Catalyst is a substance which accelerates the rate of reaction between two reactants without itself getting altered at the end of the reaction. A catalyst can, therefore, be used and reused again and again till it gets deactivated as a result of impurities present in the reactants which block the active sites of the Catalyst or react with the catalyst and change its chemical composition.
When one of the two reactants happen to be Hydrogen gas, the catalyst used is termed as Hydrogenation Catalyst.
The word "accelerates" used in the terminology implies that the hydrogenation reaction is taking place even without the catalyst, maybe at a slow pace. The fact, however, is, that the reaction practically does not take place in the absence of the catalyst. Presence of Catalyst is essential for reaction to proceed at a noticeable rate.
A promoter is a substance which enhances the activity of a catalyst. Promoters are specific for a specific type of hydrogenation. Molybdenum, Chromium, Copper, Iron are known promoters for certain specific reactions involving Raney Nickel. Promoters are not added separately to the reactants but are to be incorporated in the Catalyst metal during their preparation.
Inhibitors are substances which retard the activity of a catalyst. Sulfur and Lead are inhibitors for precious metal Catalysts. However, Sulphur is not a poison for Raney Nickel.
Presence of oxidizing agents or small amounts of deactivators causes deactivation or poisoning of a hydrogenation catalyst. Amines and Chlorides are also known to deactivate the catalyst.
Sometimes the product of the reaction, reaction intermediates or by-products act as catalytic deactivators and do not allow completion of the reaction. Under such situations, user should opt for a different type of catalyst.
The user should make a careful study of deactivators and poisons before conducting large scale hydrogenation. Care should be taken to minimize the presence of catalytic deactivators and poisons in the reaction mixture so as to prolong the life of the catalyst.
Catalyst manufactured by Vineeth Chemicals are normally resistant to catalytic poisons if present in small quantities. For more details please mail us at email@example.com or call us at +91-8149095779
DISPOSAL PRECAUTIONS : Nickel is a costly metal. Do not, therefore, discard even such of the spent Raney Nickel Catalysts which can not be reactivated any more. Even such a material can fetch good money from the manufacturers of Nickel salts.
DISPOSAL PRECAUTIONS : Palladium/ Platinum on Carbon Catalyst is a costly product. The precious Palladium/ Platinum metal from the used catalyst can be recovered. Do not therefore discard the used product as waste material. Arrangements should be made to send back the material to the manufacturer for recovery of the precious Palladium/ Platinum Metal which can be reused for making a fresh batch of the catalyst.