Synthesis and Properties of Diesters Based on Synthetic Petroleum Acids and 1,4-Butanediol

A mixture of synthetic petroleum acids (SPAs), obtained via liquid-phase oxidation of naphthene–paraffinic hydrocarbons from a kerosene fraction, was used for the catalytic esterification of 1,4-butanediol. Under optimal reaction conditions (a temperature of 120°C, a catalyst loading of 1.5 wt %, and a SPA/1,4-butanediol molar ratio of 2 : 1.5), a diester mixture was synthesized in 92% yield. These diesters were evaluated as plasticizers for polyvinyl chloride (PVC) grade S-6358. The PVC/diester blends exhibited a full swelling time of 5–6 h, which is 2–3 h shorter than that for commercial dioctyl phthalate, a commonly used plasticizer. Furthermore, the synthesized diester mixture was tested as a multifunctional additive for diesel fuels. At a concentration of 0.004 wt %, the diesters notably enhanced the thermo-oxidative stability of the diesel fuel. Separately, adding 0.05 wt % diesters lowered the cloud point of the fuel by 9°C (to –11°C) and its pour point by 5°C (to –25°C) without adversely affecting its cetane number (CN). These results demonstrate the feasibility of using SPAs as available feedstocks for functional materials and fuel additives.