katalyseeren

Katalyseeren (the catalyst) is a substance that increases the rate of a chemical reaction without being consumed in the overall process. It does so by providing an alternative reaction pathway with lower activation energy, typically by binding reactants, stabilizing transition states, and releasing products unchanged. In practical terms, catalysts are regenerated at the end of each catalytic cycle, allowing a small amount to affect many reaction events.

Catalysis is commonly divided into several classes: homogeneous catalysis, where the catalyst shares the same phase as the reactants; heterogeneous catalysis, where the catalyst is in a different phase (usually a solid) from gas or liquid reactants; and biocatalysis, in which enzymes act as highly specific biological catalysts.

Industrial use highlights include iron catalysts in the Haber-Bosch synthesis of ammonia, nickel catalysts in hydrogenation reactions, zeolites and other solid acids as catalysts in petrochemical processing, and platinum-group metals in automotive catalytic converters. Catalysts are evaluated by activity, selectivity, and stability. Quantitative measures include turnover number (TON) and turnover frequency (TOF), which describe how many product molecules are formed per catalyst site and per unit time, respectively.

Common challenges include catalyst poisoning, fouling, and deactivation, which can reduce efficiency. Ongoing research seeks to improve activity and selectivity, reduce precious-metal loading, and enable greener, more sustainable processes.

See also: catalysis; enzyme; homogeneous catalysis; heterogeneous catalysis.