Photo-thermo semi-hydrogenation of acetylene on Pd1/TiO2 single-atom catalyst

Abstract

Semi-hydrogenation of acetylene in excess ethylene is a key industrial process for ethylene purification. Supported Pd catalysts have attracted most attention due to their superior intrinsic activity but often suffer from low selectivity. Pd single-atom catalysts (SACs) are promising to significantly improve the selectivity, but the activity needs to be improved and the feasible preparation of Pd SACs remains a grand challenge. Here, we report a simple strategy to construct Pd1/TiO2 SACs by selectively encapsulating the co-existed small amount of Pd nanoclusters/nanoparticles based on their different strong metal-support interaction (SMSI) occurrence conditions. In addition, photo-thermo catalysis has been applied to this process where a much-improved catalytic activity was obtained. Detailed characterization combined with DFT calculation suggests that photo-induced electrons transferred from TiO2 to the adjacent Pd atoms facilitate the activation of acetylene. This work offers an opportunity to develop highly stable Pd SACs for efficient catalytic semi-hydrogenation process.

Mechanistic and Atomic-Level Insights into Semihydrogenation Catalysis to Light Olefins

“…Zhang and co-workers loaded single-atom Pd onto a type of oxide support featuring photocatalytic activity, i.e., TiO 2 , to synthesize the Pd 1 /TiO 2 SAC catalyst for acetylene semihydrogenation. 168 As shown in the comparison in Figure 17b,c, the increase in acetylene conversion on the catalyst under the full-spectrum light irradiation is more remarkable than that under the visible light irradiation (λ > 420 nm), suggesting that the photoexcitation of TiO 2 is the key factor for acetylene semihydrogenation reaction. By combining detailed characterization with DFT calculations, the origin of the enhanced performance was unraveled to be that the photoinduced electron transfer from TiO 2 to adjacent Pd atoms in the Pd 1 / TiO 2 SACs promoted the activation of acetylene.…”

“…Copyright 2021, American Chemical Society. (b,c) Reproduced with permission from ref . Copyright 2022, Springer Nature.…”

“…This disadvantage could be improved by using photocatalytic hydrogenation strategy. Zhang and co-workers loaded single-atom Pd onto a type of oxide support featuring photocatalytic activity, i.e., TiO 2 , to synthesize the Pd 1 /TiO 2 SAC catalyst for acetylene semihydrogenation . As shown in the comparison in Figure b,c, the increase in acetylene conversion on the catalyst under the full-spectrum light irradiation is more remarkable than that under the visible light irradiation (λ > 420 nm), suggesting that the photoexcitation of TiO 2 is the key factor for acetylene semihydrogenation reaction.…”

Single-Atom-Based Catalysts for Photocatalytic Water Splitting on TiO2 Nanostructures

“…Current literature includes the identification of single-atom on graphene-based supports (Au [59], Fe [60], Ru [61], etc. ), graphitic carbon nitride (Pt [62]), carbon paper (Pt, Ru [63]) or inorganic semiconductors such as cerium oxide (Pt [64,65], Ru [66]), alumina (Pt [67]) or TiO 2 (Pt [45,[68][69][70][71][72][73][74][75], Pd [71,[76][77][78][79][80][81], Au [71,82,83], Ir [84,85], Rh [86]). This enabled a precise evaluation of the size and distribution of the single metal atoms, as well as their local structural information (metal species on the support) [55].…”

Tripodal Pd metallenes mediated by Nb2C MXenes for boosting alkynes semihydrogenation

“…Utilizing the strong metal-support interaction (SMSI) [19][20][21] could refrain from these puzzles, which is expected to become a promising strategy to form metallenes. The SMSI can effectively reduce the high surface energy of the metal nanoparticles for one thing [22][23][24] , but also, once the selected supports possess stronger interaction with metal atoms than the metal-metal binding, the supports compel the metal atoms to spread out on the support, thus forming two-dimensional (2D) metal metallenes instead of three-dimensional (3D) metal nanoparticles 25 . More importantly, given that the unique atom arrangement of 2D metal metallenes enabled faster mass transport and easier desorption of speci c intermediate in the interlayer con guration 26 , the application of 2D metal metallene can go far towards structure-sensitive reactions.…”