Chemical and physical testing of catalysts, powders and other materials provide necessary information for optimizing, troubleshooting and developing materials and catalysts. Environex’s materials characterization capabilities provide benchmark measurements for comparison to commercial alternatives, identify optimal materials, diagnose performance or processing problems, and quantify a material’s unique characteristics.
Materials Characterization Methods
Inductively Coupled Plasma Atomic Emission Spectroscopy measures concentrations of multiple trace elements down to the ppm level depending on the instrumental detection limit. ICP-AES can be used to analyze liquid or solid samples. ICP-AES is capable of analyzing complex matrices with little interference due to the high temperatures of inductively coupled plasma.
BET surface area analysis is a physiosorption method using gas adsorption isotherms to calculate the surface area of a material. The adsorption isotherm measures the quantity of gas adsorbed by the solid at a constant temperature as a function of relative pressure. Using the BET theory, the surface area of the material is calculated. Both single and multipoint BET surface are methods can be used to determine the surface area of the material. Surface area can be used to monitor a material’s solubility, absorptive capacity, catalytic activity and stability.
Pore size volume analysis uses BJH adsorption and desorption isotherms, Langmuir isotherms, and t-plots to determine a material’s overall porosity (nonporous or porous), pore types (open pores, closed pores) and size (macropores, mesopores, micropores). Pore size and BJH pore volume are important characteristics relating to the material’s solubility, absorptive capacity, catalytic activity, stability, chemical reactivity of solids and the physical interaction of solids with liquids and gases.
Temperature Programmed Reduction (TPR) analysis is a chemisorption method which determines the temperatures needed for complete reduction of a material using hydrogen as the reducing gas. The consumption of hydrogen is measured as a function of temperature and time. The area under the TPR curve represents the total hydrogen consumed. This area is used to calculate the oxygen storage capacity of the material. Oxygen storage capacity is an important parameter for developing oxidation catalysts for oxygen limited reactions, such as TWC catalyst for automobile exhaust treatment. Common oxygen storage materials include cerium oxide powder, zirconium oxide powder, and other mixed rare earth oxides.
Mean particle sizes and particle size distribution are measured using electrical zone sensing in a wet dispersion. Particle sizes can be measured between 0.3 µm to 300 µm. Particle size analysis is important for efficient use and selection of raw materials, monitoring and optimizing in-process materials and characterizing final products.
Coated materials are tested for adhesion using mechanical stress and ultrasonic techniques. Adhesion testing results can be used to optimize particle size of the coating, optimize coating formulation and refine the coating technique.
Crush Strength Testing is important to determine the physical strength of catalyst substrates, whether they are monoliths, beads or pellets.
Attrition Testing is available to determine the physical durability of a powder or pellet, modeling the harsh environment it might see in service.
Scanning Electron Microscopy is crucial to understanding the micro-scale morphology of particles. These properties can impact physical durability, catalytic performance and coatability of a catalyst or powder.