Abstract
In order to mitigate climate change driven by the observed high levels of carbon dioxide (CO2) in the atmosphere, many micro and nano-porous materials are being investigated for CO2 selectivity, capture and storage (CCS) purposes, including zeolites, metal organic frameworks (MOFs), functionalized polymers, activated carbons and nano-silicate clay minerals. Key properties include availability, non-toxicity, low cost, stability, energy of adsorption/desorption, sorbent regeneration, sorption kinetics and CO2 storage capacity. Here, we address the crucial point of the volumetric capture and storage capacity for CO2 in a low cost material which is natural, non-toxic, and stable. We show that the nano-silicate Nickel Fluorohectorite is able to capture 0.79 metric tons of CO2 per m3 of host material - one of the highest capacities ever achieved - and we compare volumetric and gravimetric capacity of the best CO2 sorbent materials reported to date. Our results suggest that the high capture capacity of this fluorohectorite clay is strongly coupled to the type and valence of the interlayer cation (here Ni2+) and the high charge density, which is almost twice that of montmorillonite, resulting in the highest reported CO2 uptake among clay minerals.
Highlights
A current major challenge in science and technology is the development of low cost materials with large CO2 capture and storage (CCS)[1] capacity, retention ability and sorption selectivity[2]
The high-pressure CO2 uptake at room temperature (Fig. 1a) shows a maximum CO2 intercalation of 28% in weight for Nickel-fluorohectorite clay (NiFh) clay at the final pressure of 55 bar. This value is equivalent to 6.45 mmol of CO2 per gram of NiFh, which corresponds to 0.795 ton of CO2 per m3 of clay at 55 bar and room temperature, given the crystallographic density of the clay (2.8 g/ml)
This result demonstrates that NiFh is able to intercalate one of the largest amounts of CO2 per volume of material of all porous materials reported in literature
Summary
Can capture a large amount of CO2 depending on the type of interlayer cation, and that Nickel-fluorohectorite clay (NiFh), in particular, will retain CO2 up to a temperature of 35 °C at ambient pressure[23]. The captured CO2 can subsequently be released by heating above this temperature. These conditions are highly relevant for mapping out and understanding the mechanisms involved in CO2 capture and retention by nano-silicates, either in geological formations, or in technological CO2 absorbent materials
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