3.2.3. Physical Adsorption

The specific Brunauer-Emmet-Teller surface areas (*SBET*) of the CaO catalysts were measured by nitrogen physisorption at 77 K using an ASAP 2020 PLUS HD88 apparatus (Micromeritics, Norcross, Georgia, USA). Before the measurements, the samples were evacuated at 573 K for 3 h.
