Like biological and industrial reations. Thanks.
Reactions that have high Activation Energy need catalysts to speed up reactions. These reactions aren't spontaneous since the reactants do not have enough energy to overcome the activation energy barrier. Catalysts are compounds that speed up reactions by providing an alternative pathway for the reaction. It is a common misconception that catalysts lower the activation energy. It doesn't actually lower the activation energy, instead it provides an alternative pathway with lower activation energy. For example, breakdown of hydrogen peroxide happens in nature but, relatively slowly. When you add a little bit of manganese dioxide, the breakdown happens a lot faster. Another example is, breakdown of glucose in the body. It is facilitated by an enzyme called amylase (or carbohydrase). An industrial example is the use of vanadium pentoxide (V2O5) in the Contact process, where SO2 is converted to SO3 in the presence of V2O5. Hope that helps!