Particle size effect in liquid-phase hydrogenation of phenylacetylene over Pd catalysts: Experimental data and theoretical analysis

Unraveling the Role of Site Isolation and Support for Semihydrogenation of Phenylacetylene

“…In Pd@SBA‐15 which has multiple active sites nearby, sequentially hydrogenate phenylacetylene to ethylbenzene occurs with ease. Although it is expected to form oligomers if we have multiple active sites close to each other, but we did not observe any oligomerised products, probably due to the use of lower reaction temperatures . A common approach to improve the styrene selectivity is to reduce ensembles of catalytically active sites via modification with inert components, often called “active site isolation”.…”

“…According to this concept, the isolation of the surface Pd atoms inhibits the formation of multi‐σ‐adsorbed species and subsequently the formations of ethylbenzene, oligomers as well as carbonaceous deposit, while the selectivity to ethylbenzene is enhanced. The DFT calculations have also demonstrated that the additives have lower activation energy for the styrene desorption than for further hydrogenation, making the catalyst more selective in nature . Therefore, the geometrical and electronic properties remarkably influence the catalyst performance for the selective hydrogenation of phenylacetylene.…”

“…Althoughi ti se xpected to form oligomers if we have multiple active sites close to each other,b ut we did not observe any oligomerised products, probably due to the use of lower reaction temperatures. [31] Ac ommon approach to improvet he styrene selectivity is to reduce ensembles of catalyticallya ctive sites via modification with inert components, Scheme2.Possiblep roducts of phenylacetylenereduction to different products. often called "active site isolation".…”

“…The DFT calculationsh ave also demonstrated that the additives have lower activation energy for the styrene desorption than for further hydrogenation,m aking the catalyst more selective in nature. [31,32] Therefore, the geometricala nd electronic properties remarkably influence the catalyst performance for the selective hydrogenation of phenylacetylene. Given the crystal structure of PdIn we can see that each Pd atom is surrounded by In atoms in the most exposed (110) plane of PdIn as depicted Figure S4 Table 2a nd represented in Figure 7.…”

Single-atom Pd dispersed on nanoscale anatase TiO2 for the selective hydrogenation of phenylacetylene

“…In the meantime, the phenylacetylene molecules adsorbed on Pd atoms as a result of the interaction between π bond of triple bonds and the unoccupied dorbital of Pd are easily activated, followed by the cleavage of π bond. The H atoms formed around Pd atoms then attack the activated phenylacetylene to form styrene [63,64]. Styrene could also be activated and further interact with the dissociated H atoms to form ethylbenzene.…”