Effect of Synthesis Parameters on the Formation of Zeolitic Imidazolate Framework 8 (ZIF-8) Nanoparticles for CO₂Adsorption

Abstract

Zeolitic imidazole frameworks-8 (ZIF-8) is a subclass of metal-organic frameworks (MOFs) with the transition metal cations (Zn 2þ ) linked by imidazolate anions forming tetrahedral frameworks in zeolite-like topologies. This article reports on the synthesis of ZIF-8 nanoparticles by varying the synthesis parameters at room temperature. The crystallization duration, molar ratios, and pH of the mixture solution were varied in order to study the effects of these parameters on the formation of ZIF-8 nanoparticles. The structural and morphology transformation of the resultant particles were characterized using x-ray diffraction, field emission scanning electron microscopy, and Brunauer-Emmett-Teller (BET) surface analysis. The CO 2 adsorption characteristics of ZIF-8 nanoparticles were tested using CO 2 physisorption analysis. Mature structural evolution was observed for ZIF-8 synthesized at 60 and 1440 min, but insufficient crystallization was found for ZIF-8 synthesized at 5 min. Meanwhile, ZIF-8 nanoparticles synthesized under lower amount of methanol resulted in larger particle size and higher crystallinity. Poorly intergrown ZIF-8 nanoparticles were observed for samples synthesized using a mixture solution with pH 8.2. Although different particle sizes and relative crystallinities were obtained for the ZIF-8 samples, synthesis using different molar ratios of the mixture solution, insignificant variations of BET surface areas, and CO 2 adsorption capacities were found.

Influence of the 2-methylimidazole/zinc nitrate hexahydrate molar ratio on the synthesis of zeolitic imidazolate framework-8 crystals at room temperature

“…The adsorbed nitrogen in all samples at low pressures ( P / P 0  < 0.08) increased steeply, suggesting the existence of micropores. The results were in line with those reported previously 29,33,34 . Furthermore, the isotherms of ZIF-8 prepared at Hmim/Zn molar ratio of 4 and 8 exhibited hysteresis loop near P / P 0  = 1, indicating the presence of interparticle mesoporosity and macroporosity between ZIF-8 particles 35 , in consistent with SEM results.…”

“…27 and Li et al . 33 . This is mainly due to the different synthesis conditions as well as to the different pre-treatment before N 2 adsorption.…”

Water-based synthesis of zeolitic imidazolate framework-8 for CO2 capture

“…As the reaction temperature increased from 25 when H 2 O/Hmim was 100 : 1, which might be due to the presence of amorphous materials in the ZIF-8 samples. 38 The results are consistent with the relative crystallinity as shown in Fig. 1. …”

Synthesis of zeolitic imidazolate framework-8 on polyester fiber for PM2.5 removal

“…The results were in line with those reported previous. 25,30,31 Furthermore, the isotherms of ZIF-8 exhibited hysteresis loop near P/P 0 ¼ 1, indicating the presence of interparticle mesoporosity and macroporosity between ZIF-8 particles. 32 The main ltration mechanism is the strong adsorption force of various porous structures on the substance rather than a simple sieve effect.…”