What Does catalysis Mean
The etymology of catalysis leads us to the Greek word katálysis , which can be translated as "dissolution . " The term is used to refer to the increase in the speed of a chemical reaction due to the participation of a catalyst .
Accelerate a chemical reaction
Catalyst is called , meanwhile, the substance that, used in a limited amount, manages to accelerate the speed of a reaction and can then be recovered without having undergone substantial modifications (its mass, for example, does not undergo changes).
Catalysis accelerates a chemical reaction
Catalysis, in short, is the process that allows to increase the speed of a reaction through the intervention of a catalyst. When the synthesis of an industrial product is carried out, it is usual for a catalysis to be developed to reduce the time required for the operation.
While a catalyst promotes catalysis, an inhibitor achieves the opposite effect. What inhibitors do is disable throttle .
The vast majority of chemical products that are generated commercially use catalysts at some point in production. When refining oil , for example, catalysis is very important.
General ranking
There are different classes of catalysis depending on the type of catalyst. The homogeneous catalysis is carried out when the catalysts and the reactants in the same phase. In this framework, catalysts and reagents combine creating an unstable intermediate, which continues to combine with more reagents to form products and, in turn, regenerate the catalyst.
The heterogeneous catalysis , on the other hand, implies that the catalysts and reagents are in different phases. What these catalysts do is provide a surface on which the reaction can be triggered.
Homogeneous catalysis
Summarizing the aforementioned, in this type of catalysis, the catalysts cause a change in the reaction mechanism by combining with certain reagents to generate instability. Within homogeneous catalysis we can find another classification, which gives rise to acid and organometallic compounds .
From the first we can say that the homogeneous catalyst that is most frequently studied is the proton , because water is the most common solvent and generates protons through self-ionization . In the hydrolysis of esters, for example, acids are used to speed up the process; if they are not included, then almost all aqueous solutions do not hydrolyze (their rate is so low that hydrolysis cannot be observed).
With respect to the other class, the use of soluble organometallic compounds are included in the homogeneous catalysis, while that of metals on a solid or bulk support belongs to the heterogeneous. The hydroformylation , a process for starting aldehydes alkene is a very common example and the Wacker process for converting ethylene to acetaldehyde, and Cativa , obtaining acetic acid and CO taking MeOH.
We must distinguish homogeneous catalysis from heterogeneous
Heterogeneous catalysis
When talking about different phases , reference is made to gas, liquid and solid , without neglecting water and oil . For the reaction to take place, the heterogeneous catalyst has to be able to absorb at least one of the reactants, which in turn have to spread on its surface.
After the reaction is complete, the products need to be absorbed so that they spread a certain distance from the surface of the solid. Often this relocation of products and reagents between two phases plays a determining role in the speed at which the reaction occurs, more precisely by limiting it.
To successfully carry out heterogeneous catalysis it is important to investigate the chemical aspects of the surfaces and the phenomena associated with them and the other components used throughout the reaction.