Evaluation of porous structure by Kr and Xe desorption halftimes with X-Ray Fluorescence analysis

Abstract

X-Ray Fluorescence analysis based on excitation with 109 Cd source and registration of characteristic X-rays with Si(Li) detector was used to record the kinetics of desorption of Kr and Xe from carbonaceous samples of 1–100 mg after their treatment with the inert gases at temperatures from 20 to 700 °C. Activated coals with a known pore distribution were used to demonstrate that the Kr desorption half-life is inversely proportional to the square of the pore diameter in the range from 0.7 nm to 50 nm. Although the absorption of Xe was 2–10 times higher in the same pores than the absorption of Kr, the desorption of Xe was about 2.83 times slower than the desorption of Kr. The later fact speaks in favor of using Kr and Ar as a marker for evaluating porous structures rather than Xe. • Simultaneous ED-XRF control of Kr, Xe, Fe, Cu, Zn, Pb, and H in carbon samples. • Evaluation of pore diameters by halftimes of Kr and Xe desorption. • Clarification of correlations between metallic admixtures and pore distribution. • In the same pores, Xe desorption is by 2.83 times slower than that of Kr.