Origin of the Increase of Activity and Selectivity of Nickel Doped by Au, Ag, and Cu for Acetylene Hydrogenation

Abstract

Activity and selectivity are both important issues in heterogeneous catalysis and recent experimental results have shown that Ni catalysts doped by gold exhibit high activity for the hydrogenation of acetylene with good selectivity of ethylene formation. To unravel the underlying mechanism for this observation, the general trend of activity and selectivity of Ni surfaces doped by Au, Ag, and Cu has been investigated using density functional theory calculations. Complete energy profiles from C 2 H 2 to C 2 H 4 on Ni(111), Au/Ni(111), Ag/Ni(111) and Cu/Ni(111) are obtained and their turnover frequencies (TOFs) are computed. The results show that acetylene adsorption on Ni catalyst is strong which leads to the low activity while the doping of Au, Ag, and Cu on the Ni catalyst weakens the acetylene adsorption, giving rise to the increase of activity. The selectivity of ethylene formation is also quantified by using the energy difference between the hydrogenation barriers and the absolute value of the adsorption energies of ethylene. It is found that the selectivity of ethylene formation increases by doping Au and Ag, while those of Cu/Ni and Ni are similar.

Atomically Dispersed Ruthenium Species Inside Metal–Organic Frameworks: Combining the High Activity of Atomic Sites and the Molecular Sieving Effect of MOFs

“…A high selective catalyst should have a low desorption energy and a high hydrogenation barrier of ethylene. So the difference (Δ E ) between the hydrogenation barrier and the desorption energy of C 2 H 4 is calculated to estimate the selectivity (Supporting Information, Table S8) . We find that Ru 3 @ZIF‐8 has higher Δ E (0.28 eV) than Ru 1 @ZIF‐8 (−0.32 eV), suggesting the Ru 3 @ZIF‐8 is more selective to semi‐hydrogenation of acetylene.…”

Fabrication of supported Pd–Ir/Al2O3 bimetallic catalysts for 2‐ethylanthraquinone hydrogenation

“…In addition, bimetallic catalysts often exhibit advantageous properties compared to analogues containing only one of the constituent metals . Such hybrid materials may offer opportunities for synergistic inter‐metallic interactions that lead to improvement in catalytic performance . Pd‐based bimetallic catalysts such as Pd–Au, Pd–Ru, and Pd–Rh have been extensively studied as hydrogenation catalysts.…”

“…20,21 Such hybrid materials may offer opportunities for synergistic inter-metallic interactions that lead to improvement in catalytic performance. [22][23][24] Pd-based bimetallic catalysts such as Pd-Au, [25][26][27][28] Pd-Ru, 29,30 and Pd-Rh 31,32 have been extensively studied as hydrogenation catalysts. The combination of Pd with Ir has attracted particular attention.…”

From Static to Reacting Systems on Transition-Metal Surfaces

“…120 In order to prevent catalyst deactivation, concentration of acetylene needs to be lowered to <5 ppm by volume. 122 This process requires highly optimized catalysts that are very selective, since any ethylene that is hydrogenated together with the acetylene results in losses. 122 This process requires highly optimized catalysts that are very selective, since any ethylene that is hydrogenated together with the acetylene results in losses.…”

“…The weaker the adsorption of ethylene, the more selective the catalyst should be. 122 A similar analysis of ethylene and acetylene adsorption energies was done for Pd systems containing C, 130 used as a catalyst for selective hydrogenation of acetylene. Hence, one needs to search for a balance: the best catalyst will be a compromise between the selectivity and activity.…”