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What is a Catalyst?
Catalysts play an important role in many aspects of our daily lives. In the field of chemistry, a catalyst is a substance that promotes a chemical reaction in a smaller amount than the reactants in the reaction, but does not itself change.
Applications fields of catalyst technology
How does catalyst technology "help us in our daily lives?" Some of you may not have any idea about that. Catalysts are used in the production of raw materials for all kinds of chemical products around us, such as clothing, shoes, containers, bags, and construction materials. Catalysts are also used to purify factory and automobile emissions, removing nitrogen oxides (NOx) and sulfur oxides (SOx) that cause acid rain. Other products such as pharmaceuticals, foods, fertilizers, and agricultural chemicals are also synthesized using catalysts.
Typical fields where catalyst technology is used
Swipe sideways→ to view the table.
| Fields | Application (example) | Catalysts used (example) |
|---|---|---|
| Resources/Energy | Crude oil processing | Hydrodesulfurization catalysts |
| Petroleum product refining | Catalytic reforming catalysts | |
| Refining of petrochemical feedstock, gasoline, kerosene, diesel oil | Fluid Catalytic Cracking catalysts | |
| Heavy oil | Heavy oil desulfurization catalysts | |
| Conversion of solid coal to gas | Coal gasification catalysts | |
| Purification of energy sources (Hydrogen) such as fuel cells (Generation of hydrogen by decomposition of ammonia molecules) |
Ammonia synthesis catalyst | |
| As a process of artificial photosynthesis (Generation of hydrogen by electrolysis of water) |
Manganese catalyst | |
| Improving the performance and durability of fuel cells for fuel cell electric vehicles (FCEV) | Electrode catalyst | |
| Environment/consumer (household use) | Removal of nitrogen oxides (NOx) | NOx storage-reduction catalyst |
| Removal of sulfur oxides (SOx) | Desulfurization catalyst | |
| Removal of soot | PM combustion catalyst | |
| Deodorization | Deodorizing catalyst | |
| Removal of VOCs (*) | VOC decomposition catalyst | |
| Air purification | Photocatalyst | |
| Gasification of biomass (*) (Converting biomass-derived compounds into useful compounds) |
Biomass conversion catalyst |
* VOCs (volatile organic compounds)
A generic term for organic compounds that exist as gases in the atmosphere at room temperature and pressure and have boiling points between 50℃ and 260℃. (Toluene, xylene, ethyl acetate, etc., contained in paints, printing inks, adhesives, cleaning agents, gasoline, thinners, etc.)
* Biomass
Reusable organic resources derived from plants and animals. (Wood, seaweed, garbage, paper, animal carcasses and excreta, plankton, etc.)
How a catalyst works
Catalysts can be broadly divided into two types: "homogeneous catalysts" and "heterogeneous catalysts". Homogeneous catalysts are catalysts that work by dissolving in solution, etc. They include acids and bases (substances that work in pairs with acids) and complex (*) catalysts in which an organic compound is bonded to a metal. Heterogeneous catalysts, on the other hand, are catalysts that work in the solid state, and include supported (*) catalysts in which active ingredients like precious metals are immobilized on carriers (*) such as metal oxides, activated carbon, and alumina (a white powder used as a raw material for aluminum).
* Complex
A compound in which some kind of substance is bound around a metal element. It refers to a complex of a metal ion and a ligand bound to it. Depending on the type of metal and ligand, it can have various structures such as a linear 2-coordinated structure, planar 4-coordinated structure or octahedral 6-coordinated structure.
- Typical transition metal complexes and their forms
-
* Carrier / supporting
A carrier is a substance that serves as a base for fixing other substances. Alumina, silica, and activated carbon are often used as carriers for catalysts and adsorbents. Supporting is to fix a substance such as a metal to a base.
- Structure and role of supported catalysts
-
Homogeneous catalysts
Homogeneous catalysts are used in many organic synthetic reactions, and are suitable for specific reactions because they dissolve and work with the reactants.
Reactant + Catalyst → [Reaction intermediates] → Products + Catalyst
Reactant + Catalyst
↓
[Reaction intermediates]
↓
Products + Catalyst
Catalysts and reactants combine to form reaction intermediates. These reaction intermediates (*) decompose themselves or collide with other molecules, transforming into stable products and regenerating the catalyst, and the reaction proceeds by repeating this process.
* Reaction intermediates (intermediates)
Substances produced in the process from the initial reactants to the final product when a series of chemical reactions occur in succession. Reactions indicated by chemical reaction formulas are rarely completed by a single elementary reaction (a chemical reaction in which one or more chemical species react directly to a product in a single step through a transition state), but only by a series of elementary reactions that occur in succession to reach the final product. Therefore, the substances produced as a result of each elementary reaction are all reaction intermediates, except for the final product.
- Typical products (for chemical products with complex structures in small quantities)
- ・Pharmaceuticals
・Pesticides
・Liquid crystal materials, etc.
- Advantages
- ・High activity in solution
- ・High selectivity can be achieved by substituting ligands to change electronic and steric elements
- Disadvantages
- ・Difficult to separate because it reacts in the same phase as raw materials and products
- ・Decomposed at high temperature
- ・Difficult to reuse expensive catalysts
- Typical products (for chemical products with complex structures in small quantities)
- ・Pharmaceuticals
・Pesticides
・Liquid crystal materials, etc.
Heterogeneous catalysts
These are used in industrial processes that produce large quantities of chemicals and in the purification of exhaust gases from internal combustion engines (ICE / Internal Combustion Engine) because of their easy separation and recovery from the product, their ability to be used repeatedly, and their generally higher durability than homogeneous catalysts.
- Advantages
- ・Easy to separate from product after reaction
- ・Functional at high temperatures
- Disadvantages
- ・Reactants are less likely to diffuse into the catalyst
- ・Generally less selective
- ・Do not contribute to catalytic activity except for the surface part of the supported metal
- Typical products (used in practical processes for manufacturing basic chemical products)
- Automobile exhaust gas purification, petroleum refining, etc.
Specific example (3-way catalysts for automobiles)
Three-way catalysts consisting mainly of platinum, palladium, and rhodium are used as heterogeneous catalysts to decompose and purify hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) contained in the exhaust gas from the engine.
3-way catalyst chemical reactions
- 1. Carbon monoxide (CO) → Oxidized to "Carbon dioxide (CO2)"
(CO + 12O2→CO2) - 2. Hydrocarbon (HC) → Oxidized to "Water (H2O)" and "Carbon dioxide (CO2)"
(HC + 32O2→H2O + CO2) - 3. Nitrogen oxide (NOx) → Reduced to "Nitrogen (N)" and "Water (H2O)"
(2NO + 2H2→N2 + 2H2O)
About products
We will introduce a wide variety of exhaust gas purification catalysts developed and manufactured by Cataler, as well as electrocatalysts for fuel cells, carbon materials for storage batteries, and battery materials for next-generation vehicles.
Automotive catalyst
Automotive catalysts may not be visible to the general public, but they are a necessary technology to clean harmful gases emitted from engines.