Effect of salt modification on thermal behavior, immersion heats and methane adsorption properties of chabazite tuff

Abstract

In this study, the adsorption of methane (CH4) on chabazite tuff from Bala, Turkey, and that of salt-treated forms (Na+, K+, Li+, Ca2+ and Mg2+) was investigated. Structural and thermal characterization of chabazite samples were examined using X-ray diffraction, X-ray fluorescence, thermogravimetry, differential thermal analysis and N-2 adsorption methods. The heats of immersion of the zeolite samples were measured with a Calvet-type C-80 calorimeter. At 30 A degrees C, the Q (imm) values for heat of immersion decreased in the following order: Mg-CHA (113.62 J g(-1)) > Li-CHA (112.82 J g(-1)) > CHA (108.50 J g(-1)) > Ca-CHA (99.82 J g(-1)) > Na-CHA (80.00 J g(-1)) > K-CHA (63.79 J g(-1)). Adsorption properties of methane for all chabazite samples were obtained at 0 and 25 A degrees C pressures up to 100 kPa. It was found out that CH4 adsorption capacities of the natural and salt-treated chabazites at 0 A degrees C (0.831-1.315 mmol g(-1)) were higher than those at 25 A degrees C (0.672-1.163 mmol g(-1)) as expected.