Ultradeep Removal of Moisture in Gases to Parts-per-Billion Levels: The Exploration of Adsorbents

Abstract

Owing to the rigid standards of manufacturing semiconductor components, decrease of the moisture to parts-per-billion (ppb), at a global level, is always vital but extremely nerve-racking in the production of high-purity gases. Herein, typical adsorbents including oxides (SiO2 and γ-Al2O3), zeolites (4A and NaX), and metal–organic frameworks (MOFs; HKUST-1, UiO-66, and ZIF-8) are investigated with respect to the abilities of ultradeep dewatering from N2. Compared with other adsorbents, NaX performs much better on both dewatering efficiency (DE, from 2750 to 66 ppb) and the adsorption capacity (AC, 1.55 × 104 L N2·g–1). Moreover, it is for the first time experimentally and theoretically proved that the dewatering ability of X zeolite mainly depends on its cation species (Na+, Li+, K+, Cs+, Mg2+, Ca2+, Sr2+, or Ba2+), the forces between the zeolite and H2O, and the number of H2O molecules per cell of the zeolite. CaX thus shows a fascinating DE from 2750 to 33 ppb, a huge AC of 9.08 × 104 L N2·g–1, and an ideal reusability, compared with results of the scarce contributions reported to date.

Enhancing oxidation resistance of Cu(I) by tailoring microenvironment in zeolites for efficient adsorptive desulfurization

“…For instance, the water content of BP commercial diesels is in the range of 100 and 500 ppmw (parts per million by weight) 35 . Such water in fuels not only accelerates the oxidation of Cu(I), but also competes with thiophenic sulfur compounds to interact with active sites in adsorbents 36 . Hence, from the viewpoint of practical application, it is extremely desirable to develop an approach to tune the nature of Cu(I)Y zeolite, so that the accessibility of Cu(I) sites to moisture can be excluded and the stability of Cu(I) is thus improved.…”

Adjusting accommodation microenvironment for Cu+ to enhance oxidation inhibition for thiophene capture

“…Commercial fuels contain more or less water; for example, there are 100–500 ppm of water in BP commercial diesels. The water in fuels is able to speed up the oxidation of Cu + , and in the meanwhile cause the competition of aromatic sulfur compounds for binding active sites in the adsorbents 18,43 . On the basis of these results, the model fuel containing 300 ppm water was used to explore the adsorption capacity.…”