Spanish people know what’s what.

Why are we supposed to toil for cleaning up catalytic converters and struggle against pollution, when the solution is up to the fridge?

True. A simple “squeeze” of citric acid can smarten up the catalytic converters of diesel car exhaust. In fact, in diesel engines, catalytic converters contain a honeycomb of platinum that cleans up exhaust gases by turning poisonous carbon monoxide and unburned hydrocarbons into more benign carbon dioxide. This breaks down molecules that could contribute to smog. But sulphur in the fuel and phosphorus from anti-wear oil additives can gum up a converter and prevent it from working.

Henceforward the intuition of the scientists from the Institute of Catalysis and Petrolchermistry in Madrid that have found that a dilute solution of citric acid can wash out the catalyst killers without damaging the precious metal. How? Testing on a  simulated stream of exhaust gases: the citric acid from a catalyst that had been used for 48.000 kilometres, in a wash cycle that took six hours at 80 °C., removed up to 90% of the sulphur and  82% of the phosphorus.

From “ Le Scienze” 08/05/2005