How does a catalyst achieve the catalytic process?

The catalytic process of a catalyst is generally that the catalyst reacts with one of the reactants to form a transition substance, and then reacts with another reactant to form a product, and the catalyst is regenerated at the same time. The transition material generated by the catalyst is less energetic than the transition material without the catalyst, thus making the reaction easier to occur and proceed. That's how it relieves.

And that's why the catalyst is involved in the chemical response.

Reducing the activation energy of the reaction is like walking, when there is no catalyst, you have to climb over a mountain, and after adding the catalyst, it is like digging a tunnel in the mountain, and passing through it directly, which naturally saves time and effort.

For example, nitrogen dioxide and carbon monoxide react to form nitric oxide and carbon dioxide, in order to get the product, you must first split nitrogen dioxide and carbon monoxide into atoms, and then you have to overcome the bond energy of covalent bonds (you understand it this way in high school, maybe you don't know this reaction, but it's just an example, don't care why) not using a catalyst is like using brute force, using a catalyst is like using ingenuity, high school students actually don't understand so much, just like the tunnel you understand.

It's not a catalyst that splits the molecule into atoms, and it can be dismantled without a catalyst, but the time is relatively long and the reaction is very slow, and the catalyst changes the reaction process to make the reaction faster, as if it was a detour and now it is straight.

How is the new catalyst for the conversion of carbon dioxide into fuel?

The role of catalysts is to change the reaction pathway, reduce or increase the activation energy of the reaction, and can speed up or slow down the chemical reaction. For example, after a chemical reaction between A and B to form AB, the required activation energy is E, and after adding catalyst C, the reaction is carried out in two steps, and the required activation energy is F and G, respectively, where F and G are less than E. Catalysis can be divided into homogeneous catalysis, heterogeneous catalysis, biocatalysis, autocatalysis and other types, in which autocatalysis refers to the self-catalysis of reaction products, which is one of the necessary conditions for chemical oscillation.

The role of catalysts in chemical contrast is called catalysis. Solid catalysts are also known as catalysts in industry.

The composition, chemical properties and mass of the catalyst itself do not change before and after the reaction; It calms the relationship between the reaction system and the relationship between the lock and the key, which is highly selective (or specific).

For example, manganese dioxide plays a catalytic role in the thermal decomposition of potassium chlorate, accelerating the rate of chemical reactions, but it does not necessarily have a catalytic effect on other chemical reactions. Some chemical reactions are not the only catalyst, for example, magnesium oxide, iron oxide and copper oxide can also play a catalytic role in the thermal decomposition of potassium chlorate, and red brick powder or copper oxide can also be used as catalysts when potassium chlorate is used to produce oxygen.

1. Substances that can change the chemical reaction rate of reactants in chemical reactions (both increase and decrease) without changing the chemical equilibrium, and their quality and chemical properties have not changed before and after the chemical reaction are called catalysts (solid catalysts are also called catalysts).

Second, the principle of catalysis:

1. The phenomenon of accelerating or slowing down the rate of chemical reaction due to the intervention of catalysts is called catalysis. In catalytic reactions, the catalyst reacts chemically with the reactants, changing the reaction pathway, thereby reducing the activation energy of the reaction, which is the reason why the catalyst can increase the reaction rate. For example, in the chemical reaction A+B AB, the required activation energy is E, and after adding catalyst C, the reaction is carried out in two steps, and the required activation energy is F and G respectively, where F and G are less than E.

2. A+C AC---AC+B AB+C, the activation energy of these two steps is much smaller than the E value. According to Arrhenius' formula k=ae-e rt, the e value decreases due to the catalyst participation in the reaction, resulting in a significant increase in the reaction rate. In some reactions, after the catalyst participates in the reaction, the activation energy e value does not change much, but the value of the pre-factor A increases significantly (or explained as the increase of activation entropy), which also leads to the acceleration of the reaction rate.

3. Types of catalysis:

1. Homogeneous catalysis. The catalyst and reactants are both in the same phase for catalytic action, such as homogeneous acid-base catalysis, homogeneous complexation catalysis, etc. Homogeneous catalysis is mostly carried out in the liquid phase.

The active center of the homogeneous catalyst is relatively homogeneous, the selectivity is high, and the side reactions are few, but the catalyst is difficult to separate, ** and regenerate.

2. Heterogeneous catalysis. Catalysis that occurs at the interface of two phases. Usually the catalyst is a porous solid and the reactants are liquids or gases.

In heterogeneous catalytic reactions, the solid catalyst has a chemical adsorption effect on the reactant molecules, which activates the reactant molecules, reduces the activation energy of the reaction, and accelerates the reaction rate. The surface of the solid catalyst is inhomogeneous, and only some points have chemical adsorption of reactant molecules, called active centers. Most of the catalytic effects in industrial production belong to heterogeneous catalysis.

3. Biocatalysis. Catalytic reactions carried out in organisms under the action of enzymes. The catalytic effect of enzymes has the characteristics of high selectivity, high catalytic activity, and mild reaction conditions, but it is greatly affected by factors such as temperature, pH value in solution, and ionic strength.

4. Automatic catalysis. Autocatalysis of reaction products. In some reactions, the products or intermediates of some reactions have a catalytic function, so that the rate of the reaction is greatly accelerated after an induction period. Autocatalysis is one of the necessary conditions for chemical oscillations to occur.

5. Others include electrocatalysis, photocatalysis, photocatalysis, etc.

Hello Definition of Catalyst.

A substance that can significantly change the reaction rate and its chemical properties and quantity remain basically unchanged before and after the reaction. There are positive catalysts (i.e., accelerating the reaction rate) and negative catalysts (i.e., reducing the reaction rate), which are generally referred to as positive catalysts.

Catalytic principle. Whether a chemical reaction can be carried out depends on the change of free energy, but only according to the change of free energy, it is not possible to judge whether the reaction can be completed, because the completion of the chemical reaction also depends on the energy barrier of the reaction, that is, if the energy barrier of the reaction is very high, a certain amount of energy must be provided for it, and the energy barrier must be crossed to complete the reaction. This energy barrier is called activation energy. The role of the catalyst is to reduce the activation energy, so that the chemical reaction can occur in a relatively non-harsh environment.

The catalyst changes the reaction rate because it changes the reaction pathway, which reduces the activation energy of the reaction.

The catalyst does not participate in the reaction, but only changes the reaction rate to speed up the reaction.

The activation energy of the reaction can be reduced. The activation energy of the reaction between the raw material and the catalyst is relatively low, and their products may be highly active and easy to react, such as potassium chlorate plus manganese dioxide is potassium permanganate.

The catalyst also participates in the reaction, but eventually it will break away from the reaction, so the teacher will tell you that the catalyst does not participate in the reaction.

It looks the same as the one on the Internet, and I don't know who copied whose ......Let me suggest a new one.

Studies of chemisorption, infrared spectroscopy, low-energy electron diffraction (LEED) and reaction mechanism have shown that in the vast majority of heterogeneous catalytic reactions, at least one reactant molecule interacts with the catalyst surface to form a metastable intermediate compound, thereby realizing the activation of the reactant molecule. This intermediate compound is formed by dissociative chemisorption, transfer of protons or electrons, or rearrangement of chemical bonds.

In homogeneous catalytic reactions, catalytic initiation is the formation of highly reactive intermediate complexes or intermediate compounds between a reactant and a catalyst. This intermediate complex reacts with other reactants that may also be in a coordination state to produce the final product of the catalytic reaction.

In general, the catalyst does not essentially not participate in the reaction, but is the original substance that is formed through a series of roundabout reactions with the reactants, so it seems that there is no reaction on the surface. And it is these roundabout reactions that change the mechanism of the reaction, so that the activation energy of the total reaction is reduced.

[Catalyst] A substance that can change the speed of a chemical reaction without changing its chemical composition, chemical properties and quantity before and after the reaction is called a catalyst. A positive catalyst can speed up the reaction, and a negative catalyst (inhibitor) can slow down the reaction.

Catalytic reactions] reactions with the participation of a catalyst. If the catalyst and reactants are in the same uniform gas or liquid phase, it is called homogeneous catalysis. If the catalyst and reactants are not in the same phase, and the reaction takes place only at the interface between the catalyst and the reactants, it is called heterogeneous catalysis.

There is also a type of catalytic reaction called biocatalysis, or enzyme catalysis, which is different from both homogeneous and heterogeneous catalysis, but has some characteristics of both.

The catalysts commonly used in the esterification reaction in the factory are: concentrated sulfuric acid, concentrated hydrochloric acid, p-toluenesulfonic acid, thionyl chloride.

In the experiment of the reaction of anhydrous ethanol and glacial acetic acid to produce ethyl acetate, concentrated sulfuric acid is used as a catalyst and water absorbent, and if the catalytic mechanism is O in the carbonyl group polarized by hydrogen ions, the ability of carbonyl C to be attacked by nucleophiles is enhanced.

There are many catalysts commonly used in industry, such as: vanadium pentoxide used to catalyze sulfur dioxide in the sulfuric acid industry, platinum rhodium alloy is used as a catalyst for catalytic oxidation of ammonia to nitric oxide, iron catalyst (iron-based metal) is used in the synthetic ammonia industry, nickel or platinum is used for dehydrogenation and hydrogenation in the petrochemical industry, rhenium for catalytic reforming, etc.

Other Definitions. There is also a saying that catalysts are involved in chemical reactions. In a total chemical reaction, the role of the catalyst is to reduce the activation energy required for the reaction to occur, essentially turning a relatively difficult reaction into two chemical reactions that can easily occur (the opposite is called an inhibitor).

In these two reactions, the catalyst plays the role of reactant in the first reaction, and the catalyst plays the role of product in the second reaction, so in terms of the overall reaction equation, the catalyst does not change before and after the reaction.