1. Physical state
Homogeneous catalyst:

A homogeneous catalyst means that the catalyst and reactants are in the same physical phase, usually the liquid phase. Classic examples are catalysts in solution, such as catalytic reactions in acidic or alkaline solutions.
Heterogeneous catalysts:

Heterogeneous catalysts mean that the catalyst and reactants are in different physical phases. Generally, the catalyst is a solid, while the reactants may be gases or liquids. Common examples include the use of solid catalysts in gas phase reactions.
2. Reaction mechanism
Homogeneous catalyst:

During the reaction, the catalyst and reactants are mixed in the same phase, and the reaction proceeds through a uniform reaction medium. There can be direct interaction between the catalyst and reactant molecules. Usually the reaction rate is relatively fast under certain conditions.
Heterogeneous catalysts:

The reaction occurs on the surface of the solid catalyst. The reactants first need to diffuse to the surface of the catalyst, and then the reaction occurs. Therefore, the reaction rate is limited by diffusion. The surface properties of catalysts have an important impact on catalytic performance.

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3. Separation and reuse
Homogeneous catalyst:

Homogeneous catalysts are usually difficult to separate after the reaction and need to be separated by evaporation, precipitation or extraction, which may increase the complexity of subsequent processing.
Heterogeneous catalysts:

Heterogeneous catalysts are often easy to separate and reuse. For example, solid catalysts can be easily separated by methods such as filtration, sedimentation, or centrifugation, which makes reuse in industrial applications more convenient.
4. Catalyst stability
Homogeneous catalyst:

Homogeneous catalysts may be affected by heat, light, etc. during the reaction process, resulting in catalyst failure or degradation. Therefore, the stability requirements for batch reactions are higher.
Heterogeneous catalysts:

Heterogeneous catalysts usually have high thermal stability, and solid catalysts are not easily consumed or degraded during chemical reactions and can better maintain their catalytic activity.
5. Application areas
Homogeneous catalyst:

It is mostly used in the fields of organic synthesis, biocatalysis and other fields. For example, many organic reactions (such as esterification reactions, etc.) use homogeneous catalysts.
Heterogeneous catalysts:

It is widely used in industrial processes such as petroleum refining, hydrogenation reactions, oxidation reactions, etc., especially in gas reactions or multi-phase reactions.