Synthesis of copper exchanged heteropolyacids supported on MCM-48 and its application for CO2 adsorption

Copper-encapsulated heteropolyacid-impregnated mesoporous MCM-48 (Cu-HPA-MCM-48) with copper in a reduced state was synthesized, and the CO2 adsorption capacity was monitored. The synthesized material was characterized by XRD, N2 adsorption–desorption, FT-IR, DSC, CO2-TPD and XPS. The low angle X-ray diffraction pattern of the Cu-HPA-MCM-48 demonstrates the encapsulation of copper inside the pore by the disappearance of higher-order peaks. This result is further supported by the presence of Cu2p3 and W4f peaks in XPS. The CO2 adsorption capacity of Cu-HPA-MCM-48 was 70 mg/g at 25 °C. The energy of desorption and the heat of the reaction (ΔHr) were 21.2 kJ/mol and 490 Btu/lb, respectively, as determined by CO2-TPD and DSC. As the ΔHr value of Cu-HPA-MCM-48 approaches the CO2 benchmark value (580 Btu/lb), the catalyst exhibited improved CO2 capturing capacity.