Hydrothermal catalytic deoxygenation of palmitic acid over nickel catalyst

Abstract

Fatty acid has recently received considerable interest as a possible precursor for producing renewable hydrocarbon. In this study, we investigated hydrothermal catalytic deoxygenation of palmitic acid to produce paraffin over a Ni/ZrO 2 catalyst with no or low-pressure (100 psi) external supply of H 2. The results show that the presence of water greatly improved conversion of palmitic acid and paraffin yield. Significant improvement was attributed to the formation of in-situ H 2. Without an external H 2 supply, a 64.2 C% conversion of palmitic acid was achieved in the presence of water, while only a 17.2 C% conversion was achieved without water. The results also show that the presence of water suppressed the side reactions of palmitic acid, specifically ketonization and esterification. We concluded that, compared with decarboxylation and hydrodeoxygenation, decarbonylation was the major route for palmitic acid deoxygenation catalyzed by Ni/ZrO 2. Varieties of shorter-chain paraffin (C 8-C 14) were formed through hydrogenolysis, which also produced a considerable amount of CH 4. A viable reaction pathway for hydrothermal catalytic deoxygenation of palmitic acid in the presence of Ni/ZrO 2 was suggested. The results show that hydrogenolysis and decarbonylation were the major reactions that occurred. This study demonstrates that this hydrothermal catalytic process is a promising approach for producing liquid paraffin (C 8-C 15) from fatty acids under no or low-pressure H 2 .

Fatty acid decarboxylation reaction kinetics and pathway of co-conversion with amino acid on supported iron oxide catalysts

“…When the Fe 2 O 3 / MCM-41 magnetic catalyst was employed, the maximum conversion of palmitic acid was 68.1% at 342 C, while that of Fe 2 O 3 /Al-MCM-41 reached 77.4% at 350 C. During fatty acid deoxygenation, the desired product had one less carbon than the corresponding acid. [33][34][35] In addition to deoxygenation reactions, a series of reactions could happen spontaneously on the Fe 2 O 3 /MCM-41 catalyst. These transformations mainly involved isomerization, cracking, hydrogenation, and cyclization reactions.…”

“…shows the XRD patterns of the prepared Fe 2 O 3 /MCM-41 and Fe 2 O 3 /Al-MCM-41 catalysts. In the large-angle range, the diffraction peaks at 31.66 ,35.56 , 43.28 , and 57.36 are attributed to the (220), (311), (400), and (511) reections of maghemite (g-Fe 2 O 3 ; referenced to JCPDS 25-1402) 27,28. Mineral clinoptilolite was employed as an aluminum source.…”

Diesel Precursors Via Catalytic Hydrothermal Deoxygenation of Aqueous Canola Oil Emulsion

“…We are unaware of any reports on catalytic hydrothermal deoxygenation of TAG over nickel supported on carbon (Scheme ). However, there have been related studies that involved nickel (Miao et al, ; Yang et al, ). For instance, Miao et al, reported the formation of renewable hydrocarbons over nickel supported on ZrO 2 under low external H 2 pressure (100 psi) in a hydrothermal medium (Miao et al, ).…”

“…However, there have been related studies that involved nickel (Miao et al, ; Yang et al, ). For instance, Miao et al, reported the formation of renewable hydrocarbons over nickel supported on ZrO 2 under low external H 2 pressure (100 psi) in a hydrothermal medium (Miao et al, ). It was shown that the use of water improved conversion of palmitic acid to 64.7C % as opposed to just 17.2C % achieved in the absence of water.…”

Catalytic hydrothermal processing of lipids using metal doped zeolites

“…Various catalysts have been investigated in different types of reactors (batch and continuous) to upgrade different fatty acids and vegetable oils such as carbon based catalysts [14,15], Nickel supported catalysts (NiZrO2) [16] and noble metal based catalysts supported on carbon (Pd/C and Pt/C) [7,17]. However, acidic catalysts such as zeolites have been shown to be more suitable for producing lighter fractions from lipids.…”