The mass of sorbent per differential length of the reactor is calculated from the mass flow rate of MgCl2, the gas flow rate 𝑉 ̇ and the differential gas volume 𝑑𝑉 as shown in eq. (18). Note that since it is a solid, the sorbent is assumed to not contribute to the volume or volumetric flow rate of the flowing phase, which are thus defined as those of the gas phase.