Construction, formation mechanism and adsorption properties for ethyl mercaptan of H2Nb4O11 nanotubes

Abstract

Designing an efficient adsorbent for removal mercaptans is of great importance to the purification of natural gas. Low-dimensional protonated nanomaterials with abundant surface hydroxyl and Brønsted acid (BA) sites have been the promising candidates for the adsorption desulfurization. Herein, a novel niobate nanotubes, H2Nb4O11 nanotubes (HNO-NTs), were constructed through a two-step intercalation strategy following freeze drying under vacuum as highly active solid acid adsorbents. The formation mechanism and textural features of the as-prepared HNO-NTs were investigated. The resulted HNO-NTs are more regular than H4Nb6O17 nanotubes, and the specific surface area of the former (ca. 222.6 m2 g−1) is higher than that of the latter (174.0 m2 g−1). The dynamic adsorption experiments shown that HNO-NTs have a high ethyl mercaptan (EM) adsorptive capacity of 52.27 mg∙g−1 with a gas hourly space velocity (GHSV) of 6000 h−1, which is greatly improved compare with that of H4Nb6O17 nanotubes (26.84 mg∙g−1). Moreover, the regenerated HNO-NTs still maintained an excellent performance after ten adsorption-desorption cycles. Finally, the possible mechanism of the adsorption of EM over HNO-NTs was proposed. This work is expected to provide a new strategy to synthesize polyniobate nanotubes and use as adsorption separation.