katalysoima

Katalysoima, or catalysis, is the acceleration of a chemical reaction by a substance called a catalyst, which is not consumed in the overall process. The catalyst provides an alternative reaction pathway with a lower activation energy, allowing more reactant molecules to react in a given time without altering the reaction's thermodynamic feasibility. Catalysts are distinct from reagents in that they are recovered after the reaction and may participate in multiple turnovers. They may be homogeneous (in the same phase as reactants), heterogeneous (in a different phase, often a solid), or enzymatic (biocatalysis, using biological molecules such as enzymes). Homogeneous catalysts often enable high selectivity under mild conditions; heterogeneous catalysts are common in industrial processes and easily separated. Enzymes provide highly specific catalysis under physiological conditions.

Key properties include reaction rate enhancement, selectivity (chemo-, regio-, and enantioselectivity), turnover number (TON) and turnover frequency (TOF). Catalysis can fail due to deactivation by poisoning, sintering, or fouling, and catalyst recovery or regeneration is often important. Applications span energy, environment, and chemical manufacture: synthesis of ammonia on iron catalysts, catalytic converters for vehicle exhaust (platinum-group metals), polymerization catalysts, and many pharmaceutical syntheses. In green chemistry, catalysis aims to increase efficiency and reduce waste.

Historically, understanding of catalysis advanced in the 19th and 20th centuries, with models describing surface reactions and enzyme catalysis shaping modern kinetics and mechanism theory.