The Sorbent Works Until Real Air Touches It

Solid-sorbent direct air capture (DAC) systems use amine-functionalized materials to adsorb CO2 from ambient air at ~400 ppm. These sorbents degrade through oxidative, thermal, and humidity-driven mechanisms, with operational lifetimes ranging from 0.25 to 5 years. Since sorbent replacement is a major cost driver, DAC cannot reach target costs of <$100/tonne CO2 without sorbents lasting 3–5+ years under real atmospheric conditions — but most performance data comes from lab tests that omit real-world contaminants.

Limiting warming to 1.5°C requires 5–10 Gt CO2/year of negative emissions by 2050 according to IPCC scenarios. DAC is the most location-flexible negative emissions technology. Current costs of $400–600/tonne CO2 must drop 4–6× for viability, and sorbent lifetime is the dominant variable in cost projections.

Metal-Organic Frameworks (MOFs), supported amines on silica/alumina, and temperature-swing adsorption (TSA) processes have all been tested — some achieving >90% capture efficiency in lab conditions. Climeworks and Global Thermostat have deployed commercial-scale systems. However, most accelerated aging studies use CO2-free, dry air, yet real atmospheric conditions include moisture, SOx, NOx, and particulates that accelerate degradation by poorly characterized mechanisms. The energy penalty for regeneration (80–120°C heat per cycle) compounds degradation through thermal cycling. No standardized degradation testing protocol exists that replicates real atmospheric contaminants across diverse climates.

Standardized accelerated aging protocols that replicate real atmospheric contaminant profiles (humidity, SOx, NOx, particulates) across different climatic regions. Sorbent chemistries resistant to oxidative degradation while maintaining high CO2 capacity. Field-validated lifetime data from operating DAC plants in diverse climates to calibrate lab predictions against actual performance.

A team could design an accelerated aging test rig that exposes DAC sorbent samples to controlled atmospheric contaminant profiles (SO2, NO2, humidity cycles) and measures capacity degradation over time. Comparing degradation rates under lab-clean vs. contaminant-loaded air would quantify the real-world performance gap. Chemistry, materials science, and environmental engineering skills apply.