Neutralization of Acidic Exhaust Gas Components by Overbased Additives in Marine Oils: Effects of the Acid Composition on the Neutralization Mechanism

Using a combination of IR spectroscopy and small-angle X-ray scattering methods, the study investigates the initial steps of the neutralization of commercial additives, such as overbased calcium alkylbenzene sulfonate and calcium alkyl salicylate, by a number of model acids. The model acids included sulfuric acid, nitric acid (both simulating acidic products of marine fuel combustion), and acetic acid. For the sulfonate additive, it was shown that the amorphous CaCO3 core crystallizes, predominantly into vaterite, with a simultaneous slight increase in the size of the additive's solid core. In the case of the salicylate additive, no CaCO3 crystallization was observed, and the solid core was slightly reduced in size. The paper proposes an explanation for these transformations, which rests on the difference in the strength of the acids that constitute the shell of the additive's nanoparticles, and in the water solubility of the calcium salts produced.

Automated summary

Using IR spectroscopy and small-angle X-ray scattering methods, this study investigates the initial steps of neutralization of commercial additives by model acids. The results show that the sulfonate additive crystallizes into vaterite with an increase in size, while the salicylate additive does not crystallize and has a slightly reduced size. The authors propose an explanation based on the strength of the acids and water solubility of the calcium salts.