Controllable creating mesoporous coordination unsaturated sites in UiO-66 single crystals for efficient conversion of hydrogen sulfide into polysulphur

Abstract

We report herein a facile pyrolysis etching strategy for the fabrication of UiO-66-xs single crystals with tunable coordination unsaturated zirconium sites (Zr-CUS) as well as interconnected mesoporosity. The synthesis is realized by having pristine UiO-66-xs subjected to thermal treatment, which results in the selective decomposition of thermal-sensitive organic linkers and hence the creation of permanent mesoporosity, leaving abundant Zr-CUS with enhanced degree of exposure. The prepared hierarchically porous UiO-66-xs (HP-UiO-66-xs) were innovatively applied for mild oxidation of H2S into polysulphur, achieving near 100 % H2S conversion and polysulphur selectivity in a wide range of temperatures. The superior activities can be well maintained in a continuous test of over 50 h. The Zr-CUS of HP-UiO-66-xs effectively activate H2S and O2 via the “adsorption dissociation tandem hydrogen transfer” mechanism, and the abundant mesochannels ensure efficient transport of reactants and bulky products in and out HP-UiO-66-xs, leading to catalytic activities superior to those of traditional H2S selective oxidation catalysts.