| − | Catalysts that are in a different phase than the reactants.<ref>Wile, Dr. Jay L. ''Exploring Creation With Chemistry''. Apologia Educational Ministries, Inc. 1998</ref>
| + | A '''heterogeneous catalyst''' is a [[catalyst]] which is in a different [[phase]] than the reactants.<ref>Wile, Dr. Jay L. ''Exploring Creation With Chemistry''. Apologia Educational Ministries, Inc. 1998</ref> Typically heterogeneous catalysts are [[solid]] particles in a [[packed bed reactor]], over which a [[liquid]] reactant stream is flowed. |