The present invention is directed to an improved apparatus and method of minimizing catalyst poisoning by inorganic deposits from lube oil additives and particulate matter, especially in aircraft. More specifically, the present invention is directed to an air purification system comprising an upstream metallic foam trap and downstream converter, wherein the trap physically blocks inorganic deposits and particulate matter from poisoning the downstream catalysts. The present invention is also directed to a metallic foam trap containing a coat comprising a first metallic thermal arc sprayed layer and optionally a second refractory metal oxide.