Study of process parameters that enable direct spray drying synthesis of UiO-66-NH₂

This study explores the direct spray drying synthesis of UiO-66-NH₂, a zirconium-based metal-organic framework (MOF). Focusing on the impact of process parameters on yield and purity, this research employs a solvent-free approach, integrating continuous manufacturing principles for a more sustainable and efficient production process. The influence of gas flow rate, inlet temperature, feed flow rate, and precursor solutions solid loading (SL) were systematically investigated. The prepared samples, mainly at two different precursor solid loadings; labelled as 3%SL-UiO-66-NH₂ and 6%SL-UiO-66-NH₂, were fully characterised and benchmarked against the solvothermal prepared sample. X-Ray diffraction (XRD) analysis indicated the ability to prepare a totally crystalline UiO-66-NH₂ at 150 °C inlet temperature at 3% and 6% SL, without any preheating/mixing steps, and regardless of the other process conditions. Thermogravimetric analysis (TGA) indicated the presence of a higher degree of structural defects within the 3%SL-UiO-66-NH₂ sample. The CO₂ adsorption capacity was consistent with the decreasing order of surface area and defects as 3%SL-UiO-66-NH₂ > STH-UiO-66-NH₂ > 6%SL-UiO-66-NH₂. This work provides insight into green synthesis and process optimization for MOF synthesis which is beneficial for industrial applications.