Abstract
Refinery high temperature naphthenic acid corrosion is known to generate oil soluble iron naphthenates and solid iron oxide as corrosion products. Associated chemical reactions have been written for a long time but are barely sufficient to resolve the comprehensive mechanism necessary to model their kinetics. A mechanism for naphthenic acid corrosion is proposed to be proceeding via formation of active intermediate by adopting the Lindemann-Hinshelwood approach. The rate law for the calculation of pure naphthenic acid corrosion rate was derived using a pseudo steady state hypothesis which could simulate laboratory corrosion data reported in the literature. The rate equation was also validated by experimental corrosion tests conducted in a high temperature flow-through reactors for carbon steel using a model oil solution of petroleum derived acids by manipulating solution concentration and temperature. Also, the formation of the solid iron oxide is proposed to be a result of the decay of active intermediate as an alternative mechanism in contrast with the currently accepted thermal decomposition pathway.
