIF-8 catalyst. The conversion rate of 80.7% and selectivity of 92.2% were obtained at 70 °C and 4 h in the semi-hydrogenation of phenylacetylene.
Graphical Vapor trail : Metal silicide (Pd 2 Si, Ni 2 Si, CoSi, Fe x Si, and Cu 6.69 Si) catalysts supported by SBA-15 are prepared by chemical vapor deposition. Of the SBA-15-supported metal silicide catalysts, Ni 2 Si/SBA-15 presents a modest activity, notable selectivity to styrene (>90 %), and high stability in the selective hydrogenation of phenylacetylene. Metal silicide (Pd 2 Si, Ni 2 Si, CoSi, Fe x Si, and Cu 6.69 Si) catalysts supported by SBA-15 have been prepared by a chemical vapor deposition method under a H 2 atmosphere using (CH 3 ) 2 SiCl 2 as the Si source. Of the SBA-15-supported metal silicide catalysts, Ni 2 Si/SBA-15 presented a modest activity, notable selectivity to styrene (>90 %), and high stability with respect to the selective hydrogenation of phenylacetylene, which is attributed to the active-site isolation and electron transfer in the silicide. Furthermore, Ni 2 Si/SBA-15 also has a high selectivity to diphenylacetylene and 1,4-butynediol, which demonstrates that Ni 2 Si/SBA-15 is a promising, low-cost catalyst alternative to noble-metal catalysts as a selective hydrogenation catalyst.
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