A catalyst makes a chemical reaction go faster but does not get used up. It lowers the activation energy by giving a different way for the response to happen. It takes part in the reaction but stays the same at the end. Many people think a catalyst makes more product or breaks bonds, but it does not. It only helps reactions go faster.

Key Takeaways

• A catalyst makes chemical reactions happen faster and does not get used up. It helps reactions go quicker, but does not change what is made at the end.

• There are two main kinds of catalysts. Positive catalysts make reactions faster. Negative catalysts, called inhibitors, make reactions slower.

• Catalysts are important in daily life. They help make things like plastics and food. They also help lower pollution and save energy in factories.

Catalyst Definition

What Is a Catalyst

A catalyst is like a helper in a chemical reaction. It makes the reaction go faster, but it does not get used up. The catalyst stays the same after the reaction ends. If you add a catalyst, you do not get more product. You just get the product in less time. Reactants change into products, but a catalyst does not change.

Tip: A catalyst helps you finish a reaction faster. It does not change what you get at the end.

Scientific Role

• A catalyst lowers the activation energy for a reaction. Activation energy is the smallest amount of energy needed to start. With a catalyst, particles have an easier way to react. This lets more particles react at once, so the reaction is quicker.

• On the molecular level, a catalyst gives a new path for the reaction. This path needs less activation energy. The catalyst can make temporary bonds with reactants. These bonds, like hydrogen bonds, help the reaction happen. The energy from these bonds helps the reaction move forward.

• A catalyst can form short-lived intermediates with reactants. For example, it might join with one reactant to make an intermediate. This intermediate reacts with something else, and the catalyst is free again. The catalyst is not used up in this process.

Catalyst type

1. Catalysts are classified based on their effect on the rate of a chemical reaction.

Catalysts are divided into two main categories: positive catalysts make reactions faster. Negative catalysts, also known as inhibitors, slow down reactions. You can see the difference between them in the table below:

2. Based on the phase (state) of the catalyst and reactants, catalysts can be categorized as follows:

• Homogeneous catalysts: The catalyst and reactants are in the same phase (usually gas or liquid).

• Heterogeneous catalysts: The catalyst and reactants are in different phases. Typically, the catalyst is a solid, while the reactants are gas or liquid. (Click to view heterogeneous catalyst categories.)

• Biocatalysts: Enzymes are highly efficient and selective biocatalysts. They are proteins that catalyze nearly all biochemical reactions in living organisms.

Catalyst Uses

A catalyst accelerates a reaction by lowering its activation energy (the minimum amount of energy required for a reaction to occur). While participating in the reaction, its mass and chemical properties remain unchanged afterward. This means that a very small amount of catalyst can effectively convert a large amount of reactants, resulting in a highly efficient reaction.

Main application areas

Catalysts are used in nearly every aspect of modern industry and life. Here are a few of the most important areas:

1. Chemical Production (Core Application)

This is the largest and most important application area for catalysts. The production of the vast majority of chemical products relies on catalysts.

• Petroleum refining and cracking: Using catalysts such as zeolites, heavy, macromolecular hydrocarbons in crude oil are "cracked" into lighter, high-value, smaller products such as gasoline, diesel, propylene, and ethylene. The fuel and plastics we use all come from this process.

• Synthetic polymer materials: The production of plastics (such as polyethylene and polypropylene), synthetic fibers (such as polyester and nylon), and synthetic rubber requires specific catalysts (such as Ziegler-Natta catalysts) for the polymerization of monomers (such as ethylene and propylene).

• Production of sulfuric acid and nitric acid: These are two of the most important basic chemical raw materials. Their production processes (contact sulfuric acid production and ammonia oxidation production of nitric acid) both rely on catalysts (vanadium pentoxide and platinum-rhodium mesh).

2. Environmental protection

Catalysts play a key role in reducing pollution and protecting the environment. The most typical example is automobile exhaust treatment.

• An automotive three-way catalytic converter: Installed in the vehicle's exhaust pipe, it contains a honeycomb-shaped catalyst (typically containing precious metals such as platinum, palladium, and rhodium). It simultaneously reduces three harmful substances in exhaust gas:

• Carbon monoxide (CO) is oxidized to carbon dioxide (CO₂);

• Hydrocarbons (HC) are oxidized to carbon dioxide (CO₂) and water (H₂O);

• Nitrogen oxides (NOx) are reduced to nitrogen (N₂).

• Industrial waste gas treatment: This process treats organic waste gas and nitrogen oxides emitted by factories, using a similar principle to automobile exhaust treatment.
  

Everyday Examples

Catalysts are in many things you use every day. Here are some examples:

• You use bottles, paper, and clothes made with catalysts.

• When you eat bread or cheese, you enjoy what catalysts do.

• Catalysts also help treat waste, lower greenhouse gases, and support green chemistry.

When you see a car, eat a sandwich, or use plastic, remember a catalyst helped make it.

You can find catalysts all around you. They help reactions go faster by lowering activation energy. This makes things work better and quicker.

• Catalysts help new ideas in factories and energy.

• They make the air cleaner by using catalytic converters.
  Think about how catalysts help technology and keep the Earth safe every day.

FAQ

What happens to a catalyst after a reaction?

You can get the catalyst back after the reaction. It stays the same and does not change. The catalyst is not part of the product. It does not get used up.

Can you use the same catalyst for different reactions?

Most catalysts only work for certain reactions. You must pick the right catalyst for each process. One catalyst cannot help every reaction.

Why do you need catalysts in industry?

Catalysts save energy and time for companies. They make reactions go faster and work better. This helps lower costs and makes less waste.