(725g) Fast Mechano-Chemical Synthesis N-Doped Uio-66 with Dopamine to Enhance Chlorobenzene Competitive Adsorption Under Humid Air

In this work, we initiated a novel mechanochemical strategy to prepare N-doped UiO-66(Zr) using dopamine (UiO-66(Zr)@DA) with competition coordination with Zr⁴⁺, and then investigated their adsorption towards chlorobenzene/acetaldehyde under humid air conditions. To further confirm the speculation, the prepared composites UiO-66(Zr)@DA were characterized by N₂ adsorption, X-ray diffraction, scanning electron microscopy and Fourier transform infrared analysis. Meanwhile, temperature programmed desorption (TPD) experiments were conducted to estimate the desorption activation energy of chlorobenzene/acetaldehyde on the UiO-66(Zr)@DA.

In comparison with the UiO-66(Zr) previously reported, the composites particles were more irregular texture, suggesting a lower crystallinity of the M-UiO-66(Zr) [01]. The particle size of it in this work was about 100 nm, which was similar to the crystals reported in the literature [02]. After being composited with DA, pronounced changes can be found in particle size and morphology of the UiO-66(Zr) composites. No any micro-sized aggregation of spheres appeared in all the M-UiO-66(Zr) composites, indicting no occurrence of dopamine self-polymerization during process of composite formation. Their crystal particle size firstly increased and then decreased with increasing DA content (< 7.0 wt%). More interestingly, the composites particle depicts a more regular cubic-like shape in compared to parent UiO-66(Zr). Among which, the M-UiO-66(Zr)@DA_3.0 possessed the largest crystal particle size (250-300 μm) with high crystallinity (Fig. 1c). Different from other composite MOFs [03, 04], it contributed to UiO-66 crystallization by adding a fraction of dopamine into the UiO-66 framework. This may arise from the deprotonation of the amino group of DA and thus promoted the coordination between the oxygen groups of terephthalic acid and Zr⁴⁺ mental center in the UiO-66(Zr).

Obviously, the M-UiO-66(Zr)@DA_3.0 possessed the highest adsorption uptake towards acetaldehyde covering the whole measured pressure range. The uptake value of acetaldehyde on the N-doped UiO-66 was increased by 33 and 140% compared to that on the UiO-66 and UiO-66-NH₂, respectively. The significant increase of adsorption capacity can be mainly attributed to the increase of electron density of Zr-O cluster caused from N coordination, which efficiently enhanced the interaction towards benzene with attract electron group.