CORROSION OF STAINLESS-STEEL DURING ACETATE PRODUCTION

Corrosion of types 304, 304L, 316, and 316L (UNS S30400, S30403, S3160 0, and S31603, respectively) stainless steel (SS) during the esterific ation of acetic acid (CH3COOH) and alcohol or glycol ether was investi gated The catalyst for this reaction, sulfuric acid (H2SO4) or para-to luenesulfonic acid (PTSA), was shown to cause more corrosion on reacto r equipment than CH3COOH under the process conditions commonly practic ed In industry. The corrosive action of the catalyst occurred only in the presence of water. Thus, for the batch processes, corrosion occurr ed mostly during the initial stage of esterfication, where water produ ced by the reaction created an aqueous environment, After mater was di stilled off, the corrosion rate declined to a negligible value, The co rrosion inhibitor copper sulfate (CuSO4), often used in industrial ace tate processes, was found to work well for a low-temperature process ( < 95 degrees C) such as in production of butyl acetate, but it acceler ated corrosion in the glycol ether acetate processes where temperature s were > 108 degrees C, Process conditions that imparted low corrosion rates were determined.