Hapetuskatalyytti

Hapetuskatalyytti, or oxidation catalyst, is a substance that increases the rate of oxidation reactions by providing active sites for the transfer of oxygen from an oxidant to a substrate, while remaining chemically unchanged over many cycles. In industrial chemistry, oxidation catalysts are typically solids that operate heterogeneously, although homogeneous catalysts are used for some liquid-phase processes.

Common materials include noble metals such as platinum, palladium, and rhodium, often dispersed on oxide supports like aluminum oxide, ceria, or titania. Metal oxides such as vanadium pentoxide on titanium dioxide, or copper- and manganese-based oxides, are also widely employed. The catalysts enable key steps such as activation of molecular oxygen on the surface and transfer of reactive oxygen to the substrate. In oxide catalysts, lattice oxygen can participate directly in the reaction, a mechanism known as Mars-van Krevelen.

Applications span automotive and chemical industries. Automotive exhaust catalysts (three-way catalysts) use Pt/Pd/Rh on oxide supports to convert carbon monoxide, hydrocarbons, and nitrogen oxides into carbon dioxide, water, and nitrogen. In industry, oxidation catalysts are used for processes such as the oxidation of sulfur dioxide to sulfur trioxide in the contact process, and for selective oxidations of alcohols and hydrocarbons to aldehydes, ketones, or acids.

Performance considerations include activity, selectivity, and stability, as well as resistance to sintering and catalyst poisoning. The high cost of noble metals, and deactivation by coking or sulfur compounds, are ongoing challenges. Research in hapetuskatalyytit focuses on improving efficiency and durability through nanostructuring, bimetallic systems, and advanced supports that enhance oxygen storage and redox properties.

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