Defect Engineering and Nickel Synergize to Accelerate Ruthenium-Catalyzed Dicyclopentadiene Hydrogenation

A new catalyst developed by researchers in China has achieved the rapid and nearly complete hydrogenation of dicyclopentadiene under conditions mild enough to challenge conventional industrial expectations. The material converts dicyclopentadiene into tetrahydrodicyclopentadiene with 100% conversion and approximately 100% selectivity in only 25 minutes, using a temperature of 35 °C and a hydrogen pressure of 1 MPa. The advance combines defect engineering in a cerium-based metal–organic framework with the addition of nickel to finely tune ruthenium active sites. The resulting catalyst, identified as Ru₁Ni₁.₅@UiO-66(Ce)-12 h, illustrates how precisely designed interfaces between a porous support and bimetallic nanoparticles can accelerate hydrogen transfer while suppressing unwanted reaction pathways.

Dicyclopentadiene, commonly abbreviated as DCPD, is an important industrial olefin used in the production of specialty polymers, resins, fuels and high-performance materials. Its molecule contains two carbon–carbon double bonds arranged within a rigid bicyclic structure, making complete hydrogenation chemically demanding. Hydrogenation must proceed efficiently while avoiding excessive reaction temperatures, over-hydrogenation, skeletal rearrangement or the formation of undesired by-products. Conventional noble-metal catalysts can provide high activity, but their performance often depends strongly on particle size, metal dispersion, electronic structure and the nature of the support. The researchers’ strategy addresses all of these factors simultaneously by creating a catalytic environment in which ruthenium, nickel and the cerium-containing framework cooperate at the atomic and nanoscale levels.

At the heart of the system is UiO-66(Ce), a metal–organic framework constructed from cerium-oxo clusters connected by organic linkers. MOFs are crystalline porous materials whose internal channels can concentrate reactant molecules near catalytic sites, while their inorganic nodes can influence the electronic properties of supported metals. In this work, the researchers introduced structural defects into UiO-66(Ce) using cyanuric acid, which acted as molecular “etching scissors.” Rather than simply damaging the framework, controlled etching removed or disrupted selected linker connections and generated a more chemically open and reactive support. These defects exposed additional cerium-oxo environments, modified the local pore structure and created anchoring points capable of interacting strongly with metal species.

The defect-rich framework was then used to stabilize highly dispersed ruthenium–nickel nanoparticles. Ruthenium is well known for its ability to activate molecular hydrogen and catalyze carbon–carbon double-bond hydrogenation, but isolated or very small Ru particles can exhibit electronic characteristics that differ substantially from bulk ruthenium. Nickel was introduced as a promoter rather than merely as a second catalytic component. The researchers found that the Ni species altered the chemical environment of ruthenium and formed Ni–Ru bonds, while interactions between the metals and the cerium-oxo clusters generated Ce–O–Ru/Ni interfaces. These interconnected junctions created pathways for electron redistribution across the support and the bimetallic particles.

Electron transfer is central to the catalyst’s performance. In a conventional metal catalyst, hydrogen must adsorb, dissociate and subsequently react with an olefin at an appropriate balance of bond strength. If hydrogen binds too weakly, activation becomes slow; if it binds too strongly, the surface can become saturated with hydrogen or release reaction products inefficiently. The same principle applies to the carbon–carbon double bond. The Ru₁Ni₁.₅@UiO-66(Ce)-12 h catalyst was designed to make ruthenium electron-rich through the combined influence of defective cerium-oxo clusters and nickel. According to the study, electrons can migrate from the Ce-based nodes and Ni-containing species toward Ru⁰ sites, changing the orbital occupancy and adsorption behavior of the active metal.

The defects and nickel promoter therefore perform complementary functions. Defect engineering changes the microenvironment around the nanoparticles, increases the accessibility of support-bound metal sites and exposes cerium centers that can participate in interfacial bonding. Nickel provides an additional electronic and geometric lever through Ni–Ru interactions. Together, these effects regulate the abundance, distribution and electronic state of metallic Ru⁰ sites. The researchers report that the modified sites have an enhanced ability to adsorb and activate both H–H bonds in hydrogen and C=C bonds in dicyclopentadiene. A plausible catalytic sequence begins with hydrogen adsorption and dissociation at the Ru–Ni or metal–support interface, followed by transfer of hydrogen atoms to the two unsaturated bonds of DCPD. The porous framework helps bring the reactant into contact with these sites and may also limit uncontrolled aggregation of the nanoparticles.

The performance reported for the optimized material is striking because it is achieved under comparatively gentle conditions. At 35 °C and 1 MPa, the catalyst completed DCPD hydrogenation in about 25 minutes, producing tetrahydrodicyclopentadiene with essentially complete selectivity. The product is valuable because hydrogenating the unsaturated bonds changes the reactivity and physical properties of DCPD while preserving the carbon skeleton. High selectivity is particularly important in industrial processing, where separation and purification of side products can add substantial energy and cost. By reducing the need for elevated temperatures, the catalyst could also lower energy consumption, although broader process evaluations would be required before judging its commercial advantages.

The study emphasizes that the best performance did not arise simply from adding more ruthenium or nickel. Instead, catalytic activity depended on matching the defect concentration of the UiO-66(Ce) support with the amount of nickel promoter. Too few defects would provide insufficiently accessible interfacial sites, while excessive structural disruption could compromise the framework’s porosity, stability or ability to anchor nanoparticles. Similarly, the nickel content had to be controlled so that Ni–Ru interactions improved hydrogen and olefin activation without blocking ruthenium sites or producing less selective metal ensembles. The designation “12 h” in the catalyst name refers to the defect-engineering treatment time used in the preparation, highlighting how synthesis conditions were used to tune the final catalytic microenvironment.

Durability is another important feature of the result. The optimized catalyst retained its structure and catalytic performance after six reaction cycles, according to the researchers. This stability suggests that the defective UiO-66(Ce) framework can confine and anchor the Ru–Ni nanoparticles strongly enough to resist severe sintering or metal loss during repeated hydrogenation. For practical catalysis, stability is as important as initial activity: a catalyst that performs rapidly but deactivates after one reaction offers little industrial value. The reported recycling result does not by itself establish long-term operation, resistance to impurities or performance at larger scale, but it provides evidence that defect-engineered MOF supports can serve as robust hosts for bimetallic hydrogenation catalysts.

The work offers a broader blueprint for designing noble-metal catalysts with lower precious-metal requirements and more precisely controlled active sites. Rather than treating the support as an inert scaffold, the researchers use the cerium-oxo framework as an electronic participant, the defects as chemical access points and nickel as a promoter that reshapes ruthenium’s behavior. This coordinated approach could be extended to other selective hydrogenation reactions involving olefins, alkynes, carbonyl compounds or biomass-derived molecules. The central lesson is that catalytic performance can emerge from a carefully engineered network of charge-transfer channels and confined interfaces, not from the isolated properties of any single element. If the material can be produced reproducibly and tested under continuous-flow and industrially relevant conditions, it may help move MOF-supported bimetallic catalysts closer to real-world applications in low-temperature hydrogenation.