Catalysis & Process Chemistry
·
Heterogeneous Hydrogenation Catalysis
Hydrogenation Catalyst
How fast does the gap between atomically dispersed and 1-2 nm clustered 0.3 wt% Pd catalysts decay under 10 bar H2 with 2 ppm H2S and 200 ppm CO feed?
THE QUESTION
For heterogeneous catalysts differing in active-site ensemble (single-atom versus small-cluster), can turnover and selectivity be ranked correctly — and does the electronic or geometric descriptor dominate? · Verifier: Parallel flow-reactor test on a held-out set, 6-10 weeks
WORK ORDER
Ensemble persistence in atomically dispersed and clustered palladium catalysts under poison-bearing feed
BACKGROUND
What this Apodex Lab is
Heterogeneous metal catalysts drive selective industrial hydrogenations, from purifying ethene feedstocks to processing oils. Because precious metals such as palladium represent a substantial fraction of catalyst cost at loadings of 0.1 to 5 wt%, formulations using isolated single metal atoms on solid supports are widely promoted to maximise atomic efficiency. In commercial chemical plants, however, catalysts operate for years under high hydrogen pressures and continuous exposure to poisons such as sulfur and carbon monoxide. What matters industrially is operational durability and poison tolerance rather than theoretical atomic efficiency under pristine laboratory conditions.
The performance of single-atom catalysts is typically compared against small clusters using fresh, ex-situ characterisation and activity tests lasting tens of hours on clean feeds. These comparisons assume that the active-site geometry produced during synthesis remains fixed during turnover. Under reaction conditions, however, metal atoms restructure dynamically. The rate at which the structural and catalytic gap between an atomically dispersed metal and a small cluster decays under realistic feeds has never been quantified. Without measured decay constants for site persistence under poison-bearing gas, catalyst developers cannot determine whether single-atom dispersion provides a durable advantage or whether deactivation eliminates that benefit over time.
The Hydrogenation Catalyst Apodex Lab evaluates matched pairs of palladium and palladium-silver catalysts on gamma-alumina extrudates at 0.3 wt% metal loading over 700 hours at 10 bar, using an acetylene feed spiked with 2 ppm hydrogen sulfide and 200 ppm carbon monoxide. Destructive sampling of sub-beds at 150, 350 and 700 hours, combined with continuous chromatographic logging, delivers decay half-lives for both the atomically dispersed metal fraction and the within-pair performance gap in turnover and ethene selectivity. If the dispersion and performance gaps collapse rapidly, suppliers can avoid investing in dedicated single-site precursor manufacturing lines and refocus development on poison-tolerant overlayers.
WHY NOW
Why the field is spending on an assumption
Catalysis research routinely correlates activity and selectivity with as-synthesised active sites, treating single-atom and small-cluster ensembles as static features. However, active sites reconstruct during turnover under reaction conditions. In practice, catalyst survival under poison-bearing feeds matters far more than fresh-sample descriptor rankings. Published studies evaluate fresh materials over tens of hours on clean feeds, leaving the operational lifetime of atomically dispersed sites unmeasured. Without measured decay rates under realistic poison concentrations, suppliers cannot determine whether single-atom dispersion persists long enough in service to justify isolated-site synthesis routes over durable small clusters.
WHAT WE’D BUY
What we would ask a laboratory to run
We are not buying the answer. We are buying a measurement with an interval — and the bars it will be compared against.
This work order tests four alumina-supported catalysts in parallel micro-reactors under 10 bar hydrogen with 2 ppm H2S and 200 ppm CO for up to 700 h: two matched pairs of atomically dispersed versus 1-2 nm clustered formulations at 0.3 wt% metal loading (pure palladium and palladium-silver). Sub-beds are withdrawn at 150, 350, and 700 h for blinded electron microscopy, X-ray absorption spectroscopy, and chemisorption. The laboratory delivers three estimates with 95% confidence intervals: the half-life of the atomically dispersed fraction gap to within ±55% relative, the half-life of the turnover frequency and selectivity gaps from continuous gas logging to within ±30% relative, and the remaining dispersion difference at 700 h to an interval half-width of at most 0.07.
SCOPE & LIMITS
Because the test feed contains only two fixed poisons, the measured decay rate provides an upper bound on catalyst ensemble persistence under complex refinery gas mixtures containing additional poisons like arsine or mercury.
WHO EXECUTES
The kind of lab that can run this
A catalysis contract laboratory with parallel continuous-flow hydrogenation capacity (catalytic static mixer or fixed-bed micro-reactor banks, 1-30 bar H2, sulfur/CO-spiked feeds), plus access to a synchrotron or neutron beamline and aberration-corrected STEM/EXAFS for site-resolved characterisation of spent samples.
EXECUTOR KIND
wet-lab
WAYS IN
FOR PIs, LABS & CROs
Complete tasks no model can.
Paid per task, credited by name — a “Verified by” line for as long as the discovery it settled exists. You choose the work: browse the tasks above, respond to what you can actually run.
CREATE AN APODEX LAB
Have a question of your own?
Give it its own laboratory. Watch it decompose into an executable manifest.
ASK A FOLLOW-UP QUESTION
Push on our assumptions.
Every Apodex Lab lists what it doesn’t know. Good questions compound.
Every Apodex Lab shares the same verified-knowledge ledger. No laboratory works alone.