Transformation of refinery cracked naphtha stream into efficient lubricity improvers for ULSD

A new route for the conversion of refinery light cracked naphtha (LCN) stream into lubricity improvers for ultra-low sulphur diesel (ULSD) was developed through a simple chemical process involving olefin epoxidation and esterification reactions. Two different methods viz., H₂O₂/glacial acetic acid and m-chloroperbenzoic acid (m-CPBA), were found to be suitable for the epoxidation of LCN. The LCN epoxide was subjected to an esterification reaction via epoxide ring opening using different long chain (C₄ - C₁₈ alkyl groups) organic acids to get the hydroxy ester derivatives of LCN. The lubricating property of the newly synthesized hydroxy esters was studied by dosing them with ULSD at 300 and 150 ppm (wt/vol) concentrations. Amongst them, LCN hydroxy ester derived from stearic acid showed the best lubrication-enhancing property at both dosage levels. The scanning electron microscope (SEM) image and energy dispersive spectra (EDS) of the high-frequency reciprocating rig (HFRR) specimen support the lubricating action of the LCN esters through the formation of a protective layer between the metallic surfaces. The synergy of simple chemical processes and efficient lubricity action makes these LCN esters as promising materials for low-cost and scalable additives for ULSD.

Graphical abstract

The olefin-rich light cracked naphtha obtained from the fluidized catalytic cracker unit of the oil refinery was converted into hydroxy esters through an epoxidation reaction followed by the esterification with different carboxylic acids. The hydroxy esters at low dosage levels (150/300 ppm) enhance the lubricating property of ultra-low sulfur diesel.