Green diesel production through simultaneous deoxygenation of palmitic acid and desulfurization of 4,6-Dimethyl-dibenzothiophene over commercial CoMo/Al2O3

Document Type: Research Paper

Authors

Chemical Engineering Department, Faculty of Engineering Chulalongkorn University Bangkok 10330, Thailand.

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 vs. the sulfur-containing LGO.

Graphical Abstract

Green diesel production through simultaneous deoxygenation of palmitic acid and desulfurization of 4,6-Dimethyl-dibenzothiophene over commercial CoMo/Al<sub>2</sub>O<sub>3<sub/>

Highlights

  • 4,6-di-methyl-di-benzothiophene was used as a sulfur-containing light gas oil.
  • Deoxygenation of palmitic acid led to approx. 100% conversion at reaction temperature of 300 oC in the presence of 4,6-di-methyl-di-benzothiophene.
  • The formation of heavy products and lack of sulfur caused a gradual pressure drop over time.
  • The best reagent for CoMo/Al2O3 reactivation was dimethyl-disulfide.

Keywords


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