Use of Catalysis

Using a catalyst in a chemical reaction speeds up its rate, and green chemistry's ninth principle is simply to prefer catalytic routes over stoichiometric ones wherever possible. Catalysts help in three connected ways: they increase a reaction's selectivity (steering the reaction toward the desired product and away from unwanted side products), they minimise waste (because a more selective reaction produces less unwanted byproduct in the first place), and they reduce both reaction times and energy demands (since a catalysed pathway typically has a lower activation-energy barrier than the uncatalysed reaction). Because a catalyst is regenerated at the end of the cycle rather than consumed, a small amount of catalyst can process a very large amount of reactant over time, which is why catalytic routes are generally far more atom- and energy-efficient than routes relying on stoichiometric reagents that are used up and discarded after a single reaction. A 'Complete the Chart' activity accompanying this section asks the student …