Nitrogen enriched solid sorbents for CO2 capture

Reducing anthropogenic CO2 emissions to slow down the consequences of climate change concerns all developed countries. In the short term, one of the most viable options to cut down carbon emissions consists on CO2 capture and storage from large stationary sources such as power stations, cement plants, refineries, etc. The near-ready-to-use technology at this scale is amine scrubbing. However, it is still necessary to reduce the cost of the capture step. Adsorption with solid sorbents is one of the promising options. In this work, a series of materials obtained from a commercial activated carbon were evaluated as potential high capacity carbon dioxide adsorbents. Functionalisation of the parent carbon by heat treatment with gaseous ammonia was carried out in order to introduce nitrogen functionalities of basic character to the carbon structure. The aim was to improve the selectivity and capacity of the sorbents towards CO2 capture. The sorbents were characterised in terms of texture, chemical composition, and surface chemistry. The textural characterisation involved N2 and CO2 adsorption isotherms at -196 oC and 0 oC, respectively. The surface chemistry was studied through temperature programmed desorption analysis in a thermobalance coupled to an FTIR for the evolved gas analysis. The capture performance of the sorbents was evaluated by means of a thermogravimetric analyser, recording the mass uptake of the samples when exposed to a CO2 atmosphere.