Modification of natural clinoptilolite zeolite to enhance its hydrogen adsorption capacity

• Published in: Research on chemical intermediates 2024-03, Vol.50 (3), p.1455-1473
• Main Authors: Akyalcin, Sema, Akyalcin, Levent, Ertugrul, Ecem
• Format: Article
• Language: English
• Subjects: Adsorption; Ammonia; Catalysis; Chemistry; Chemistry and Materials Science; Clinoptilolite zeolites; Desorption; Hydrogen; Inorganic Chemistry; Isotherms; Physical Chemistry; X-ray fluorescence
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-023-05212-2

In this study, natural clinoptilolite was treated with HCl, HNO 3 , and C 2 H 2 O 4 at various concentrations (0.1, 0.5, and 1.0 M) at different temperatures (60, 70, and 80 °C) and treatment times (2, 3, and 4 h). The hydrogen adsorption capacity of natural clinoptilolite increased from 0.446 to 3.255 mmol/g after treating with 0.5 M HNO 3 at 80 °C for 2 h. The correlation of the newly produced textural and structural properties with hydrogen adsorption ability is explained by characterizing the modified clinoptilolites using X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, and temperature programmed desorption of ammonia (NH 3 -TPD) measurements. The results show that the hydrogen adsorption capacity of modified clinoptilolites is associated with both the quantity and strength of the strong acid sites, in addition to the enhanced surface area and micropore volume. The hydrogen adsorption data for natural and acid-treated clinoptilolite samples at 77 K obeyed the Freundlich isotherm model.