Platinum catalyst poisoning refers to the phenomenon that the activity of the platinum catalyst is significantly reduced or even completely lost due to the presence of certain substances.
Causes and mechanisms of poisoning
Chemical adsorption poisoning:
Many sulfur-, nitrogen-, phosphorus-, arsenic- and halogen-containing compounds are prone to chemical adsorption on the surface of platinum catalysts. This prevents the reactant molecules from approaching the catalyst surface for normal catalytic reactions, resulting in a decrease in catalyst activity.
Carbon monoxide (CO) is also a common substance that causes platinum catalyst poisoning.
Poisoning of reaction intermediates:
During the catalytic reaction, some intermediate products that inhibit the platinum catalyst may be generated. For example, in some organic synthesis reactions, some carbon-containing polymers or coke-like substances will be produced, which will be deposited on the surface of the platinum catalyst, covering the active sites, and may further react with platinum, changing its surface structure and electrons. properties, ultimately leading to a reduction in catalyst activity. In addition, metal or metal compound impurities generated in some reactions may also form alloys with platinum or cover its surface, destroying the original active structure of the catalyst.