Why is catalyst characterization important?
Characterization is critical for both the design and development of novel catalysts but also for process development and optimization, including scale-up and troubleshooting. Most heterogeneous catalysts for example consist of a catalytically active metal or metal oxide located on the surface of a metal oxide support and so it is important to optimize the structure and surface chemistry to provide the appropriate selectivity and reactivity for the process of interest. Other characteristics such as particle size, porosity, and surface area are also important for optimizing diffusion and adsorption for example.
How can Malvern Panalytical’s solutions help?
Malvern Panalytical have a range of complementary solutions for the physical, structural, and elemental analysis of catalyst materials including particle size, particle shape, Zeta potential, elemental composition, and crystal structure:
X-ray fluorescence (XRF) is widely used for analyzing the elemental composition of a range of catalysts due to its high precision and reproducibility. Examples include Pt, Pd, and Rh in catalytic converters; Al, Ni, V, Ti, Fe, and S in FCC catalytic processes; and Si/Al ratios in zeolites. XRF can also be used to detect the presence and concentration of catalyst poisons that cause chemical deactivation, including Cl, S, Sn and Pb. XRF analysis can save a lot of time and money compared with alternative techniques, and Malvern Panalytical provides three main solutions: EDXRF benchtop systems such as Epsilon 4, floor-standing WDXRF systems such as Zetium, and on-line solutions such as Epsilon XFlow. Malvern Panalytical also provides several sample preparation solutions for XRF, ICP, and AA through its Claisse portfolio.
X-ray diffraction (XRD) is a fundamental tool for the design, development and production of catalysts since it can provide information on the bulk structure and composition of solid catalysts materials such as metal oxides and Zeolites. XRD systems are routinely used for monitoring the production of FCC catalysts, in particular analysing unit cell size and crystallinity. XRD can also be used to determine crystallize size either by analysing peak widths from a typical diffraction measurement or by using Small Angle X-ray Scattering (SAXS). Non-crystalline materials can also be studied using Pair Distribution Analysis (PDF). Malvern Panalytical provide two main XRD solutions, Aeris compact XRD diffractometer for routine analysis and Empyrean multi-purpose diffractometer for more detailed structural analysis.
Laser diffraction is a widely used particle sizing technique for materials ranging in size between hundreds of nanometers and several millimeters, and can be applied to wet or dry dispersions in the laboratory or on a process line. For catalyst applications, the particle size data generated using laser diffraction can be used to calculate a specific surface area (SSA) by converting the reported volume distribution into a surface area distribution. Pressure titrations can also help to understand the risk of attrition, an important factor for predicting the life of catalysts in fluidized bed reactors. Malvern Panalytical’s Mastersizer 3000 is the most widely used particle sizing tool for catalyst analysis in a laboratory setting, while Insitec can be used for on-line analysis in a production environment.
In addition to the techniques mentioned above, Malvern Panalytical offers several other solutions for catalyst analysis, including the Zetasizer, which is used to evaluate the size and stability of particulate dispersions, and the Morphologi 4, which uses image analysis to determine particle shape and size distribution. The Morphologi 4 is also available with an integrated Raman spectrometer, which provides particle-specific chemical information.