Classification Of Precious Metal Catalysts

Catalysts can be classified according to whether the active component is supported on a support:

Unsupported Metal Catalysts: These are metal catalysts without a support. They can be further divided into single-metal and alloy types based on their composition. They are typically used in the form of framework metals, metal meshes, metal powders, metal particles, metal scraps, and metal evaporation films.

Supported Metal Catalysts: These are catalysts in which the metal component is supported on a support. This improves the dispersion and thermal stability of the metal component, giving the catalyst a suitable pore structure, shape, and mechanical strength. Most supported metal catalysts are prepared by impregnating a metal salt solution onto a support, followed by precipitation conversion or thermal decomposition and reduction.

Multi-metal Catalysts: These catalysts consist of two or more metals. Examples include platinum-rhenium bimetallic (or multi-metallic) reforming catalysts supported on chlorine-containing γ-alumina. They exhibit superior performance compared to the aforementioned platinum-only reforming catalysts. In these catalysts, the multiple metals supported on the support can form binary or multi-metal clusters, significantly improving the effective dispersion of the active component.