https://doi.org/10.1016/j.ccst.2022.100028
“The CO2 loading capacity measurements were carried out by using a gas absorption setup that is shown in Fig. 2. The equipment description and calculation of CO2 loading capacity are explained elsewhere (Ramezani and Di Felice, 2019; Ramezani et al., 2018). The rig consists of a 1 L reactor, pressure transmitter (accuracy, ± 0.15% FS), temperature sensor (uncertainty of ± 0.1 K), two impellers, vacuum pump, gas storage tank, gas cylinders and water bath (uncertainty of ± 0.1 K).
Fig. 2. Schematic diagram of the gas absorption setup: 1) vacuum pump; 2) pressure transmitter; 3) temperature indicator; 4) gas storage tank; 5) equilibrium cell; 6) heat jacket connected to water bath; 7) external magnetic stirrer; 8) water bath.
Before starting the experiment, N2 is supplied to the reactor to remove any trace gases. The fresh solvent is fed into the reactor and then a vacuum pump is used to remove N2. The fresh solvent was allowed to reach the desire temperature and the pressure and temperature measurements are recorded using sensors. The system is left to reach equilibrium and vapor pressure of solvent (PV) is recorded. At stable pressure and temperature, CO2 is introduced from the gas storage tank to the reactor. The total moles of CO2 injected into the reactor from gas storage tank is calculated using equation (1).(1)(nCO2)i=VTRTT(P1z1−P2z2)where TT is temperature (K) and VT is volume of gas storage tank (L). P1 and P2 are initial and final pressure of CO2 in the gas storage tank before and after injection of CO2 to the reactor, respectively. Z1 and Z2 refer to the CO2 compressibility factors at pressures P1 and P2, respectively. The compressibility factors of CO2 were calculated using the Peng-Robinson equation of state (Peng and Robinson, 1976). The reactor is then allowed to reach the vapor-liquid equilibrium. Thereafter the total pressure in the reactor is recorded (Ptot). The total moles of CO2 that remains in the reactor (nCO2)f is calculated by equation (2).(2)(nCO2)f=(Ptot−PV)(VR−VS)RTRZ3where VR and VS are the volumes of the reactor (L) and solvent (L), respectively. Z3 is the CO2 compressibility factors at final pressure. The CO2 loading capacity (α) of MDEA + KLys solutions at different temperatures and different KLys concentrations was obtained using equation (3).(3)α=(nCO2)i−(nCO2)fnMDEA+KLys
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