Open and Hierarchical Carbon Framework with Ultralarge Pore Volume for Efficient Capture of Carbon Dioxide

Amine-impregnated adsorbents are promising candidates for the selective capture of CO₂ from flue gas. The key is to develop suitable supports possessing large pore sizes and very large pore volumes, and the material has to be facilely synthesized from readily available reagents. In this work, hierarchical carbon nanosheet (CNS) featuring large pore width (30-100 nm) and extraordinarily huge pore volume (8.41 cm³/g) was prepared through controlled carbonization of glucose and dicyandiamide. The CNS was physically impregnated with pentaethylenehexamine (PEHA) to act as adsorbents for selective capture of CO₂. Owing to the unique porosity of CNS, the amount of amine loading in CNS can be ultrahigh (6 g PEHA/g CNS) in comparison with those of known amine-impregnated adsorbents, and the CO₂ capacity in a flow of 15 v/v % of CO₂ balanced in N₂ was up to 5.0 mmol/g at 75 °C. The synthesized PEHA-CNS composite materials perform well in capturing CO₂ under humid condition and display good stability in a test of 10 adsorption-desorption cycles. It is believed that the CNS synthesized in this work has great potential to act as a support material for CO₂ adsorption.