Continuous Hydrothermal Decarboxylation of Fatty Acids and Their Derivatives into Liquid Hydrocarbons Using Mo/Al₂O₃ Catalyst

Abstract

In this study, we report a single-step continuous production of straight-chain liquid hydrocarbons from oleic acid and other fatty acid derivatives of interest including castor oil, frying oil, and palm oil using Mo, MgO, and Ni on Al 2 O 3 as catalysts in subcritical water. Straight-chain hydrocarbons were obtained via decarboxylation and hydrogenation reactions with no added hydrogen. Mo/Al 2 O 3 catalyst was found to exhibit a higher degree of decarboxylation (92%) and liquid yield (71%) compared to the other two examined catalysts (MgO/Al 2 O 3 , Ni/Al 2 O 3 ) at the maximized conditions of 375 °C, 4 h of space time, and a volume ratio of 5:1 of water to oleic acid. The obtained liquid product has a similar density (0.85 kg/m 3 at 15.6 °C) and high heating value (44.7 MJ/kg) as commercial fuels including kerosene (0.78–0.82 kg/m 3 and 46.2 MJ/kg), jet fuel (0.78–0.84 kg/m 3 and 43.5 MJ/kg), and diesel fuel (0.80–0.96 kg/m 3 and 44.8 MJ/kg). The reaction conditions including temperature, volume ratio of water-to-feed, and space time were maximized for the Mo/Al 2 O 3 catalyst. Characterization of the spent catalysts showed that a significant amount of amorphous carbon deposited on the catalyst could be removed by simple carbon burning in air with the catalyst recycled and reused.

Efficient non-noble Ni–Cu based catalysts for the valorization of palmitic acid through a decarboxylation reaction

“…(2), HDO (3)), and indirect DCX (4)(5)(6). DCX ( 1) is the main route, wherein PA is directly converted to n-PD and CO2.…”

“…The product distribution in this case also demonstrated the reactivity order of DCX >> HDO, indicating that the same reaction pathway is followed using both FAs. Other reaction pathways are possible, as shown by DCX (4-5) and esterification (6). The intermediate n-hexadecanal formed in the hydrogenolysis step (3) can be dehydrogenated leading to a ketene intermediate, followed by a DCN and a hydrogenation step to form n-PD (4).…”

“…The continuously increasing world energy demand (+2.9% in 2018, the fastest since 2010) has driven the high utilization of fossil resources that today represent 85% of the global primary energy consumption (coal, oil, and natural gas) [1][2][3]. Besides being insufficient to satisfy the energy needs of a developing society, the imminent depletion of fossil resources and the anthropogenic climate change because of greenhouse gas emissions are of major concerns [4][5][6].…”

“…DCX of FA using carbon-supported metallic catalysts has attracted much attention, wherein noble metal-based catalysts play an important role. Their use under high-pressure of hydrogen or carbon dioxide enhanced the feedstock conversion and liquid products yield [6,10,15,[39][40][41]. Among all catalysts studied, Pd and Pt-based catalysts showed best catalytic performances to hydrocarbons.…”

Kinetic Model of Crude Palm Oil Hydrocracking Over Ni/Mo ZrO2–Pillared Bentonite Catalyst

“…There are several host materials commonly used such as zeolite, alumina and other alumina-silicate type material. Catalysts such as Mo/Al 2 O 3 [13], Pd/HTlc and Ru/HTlc [11], CoMo/Alumina and NiMo/Alumina [12,14] as well as NiMo/zeolite has been reported being used on cracking process. The most suitable catalyst concluded so far for vegetable oil hydrocracking is Ni and Mo metals [2,3,6,10].…”