Vacprep 061

Nitrogen adsorption experiments were performed on a Micromeritics TriStar II Plus at 77 K (Micromeritics Instrument Corporation, Norcross, GA). Samples were dried on a Micromeritics VacPrep 061 sample degas system at 95 °C under flowing N₂ gas prior to analysis. Surface area was determined by use of the Brunauer-Emmett-Teller (BET) method and total pore volume was determined by the single point method at relative pressure (P/P₀) of 0.97. An individual sheet was determined to have a BET surface area of 51 m²·g⁻¹ and a single point total pore volume of 0.188 cm³·g⁻¹.

The crystalline phases of the MOF-801, MIP-202, and Muc-Zr MOF were characterized by X-ray powder diffraction using a RIGAKU MINIFLEX 600 diffractometer and a BRUKER France SAS AXS D8 ADVANCE diffractometer. Thermo-gravimetric analyses (TGA, TA Instruments SDT Q600 Thermal Gravimetric Analyzer, New Castle, DE, USA) were recorded using a ramp of 10 °C/min. The textural properties of the materials were characterized by nitrogen adsorption at 77 K using a micromeritics VacPrep 061 (sample degas system) and a micromeritics TriStar (Surface Area and Porosity Analyzer (TriStar 3000 gas adsorption analyzer (Micromeritics, Norcross, GA, USA). The equivalent specific surface areas were determined using the BET transform of the sorption isotherm in the relative pressure range between 0.005 and 0.05, taking 0.162 nm² as the cross-sectional area for adsorbed nitrogen molecules. Scanning electron microscopy (SEM) was performed using a using a Hitachi S4800 microscope (Hitachi, Tokyo, Japan). The ultrasonic bath was an Elma transonic Ti-H-5 brand (Singen, Germany). Fourier transform infrared spectroscopy in transmission mode has been performed using a IFS55 Bruker spectrometer (Bruker, Paris, France) (MCT cryodetector) with a 2 cm⁻¹ resolution in a spectral domain 6000–400 cm⁻¹. The different powdered materials were diluted using dry KBr before being pressed and further analysed.

Before gas adsorption measurements (n = 2) were carried out in a Tristar II 3020 (Micromeritics, Norcross, GA, USA), the samples were dried under vacuum (0.15 mbar) overnight at 30 °C (VacPrep 061, Micromeritics, Norcross, GA, USA). The samples were analyzed at 77.350 K using a nitrogen relative pressure (p/p₀) in the 0.01–0.99 range. The specific surface area of the powders was calculated using the Brunauer, Emmmett and Teller (BET) adsorption theory (7-point analysis in the 0.05–0.2 p/p₀ range). To determine the macro- and mesopores size distribution, a modification to the Kelvin equation (Equation (1)) was used (Barrett–Joyner–Halenda method) [2 (link)].
$\log \left(\frac{\mathrm{P}}{{\mathrm{P}}_0}\right)=\frac{2\mathsf{\sigma }\mathrm{V}}{{\mathrm{RTr}}_{\mathrm{k}}}$
where σ and V are the surface tension and molar volume of liquid nitrogen, respectively, R is the universal gas constant, T the absolute temperature and r_k the Kelvin radius. The radius of the pores at the different relative pressures follows directly from the sum of the thickness of adsorbed nitrogen layer with the r_k.

The PSD of the MgSt brands was measured using laser diffraction in dry dispersion mode at a dispersion pressure of 0.5 bars. The cumulative undersized particle parameters d₁₀ (μm), d₅₀ (μm) and d₉₀ (μm) were calculated. Morphological evaluation of the studied MgSt brands was conducted using scanning electron microscopy (SEM). The SSA of the studied MgSt brands was determined by nitrogen adsorption using the Brunauer-Emmett-Teller (BET) method. Samples of approximately 1 g were dispensed into 3/8” OD sample tubes and prior to analysis, the tubes were outgassed using a VacPrep 061 (Micromeritics, USA) outgassing unit under vacuum at ambient temperature for a minimum of 15 h. Experiments were conducted using a Tristar 3030 instrument (Micromeritics, USA). For each sample tube, specific surface area was calculated from a linear fit of the adsorption isotherm in a relative pressure range of 0.05–0.30 Pa. Three samples tubes were tested for each brand of MgSt and the reported results are the mean values of triplicate determinations [40 ].