The preparation of X-ETS-4 by ion-exchanged method and adsorption performance of C3F8/N2

Octafluoropropane (C3F8) is widely used as etching agent in refrigeration, air conditioning and semiconductor industries. However, due to its long lifespan and strong infrared absorbing ability, once C3F8 is emitted, the atmospheric radiation absorbing ability will be permanently altered, which will result in a serious greenhouse effect. Therefore, the efficient removal technology of C3F8 is crucial in protecting the environment and alleviating the greenhouse effect. In this work, a series of X-ETS-4 (X: Mg, Ca, Sr, Ba) molecular sieves were synthesized by solvothermal and ion-exchange method. The morphology and structure of the prepared X-ETS-4 were characterized by FT-IR, XRD, and SEM, etc. The adsorption performance of the X-ETS-4 on C3F8 are determined by fixed-bed adsorption breakthrough experiments and single-component isothermal adsorption experiments. The adsorption mechanism was investigated using different adsorption theoretical models. The results show that Ba-ETS-4 exhibits high adsorption capacity and high adsorption selectivity for C3F8, achieving C3F8 adsorption separation at very low concentration (C3F8/N2 volume ratio = 1:400). The saturated adsorption capacity of Ba-ETS-4 on C3F8 reaches 155.17 mg/g (298 K, 170 kPa), which is 15.49 times more than that of Na-ETS-4. In addition, the ideal adsorption solution theory (IAST) separation selectivity of C3F8/N2 reaches 341–941 in the pressure range of 0–170 kPa.