ABSTRACT
Characterization of nanoporous materials is important for the quantification and prediction of their physical, chemical, and mechanical properties. Successful applications of nanoporous materials require detailed characterization. As discussed in Chapter 5, nanoporous materials are mainly of two types, such as crystalline-like zeolites or amorphous mesoporous materials. Characterization of nanoporous materials is thus based on several techniques, which are applicable for crystalline as well as amorphous structures. Generally, the structure elucidation of nanoporous materials can be carried out by powder X-ray diffraction (XRD) techniques in combination with scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Other spectroscopic techniques like Fourier transformation infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopy are also to measure the hydroxyl bond strength of zeolites and mesoporous materials. In addition, the thermal stability, which is an important parameter for the application of nanoporous materials, particularly as catalysts, has also been studied by different calorimetric techniques like thermogravimetry-differential thermal analysis (TG-DTA). Nanoporous materials with simple geometries can be characterized by means of transport coefficients such as diffusion and viscosity of the fluid or the gas flow through the material. Due to the porous structure, adsorption-desorption is an important method to serve as a fingerprint of the internal pore structure of the material and allows one to evaluate specific surface area, pore size, pore volume, and wall thickness. All the methods mentioned above require a lengthy sample processing period, depending on the quality of the sample, having all the instruments to analyze the samples is demanding as for the routine analysis visualization is not there, either for the bulk or the surface. Compared with different surface and bulk characterization techniques like XRD, UV-vis, IR, etc., the calculation time for molecular simulation techniques is reasonable, requiring only software and multiple processor units, which consequently provide valid data to support or design new materials. One can visualize the bulk, the surface, location of impurity, and the reason for a specific site to be active. One has to consider that there are several methods to characterize nanoporous materials, but due to their complex structures and unavailability of proper methods, molecular-level understanding is still distant. It has already been mentioned that experiments have their own limitations; thus, the combination of experiment and computer simulation is necessary to obtain a desired material with specific functionalities for proper applications. This chapter covers structural characterization of the material mainly in terms of chemical composition, spectroscopic analysis, mechanical stability, and porosity to show the capability of simulation to
justify and validate experimental observation. It also can provide lot of space to the experimentation where it is hard and analysis is ambiguous.
