Advanced Analysis of Clay Microporosity Using High-Resolution N-Ar Adsorption Isotherms Coupled with the Derivative Isotherm Summation Method.

The textural properties of synthetic and natural clays in the sodium form and exchanged with tetramethylammonium cations (TMA) were characterized using N and Ar physisorption isotherms at cryogenic temperatures. Specific surface areas and micro/mesoporous volumes were determined using the BET and the models. The analysis requires the use of reference isotherms measured at the same temperature on the surface of non-porous materials with an identical chemical composition.

Thermodynamic data of adsorption reveal the entry of CH and CO in a smectite clay interlayer.

The ability of smectite clays to incorporate gases in their interlayers is shown to be conditioned by interlayer spacing, depending, in turn, on phyllosilicate layer composition and effective size of the charge-balancing cations. As illustrated by earlier in situ X-ray diffraction and spectroscopic characterization of the gas/clay interface, most smectites with small-size charge-balancing cations, such as Na or Ca, accommodate CO and CH in their interlayers only in a partially hydrated state resulting in the opening of the basal spacing, above a certain critical value. In the present study CH and CO adsorption isotherms were measured for Na- and Mg-exchanged montmorillonite up to 9 MPa using a manometric technique.

Optimization of Washing Processes in Solvothermal Synthesis of Nickel-Based MOF-74.

Solvothermal synthesis is the most preferable preparation technique of metal-organic frameworks (MOFs) that consists of reactants mixing, ultrasonication, solvothermal reaction, product washing, and solvent evacuation. Owing to fast reaction kinetics in solvothermal reaction, this technique allows for production of uniform MOF particles with high crystallinity, high phase purity, and small particle sizes. However, it exhibits some difficulties of washing processes that may involve the blockage of pores due to incomplete removal of reactive medium from MOF products.

Smectite fraction assessment in complex natural clay rocks from interlayer water content determined by thermogravimetric and thermoporometry analysis.

The smectite content is a key parameter to be determined for various applications of clays and clay-rich rocks. The quantity of interlayer water characteristic of swelling domains can be used to assess the smectite content in clays. We propose in this study to use a simple approach to determine water distribution in clays (mainly between pores and interlayers) by means of thermoporometry and thermogravimetric analysis.