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 ۲۵ mL autoclave reactor (China) at temperatures of ۷۰-۱۲۰oC, Methanol Partial Pressures (MPPs) of ۰.۱-۱.۵ MPa, and reaction times of ۰-۶۰ min. The total acid number content of the samples was analyzed using ASTM D ۹۷۴ techniques. Experimental results reveal that total acid number reduction of naphthenic acids increased with increasing reaction temperature, MPP, and reaction time. Approximately ۷۴.۲۰% total acid number was reduced at a temperature of ۱۲۰oC, a MPP of ۱ MPa, and a reaction time of ۶۰ min. Experimental data revealed that total acid number removal reaction kinetics followed second-order kinetics with an activation energy of ۱۱.۲۷ kcal/mol. Therefore, subcritical methanol is able to reduce the total acid number of naphthenic acids without the addition of any catalyst.

کلیدواژه ها:

Naphthenic acid ، Subcritical methanol ، Total acid number ، Petroleum oil ، Reaction kinetics