Adsorption of small polarisable molecules using mesoporous carbonaceous materials

Discovered and first reported 11 years ago by the York Green Chemistry Centre of Excellence, Starbon® is carbonaceous mesoporous material derived from polysaccharides (starch or alginic acid). These renewable materials represent a greener, more efficient, cheaper and more selective alternative than other commercial options in reducing emissions from power stations, chemical and other large scale manufacturing plants. It has been shown that the Starbon® materials were successfully applied in chromatography, noble metals and large dye molecules adsorption. The next ambition is to utilize the unique textural properties and surface chemistry of the Starbon® for adsorption adsorption of small gas molecule. It is an interesting challenge because the microporosity is the key factor in small molecules adsorption and there is a little information about role of mesoporosity in this process. Starbons® have much lower microporosities, but adsorb up to 65% more CO2 than activated carbon. Furthermore, novel Starbons®-graphene composite materials developed during the project adsorb even more CO2 due to their very microporous combination with graphene. During the project it has been demonstrated that the adsorption capacity of the micropore system to adsorb small molecules could be significantly increased in the presence of mesopore. This phenomenon has been shown on the example of adsorption of small polarizable molecules such as CO2 and NH3.
It has been found that carbonaceous materials could adsorb ammonia by micropores (reversible process) and chemically interact with their surface functional groups (irreversible process). The chemisorption of ammonia onto the Starbon® being correlated with the functionality surface and the temperature of the adsorption. Moreover, the NH3 interaction with Starbons® led to new bio-based nitrile-containing mesoporous materials. The introduction of nitrogen is expected to improve CO2 capture performance, heavy-metal binding, conductivity and catalytic activity, most notably in the metal-free oxidative reduction reaction. Because Starbons® display a high adsorption of CO2 and NH3 there may be potential to use them in the adsorption of other small molecules, as NOx, SOx. Further research would need to take place in order to discover Starbon® potential in adsorption of these small molecules.