Application of Raman spectroscopy and chemometrics in the mechanochemical synthesis of TIFSIX-3-Ni HUMs using twin screw extrusion

Hybrid ultra-microporous materials (HUMs) are a novel category of porous materials featuring a distinctive 3D structure composed of square lattice layers. In this study, HUMs was produced on a small scale using either solvothermal or ball milling synthesis methods. Building on the successful synthesis of HUMs via ball milling, twin-screw extrusion (TSE) appears to be a suitable method for large-scale and potentially continuous synthesis. The effect of process parameters, such as feeding rate, screw speed, barrel temperature, and liquid-to-solid ratio L/S (m/m), on the properties of the TIFSIX-3-Ni HUM was investigated. The results are presented in two sections: In the first section, we conducted a characterization and qualitative investigation to determine the crystallinity of the collected powder by analysing PXRD diffractograms. The second section involves a quantitative study using partial least squares (PLS) multi-variate analysis to measure the conversion rate of the HUM acquired. This was achieved by utilizing the most effective developed calibration model. The PXRD analysis revealed that the most favourable parameters for producing the HUM involve operating at 50 and 150 RPM, at L/S of 0.5 (m/v), and manually feeding. The highest yield of inactivated TIFSIX-3-Ni was 77.7 %, achieved using Raman spectroscopy combined with the PLS model for quantitative analysis This study marks the first successful continuous synthesis of HUMs and the development of a predictive model for process optimization.