(137c) Liquid-Phase Decarboxylation of Naphthenate Acids in Oil

Naphthenic acids in crude oil cause serious corrosion in oil production and refining processes, especially at high temperature (230-400°C). Hydrotreating is effective in removing these components, but a non-hydrogenative method for treating gas oils or whole crude oil would be much cheaper. In this study, catalytic decarboxylation of naphthenic acids in liquid-phase was studied experimentally in the presence of alkali metal and alkaline earth metal oxides and carbonates. A commercial mixture of naphthenic acids in a carrier oil was used as a model system. The reagent powders of Li2O, CaO, CaCO3, BaO and MgO were tested at 385°C in a batch reactor, and their effectiveness in the decarboxylation reaction were determined based on acid conversion. TAN measurement and FTIR analysis showed the trend in decrease of acids using different catalyst (Li2O>CaO>BaO>MgO>CaCO3). The post-reacted catalysts were analyzed to trace the disappearance of naphthenic acid by using FTIR and TGA.