Do Catalysts Participate in Chemical Reactions?

Catalysts are a seemingly contradictory presence in chemical reaction systems: they can change the reaction rate, but their mass and chemical properties remain unchanged before and after the reaction. This characteristic raises questions about whether catalysts truly "participate" in chemical reactions.

The basic definition of a catalyst indicates that its main function is to change the rate of a chemical reaction without altering the thermodynamic equilibrium of the reaction itself. In other words, whether or not a catalyst is present, the initial and final states of the reaction are the same; the catalyst simply shortens the time required for the reaction to reach equilibrium.

From the core characteristics of catalysts, one of their key functions is to lower the activation energy of the reaction. Like creating a gentler path for a mountain climber, the catalyst provides reactant molecules with a reaction pathway requiring less energy.

From the perspective of their mechanism, the "catalysis" of a catalyst is not merely "observation." It first interacts with the reactants, forming unstable intermediate products, thus lowering the activation energy required for the reaction—this step is a clear process of participation. Subsequently, the intermediate products rapidly decompose, generating the target products while the catalyst restores its original structure and properties, achieving "recycling." Simply put, the catalyst is a "temporary participant" in the reaction, not an "outsider."

In high-temperature environments, the intermediate products decompose, carbon monoxide is oxidized to carbon dioxide, and nitrogen oxides are reduced to nitrogen and oxygen, while the precious metal catalyst itself is not consumed and continues to function. This technology has become standard in automobiles, effectively reducing exhaust pollution, and is a readily observable application of catalysts for ordinary people, confirming their characteristic of "participating in the reaction and regenerating." In modern large-scale chemical plants, catalysts are crucial for achieving efficient and clean production. For example, in the process of producing an important organic chemical raw material, the use of advanced catalysts with special structures can significantly improve the selectivity of the target product, suppressing side reactions from the source. Such catalysts not only improve the efficiency of a single reaction but also maintain high activity for several years under harsh reaction conditions, greatly reducing energy consumption and overall production costs, demonstrating their core economic value in large-scale production.

Catalyst selectivity is one of its most important characteristics, manifested in two aspects: different types of chemical reactions require different types of catalysts, and the same reaction system may yield different products when different catalysts are used.

For example, catalysts such as platinum, palladium, and nickel are suitable for catalytic hydrogenation reactions, while vanadium pentoxide, manganese dioxide, and molybdenum trioxide are suitable for oxidation reactions. Using ethanol as a raw material, various products such as acetaldehyde, ethylene, and diethyl ether can be obtained under different catalysts and temperature conditions. This selectivity allows chemists to "guide" chemical reactions in specific directions, which is particularly important in complex drug synthesis.

From a practical application perspective, the significance of catalysts goes far beyond simply accelerating chemical reactions. They enable many reactions that would otherwise be difficult to carry out at normal temperature and pressure, significantly reducing energy consumption and production costs, and improving product selectivity and purity. According to statistics, approximately 80% to 85% of chemical production processes use catalysts, including the synthesis of ammonia, sulfuric acid, and nitric acid, the polymerization of ethylene, propylene, and styrene, and the comprehensive utilization of petroleum, natural gas, and coal.

The efficient application of catalysts means less energy consumption and lower pollution emissions, which has profound implications for environmental protection and sustainable development.

author: Hazel
date: 2026-01-06