Sustainable and synthetic carbon polymers for safe and efficient H2 storage

Highly porous carbon microspheres have been obtained by a sustainable and facile approach that combines a microwave-assisted sol-gel process with a physical activation process. This approach is based on the use of sustainable monomers, such as phloroglucinol and glyoxylic acid, and CO 2 as a benign activating agent. By implementing a microwave-assisted polymerization step, it was possible to reduce the aging time by >90 % compared to similar processes. In addition, a three-fold reduction in activation time was achieved by increasing the activation temperature but with no deleterious effects on textural properties or H 2 storage capacity. In this way, carbon materials with BET surface area of up to 3300 m 2 g −1 and pore volume of up to 1.6 cm 3 g −1 were obtained, with >60 % of pore volume arising from micropores and with no pores larger than 3.5 nm. As a result, the carbons can store up to 9.2 wt% H 2 at −196 °C and 100 bar with the H 2 uptake mirroring trends in total porosity. Based on theoretical calculations, the working capacity could be enhanced by using a temperature pressure swing adsorption (TPSA) system (i.e., −196 °C, 100 bar to −123 °C, 5 bar) to 9.0 wt% H 2 , which is close to the total uptake at −196 °C and 100 bar. This compares to working capacity of 5.0 wt% H 2 for a PSA system at −196 °C of 100 to 5 bar. • Highly microporous carbon microspheres (BET surface area ∼ 3300 m 2 g −1 ) were obtained. • Sustainable monomers and a benign activating agent such as CO 2 were used. • A chemical-controlled CO 2 activation process enables effective porosity creation. • The carbons can store up to 9.2 wt% H 2 at −196 °C and 100 bar.