Important Features of Solid Catalysts
Activity The activity of a catalyst depends upon the strength of chemisorption to a large extent . The adsorption should be reasonably strong but not so strong that they become immobile and no space is available for other reactants to get adsorbed .
Selectivity The selectivity of a catalyst is its ability to direct a reaction to yield a particular product , e . g ., starting with Hz and CO using different catalysts , we get different products .
Shape – selective catalysis The catalytic reaction that depends upon the pore structure of the catalyst and the size of the reactant and product molecules is called shape-selective catalysis .
Cracking Isomerization of hydrocarbons in the presence of zeolites is an example of shape-selective catalysis .
An important zeolite catalyst used in the petroleum industry is ZSM-S . lt converts alcohols directly into gasoline .
Enzyme Catalysis
Enzymes are complex nitrogenous organic compounds which are produced by living plants and animals . They are actually protein molecules of high molecular mass and form colloidal solutions in water .
They are also known as biochemical catalysis .