Efficient crystal structure materials as reactive sorbent for the CO2 and CH4 adsorption and storage

Abstract

The efficient dirubidium cobalt bis(dihydrogendiphosphate) dihydrate compound is successfully synthesized in a solution and used as a reactive sorbent for the CO₂ and CH₄ gases adsorption and storage. A crystal of this Rb₂Co(H₂P₂O₇)₂·2H₂O compound has been isolated and characterized by single X-ray diffraction analysis and was found to crystallize in the triclinic system ( $P\overline{1}$ ) with the cell parameters (Å): 6.980(1), 7.370(1), 7.816(1), 81.74(1), 70.35(1), 86.34(1); V = 374.68(9) Å3, Z = 2. The crystal-packing consists of a three-dimensional framework made upon corners and edges sharing of [RbO₇], [H₂P₂O₇] and [CoO₆] entities, furthermore linked by a network of H-bonds. The UV-Vis spectroscopy revealed usual transitions between the ground state 4T1g and the upper levels 4T2g, 4A2g and 4T1g (P). Moreover, the CO₂ and CH₄ gases sorption measurements were successfully performed at two different temperatures (25 and 45 °C) and various pressures ranging from vacuum to 50 bar. Our results show that rate of CO₂ and CH₄ capturing was 3.10 mmol/g and 2.35 mmol/g at temperature 25 °C and pressure 50 bar, respectively. This compound showed a clear potential for CO₂/CH₄ adsorption and storage thereby paving the way towards its exploration and adaptation for capturing and collecting carbon dioxide and greenhouse gases from the air, and their conversion into hydrocarbon fuels using existing mature technologies. We have also conducted density functional theory calculations to study the CO₂ and CH₄ adsorption properties of Rb₂Co(H₂P₂O₇)₂·2H₂O. The simulation results show enhanced adsorption of both types of molecules on the surface of the material.