Zeolite@Mesoporous silica-supported-amine hybrids for the capture of CO2 in the presence of water

• Core-shell zeolite@mesoporous silica-supported-amine hybrids (5A@MSAs) were synthesized.
• 5A@MSAs exhibited excellent CO2 adsorption capacity (5.05 mmol/g) even in the presence of water.
• PEI shell dynamically hindered H2O molecules diffusion into 5A core through the chemical adsorption.
• 5A core maintained its good CO2 adsorption performance with the designed core@shell structure.
• 5 A@MSA-30 demonstrates a very stable cyclic adsorption–desorption performance.

The selective capture of CO2 under humid condition for the commercial adsorbents has always been a great challenge. Here, we come up with a simple and effective solution, i.e., fabrication a shell around the commercial zeolite particle which can dynamically hinder the diffusion of water molecules into the zeolite core to maintain its good CO2 capacity even in the presence of water. By a sol–gel coating process and a polyethylenimine (PEI) impregnation process, a series of 5A zeolite-based hybrids with a shell of mesoporous silica-supported-amine (5A@MSAs) were fabricated. The performance of CO2 separation from the simulated flue gas (with 15:85 v/v CO2/N2 and moisture) was investigated by TG and MS in a flow system. Among the obtained adsorbents, 5A@MSA-30 was demonstrated to be the best candidate for CO2 capture from the simulated humid flue gas, with the CO2 uptake as high as 5.05 mmol/g at 298 K. The results of 10 cyclic adsorption/desorption operation suggested that the PEI molecules can be stably holden in the mesoporous silica shell, resulting in a remained CO2 adsorption capacity. The amine modified zeolite not only maintained but also significantly promoted the ability of CO2 capture under humid condition; therefore, it would be a promising solution for the commercial adsorbents to capture CO2 in the presence of water.

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