Geopolymers are synthetic inorganic polymers obtained from an aluminosilicate powder and an aqueous solution of alkaline hydroxides or silicates. The material is mesoporous and a multidimensional and functional porosity can be generated through the addition of fillers or the use of specific techniques.
The mix-design of the mixture, pure or composite, allows to change the chemical-physical properties of the final material, also thanks to the nucleation of zeolitic phases. Geopolymers also possess ion exchange and electrostatic interaction capabilities.
By virtue of these characteristics, ISTEC has developed geopolymer matrices and composites containing zeolites, for the adsorption of CO2. Because of the high selectivity coupled with a good absorption capacity, these materials are suitable for the separation and removal of pollutants in gaseous phase.
The water-based reaction, the low consolidation temperature (<100 ° C), the use of low-cost and possibly waste raw materials, make the material both economically and environmentally sustainable.
The possibility to change the stoichiometry and composition, even with the addition of functional fillers, makes these materials extremely versatile. Another industrially advantageous aspect is the possibility to modulate the porosity and give complex shapes to the material. Post-combustion capture of CO2 represents a feasible measure for reducing the greenhouse effect from fossil fuels in stationary installations, since it can be accomplished downstream without substantial change to the existing processes and facilities. Physical adsorption with solid sorbents is economically competitive with respect to other well-established chemical adsorption technologies.
Biogas purification is another possible application.