Evaluating CO2 desorption performance of MEA solution with MnOx/HZ catalytic packings by visualization method

Abstract

The high energy consumption in the CO2 desorption process is one of the main issues of the chemical absorption method. To address this issue, a MnOx modified HZSM-5 catalyst (MnOx/HZ) was prepared by impregnation method and used as catalytic packing to improve the CO2 desorption rate in the monoethanolamine (MEA) solution. Since the catalytic effects mainly work around the catalytic packing, a visualization method, which can measure the CO2 desorption rate per unit surface area (vCO2/area) of a single packing, is proposed to avoid some uncertain effects occurring as the conventional bubbling method is used. The results showed that the vCO2/area of the MnOx/HZ catalytic packing is 10.06 μmol·cm−2·s−1 at 80 °C, which is 1.78 times of that of HZSM-5 and 15 to 60 times of that of commercial packings. Actually, the MnOx/HZ has more Brønsted and Lewis acid sites than HZSM-5 according to the pyridine adsorption infrared spectroscopy (Py-IR) characterization. As a result, the apparent activation energy (Ea) of the CO2 desorption reaction with the addition of MnOx/HZ can be reduced by 58.6% and 18% compared with the addition of ceramic saddle ring packing and HZSM-5, respectively. However, the catalytic performance of MnOx/HZ packings degrades gradually due to the blockage of micropores by the reaction product, that needs to be settled in the future.