Catalysts in industry
Catalysts play a critical role in modern industry. Today, catalysts are involved in the production of over 80 percent of all manufactured products. Moreover, approximately 90 percent of all industrial chemicals produced in the world use catalysts within the manufacturing process.
While “catalyst for change” has become a part of our everyday vocabulary, in the world of materials science a catalyst refers to a substance that initiates or accelerates a chemical reaction while not itself changing chemically or physically. Many of the materials humans enjoy in their daily lives depend on catalysts—from the production of plastic bottles from petroleum to the making of paper from pulp to the conversion of milk into cheese. What’s more, catalysts can help the environment by reducing toxic manufacturing byproducts, unlocking biofuels, and bringing about more efficient batteries.
Industrial catalyst properties
Because catalysts play an important role in the industrial production of materials and environmental protection, chemical engineers, plant managers, quality control technicians and researchers require a battery of scientific instruments to characterize catalysis. Of particular interest is understanding the thickness, distribution, and chemical composition of a catalyst relative to its supporting material. Too much material may waste precious commodities such as platinum, while too little material or poor distribution may make the catalyst ineffective.
Bright field transmission electron microscopy image of iron oxide quantum dots, which are used as a catalyst in a variety of chemical processing reactions. (Data courtesy of the Regional Centre of Advanced Technologies and Materials. Palacky University, Olomouc, Czech Republic.)
As researchers work to characterize catalysts, they typically turn to a range of scientific techniques:
X-ray Fluorescence spectrometry
XRF reveals the elemental composition of materials by measuring the characteristic X-ray emissions in the XRF instrument. Since most heterogenous catalysts are composed of elemental materials, XRF is typically a first-line technique in validating the quality and quantity of the elements in a catalytic material.
X-ray photoelectron spectroscopy
XPS is one of the most surface-sensitive analytical techniques. Similar in nature to X-ray fluorescence, XPS detects photoelectron emissions from an excited sample. Since photoelectrons have very weak energies compared to characteristic X-rays, XPS reveals chemical information from only the top few layers of atoms. In the field of catalysis, this is highly useful information. For example, XPS can determine the shifts in chemical states in a catalyst that has been exposed to air compared to a pristine sample. XPS can illustrate a catalyst’s performance in studying the quality of the active materials in the catalytic process.
XRD characterizes crystalline materials and can be used to determine the crystallite size of nanoparticles that carry a catalyst material. This analysis is particularly useful in determining the quality of the catalyst in a recycling process.
FTIR interrogates molecular bonds. Certain experiments can be set up to monitor the activity of acid-based catalysts when the catalytic material is introduced to a reactant. FTIR can be analyzed in-situ (in its own environmental condition) and even in operado (as the reaction takes place) to probe the working states of catalysts.
Raman spectroscopy also provides information about molecules and is complementary to FTIR. Raman shows the slight differences in the chemical sites in a catalyst material that can affect the reactivity of the various sites, helping engineers optimize the catalytic material for greater efficiency. Raman spectroscopy and infrared spectroscopy can be used microscopically to study catalytic particles as small as 1 micron for Raman microscopy and 10 microns for infrared microscopy.
EM is capable of examining materials down to the sub-angstrom level, enabling the visualization of a catalyst’s morphology and elemental distribution. Combining electron microscopy with energy-dispersive X-ray spectroscopy (EDS), today’s instrumentation enables automated nanoparticle analysis of the material’s structure and the chemistry of catalysts and their carrier materials—enabling researchers to analyze the quality of catalysts and develop new catalyst materials.
Industrial catalyst analysis
While no one analytical technique is capable of fully studying and monitoring catalysts and their activated materials, researchers can obtain the information they need using several techniques in combination. To learn more about catalyst characterization techniques and their industrial value, please watch our on-demand webinar, “Characterization of Catalysts.”
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