Catalyst in Chemistry

Catalyst is a term you may come across while studying chemistry, particularly while learning about chemical reactions. Some chemical reactions happen rapidly, while others take a long time and require more materials or effort. A catalyst can help with this. What does the word catalyst mean? In this lesson, we’ll discover.

In chemistry, what is a catalyst?

In chemistry, catalysts are chemicals that change the rate of a reaction by modifying the reaction route. A catalyst is usually used to speed up or raise the rate of a reaction. Catalysts, on the other hand, are employed to break or reestablish chemical bonds between atoms in molecules of various elements or compounds. Catalysts, in essence, stimulate molecules to react, making the entire reaction process easier and more efficient.

The following are some of the most important characteristics of catalysts:

1.A chemical reaction is not started by a catalyst.

2.The reaction does not consume a catalyst.

3.Catalysts have a tendency to react with reactants to generate intermediates while also assisting in the production of the final reaction product. 

A catalyst can regenerate after the entire procedure.

Solid, liquid, or gaseous catalysts are all possible. Metals or their oxides, such as sulfides and halides, are among the solid catalysts. Catalysts include semi-metallic elements including boron, aluminum, and silicon. In the same way, pure liquid and gaseous elements are used as catalysts. These components are sometimes combined with appropriate solvents or carriers.

A catalytic reaction is one that involves the use of a catalyst in their system. Catalytic action, in other terms, is a chemical interaction between a catalyst and a reactant. As a result, chemical intermediates are formed, which can easily react with each other or with another reactant to generate a product. The catalyst is replenished when the reaction between the chemical intermediates and the reactants occurs or takes place.

The reaction modes between the catalysts and the reactants normally vary a lot, and it’s even more complicated with solid catalysts. Acid-base reactions, oxidation-reduction processes, coordination complex creation, and free radical production are examples of reactions. Surface characteristics and electrical or crystal structures have a big impact on the reaction mechanism of solid catalysts. Some solid catalysts, such as polyfunctional catalysts, can react with the reactants in several ways.

A Short History about catalyst

 In its broadest sense, a catalyst is something that accelerates the rate of a process. The word catalyst comes from the Greek v, which means “to annul,” “to join,” or “to pick up.” Meanwhile, chemist Elizabeth Fulhame pioneered the concept of catalysis, which she explained in her book published in 1794. The material of this book was based on her oxidation-reduction investigations.

Gottlieb Kirchhoff, a Russian chemist of German ancestry, studied the first chemical reaction in organic chemistry that used a catalyst in 1811. In 1835, a Swedish chemist named Jöns Jakob Berzelius used the term catalysis to describe reactions that were accelerated up by particular compounds. After the reaction, the chemicals remained unaltered.

Types of catalyst  with Examples

Depending on the necessity or demand of the chemical reaction, many types of catalysts might be utilized. The following are some of them:

1.Positive Catalysts

Positive catalysts are those that speed up the rate of a chemical process. It accelerates the reaction by lowering the activation energy barriers, allowing a high number of reaction molecules to be transformed into products, increasing the percentage of product yield.

Positive catalyst example: In the Haber’s method for preparing NH3, iron oxide functions as a positive catalyst, increasing the yield of ammonia despite less nitrogen reaction.

2.Negative Catalysts 

Negative catalysts and catalysts that slow down the rate of reaction. It slows down the reaction by raising the activation energy barrier, which reduces the amount of reactant molecules that can be converted into products, slowing down the reaction.

Negative catalyst example: Acetanilide, which serves as a negative catalyst to slow down the decomposition of hydrogen peroxide into water and oxygen, is used to slow down the decomposition of hydrogen peroxide.

Accelerators or promoters

A promoter or accelerator is a chemical that boosts the catalytic activity.

For example, in Haber’s process, the Promoters are molybdenum or a combination of potassium and aluminum oxides.

Inhibitors or Catalyst Poisons

Catalyst poisons or inhibitors are substances that reduce the action of the catalyst.

When the catalyst palladium is poisoned with barium sulfate in quinolone solution during the hydrogenation of an alkyne to an alkene, the reaction is stopped at the alkene level. Lindler’s catalyst is the name of the catalyst.

Units

“Katal ” is a derived SI unit for measuring a catalyst’s catalytic activity. It’s also measured in moles per second. If we were to describe a catalyst’s productivity, we could use the turnover number (or TON). The turnover frequency (TOF), which is TON per time unit, can be used to describe catalytic activity. The enzyme unit is also its biochemical equivalent.

Conclusion 

We conclude that Chemical reactions are faster and more energy efficient when catalysts are used. Selectivity is another important attribute of catalysts, which allows them to control a process to enhance the amount of desired product while reducing the number of undesired byproducts.