Sustainable and scalable continuous synthesis of metal-organic frameworks for CO₂ capture

This study demonstrates a continuous method for the production of high-quality ZIF-8 and HKUST-1 (surface areas over 1500 m²/g) under mild synthesis conditions (ambient pressure and temperatures below 100°C) with only environmentally preferable green solvents (water and ethanol) being used in the entire synthesis process. High yields of metal organic frameworks (MOFs) are achieved (65% for ZIF-8 and 79% for HKUST-1). The comparison between the as-synthesized samples and commercially available equivalents with respect to shape, size, surface area, thermal stability and CO₂ uptake capability was conducted in this research. The synthesized MOFs both show competitive CO₂ adsorption ability under a pressure in the range of 1–5 bar. Under a pressure of 5 bar,CO₂ uptake capacity of ZIF-8 and HKUST-1 is 3.83 mmol/g and 6.68 mmol/g, respectively, which are 3.81 mmol/g and 6.62 mmol/g, respectively, for commercialized samples. The synthesized HKUST-1 has higher values compared to the commercialized one within this range of pressures. This indicates the method developed in this study is promising to to be used for the continuous production of high-quality MOFs for CO₂ capture applications.