Catalytic Deoxygenation of Rapeseed Oil into Drop-in Fuel Under Hydrothermal Condition Causing in-Situ Hydrogen Production

The existent catalytic process to produce drop-in fuel from triglyceride resources has consumed a large amount of the hydrogen deriving from fossil resources. For targeting the cost-reasonable and the eco-friendly production, catalytic deoxygenation of rapeseed oil was tested under hydrothermal condition in the present work. For the test reaction, the supported Pt catalyst was employed in order to activate simultaneously aqueous phase reforming (APR) of the glycerol split by the initial triglyceride hydrolysis. In the presence of Pt/Al₂O₃ catalyst, 22.0 % of the split fatty acids was converted mainly into the C17 hydrocarbons at 593 K for 4.5 h. Although only 1.2 % of the C17 hydrocarbons was formed into the branched structure, Pt/H-ZSM5 catalyst resulted in 22.6 % of the selectivity to the blanched structure. There is none of the early work to add the in-situ isomerization of the produced hydrocarbon for enhancing the cold flow property into the catalytic hydrothermal deoxygenation, to the best of our knowledge. Also, APR of the reagent glycerol was carried out separably in order to estimate quantitatively the in-situ hydrogen production. For the correct estimation, 1-tetradecene was mixed as the hydrogen accepter into the glycerol aqueous solution. The separable APR reaction operated in the presence of the hydrogen accepter is one of our research originalities. The hydrogen yield on the basis of the reaction stoichiometry reached 39.6 % for the separable APR reaction catalyzed by Pt/Al₂O₃ at 593 K for 1.5 h, and is very high as compare to the early work where the glycerol APR was operated under the similar reacting condition without adding the hydrogen accepter. But, 39.6 % of the hydrogen yield does not satisfy an amount of the hydrogen required for the perfect deoxygenation of the triglyceride feedstock. These results indicate that modification of the catalyst should be studied for enhancing both the APR and the deoxygenation activities without degrading the isomerization activity in our future work.