What are catalysts divided into morphology? 10

Catalysts are characterized by catalytic activity, selectivity, lifetime, or stability.

1. Catalytic activity: The catalyst participates in the chemical reaction, reduces the activation energy of the chemical reaction, and greatly accelerates the rate of the chemical reaction, which indicates that the catalyst has catalytic activity. The rate of catalytic reaction is a measure of the activity of the catalyst, and the activity is the most important index to evaluate the quality of the catalyst.

2. Selectivity: A catalyst only has an obvious acceleration effect on a certain type of reaction, and has little or no acceleration effect on other reactions, which is the selectivity of the catalyst. The selectivity of the catalyst determines the direction of the catalytic action, and the direction of the chemical reaction can be controlled or changed by selecting different catalysts.

3. Life or stability: The stability of the catalyst is expressed in life, which includes thermal stability, mechanical stability and anti-toxicity stability.

Overview of catalysts

1. Definition: A substance that can change the chemical reaction rate of other substances in a chemical reaction, but its mass and chemical properties have not changed before and after the reaction is called a catalyst (also known as a catalyst).

2. Function: change the chemical reaction rate of other substances.

3. Emphasis: The role of the catalyst is to change the chemical reaction rate of other substances, which may be accelerated or slowed down, and should not be simply understood as a catalyst that can only accelerate the chemical reaction rate of other substances.

The three main characteristics of catalysts are as follows:

1. High efficiency: the catalytic efficiency of enzymes is higher than that of inorganic catalysts, making it faster;

2. Specificity: an enzyme can only catalyze one or a class of substrates, such as proteases can only catalyze polypeptides, and dipeptidase can catalyze various kinds.

dipeptides formed;

3. Mildness: It means that the chemical reaction catalyzed by enzymes is generally carried out under milder conditions.

Catalytic bending relenting agent refers to a substance that can change the reaction speed of other substances in a chemical reaction, and its own quality and chemical properties have not changed before and after the chemical reaction Some catalysts can indeed slow down the reaction rate, and what the book says only refers to the usual situation, generally speaking, junior high school and high school teaching without special instructions are understood to accelerate the reaction rate.

All it takes to know is that catalysts are not just used to speed up the reaction rate. Once the reversible reaction reaches equilibrium, the addition of a catalyst does not break the equilibrium, but only accelerates the forward and reverse reactions at the same time. The degree of acceleration is the same.

The nature of the catalyst is to play the role of catalysis, reduce (or increase) the reaction activation energy of the reactants, accelerate the reaction rate, or slow down, but it does not participate in the chemical reaction, only plays the role of catalysis.

The five basic characteristics of a catalyst are as follows:

1) The catalyst can accelerate the rate of chemical reactions, but it does not enter the measurement of chemical reactions;

2) The catalyst is selective to the reaction, that is, the catalyst is selective to the reaction type, reaction direction and product structure;

3) Catalysts can only accelerate chemical reactions that are thermodynamically possible, but cannot accelerate reactions that cannot be thermodynamically possible;

4) The catalyst can only change the rate of the chemical reaction, but not the position of the chemical equilibrium;

5) The catalyst does not change the chemical equilibrium, which means that the catalyst that works in the positive direction is also effective in the opposite direction.

A catalyst generally refers to a substance that increases the rate of a reaction without changing the Gibbs free energy change in the total standard of the reaction. It can also be expressed as a substance that can increase the rate of chemical reaction without changing the chemical equilibrium in a chemical reaction, and its mass and chemical properties do not change before and after the chemical reaction. According to statistics, more than 90% of industrial processes use catalysts, such as chemical, petrochemical, biochemical, environmental protection, etc.

There are many types of catalysts, which can be divided into liquid catalysts and solid catalysts according to their states; According to the phase state of the reaction system, it can be divided into homogeneous catalysts and heterogeneous catalysts, and homogeneous catalysts include acids, alkalis, soluble transition metal compounds and peroxide catalysts. Catalysts play an extremely important role in the modern chemical industry, for example, iron catalysts are used in the production of ammonia, vanadium catalysts are used in the production of sulfuric acid, and different catalysts are used in the polymerization of ethylene and the production of rubber from butadiene.