Addressing the quantitative conversion bottleneck in single-atom catalysis

“Single-atom catalysts (SACs) offer many advantages, such as atom economy and high chemoselectivity; however, their practical application in liquid-phase heterogeneous catalysis is hampered by the productivity bottleneck as well as catalyst leaching. Flow chemistry is a well-established method to increase the conversion rate of catalytic processes, however, SAC-catalysed flow chemistry in packed-bed type flow reactor is disadvantaged by low turnover number and poor stability. In this study, we demonstrate the use of fuel cell-type flow stacks enabled exceptionally high quantitative conversion in single atom-catalyzed reactions, as exemplified by the use of Pt SAC-on-MoS2/graphite felt catalysts incorporated in flow cell. A turnover frequency of approximately 8000 h−1 that corresponds to an aniline productivity of 5.8 g h−1 is achieved with a bench-top flow module (nominal reservoir volume of 1 cm3), with a Pt1-MoS2 catalyst loading of 1.5 g (3.2 mg of Pt). X-ray absorption fine structure spectroscopy combined with density functional theory calculations provide insights into stability and reactivity of single atom Pt supported in a pyramidal fashion on MoS2. Our study highlights the quantitative conversion bottleneck in SAC-mediated fine chemicals production can be overcome using flow chemistry.”

Fig. 3: Characterisation of the M1-MoS2-GF catalysts.

figure 3

a Pt L3-edge XANES spectra; b Comparison between the experimental and calculated spectra using the pyramidal Pt-3S model (inset). The colour scheme used is as follows: light-cyan for Mo; yellow for S; white for Pt. Outer MoS2 atoms are omitted for the sake of clarity; c FT-EXAFS spectra of various catalysts. Dotted lines represent the fitting of the FT-EXAFS spectra; d False-coloured micro-CT image of the 3D structure of the M1-MoS2 array on graphite felt; e Mercury intrusion porosimetry and f Compressive strain–stress curves of blank GF and M1-MoS2-GF. Inset shows the comparison of the stress at 50% strain and compressive modulus at 15 ~ 20% strain. Error bars (SD) were presented from 5 individual tests. M = Co for (df); Scale bar: d, 100 µm.

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