Scalable synthesis and stability
In order to promote the industrialization of MOFs materials, it is the general trend to produce stable MOF materials at low costs and with simple operation processes. Therefore, a water-based and scalable synthesis was developed at room temperature for the large-scale preparation of [Zn2(bpy)(btec)(H2O)2]·2H2O.39As shown in Figure 7a, only by mixing the metal salt and the ligands in aqueous solution and stirring for 30 minutes, then filtering and drying, can we obtain more than 320 g of product at room temperature. TGA and DSC were tested on [Zn2(bpy)(btec)(H2O)2]·2H2O to explore its thermal stabilities (Figure 7b). Below 150 °C, the initial weight loss of ~14% was accounted for by the loss of water molecules, and then Zn2(bpy)(btec) can stabilize up to about 410 °C before its decomposition.
Besides, the adsorbents require relatively high thermostability to keep a long operation lifetime, The real C2H2-relevant separation tasks are typically implemented under more extreme conditions, typically containing a trace amount of water and acidic gases.40Herein, the structural stability of Zn2(bpy)(btec) was examined in detail. As depicted in Figure 7c, d, the PXRD patterns of those materials treated under extreme conditions (acid, base, or boiling water) coincide with those of pristine samples, which indicates that its structure has no framework collapse and still retains its crystallinity. After such treatment, its C2H2adsorption is largely maintained, comparable to the initial value (Figure S11), which demonstrated that this material is highly stable in the acidic/basic solutions (pH=1~13), even in the water up to 120 °C. The water and thermal stability of Zn2(bpy)(btec) has been superior to most C2H2-separated MOFs (Figure 7e). Its exceptionally high stability is due to its dense structure forming by the strong multiple hydrogen bonding interactions and offset π-π stacking interactions (Figure S12).