Typically, benzene is used in the freeze-drying process, however, it usually preceded by exchange with several intermediate solvents such as methanol and ethanol. While, in supercritical CO2 procedure, the mother liquor is firstly exchanged with intermediate solvents, and then with liquid CO2. Next, the temperature is increased to transform the liquid CO2 to the supercritical region. Then, reducing the pressure transfers CO2 to the gas phase, where the entrapped gas can be easily desorbed from the pores without baring any damage to framework. Finally, the framework is cooled to ambient temperature.