Catalytic Deoxygenation Of Fatty Acids Research Articles

Effect of various silica-supported nickel catalyst on the production of bio-hydrocarbons from oleic acid

The conversion of fatty acids into bio-hydrocarbons can be carried out through a deoxygenation (DO) reaction. Catalytic deoxygenation of fatty acids can occur through three reaction pathways: decarbonylation, decarboxylation, and hydrodeoxygenation. In this study, three kinds of silica were prepared: (i) silica obtained from the rice husk ash (RHA); (ii) synthetic mesoporous silica SBA-16; and (iii) commercial silica. All prepared silica was used as supported nickel (Ni) catalyst for bio-hydrocarbon production through DO reaction of oleic acid. The objective of this study was to investigate the effect of variations of silica on the reaction pathway and final products composition of DO reaction of oleic acid. The catalysts were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), surface area analysis, and NH3-temperature-programme desorption. Based on XRF and XRD analysis results, it can be concluded that nickel was successfully impregnated into all silica. All samples of catalysts were used in a reaction carried out at temperature of 285 °C under a pressure of 40 bar H2 for 2h. The results showed that all catalysts were able to convert oleic acid to bio-hydrocarbon with differences in products composition. The highest oleic acid conversion of 98.25% was achieved with Ni/RHA catalyst but the obtained liquid products was the lowest among other catalysts. It is found that this phenomenon was closely related to the acidity properties of the catalyst.

Production of Bio hydrocarbons from Vegetable Oils and Animal Fats Using Magnesium Oxide as Catalyst

Bio hydrocarbons are renewable fuels that can be produced through the catalytic deoxygenation of fatty acids, resulting in compositions like gasoline, kerosene, and diesel fractions derived from petroleum. The objective of this study is to generate gasoline, kerosene, and diesel from vegetable oils and animal fats using an MgO catalyst synthesized through the calcination of Mg-citrate. The characterization of the MgO catalyst, employing Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface adsorption method, revealed the presence of crystalline MgO and showed that mesoporous MgO with average pore size of 15.52 nm and exhibiting a surface area of 35.68 m2 g-1. The MgO catalyst was utilized in the deoxygenation reaction of palm oil, palm wax, and chicken fat, leading to the production of bio hydrocarbons with paraffin and olefin compositions like those found in gasoline, kerosene, and diesel derived from petroleum. Gas Chromatography-Mass Spectroscopy (GCMS) analysis of the liquid product demonstrated that the highest quantity of gasoline was derived from palm wax, followed by palm oil and chicken fat. Palm wax exhibits promising potential as a raw material for gasoline production through the deoxygenation reaction, specifically through decarboxylation and decarbonylation processes facilitated by the MgO catalyst.

Catalytic deoxygenation of fatty acids via ketonization and α-carbon scissions over layered alkali titanate catalysts under N2.

The ketonization of fatty acid with subsequent McLafferty rearrangement of the fatty ketone allows the deoxygenation to hydrocarbons. Here, we report the cascade reaction of palmitic acid (C16) to hydrocarbons (≤C14) over lepidocrocite-type alkali titanate K0.8Zn0.4Ti1.6O4, K0.8Mg0.4Ti1.6O4, and K0.8Li0.27Ti1.73O4 and the reassembled TiO2 catalysts at ≤400 °C under atmospheric N2 in a continuous fixed-bed flow reactor. The C16 acid is coupled to C31 ketone prior to the scissions mostly to a C17 methyl ketone and C14 hydrocarbons (i.e., the McLafferty rearrangement). The hydrocarbons yield increases with temperature and is proportional to partial charge at the O atom, suggesting that basic sites are responsible for C31 ketone scissions. The layered alkali titanate catalysts with two-dimensional (2D) space inhibit diffusion of the ketone primarily formed and promote its scissions to hydrocarbons within the confined space. Otherwise, low hydrocarbons yield (but high ketone yield) is obtained over TiO2 and the Mg/Al mixed oxide catalysts possessing no interlayer space. Meanwhile, the semi-batch experiment with pre-intercalated palmitic acid favors a direct deoxygenation, demonstrating the essential role of reaction mode toward ketone scission reaction pathway. Over K0.8Li0.27Ti1.73O4, the complete palmitic acid conversion leads to ∼47% hydrocarbons yield, equivalent to ∼80% reduction of the oxygen content in the feed under N2.

Recent advancement in deoxygenation of fatty acids via homogeneous catalysis for biofuel production

Fuel-like hydrocarbons (also known as biofuel) isolated from the deoxygenation of fatty acids present different advantages as compared with fossil fuels. In particular, the homogeneous and heterogeneous catalytic deoxygenation methods have been the center of attention during recent years. Although catalytic deoxygenation of fatty acids via heterogeneous catalysis has been widely investigated, there is a high demand to review the progress in using the homogeneous catalysis pathways. Among the various homogeneous pathways, radical-based reactions and transition metal catalysis demonstrate the most promising results in the decarboxylation and decarbonylation processes. It is shown that radical-based reactions are more active in decarboxylation meanwhile the transition metal catalysts are rather selective to decarbonylation of fatty acids. Besides, the reaction conditions and type of catalysts are capable of enhancing biofuel production. Homogenous catalysis provides the huge potential for commercializing viability of biofuel via deoxygenation of fatty acids.

Preparation of reduced Ni-Nb-O composite hydrogenation catalysts for highly selective conversion of free fatty acids to n-alkanes

Catalytic deoxygenation of fatty acids to alkanes is an ideal route to produce biodiesel with high heating value. However, traditional transition-metal sulfide and noble metal catalysts are sulfide-contaminated, high cost, or easily poisoned. To overcome the above issues, this work developed a non-noble and sulfide-free reduced transition-metal composite NixNbyOz, which was effective to selectively hydrogenate stearic acid, a typical fatty acid model compound, to diesel-range alkanes. By using a simple slurry method, reduced NixNbyOz catalysts have been successfully prepared with an outstanding catalytic performance. The results showed that catalyst Ni0.5Nb0.5Oz effectively converted stearic acid to n-alkanes with nearly 100% conversion and >99% n-alkanes selectivity at mild conditions (513 K and 3.5 MPa of H2 pressure). Appropriate Nb species improved the dispersion of Ni species, which may supply more hydrogenation active sites. Two possible reaction routes of stearic acid were proposed, and the hydrogenolysis of stearyl stearate was confirmed as the rate-determining step based on the kinetics experiments. Because of moderate acidity of Nb species, the ratio of C17/C18 alkane was not markedly affected by reaction conditions when the conversion of stearic acid was higher than 99%. Moreover, catalyst Ni0.5Nb0.5Oz showed a high recycle ability and compatibility for other long-chain fatty acids, demonstrating that catalyst Ni0.5Nb0.5Oz is a promising green catalyst for producing biodiesel from fatty acids.

Green diesel production from palm fatty acid distillate over SBA-15-supported nickel, cobalt, and nickel/cobalt catalysts

The utilization of non-edible and low-cost feedstock in bioenergy research is getting more attention in recent decades. Catalytic deoxygenation of fatty acids from waste oil feedstocks is a promising route to produce diesel-like hydrocarbons. Here we report the conversion of palm fatty acid distillate (PFAD), a low-value side product of physical refining of crude palm oil, into green diesel using a solventless and hydrogen-free deoxygenation (DO) reaction using catalytic deoxygenation over solid acid catalysts (Co/SBA-15, Ni/SBA-15, and Ni–Co/SBA-15) with total metal loadings of 5 wt%. Metal precursors (Ni, Co, Ni–Co) were doped on the mesostructured catalyst supporter, SBA-15 by wet impregnation. The catalysts were characterized by nitrogen adsorption-desorption isotherm analysis, X-ray diffraction, X-ray fluorescence, infrared spectroscopy, and high-resolution transmission electron microscopy with elemental mapping. The DO reaction was carried out in a semi-batch reactor with a catalyst loading of 10 wt% at 350 °C for 3 h. The use of both Ni/SBA-15 and Ni–Co/SBA-15 afforded products with high contents of liquid hydrocarbons (C8–C17) with yields of 85.8% and 88.1%, respectively, and selectivity for diesel-range hydrocarbons (C13–C17) above 85% were achieved. Cobalt seems to have a larger particle size, then associates with the carbon formation and introduces coke formation. It blocks some pores and deactivates the active sites of the catalyst, thus reducing the catalytic activity.

Metal Oxide-Promoted Hydrodeoxygenation Activity of Platinum in Pt-MOx/Al2O3 Catalysts for Green Diesel Production

Catalytic deoxygenation of fatty acids into renewable hydrocarbons (green diesel) was investigated over 4Pt-8MOx/Al2O3 (M = Mo, Re, W, and Sn) catalysts prepared by the wet impregnation method. Platinum deposited on MOx-modified γ-Al2O3 showed higher catalytic hydrodeoxygenation activity than that of the “neat” Pt/Al2O3 catalyst. The promotional effect of metal oxides (MOx) decreased in the following order: MoOx > ReOx > WOx > SnOx. Characterization studies revealed that metal oxides affect the textural and electronic properties of Pt. Supported Pt facilitated the reduction of these metal oxides. Synergy and electronic contact between Pt and MOx determined the catalytic deoxygenation performance. Fatty acid conversion increased with increasing metallic nature (decreasing binding energy) of Pt. Hydrodeoxygenation product selectivity correlated with the extent of metal oxide reduction. Among the catalysts, 4Pt-8MoOx/Al2O3 had the optimum dispersion, electron-rich Pt, and reduced Mo5+ species, enabling quant...

Selective production of linear α-olefins via catalytic deoxygenation of fatty acids and derivatives

Various homogeneous, heterogeneous, and enzyme catalysis strategies for the selective synthesis of linear α-olefins from fatty acids and their derivatives are reviewed.

Silica support modifications to enhance Pd-catalyzed deoxygenation of stearic acid

The catalytic deoxygenation of fatty acids has recently received significant attention as a low-hydrogen approach to biomass feedstock deoxygenation for production of hydrocarbon fuels with superior properties to biodiesel. Unfortunately, it is a challenging reaction to push to high yields. Of typical catalysts, Pd/C is typically reported to give the best performance, while most oxide supports are inferior, with exceptions for very specific preparation and pre-treatment protocols. Here, we investigate the role of organosilane-modified silicas as supports for the Pd-catalyzed deoxygenation of stearic acid at 300°C under inert atmosphere. Comparing aminopropylsilane-modified, phenylsilane-modified, and unmodified silica supports with Pd incorporated by several methods, it is first shown that changes in dispersion alone do not account for improvements in deoxygenation yields. Capping silanols with phenylsilane is also ineffective on its own in improving deoxygenation yields. The most effective treatment is shown to be a co-deposition of phenylsilane and aminopropylsilane before Pd incipient wetness impregnation, followed by direct reduction of the catalyst, which gives heptadecane yields >85%, exceeding even the productivity of Pd/C. These results demonstrate that basic, aromatic-rich surfaces are accessible through organosilane grafting and that these surfaces can control Pd particle sizes and the adsorption of stearic acid and products. This work improves our understanding of support effects for biomass feedstock deoxygenation catalysts and could help design new catalysts that take advantage of modified inorganic supports.

Catalytic Deoxygenation of Fatty Acids: Elucidation of the Inhibition Process

AbstractCatalytic deoxygenation of unsaturated fatty acids in the absence of H2 is known to suffer from significant catalyst inhibition. Thus far, no conclusive results have been reported on the cause of deactivation. Here we show that CC double bonds present in the feed or the products dramatically reduce the deoxygenation activity of supported palladium catalysts. In the case of stearic acid deoxygenation the addition of 0.1 equivalents of a mono‐unsaturated fatty acid or olefin already reduces the catalytic deoxygenation activity by 60 %. This effect becomes more pronounced with an increasing number of double bonds. The inhibition is shown to be reversible in H2 atmosphere, indicating no significant contribution from irreversibly deposited hard coke. Furthermore, the type of support material has no apparent effect on catalyst inhibition. Hence we propose that initial catalyst inhibition proceeds through reversible adsorption of CC double bonds on the palladium active sites.

Catalytic deoxygenation of fatty acids and their derivatives to hydrocarbon fuels via decarboxylation/decarbonylation

AbstractFatty acids and their derivatives can be converted to renewable and carbon‐neutral fuel‐like hydrocarbons that are entirely fungible with fossil fuels. Typically, these hydrocarbon‐based biofuels are obtained through hydrotreating, a method which has the significant disadvantages of requiring problematic sulfided catalysts and high pressures of hydrogen. In recent years, decarboxylation/decarbonylation has been proposed as an alternative method, as this approach has the advantages of permitting the use of simpler catalysts and requiring less hydrogen than hydrotreating. In this contribution, the deoxygenation of fatty acids and their derivatives to fuel‐like hydrocarbons via decarboxylation/decarbonylation is critically reviewed. The main aspects discussed include the influence of the feed, catalyst, reactor system and reaction conditions on the decarboxylation/decarbonylation reaction, as well as the reaction mechanism and catalyst deactivation/regeneration. Copyright © 2012 Society of Chemical Industry

Influence of Hydrogen in Catalytic Deoxygenation of Fatty Acids and Their Derivatives over Pd/C

The influence of hydrogen on the catalytic deoxygenation of fatty acids was investigated in the semibatch reactor over a mesoporous 5 wt % Pd/C (Sibunit) catalyst. Transformations of a model fatty ...

Catalytic Deoxygenation of Fatty Acids and Their Derivatives

Catalytic deoxygenation including decarboxylation/decarbonylation of fatty acids and their esters has been investigated over Pd supported on active carbons in a semibatch reactor. The main studied parameters were catalyst acidity, type of feed, effect of solvent, and gas atmosphere. High yields of the desired product, n-heptadecane, were achieved in the decarboxylation of stearic acid at 300 °C under helium. The results demonstrate that the catalytic transformation of fatty acids proceeded mainly via decarboxylation, whereas decarbonylation was the main route for esters, according to gas-phase analysis. The gas atmosphere and the acidity of the catalyst were important factors for determining product selectivity. Over alkaline catalysts as well as under a hydrogen atmosphere, higher yields of n-heptadecane were obtained. The decarboxylation of unsaturated fatty acids leads to hydrogenated products, which reacted further to hydrocarbons.