Physicochemical characterization of solid catalysts: Morphological, structural, textural, reducibility, and acid-base insights

Catalysis is a cornerstone of chemical manufacturing, with most industrial chemicals produced via catalytic processes. Heterogeneous catalysts are especially valued for their ability to operate under mild conditions, enhancing process efficiency and sustainability. Establishing structure-performance relationships requires comprehensive characterization of key physicochemical properties, such as structural, textural, reducibility, acid-base, and morphological characteristics, which directly influence catalytic activity, selectivity, and stability. This article presents a guide on the characterization of solid catalysts, providing practical insights for both novice and experienced researchers. It addresses morphological analysis through SEM and TEM, which provides essential information on particle size, shape, and distribution. Structural features, such as crystalline phase identification, crystal size, and crystallinity, are investigated using X-ray diffraction, while molecular structure is analyzed using Raman spectroscopy. Textural properties, such as surface area, pore volume, and pore size distribution, are discussed with gas physisorption. Reducibility is explored through temperature-programmed reduction, while acid-base properties are evaluated via NH ₃-TPD, CO ₂-TPD, and FT-IR spectra of pyridine to determine the amount, strength, and nature of acid and basic sites. Each section provides an overview of the theoretical principles behind these techniques, practical tips for accurate data acquisition, and case studies illustrating how to extract and interpret the most relevant information. Special emphasis is placed on ensuring that researchers can effectively extract and interpret data from each method correctly, helping to optimize catalyst characterization for the design and improvement of catalytic heterogeneous processes.