Green diesel production through simultaneous deoxygenation of palmitic acid and desulfurization of 4,6-Dimethyl-dibenzothiophene over commercial CoMo/Al₂O<sub>3<sub/>

Abstract

This study investigated the deoxygenation of palmitic acid as a model compound of palm fatty acid distillate (PFAD), in the presence of 4,6- di-methyl-di-benzothiophene as a sulfur-containing light gas oil (LGO). Reactions were performed at the pressure of 25 barg, liquid hourly space velocity (LHSV) of 1.7 h^-1, and H₂/oil of 630 NL/L over CoMo/Al₂O₃ as catalyst. The effect of temperature was studied in the range of 275-300 ^oC. Both deoxygenation and desulfurization led to approximately 100% conversions at 300 ^oC, while at 275 ^oC, palmitic acid deoxygenation was recorded at a higher conversion rate compared with that of the desulfurization of 4,6- di-methyl-di-benzothiophene. The presence of 4,6- di-methyl-di-benzothiophene during the deoxygenation of palmitic acid resulted in high conversions (>95%). Pressure drop studies showed that the formation of heavy products caused a gradual pressure drop throughout the reactor over time. The catalyst was deactivated during 10 d. Two different sulfur-containing reagents were used for catalyst reactivation including dimethyl-disulfide in n-C18 and LGO containing 484 ppmw of sulfur. Reactivation with 2 wt.% of dimethyl-disulfide in n-C18 at 320 ^oC for 36 h led to more favrable performance recovery <em>vs.</em> the sulfur-containing LGO.