katalysators

Katalysators, often called catalysts in English, are substances that accelerate chemical reactions without being consumed in the overall process. They provide an alternative reaction pathway with lower activation energy, allowing more reactant molecules to be converted to products per unit time. After the reaction, the catalyst remains chemically unchanged, although its surface may require regeneration if it becomes poisoned or fouled.

Catalysis occurs in several forms. Heterogeneous catalysts are solids that interact with reactants in gas or liquid form on their surfaces. Homogeneous catalysts operate in the same phase as the reactants, typically in solution as metal complexes, and can offer high selectivity. Biocatalysts are biological molecules, mainly enzymes, that perform highly specific transformations under mild conditions.

Mechanisms typically involve adsorption of reactants to the catalyst surface, surface reactions forming intermediates, and desorption of products. The catalyst’s active sites and surface structure determine activity and selectivity. Performance can be limited by poisoning, sintering, or fouling, and may require regeneration or replacement. Catalysts are often supported on materials or designed as nanostructures to maximize active area.

Applications include important industrial processes such as iron catalysts for ammonia synthesis (Haber-Bosch), nickel catalysts for hydrogenation and reforming, and cobalt or iron catalysts for Fischer–Tropsch synthesis. Automotive catalytic converters use platinum, palladium, and rhodium to oxidize carbon monoxide and hydrocarbons and to reduce nitrogen oxides. Catalysis also enables various fine-chemical syntheses and environmental technologies, including air and water remediation.

History and outlook: The concept emerged in the 19th century, with early work associated with Jöns Jacob Berzelius. Ongoing research seeks more selective, robust catalysts, including nanostructured and single-atom catalysts, as well as catalysts for sustainable energy applications such as electrochemical and photocatalytic CO2 reduction.