Synthesis of ZSM-5 with high sodium content for CO2 adsorption

• This MS investigated the CO2 adsorption capacity of ZSM-5 synthesized with high sodium content.
• It was possible to obtain ZSM-5 pure and crystalline in the three different Si/Al ratios studied (25, 50 and 75).
• CO2 adsorption data fitted and analyzed by two models: Langmuir Single-Site (SSL) and Dual-Site Langmuir (DSL).
• The sample with Si/Al ratio equal 25 presented the higher affinity for CO2 molecules.

In this study, a fast synthesis of ZSM-5 zeolites with high-sodium content at three Si/Al ratios (25, 50 and 75) was carried out. Samples were characterized by thermogravimetric analysis (TG/DTG), nitrogen adsorption/desorption isotherm, X-ray diffraction (XDR), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The zeolites were tested on CO2 adsorption in a pressure range from 0 to 600 kPa and at a temperature of 303 K. Single-Site Langmuir (SSL) and Dual-Site Langmuir (DSL) models were used for fitting and analyzing the experimental data. According to the characterization techniques, pure and crystalline ZSM-5 was obtained for all Si/Al ratios under study. The CO2 adsorption/desorption isotherms showed that the sample with Si/Al equal to 25 has higher affinity for CO2 molecules. This result was confirmed by fitting the experimental data to the DSL model, which obtained better representation of the data by comparison with the SSL model. Recycling tests showed that all three zeolites were easily regenerated after the adsorption process.

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