Adsorbent Eases Carbon Capture

Figure 1. Metal-organic-framework material provides high uptake capacity and selectivity for CO₂ and SO₂. Source: University of Nottingham."The material shows high uptake of CO₂ and SO₂. In the case of SO₂, this is the highest reported for this class of materials to date. It is also selective for these gases, with other gases — such as hydrogen, methane, nitrogen, oxygen — showing no or very little adsorption into the pores," says Schröder. "In addition to high uptake capacity and selectivity, it is also very easy to release the adsorbed gas molecules through simple reduction of pressure. The material has high chemical stability to all common organic solvents and is stable in water and up to temperatures of 400°C," he adds. The non-amine-containing solid reportedly is economically viable to produce because it's synthesized from relatively simple and cheap organic materials with water as the only solvent. (More details in a recent article in Nature Chemistry.)"…Our calculations show that the energy required to release adsorbed gas molecules from NOTT-300 is significantly less than the energy required to remove CO₂ from existing CCS [carbon capture and sequestration] technology such as amine scrubbing," notes Nick Bennett, project manager at Nottingham."…We are keen to understand the performance of the material in 'real' flue bed mixture…," comments Bennett. "NOTT-300 is stable when exposed to water vapor. However, given the mechanism by which CO₂ and SO₂ are adsorbed, it is likely that water will also be adsorbed into the pores. We do not yet know what impact this will have on the CO₂ capture properties of NOTT-300 in a mixed gas system of, say, 85% nitrogen, 12% CO₂ and 3% water. This experiment is therefore planned in the next stage of development of NOTT-300…" Further experiments should provide insights on how many regeneration cycles are possible, he adds. The researchers also intend to investigate the performance of the material in the presence of other acidic gases, to better understand possible poisoning problems."The key challenges are to synthesize the material on a multi-gram scale and then on hundreds of grams. We are currently investigating a number of ways in which this can be achieved," says Bennett. "To date, we have only made 2–3 g of the material and therefore initial scale up is looking at making 10–20 g."