The problem, with a number
For CCS logistics, ppm-level contaminants can create disproportionate risk through acid formation, corrosion and equipment malfunction.
Proof: CO₂ purification
99.9% acid-gas removal builds a scale-up path for CCS CO₂ purification
Across three consecutive studies, Krajete advanced its SC1 adsorbent from selective NOx proof, through multi-impurity testing, to reproducible breakthrough and lifetime modelling for a 1–1.5 Mtpa CO₂ case. A later pilot update adds preliminary evidence from a real wet-CO₂ stream.
Three completed laboratory studies. One clear scale-up path. Trace removal, mixed-gas validation, breakthrough modelling, and a pilot follow-up now running on a real wet-CO₂ stream.
Client & context
CCS · An international energy operator · Trace NOx and SOx polishing of CO₂ · Three laboratory studies, June 2025 to April 2026
What we measured
Continuous inlet and outlet NO/NO₂/NOx on Testo 350 and Horiba APNA-370, with Dräger tubes, Shimadzu EDX-8100 and TC/TN analysis of spent adsorbent segments.
What we did
Moved from selectivity to mixture tolerance and then to capacity, separating chemical feasibility from the engineering questions that determine equipment size and operating cost.
What the programme
had to resolve
Very low outlets, moving inlets
NO and NO₂ must be removed to very low outlet concentrations despite changing inlet levels.
SO₂ competes for capacity
SO₂ may compete for capacity or alter the adsorbent surface, and therefore had to be tested in combination with NOx.
NO₂ had to be explained
NO₂ behaviour needed clarification because it may be present without being a target acidic contaminant.
More than a removal percentage
A full-scale concept requires predictable breakthrough, material usage and redundancy, not only short-duration removal data.
Wet CO₂, not dry
The system had to remain effective in wet CO₂, across changing flow and composition.
A defensible cost basis
The programme had to provide a defensible exchange interval and cost basis, not chemistry alone.
How did the three-stage programme run?
The programme deliberately moved from selectivity to mixture tolerance and then to capacity.
All three completed studies were performed at room temperature and near-ambient pressure; pressure effects remain a separate scale-up variable.
What the instruments recorded
Capacity boundary: the 1.5-year estimate extrapolates accelerated 1,000 ppm tests to a 5 ppm full-scale case. Other contaminants, pressure, bed compaction and industrial linear velocity were not yet fully represented.
| Evidence stage | Recorded | Basis |
|---|---|---|
| June 2025, NOx | 99.8–99.9% | Average removal in CO₂; 800 mL tests averaged 99.9%, with selected outlets at 1.2–3.5 ppb |
| November 2025, NOx | 99.6% | Average across flows and concentrations in wet CO₂ |
| November 2025, SO₂ | 100%, below detection | Complete removal in the reported wet-CO₂ experiments |
| November 2025, NO₂ | Not adsorbed | Behaved as an inert gas and did not impair NO removal |
| April 2026, breakthrough | Above 99.9% | Typical removal until the final loading phase |
| April 2026, capacity | Above 7 wt.% | Total impurity uptake during combined NO and SO₂ loading |
| April 2026, model | About 1.5 years | Exchange interval for 333 m³ and 1–1.5 Mtpa under stated assumptions |
What the programme looked like
Laboratory
The wet and dry CO₂ test setup
Certified NO, NO₂ and SO₂ mixtures diluted with CO₂, with a water bubbler producing water-saturated test gas.
Breakthrough
Combined loading to breakthrough
Combined 1,000 ppm NO and 1,000 ppm SO₂ breakthrough loading in wet high-purity CO₂.
From trace removal
to breakthrough.
Validated trace removal · Mixed-gas performance · Breakthrough capacity
< 10 ppb
average outlet target achieved in the June 2025 800 mL series
> 7 wt.%
combined NOx and SO₂ impurity loading in the breakthrough study
~1.5 years
modelled full-scale exchange interval under stated assumptions
What the programme was worth
commercially
Feedstock flexibility
NOx and SO₂ removal remained high in wet CO₂ and in combined impurity mixtures.
Infrastructure protection
Very low outlet concentrations support pipeline- and compressor-compatible polishing.
Predictable service
Reproducible breakthrough supports redundant duty and standby towers, and planned material exchange.
A material-cost basis
About EUR 1.5 million per 333 m³ filling, and approximately EUR 0.7 per tonne of CO₂ at a 1.5-year interval.
A wider feedstock envelope
Impurity polishing lets CCS accept CO₂ from more diverse industrial sources while protecting capital-intensive infrastructure.
What the EUR 0.7 does not cover
The EUR 0.7/t figure is a material-only estimate, not total installed or operating cost. It excludes the full impurity cocktail and remains subject to pilot validation.
What the live pilot is showing so far
A separate update documented installation and commissioning of a pilot on a CO₂-capture system in Ghent. The feed was wet CO₂ at about 1 bar overpressure, with measured impurity levels in the 5–25 ppm range.
See CO₂ purificationNOx outlet
About 0.15–0.2 ppm, with more than 99% uptake reported.
SO₂ outlet
Below detection, under 1 ppm. Preliminary.
H₂S outlet
Below detection, under 1 ppm. Preliminary.
Hydrocarbons and odour
Odour removal observed. A qualitative early observation.
Campaign status
Measurements are ongoing. This is not a completed performance campaign.
What has to be proven before an industrial design basis
Future performance depends on connecting real impurity variability with pressure drop, breakthrough, bed capacity and material economics.
Evidence boundary
Completed evidence covers near-ambient laboratory tests in synthetic wet and dry CO₂ and accelerated breakthrough conditions. Sources: four Krajete reports, June 2025 to August 2026.
Every CO₂ source.
Safer to move.
Discuss your impurity envelope, outlet specification and scale-up basis with a Krajete engineer. See CO₂ purification