Catalysis is a process in which a substance speeds up a chemical reaction without being consumed or altered in the process. Substances that can accomplish this remarkable feat are called catalysts and are of immense importance in chemistry and biology. In chemistry, a catalyst is a substance that speeds up the rate of a reaction without itself being consumed in the reaction.
Catalysis may be divided into two main types homogeneous and heterogeneous. Homogeneous catalysis is catalysis in a solution by a soluble catalyst. Homogeneous catalysis assigns to reactions where the catalyst is in the same state as the reactants, particularly in solution.
Heterogeneous catalysis is one where the reaction components are not in a similar phase. Enzymes and other biocatalysts are frequently considered as a third category. Similar mechanical principles apply to heterogeneous, homogeneous, and biocatalysis.
Porous material can be described simply as any solid containing void spaces, i.e., space not occupied by the main framework of atoms that build up the structure of the solid. Porous materials emphasizing high surface areas, narrow pore size patterns, and tuneable pore diameters have attracted a great deal of attention due to their relevant properties and applications in various areas including adsorption, separation, sensing, and catalysis. With the development of a wide range of these materials with changing morphologies (e.g., hexagonal, cubic, rod-like), structures (e.g., silicates, carbons, metal oxides), and functionalities, this field is currently one of the most advanced in materials science.
Examples: Sponges, wood, rubber, and some rocks are porous materials. In distinction, marble, glass, and some plastics are not porous and contain very few open pockets of air (or pores). A rock with good porosity is an important feature of an oil well.