Inside a Carbon-Based Ozone Catalyst: Three Pore-Forming Routes and Cobalt-Nickel Dual-Atom Sites

Pore structure is not a footnote in a catalyst specification. It sets the specific surface area, it decides how many active sites exist, and it determines whether reactants can physically reach them. Most carbon-based ozone catalysts that fail in service do not fail because the active metal was the wrong choice — they fail because the pores were wrong, and the sites were never accessible in the first place.

That is why the preparation route deserves more attention than the datasheet. Three separate pore-forming decisions, plus one decision about how two metals sit next to each other, account for most of what this class of catalyst does in a reactor.

Route One: One Metal at a Time

Conventional co-loading puts several metals onto the carbon matrix in a single step. The predictable outcome is agglomeration: metals cluster, and the clusters block the very micropores they were meant to populate. Surface area collapses and the catalyst that tested well as a powder performs badly as a bed.

The SINOKLE R&D team took the slower road — load one metal, sinter, then load the next. Doing one thing at a time keeps the metal distribution uniform and keeps the micropore network open. The count of oxidation active sites goes up precisely because the metal is not sitting in lumps that occupy pore volume without contributing surface.

Route Two: Water-Soluble Porogens

The second route adds water-soluble porogens such as PEG, PVP and PVA during metal loading. These distribute uniformly through the mixing stage and are driven off during subsequent drying or calcination, leaving pore structure behind where the porogen used to be.

The value here is control rather than magnitude. Pore size and pore size distribution become formulation variables — things you adjust on purpose — instead of accidents inherited from whatever carbon precursor was available that quarter.

Route Three: A Sacrificial Metal Template

The third method uses a soluble metal, zinc, as a template. Zinc volatilises during calcination and, in leaving, opens channels through the body of the catalyst. Those channels are open rather than dead-ended, which is precisely what makes them useful for mass transfer rather than just adding surface area on a gas-adsorption report.

Combined, the three routes give KHC-PC1001 a micropore specific surface area of 1100-1150 m2/g and a mesopore specific surface area of 10-100 m2/g. The micropore/mesopore pairing is the point of the exercise: micropores host the sites, mesopores carry the reactants to them. Traditional coconut-shell carbon does not offer both, which is why it tends to plateau.

Cobalt and Nickel, Two Atoms Working Together

On the active-component side the design uses a cobalt-nickel dual-atom arrangement. Cobalt and nickel atoms form paired sites on the carbon carrier and, through mutual regulation of the electronic structure, lower the activation energy for ozone decomposition. Less energy per decomposition event means more radicals per unit of ozone fed.

Multi-metal heteroatom co-doping amplifies the effect further, the stated goal being a genuine 1+1>2 rather than a weighted average of two metals doing their own thing. Nitrogen doping anchors the metal atoms so the active components are not progressively stripped out during operation — the usual long-term failure mode of doped carbons, and the one that never shows up in a 30-day test.

Measured Against the Alternatives

Against conventional alumina-silicate-based catalysts, KHC-F1001 comes out ahead on three axes that matter in a fixed bed:

• Specific surface area: 1400 m2/g, against 200-400 m2/g.
• Strength: 95%, where the usual range is 80%-90%.
• Service life: 3-5 years, against a typical 1-2 years.

Strength and life get less attention than surface area in most evaluations, but in a fixed bed they decide whether the reactor is still performing in year three or has quietly become a pressure-drop problem with a catalyst in it.

Operating Window and Dosing

Core parameters for KHC-F1001: bulk density 0.45-0.55 g/cm3, pH applicability 3-11, ozone decomposition rate 90%, COD removal 70%, color removal 95%, and ozone-specific COD removal of 1.1-1.5 g O3/g COD. That last figure is the one to check against your own ozone generation cost, because it converts directly into operating expenditure.

Paired with SINOKLE CDOF, ozone oxidation performance improves by a further 4x while occupying only 10%-20% of the footprint of a conventional train. For retrofit sites where space, not chemistry, is the binding constraint, that ratio is usually the deciding number.

Field Record

The product has been run at Karamay Petrochemical, at a landfill leachate plant in Taizhou, at a pharmaceutical facility in Inner Mongolia, and at a refinery in Uzbekistan. Different water, same catalyst — which is the only kind of evidence that separates a preparation route that works from one that only works on the bench.

For engineers chasing catalytic efficiency, the lesson is that the interesting decisions were made before the catalyst ever saw wastewater: in the loading sequence, in the porogen recipe, and in the choice of what to burn away.