Nonacid Carbon Materials as Catalysts for Monoethanolamine Energy-Efficient Regeneration

Abstract

In the CO2 capture process, solid acid catalysts have been widely adopted to decrease energy consumption in the amine regeneration process owing to abundant acid sites. However, acid sites unavoidably degenerate in the basic amine solution. To address the challenge, nonacid carbon materials including carbon molecular sieves, porous carbon, carbon nanotubes, and graphene are first proposed to catalyze amine regeneration. It is found that carbon materials can significantly increase the CO2 desorption amount by 47.1–72.3% and reduce energy consumption by 32–42%. In 20 stability experiments, CO2 loading was stable with the max difference value of 0.01 mol CO2/mol monoethanolamine (MEA), and no obvious increase in the relative heat duty (the maximum difference is 4%) occurred. The stability of carbon materials is superior to excellent solid acid catalysts, and the desorption performance is comparable. According to the results of theoretical calculation and experimental characterization, the electron-transfer mechanism of nonacid carbon materials is proposed, which is not only beneficial for MEA regeneration but also the probable reason for the stable catalytic activity. Owing to the excellent catalytic performance of carbon nanotube (CNT) in the HCO3 – decomposition, nonacid carbon materials are quite promising to enhance the desorption performance of novel blend amines, which will further reduce the cost of carbon capture in the industry. This study provides a new strategy to develop stable catalysts used for amine energy-efficient regeneration.

Synergistic Catalysis of SO42–/TiO2–CNT for the CO2 Desorption Process with Low Energy Consumption

“…These results illustrated that H would transfer from catalysts to HCO 3 – and form H 2 CO 3 and then release CO 2 . Compared with CNTs, ST could not decompose HCO 3 – directly . Therefore, ST-1 and ST-2 catalyze MEACOO – decomposition more effectively through proton transfer.…”

“…The apparatus used for the CO 2 absorption–desorption experiments has been reported in our previous work . First, 100 mL of 5 M MEA aqueous solution was poured into a 250 mL three-necked flask and heated to 40 ± 1 °C using an oil bath with stirring.…”

“…The apparatus used for the CO 2 absorption−desorption experiments has been reported in our previous work. 27 First, 100 mL of 5 M MEA aqueous solution was poured into a 250 mL three-necked flask and heated to 40 ± 1 °C using an oil bath with stirring. When the temperature of the solution was stable at 40 °C, pure CO 2 was introduced into the MEA solution at a flow rate of 320 ± 8 mL/min for 2 h. Subsequently, 0.50 wt % STC-x catalyst was added to rich-CO 2 loaded MEA solution (0.56 ± 0.01 mol CO 2 /mol MEA) to catalyze MEA regeneration.…”

“…A synergistic catalytic effect is designed to be achieved. Carbon materials can catalyze HCO 3 – decomposition by charge transfer, , and solid acid can decompose MEACOO – according to a proton transfer mechanism. ,, It is worth mentioning that a large surface area and mesoporous structure led to CNTs being selected as the support. − The selection of appropriate solid acids on the CNT support will be crucial in optimizing the catalytic performance.…”

“…In our previous work, pristine carbon nanotubes (CNTs) exhibited superior activity and stability compared to widely researched H-ZSM-5 zeolites in amine regeneration, making them more promising candidates for preparing supported catalysts. 27 CNTs can efficiently catalyze HCO 3 − decomposition through unlocalized charge transfer, exhibiting excellent desorption performance and stability. Nevertheless, owing to the lack of acidity, CNTs showed insufficient catalytic performance in carbamate decomposition.…”