Catalyst support

Catalyst carrier is a special part of solid catalyst, dispersant, binder, negative carrier of active component of catalyst, and sometimes ACTS as co-catalyst or co-catalyst.Catalyst carrier, also known as support, is one of the components of supported catalyst.Generally, it is a porous material with a certain specific surface area, and the active component of the catalyst is often attached to it. The carrier is mainly used to support the active component, so that the catalyst has specific physical characteristics, while the carrier itself generally does not have catalytic activity

Catalyst support requirements

1, can dilute the density of active components, especially precious metals

2, can be prepared into a certain shape

3. The sintering between active components can be prevented to a certain extent

4, can resist poison

5. It can have mutual effect with the active component and the main catalyst.

The effect of catalyst carrier

1, reduce the catalyst cost

2, improve the mechanical strength of the catalyst

3. Improve catalyst thermal stability

4, add catalyst activity and selectivity

5. Extend catalyst life

Several primary carriers are introduced

1. Activated alumina: most commonly used carrier for industrial catalysts.Low price, high heat resistance, good compatibility of active components.

2. Silica gel: chemical composition is SiO2.Generally made from sodium silicate (na 2 si 3) acid.Silicate acid was formed after the effect of sodium silicate and acid.Silicic acid polymerization, condensation, the structure of the polymer is uncertain.

SiO2 is a widely used carrier, but its industrial application is less than Al2O3, which is due to the difficulties in preparation, weak affinity with active components, easy sintering with water vapor and other defects.

3. Diatomite: natural SiO2.It contains a few metal oxides and organics, and its pore structure and specific surface change with the origin.Acid treatment should be used before use. One is to improve the content of SiO2 and increase the specific surface, specific pore volume and primary pore radius.The second is to improve thermal stability, after acid treatment, can further increase the specific surface.Diatomite is primarily used to prepare fixed bed catalysts.

4, activated carbon: the primary ingredient is C, containing a few H, O, N, S and ash, etc..Activated carbon has irregular stone mill structure, there are carbonyl group, quinone group, hydroxyl group and carboxyl group on the surface.Activated carbon is characterized by developed pores and large surface area, thermal stability and high.

5. TiO2: it has three crystal shapes: anatase, plate titanium and rutile.Sheet titanium ore is difficult to synthesize due to instability;Anatase is formed at a lower temperature with a relative density of 3.84 and a larger specific surface area.Heated at 600~1000°C, anatase becomes rutile, which has a relative density of 4.22 and a small specific surface area.

6. Silicon carbide: the melting point of carbide ceramics is higher than 2000°C, with high heat conductivity, high hardness, strong heat resistance and impact resistance, but it is simply oxidized in an oxygen atmosphere.So SiC is often used as the carrier of catalyst in high temperature environment.

7. Molecular sieve: it is a crystalline silicate or silicoaluminate, a pore and cavity system composed of a silico-oxygen tetrahedron or alumino-aluminum tetrahedron connected by oxygen bridge bonds.It has high thermal stability, water thermal stability and acid and alkali resistance