The acetaldehyde is an important intermediate in petrochemical industry. It can be produced by the direct oxidation of ethylene in the presence of catalyst. The catalyst is corrosive hydrochloric acid solution with the addition of palladium chloride and copper chloride. As part of the production facilities, the whole catalyst regeneration system shall be made from commercially pure titanium Grade 2 (DIN 3.7035), which exhibits excellent corrosion resistance to chloride ion attack.

In catalyst regeneration process, the pump first extracts a portion of catalyst from the reactor. Before the extracted catalyst are fed into the cyclone(isolator), compressed air and hydrochloric acid are added to oxidize cuprous chloride into copper chloride and evaporate excessive acetaldehyde and water. Then, another titanium pump will tranport the chemicals in the cyclone into the regenerator. After regneration is completed, the catalyst is delivered to the flash evaporator where gas phase constituents is removed. Any piping, vessel, or equipment in contact with the catalyst during the regeneration process shall be manufactured from titanium to avoid possible corrosion.