total acid number reduction of naphthenic acid using subcritical methanol: a kinetic study

The aim of this study is to explore the capability of subcritical methanol to reduce the acidity of naphthenic acids and to determine reaction kinetics for large-scale reactor design. the experiments were carried out in a 25 ml autoclave reactor (china) at temperatures of 70-120oc, methanol partial pressures (mpps) of 0.1-1.5 mpa, and reaction times of 0-60 min. the total acid number content of the samples was analyzed using astm d 974 techniques. experimental results reveal that total acid number reduction of naphthenic acids increased with increasing reaction temperature, mpp, and reaction time. approximately 74.20% total acid number was reduced at a temperature of 120oc, a mpp of 1 mpa, and a reaction time of 60 min. experimental data revealed that total acid number removal reaction kinetics followed second-order kinetics with an activation energy of 11.27 kcal/mol. therefore, subcritical methanol is able to reduce the total acid number of naphthenic acids without the addition of any catalyst.