NOx Adsorber Desulfurization Under Conditions Compatible With Diesel Applications

One of the main drawbacks of the NOx adsorber technology vs. the other leading approach for high level NOx conversion, namely selective catalytic reduction, is its high sensitivity to sulfur. In spite of the likely availability of ultra-low sulfur fuel and protecting devices like sulfur traps, and furthermore taking into consideration additional sulfur sources such as engine oil and lubricants, a desulfurization strategy will be essential to the commercial implementation of NOx adsorber catalysts on diesel vehicles. The results presented in this paper were obtained on NOx adsorbers with proven thermal durability and efficiency in diesel engine exhaust. They show NOx performance recovery following severe sulfur poisoning, after desulfation under temperature and air/fuel mixture conditions compatible with diesel engine operation. In addition, different desulfurization tactics, tested on a synthetic gas bench simulating diesel exhaust, are depicted and discussed.