The SCR catalyst is an exhaust after-treatment system. SCR stands for "Selective Catalytic Reduction", meaning the reduction of polluting substances through partial conversion into individual and environmentally friendly substances. In more detail, the exhaust component nitrogen oxide (NOx) is converted into harmless nitrogen and water, using ammonia compounds and without the generation of further undesirable by-products.
With the new SEAT Alhambra diesel variants, SEAT launched the use of SCR catalysts, making the Alhambra TDI CR among the cleanest self-igniting engines of its class.