Isolating contiguous Pt atoms and forming Pt-Zn intermetallic nanoparticles to regulate selectivity in 4-nitrophenylacetylene hydrogenation

Abstract

Noble metals play a momentous role in heterogeneous catalysis but still face a huge challenge in selectivity control. Herein, we report isolating contiguous Pt atoms and forming Pt-Zn intermetallic nanoparticles as an effective strategy to optimize the selectivity of Pt catalysts. Contiguous Pt atoms are isolated into single atoms and Pt-Zn intermetallic nanoparticles are formed which are supported on hollow nitrogen-doped carbon nanotubes (PtZn/HNCNT), as confirmed by aberration-corrected high-resolution transmission electron microscopy and X-ray absorption spectrometry measurements. Interestingly, this PtZn/HNCNT catalyst promotes the hydrogenation of 4-nitrophenylacetylene to 4-aminophenylacetylene with a much higher conversion ( > 99%) and selectivity (99%) than the comparison samples with Pt isolated-single-atomic-sites (Pt/HNCNT) and Pt nanoparticles (Pt/CN). Further density functional theory (DFT) calculations disclose that the positive Zn atoms assist the adsorption of nitro group and Pt-Zn intermetallic nanoparticles facilitate the hydrogenation on nitro group kinetically.

Supported Pt Nanoparticles on Mesoporous Titania for Selective Hydrogenation of Phenylacetylene

“…Phenylacetylene was selectively converted to styrene in a wide phenylacetylene conversion window (20–75%), only when phenylacetylene reached full conversion, styrene selectivity slightly dropped to 80.3%. This result (80.3% styrene selectivity at 100% phenylacetylene conversion) is among the best reported to date as demonstrated in Supplementary Table 3 (Zhao et al, 1998 ; Kleis et al, 2011 ; Behrens et al, 2012 ; Montesano Lopez, 2014 ; Alig et al, 2019 ; Han et al, 2019 ). By comparison, pure mTiO 2 is inactive and shows no activity to convert phenylacetylene in the reaction time range from 7 to 26 h ( Supplementary Figure 4 ).…”

PtZn intermetallic nanoalloy encapsulated in silicalite‐1 for propane dehydrogenation

“…It indicates that the nanoparticles inside the channels of MFI zeolite were kept away from severe agglomeration and sintering even after calcination and reduction at 600°C. Besides, Figure S15 shows the lattice spacing of 0.221 nm for the nanoparticle, which well matches the interplane distance of (111) plane of intermetallic PtZn (P4/mmm) 36 . The introduction of K + weakened the bond strength of ZnOSi, resulting in a larger particle size of 2.6 ± 0.5 nm in K‐PtZn@S‐1 59 .…”

“…In both catalysts, the Pt 1 Zn 1 intermetallic alloy with isolated Pt atoms surrounded by eight Zn atoms was largely approached. Because the actual coordination numbers are usually lower due to the coordination‐unsaturated nanoparticle surface 21,25,36 . For PtZn/S‐1, as the ratio of the Pt–Pt coordination number to that of Pt–Zn was around 2 (5.6 Pt–Pt at 2.79 Å and 3.2 Pt–Zn at 2.67 Å), Pt 3 Zn structure featuring 8 Pt–Pt bonds and 4 Pt–Zn bonds for each Pt atoms were determined.…”

“…Miller and co‐workers prepared silica‐supported Pt–Zn intermetallic alloy (IMA) which displayed high ethylene selectivity (∼100%) during ethane dehydrogenation (EDH) at 600°C 21 . Under high temperature reduction condition, contiguous Pt atoms prefer to be isolated into single atoms to form Pt–Zn intermetallic nanoparticles 25,36 . Besides, Gong group prepared the Pt/Cu single‐atom alloy (SAA) by an impregnation method which showed excellent stability and propylene selectivity for at least 120 h on stream at 520°C 30 .…”

Engineering of Yolk/Core–Shell Structured Nanoreactors for Thermal Hydrogenations

“…For example, the Pt catalysts usually hydrogenate both the highly reductive alkynyl group and nitro group simultaneously, making the synthesis of 4‐aminophenylacetylene by 4‐nitrophenylacetylene hydrogenation difficult. [ 2 ] The difficulty in controlling selectivity is due to complex separations and subsequent costly purification processes. Furthermore, some traditional catalysts tend to be instable and could be deactivated at high temperature and/or in the solution due to the leaching of metal nanoparticles (NPs), carbon deposition, sintering or poisoning by toxic substances.…”