Superhydrophobic ZIF-67 with exceptional hydrostability

Abstract

Zeolitic Imidazolate Framework-67 (ZIF-67) has been used in a variety of applications including catalysis, separations, and energy storage. However, the weak hydrostability of ZIF-67, due to structural hydrolysis and degradation, dramatically limits their applicability after aqueous exposure. In this work, cosolvent-stabilized superhydrophobic, highly hydrostable ZIF-67 was synthesized at room temperature using a facile, one-pot hydrothermal synthesis route, and the effect of cosolvent concentration on ZIF-67 crystal structure properties and hydrostability was studied systematically. The underlying mechanism for the cosolvent-supported hydrostability improvement was also proposed. Furthermore, the influence of hydrotreatment on the resultant ZIF-67s' catalytic performance was studied in the ‘Sabatier reaction’ for CO₂ to synthetic natural gas (CH₄) conversion. The ZIF-67-derived calcined catalysts obtained from the hydrotreated samples of the cosolvent-stabilized ZIF-67 exhibited no prominent loss in catalytic performance and showed better CO₂ conversion, higher CH₄ selectivity, and less CO production, in comparison to the conventional ZIF-67 samples. Notably, the use of a lower ligand-to-metal ratio (∼8) in the current synthesis significantly reduced the overall chemical consumption, achieving highly economically and environmentally friendly manufacturing of exceptionally hydrostable ZIF-67.