Effect of NH4NO3 pre-treatment on hydrogen adsorption properties of Na+, K+, Ag+, Li+, H+, Ni2+, Ca2+, Cu2+ and Mg2+ exchanged natural clinoptilolite

The objective of this study was to investigate the effect of NH 4 NO 3 modification and calcination pretreatment on the hydrogen adsorption properties of Gördes clinoptilolite (CLN). The H + form (H-CLN) was obtained by modification with 1.0 M NH 4 NO 3 for 12 h followed by calcining at 450 °C for 6 h. The cation-exchanged samples of the H-CLN were obtained with 0.1 and 0.5 M of NaNO 3 , KNO 3 , LiNO 3 , AgNO 3 , Ni(NO 3 ) 2 , Ca(NO 3 ) 2 , Cu(NO 3 ) 2 and Mg(NO 3 ) 2 solutions. XRD analysis demonstrated that the pretreatment used did not lead to the loss of the crystalline structure of the samples. XRF results indicated a slight increase in the SiO 2 /Al 2 O 3 ratio, from 5.35 for CLN to 5.45–5.84 for H-CLN and its cation-exchanged forms. The BET surface areas (35.68–259.18 m 2 g −1 ) and hydrogen adsorption capacities of the CLNs (0.244–0.726 wt% at 77 K) demonstrated that the applied NH 4 NO 3 exchange and calcination pretreatment markedly enhanced the textural and gas adsorption properties. The 0.5-Li-CLN exhibited the highest hydrogen adsorption capacity of 0.726 wt%. • CLN material was prepared via calcination following ammonium exchange pretreatment. •Ion exchange applied after pretreatment. •Applied treatment procedure does not cause to progressive dealumination. •0.5-Li-CLN sample showed highest H 2 adsorption capacity.