[Show abstract][Hide abstract] ABSTRACT: Several zirconium-based metal-organic frameworks (Zr-MOFs) have been synthesized using ammonium hydroxide as an additive in the synthesis process. Their physicochemical properties have been characterized by N(2) adsorption/desorption, XRD, SEM, FTIR, and TGA, and their application in CO(2) adsorption was evaluated. It was found that addition of ammonium hydroxide produced some effects on the structure and adsorption behavior of Zr-MOFs. The pore size and pore volume of Zr-MOFs were enhanced with the additive, however, specific surface area of Zr-MOFs was reduced. Using an ammonium hydroxide additive, the crystal size of Zr-MOF was reduced with increasing amount of the additive. All the samples presented strong thermal stability. Adsorption tests showed that capacity of CO(2) adsorption on the Zr-MOFs under standard conditions was reduced due to decreased micropore fractions. However, modified Zr-MOFs had significantly lower adsorption heat. The adsorption capacity of carbon dioxide was increased at high pressure, reaching 8.63 mmol g(-1) at 987 kPa for Zr-MOF-NH(4)-2.
[Show abstract][Hide abstract] ABSTRACT: A nanosize Zr-metal organic framework (Zr-MOF, UiO-66) with a uniformed particle size around 100 nm was solvothermally synthesized and activated by solvent exchange method, vacuum drying and heating. The activation process with an exchangeable guest solvent produced the Zr-MOF with a high surface area by removal almost all guest and free terephthalic acid molecules from the pores enhancing its capacity for adsorption. The nanosize Zr-MOF also showed strong thermal stability up to 753 K. The Zr-MOF was tested for hydrogen and carbon dioxide adsorption at varying pressures and temperatures and it exhibited adsorption capacity of 1.6 wt% (H2) at 1 atm, 77 K and 79 cc (CO2) g−1 at 1 atm, 273 K, respectively. The heat of H2 adsorption was estimated to be 6–12 kJ mol−1 while the heat of CO2 adsorption was determined to be around 28 kJ mol−1.
Chemical Engineering Journal 04/2012; 187:415–420. · 4.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Zirconium-metal organic frameworks (Zr-MOFs) were synthesized with or without ammonium hydroxide as an additive in the synthesis process. It was found that addition of ammonium hydroxide would change the textural structure of Zr-MOF. The BET surface area, pore volume, and crystal size of Zr-MOF were reduced after addition of ammonium hydroxide. However, the crystalline structure and thermal stability were maintained and no functional groups were formed. Adsorption tests showed that Zr-MOF presented much higher CO2 adsorption than CH4. Zr-MOF exhibited CO2 and CH4 adsorption of 8.1 and 3.6 mmol/g, respectively, at 273 K, 988 kPa. The addition of ammonium hydroxide resulted in the Zr-MOF with a slight lower adsorption of CO2 and CH4, however, the selectivity of CO2/CH4 is significantly enhanced.Graphical abstractZr-metal organic frameworks (Zr-MOF) exhibit high CH4 and CO2 adsorption and additive of ammonium hydroxide produces Zr-MOF with higher selectivity of CO2/CH4.View high quality image (95K)Highlights► Zr-MOFs were prepared with addition of ammonia as additive. ► Ammonia additive affects textural structure of Zr-MOF. ► Nanosize Zr-MOF presents high adsorption of CH4 and CO2. ► Ammonia modified Zr-MOF exhibits high selectivity of CO2/CH4.
Journal of Colloid and Interface Science 01/2012; 366(1):120-124. · 3.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Amino-functionalized Zr-MOF (amino-Zr-MOF) was synthesized using 2-aminoterephthalic acid as an organic linker. The physicochemical properties of the material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and N2 adsorption to understand its crystalline structure, morphology, thermal stability, and porous structure. CO2 adsorption isotherms on amino-Zr-MOF were obtained at 1 atm and at different temperatures. In addition, CO2 and CH4 adsorption at high pressure (up to 10 atm) was also measured. CO2 adsorption capacity on amino-Zr-MOF was 9 mmol/g at 988 kPa, 0°C, while CH4 adsorption capacity was 3.7 mmol/g at 900 kPa, 0°C. The heat of CO2 adsorption on amino-Zr-MOF was estimated to be 29.4 kJ/mol. Continuous column tests of CO2 adsorption were performed at different concentrations of CO2 in nitrogen at 20 mL/min and 0.7 g adsorbent and total adsorbed amounts of CO2 within the column during the breakthrough time were calculated to be 4.55, 5.26 and 4.37 mmol/g at 10%, 15% and 20%CO2, respectively.
International Journal of Smart and Nano Materials. 01/2012;