Adsorption of CH4 and CO2 on Zr-metal organic frameworks

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.Figure optionsDownload full-size imageDownload high-quality image (93 K)Download as PowerPoint slideHighlights► 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.