Alkali-Induced Self-Transferring Byproduct Strategy for Strengthening Sustainable Synthesis of MOF-199 Without Waste Discharge

Abstract

To eliminate the effect of the byproduct on the yield and mother liquor in synthesizing metal–organic framework (MOF), an alkali-induced self-transferring byproduct (AISB) method is proposed by introducing alkali NaOH as a quasi-reactant which indirectly makes contact with the reactants. The quasi-reactant well captures and immobilizes the byproducts volatilized from mother liquor, simultaneously reducing reaction resistance and improving concentration gradient of reactants and intensifying the crystallization. It is found that ethanol not only acts as a solvent but also is partially oxidized by the primary byproduct HNO3. Thus, the reaction environment with a strong acid is weakened, which is convenient for the formation and existence of MOF-199. It is first confirmed by the appearance of Na2CO3 and NaNO2 in the quasi-byproduct. An improved reaction mechanism of the MOF-199 material is also proposed. Also, the resultant mother liquor can be directly used for next preparation. The reaction rate constant of the AISB method reaches up to 1201.2 mol–1·h–1. A high dry base yield up to 97.3% can be calculated based on the added Cu­(NO3)2. Especially, the obtained sample MOF-199-2S shows a specific surface area of 1734 m2·g–1, which is obviously better than the samples obtained from traditional hydrothermal methods. It exhibits a CO2 static adsorption capacity of 9.03 mmol·g–1 at 1.0 bar and 273 K. Its cyclic CO2 adsorption capacity in simulated flue gas flowing through the fixed bed is stable at around 1.25 mmol·g–1 with a small pressure drop of 1.6 bar, which benefits from its large size (0.7 mm). Notably, by replacing the quasi-reactant NaOH with Cu­(OH)2, this method provides a sustainable and ingenious strategy to synthesize MOF with zero discharge.

Hierarchical Porous MOF-199 and Zeolite Composites with High Adsorption Performance for Both Toluene and Acetone

“…As shown in Figure , the characteristic FT-IR bands of MOF-199 in the range of 4000–400 cm –1 were identified based on the previous work. , FAU LSP ( n )/MOF-199 with different FAU LSP content had a similar FT-IR spectrum to that of pure MOF-199, indicating the FAU LSP ( n )/MOF-199 composites kept most of the MOF-199’s surface chemistry . Certain discrepancies were still discovered: (i) the intensity of the adsorption bands associated with the −COOH vibrations (both symmetric and asymmetric) at 1546 and 1371 cm –1 , the bands assigned to the C–O–Cu at 1111 and 938 cm –1 , and the band attributed to the Cu–O bond at 491 cm –1 were gradually weakened on FAU LSP ( n )/MOF-199, which might be ascribed to the surface coverage of MOF-199 by FAU LSP ; (ii) the shoulder peak at 1111 and 1042 cm –1 were asymmetric of pure MOF-199, which gradually got more symmetrical with the increasing amount of FAU LSP on FAU LSP ( n )/MOF-199; (iii) the −O–H stretching vibration at around 3300 cm –1 in FAU LSP ( n )/MOF-199 emerged and much clearer (specified in the left red box of Figure ); and (iv) the IR spectrum of FAU LSP ( n )/MOF-199 tended to be flat in the range of 475–425 cm –1 due to the Si–O–Al bond bending vibration (−450 cm –1 ) in FAU LSP , and even appeared a weak peak with high FAU LSP addition.…”

Optimizing the cask effect in multicomponent natural gas purification to provide high methane productivity

“…Adsorptive separation using porous solid materials under gentle operating conditions presents a more energy‐efficient and economically viable alternative for light hydrocarbon separations, provided that the adsorbents exhibit superb selectivity and capacity for the desired guest molecules as well as sufficient stability 7–20 . Emerging as a prominent class of porous crystalline materials, metal–organic frameworks (MOFs) have shown impressive potential for gas separation and purification, beneficial from their high porosity, adjustable and consistent pore dimensions, and manageable surface chemistry 21–59 . However, previous studies mainly focused on the separation of two‐component gas mixtures.…”