Catalytic Selectivity in Acetylene Hydrogenation

Acetylene hydrogenation is a critical process in the petrochemical industry, where trace amounts of acetylene must be selectively converted to ethylene without further hydrogenation to ethane. Achieving high catalytic selectivity hinges upon tailoring active sites to favour the semihydrogenation pathway, suppressing undesired over-hydrogenation and carbonaceous by-products. Advances in catalyst design span single-atom and intermetallic systems, metal–organic frameworks (MOFs) supporting atom pairs, bimetallic nanoparticles and oxide interfaces. Fine control of adsorption energies, ensemble size and electronic structure enables precise matching of reaction intermediates’ binding strength. Mechanistic insight from density functional theory and kinetic studies has elucidated the role of reaction pathways, such as the Horiuti–Polanyi mechanism, and the influence of subsurface species on activity and selectivity. Recent strategies focus on engineering atomic ensembles, exploiting strong metal–support interactions and photo-thermo activation to enhance performance at low temperatures. Sustainable variants using earth-abundant metals and robust supports aim to reduce reliance on palladium while maintaining industrially relevant turnover frequencies.

Research from Nature Portfolio

Recent studies have demonstrated that anchoring heteroatomic metal dimers within MOF channels enables near-barrierless semihydrogenation of acetylene to ethylene, achieving conversion above 99.99% and selectivity over 90% under simulated industrial conditions. The cooperative interaction between the dual metal atoms and the porous framework support is shown to lower activation barriers and broaden the operational temperature window. Another report has introduced an intermetallic catalyst featuring trimeric Ni1Sb2 sites, designed by theoretical guidance and realised via molten-Sb trapping. This catalyst exhibits ethylene selectivity exceeding 93% at full conversion, attributed to optimised σ- and π-adsorption energies for reactant and product species. A complementary approach has tuned the crystal phase of PdCu nanoparticles, revealing that the body-centred cubic phase displays significantly enhanced activity and selectivity compared with the face-centred cubic form. Precise atomic structure determination shows that isolated Pd sites within the bimetallic lattice facilitate efficient hydrogen dissociation and minimise over-hydrogenation.

Catalytic Selectivity in Acetylene Hydrogenation publication trend

The graph below shows the total number of articles in catalytic selectivity in acetylene hydrogenation across all publications each year (not limited to Nature Index journals).

Technical terms

Semihydrogenation: Partial hydrogenation of acetylene to ethylene without further reduction to ethane.

Catalytic selectivity: Preference of a catalyst for producing the desired product over undesired by-products.

Horiuti–Polanyi mechanism: A stepwise hydrogen addition pathway involving dissociative adsorption of H₂ followed by sequential hydrogenation of the hydrocarbon.

Single-atom catalyst (SAC): Catalyst in which isolated metal atoms are dispersed on a support to maximise atom efficiency.

Metal–organic framework (MOF): Porous crystalline material composed of metal nodes and organic linkers, used to stabilise atom pairs or clusters.

Intermetallic compound: A solid-phase alloy with defined stoichiometry and crystal structure offering uniform active sites.

Adsorption energy: Energy change when a molecule binds to a catalyst surface, influencing reaction rates and selectivity.

References

1. A MOF-supported Pd1–Au1 dimer catalyses the semihydrogenation reaction of acetylene in ethylene with a nearly barrierless activation energy. Nature Catalysis (2024).
2. Photo-thermo semi-hydrogenation of acetylene on Pd1/TiO2 single-atom catalyst. Nature Communications (2022).
3. Mechanism driven design of trimer Ni1Sb2 site delivering superior hydrogenation selectivity to ethylene. Nature Communications (2022).
4. Tuning crystal-phase of bimetallic single-nanoparticle for catalytic hydrogenation. Nature Communications (2022).
5. Influence of surface structures, subsurface carbon and hydrogen, and surface alloying on the activity and selectivity of acetylene hydrogenation on Pd surfaces: A density functional theory study. Journal of Catalysis (2013).
6. Catalysts and mechanisms for the selective heterogeneous hydrogenation of carbon-carbon triple bonds. Cell Reports Physical Science (2022).
7. An Experimental Approach on Industrial Pd-Ag Supported α-Al2O3 Catalyst Used in Acetylene Hydrogenation Process: Mechanism, Kinetic and Catalyst Decay. Processes (2019).