Heterogenous catalysis holds many potentials for replacing the the outdated ’end-of-pipe’ strategy by the application of ’reactor or production integrated environmental protection’. Three industrially important reactions employing zeolites as heterogenous catalysts demostrate to which extent high product yields are achieved accompanied by a minimized amount of contaminations. This attainment includes the search for optimal reaction conditions, as well as the application of an appropriate reactor design. These vital aspects for the realization of industrial processes have to be regarded as a unit instead of investigating catalyst and process desing separately, which could lead to a substantial reduction of development costs.