Effect of Temperature and Ca(OH)₂/CO₂ Ratio on Alkylphenolate Additive AKI-152 Synthesis: A Response Surface Approach

The behavior of detergent–dispersant additives in lubricating oils depends upon their chemical makeup and production parameters to be employed in rotary equipment under harsh conditions, particularly in the upstream and downstream oil and gas industries. Alkylphenolate-based additives are extensively used, among others, due to their high alkalinity and good dispersion stability. However, their performance is extremely sensitive to the synthesis parameters, making experimental optimization time-consuming and resource intensive.

In this study, an alkylphenolate-based additive (AKI-152) was synthesized and optimized systematically via a response surface methodology (RSM), derived from a central composite design (CCD). As a result, the influence of important process variables Alkylphenol/Amino mass ratios, reaction temperature, and Ca(OH)₂/CO₂ mass ratios were assessed in respect of Total Base Number (TBN), kinematic viscosity, and corrosivity of the final product.

A quadratic regression model was developed and validated, showing good agreement between predicted and experimental results. Analysis of variance (ANOVA) indicated that the Alkylphenol/Amino ratio and Ca(OH)₂/CO₂ ratio exert the strongest influence on TBN, while temperature also contributes significantly within the investigated operating range. Numerical optimization identified a stable optimum region corresponding to TBN values of approximately 160 mgKOH/g, viscosity values close to 54 mm²/s, and corrosivity values below 0.76 g/m² under the selected optimization criteria.

These results demonstrate that the applied modeling approach can be effectively used to define suitable synthesis conditions for high-performance lubricant additives.