What Is a Palladium Catalyst?
A palladium catalyst is a compound containing palladium manufactured for use as a catalyst.
Palladium (element symbol: Pd) is a member of the platinum group of elements with atomic number 46. A palladium catalyst is an indispensable material for organic synthesis and is widely used in drug discovery, natural product synthesis, and polymer synthesis.
In particular, the palladium catalyst cross-coupling reaction, for which the Nobel Prize in Chemistry was awarded in 2010, is world-renowned. Cross coupling reactions are reactions that selectively combine two chemical substances. There are many types of palladium catalyst, and they must be used according to the raw materials and reactions in which they are used.
Uses of Palladium Catalysts
Palladium is used in catalysts, dental materials, electrical and electronic components, and jewelry. Palladium can adsorb 935 times its own volume of hydrogen, so it is also used in hydrogen storage alloys.
Palladium catalysts are made from palladium-based compounds for use as catalysts. The catalyst itself does not change before or after the reaction, but it changes the reaction rate of the reactants. It forms reaction intermediates with the reactants, and the reaction proceeds through these reaction intermediates.
Palladium catalysts are often used in organic synthesis. In particular, they are used to synthesize target compounds using cross-coupling reactions. It is an important material for pharmaceutical synthesis and natural product synthesis. In recent years, its use in catalysts for exhaust gas purification in automobile engines has increased.
Principle of Palladium Catalysts
Typical palladium catalysts include palladium chloride, palladium acetate, and palladium complexes with phosphine ligands. These catalysts are widely used in drug discovery, natural product synthesis, and polymer synthesis.
Palladium is also used in three-way catalysts in the automotive field. A ternary catalyst is a device that can remove harmful substances such as hydrocarbons, carbon monoxide, and nitrogen oxides from automobile exhaust. Metals such as palladium, platinum, and rhodium are used.
Other Information on Palladium Catalysts
1. Palladium Catalysts Are Used to Detoxify Automobile Exhaust Gases
Automobile exhaust gases contain large amounts of toxic and environmentally hazardous substances, such as nitrogen oxides (Nox), carbon monoxide (CO), and unburned hydrocarbons (HC). Palladium catalysts are used to convert these toxic components into harmless carbon dioxide, water, nitrogen, and oxygen through oxidation and reduction reactions.
Other precious metal elements such as platinum and rhodium are also used as catalysts. Palladium is in higher demand because it is primarily used as a catalyst in gasoline-powered vehicles.
Palladium catalysts are installed after the exhaust manifold, where the exhaust from the engine is concentrated. To increase the contact area with the exhaust gas, nanometer-sized palladium catalysts are uniformly dispersed in ceramics with a honeycomb-like honeycomb structure.
The disadvantages of palladium catalysts in the use of detoxification of automotive exhaust gases are they are very expensive, and they must be applied in large quantities in advance. This is because the catalysts migrate and collect on the surface of the ceramics during use at high temperatures, reducing their surface area. In response to the depletion of palladium resources, research and development is underway to reduce the amount of palladium catalysts used.
2. Palladium Catalyst Price
Palladium used in palladium catalysts is rare and expensive metal, costing several million yen per kilogram. Since most of the demand for palladium is for gasoline-powered automobile catalysts, the higher the demand for gasoline-powered automobiles, the higher the price will rise.
In recent years, the price of palladium has risen sharply. This is due to a large supply-demand gap, with mine production at 200 tons/year and demand at 300 tons/year. Stricter environmental regulations in recent years and rising demand for gasoline-powered vehicles in China and other countries, as well as the fraudulent emission control measures for diesel vehicles, are also factors accelerating the rise in demand for gasoline-powered vehicles.
Palladium is mainly produced in Russia and South Africa, which account for the majority of palladium production, 40.5% and 37.5% respectively, according to 2017 data. The limited number of producing countries has been greatly affected by supply shortages due to political instability and other factors, and the recent sharp decline in production in Russia has also caused prices to soar.