Deoxygenation Of Stearic Acid Research Articles

Catalytic Biomass Transformation to Hydrocarbons under Supercritical Conditions over Nickel Supported on Schungite

Liquid fuel production from biomass-derived molecules has received great attention due to the diminished fossil fuel reserves, growing energy demand, and the necessity of CO2 emission reduction. The deoxygenation of oils and fatty acids is a promising process to obtain “green” diesel. Herein, we report the results of the study of the deoxygenation of stearic acid to alkanes as a model reaction. Series of Ni-supported on schungite were obtained by precipitation in subcritical water (hydrothermal deposition) and for comparison via wetness impregnation followed, in both cases, by calcination at 500 °C and a reduction in H2 at 300 °C. The catalyst obtained via hydrothermal synthesis showed a three-fold higher specific surface area with a four-fold higher active phase dispersion compared to the catalysts synthesized via conventional impregnation. The catalysts were tested in stearic acid deoxygenation in supercritical n-hexane as the solvent. Under optimized process conditions (temperature of 280 °C, hydrogen partial pressure of 1.5 MPa, and 13.2 mol of stearic acid per mol of Ni), a close to 100% yield of C10–C18 alkanes, containing over 70 wt.% of targeted n-heptadecane, was obtained after 60 min of reaction.

Catalytic deoxygenation of stearic acid into olefins over Pt catalysts supported on MOF-derived metal oxides

The deoxygenation of stearic acid over Pt supported on different metal oxides can affect the product selectivity.

Catalytic Hydrothermal Deoxygenation of Stearic Acid with Ru/C: Effects of Alcohol- and Carboxylic Acid-Based Hydrogen Donors.

Catalytic hydrothermal processing is a promising technology for the production of biofuels used in transportation to alleviate the energy crisis. An important challenge for these processes is the need for an external supply of hydrogen gas to accelerate the deoxygenation of fatty acids or lipids. It follows that in situ-produced hydrogen can improve process economics. This study reports on the use of various alcohol and carboxylic acid amendments as sources for in situ hydrogen production to accelerate Ru/C-catalyzed hydrothermal deoxygenation of stearic acid. Addition of these amendments significantly increases yields of liquid hydrocarbon products, including the major product heptadecane, from stearic acid conversion at subcritical conditions (330 °C, 14-16 MPa during the reaction). This research provided guidance for simplifying the catalytic hydrothermal process of biofuel production, making the production of the desired biofuel in one pot possible without the need for an external H2 supply.

Catalytic performance of carbon-supported mixed MoW carbides for the deoxygenation of stearic acid

Supported bimetallic molybdenum and tungsten carbides are viable replacements for noble metal catalysts and are suitable for the decarboxylation/decarbonylation and (hydro-)deoxygenation of renewable triglyceride‑based feedstocks. Here, we show that the Mo:W ratio in bimetallic carbide can steer the product yield towards either aldehydes, alcohols, alkenes or alkanes. The mixed carbides with a higher Mo/W ratio (3:1) reached higher yields of aldehydes and alcohols, while the carbides with a lower Mo/W (1:3) ratio yielded high concentrations of alkenes. Interestingly, a physical mixture of two monometallic (1 +1) carbides had a similar catalytic performance to the 1:1 mixed carbides. The intrinsic activity (turnover frequency (TOF)) of the catalysts was assessed based on both H2 and CO chemisorption. The TOFH2 related linearly with the Mo/W ratio, while the TOFCO did not show a relevant relationship. Therefore H2 chemisorption is suggested as the preferred way to assess the intrinsic activities of these catalysts.

Highly Effective Schungite-Based Catalyst for Deoxygenation of Biomass Components

Nowadays, the processes for the conversion of biomass to fuels are of great interest. One of the widely studied reactions is the deoxygenation of oxygen-containing compounds. The process is performed in two main directions: in hydrogen presence (namely hydrodeoxygenation) and using supercritical fluids as a hydrogen source. The modern problem in deoxygenation is catalyst stability and selectivity. Thus, the development of novel catalytic systems is an urgent task. Schungite is a natural carbon-reach material that has high sorption ability and excellent reductive properties. These properties make this material suitable for its use as catalyst support. In this work, the study of the effectiveness of novel schungite-based catalysts in supercritical deoxygenation of fatty acids and bio-oil model compounds is presented. The catalyst synthesis was performed by the recently developed method of Ni hydrothermal deposition on the schungite surface. The synthesized catalysts were tested in the deoxygenation of stearic acid and guayacol in the supercritical hexane. The experimental results showed that the developed catalysts allow 100 % conversion of the substrate to be reached in both processes providing over 90 wt.% of gasoline and diesel-range hydrocarbon yield.

Graphitic carbon embedded FeNi nanoparticles for efficient deoxygenation of stearic acid without using hydrogen and solvent

Upgrading fatty acids to hydrocarbons via deoxygenation is significant for the synthesis of high-grade biofuels. Developing economic reaction conditions without using noble metal-based catalysts in the absence of hydrogen and solvent has promising application prospects. Herein, carbon-coated bimetallic FeNi nanoparticles were prepared via an in-situ carbonization-reduction strategy using double-metal cyanide at different temperatures for the deoxygenation of stearic acid. The size of the alloy core and the thickness of the carbon shell were found to be easily adjusted by varying temperature. Compared with monometallic Fe/C and Ni/C catalysts, the alloy catalyst exhibits an obvious improvement in both the conversion of stearic acid and the selectivity of heptadecane. ATR-IR spectra show that the insertion of the inert Fe element into Ni nanoparticles can promote carboxylic acid group adsorption but restrain hydrocarbon group adsorption. The synergistic effect of Fe and Ni elements leads to the promotion of direct decarboxylation of stearic acid and suppression of the C–C cracking reaction. Among different alloy catalysts studied, FeNi@C-800 exhibits the greatest catalytic performance with a 99.9% conversion of stearic acid and 76.8% selectivity for heptadecane. Furthermore, the catalyst can still maintain a stable catalytic performance against the leaching and ripening of metal through the protection afforded by the carbon shell. This work not only provides a powerful reaction system for the decarboxylation of stearic acid but also demonstrates an alternative catalyst to noble metals based on a convenient carbonization-reduction strategy.

A novel kinetic model applied to heterogeneous fatty acid deoxygenation

An improved kinetic model for the deoxygenation of fatty acids was developed and compared with previously developed models. The models were compared using data collected from the deoxygenation of oleic acid using a novel, extensively characterized aerogel-based catalyst and previously published data of the deoxygenation of stearic acid, resulting in an extensive analysis ranging from 275 °C to 400 °C. The novel model was able to predict the behavior of reactants, intermediates and products for all cases analyzed in this paper. Akaike and Bayesian information criterions were applied, concluding that the novel kinetic model was indeed the best model to predict the behavior of both our original data and a previously published dataset. Relevant data regarding reaction rates and selectivity for the novel catalyst was given, showing a clear practical use of the results presented in this paper for the design and optimization of deoxygenation reactors.

Rapid and green synthesis of SAPO-11 for deoxygenation of stearic acid to produce bio-diesel fractions

A grinding synthesis approach is employed to prepare water containing gel. SAPO-11G was successfully prepared by a dry gel conversion method using water containing gel assisted by microwave radiation (120–180 °C, 2 h). Compared to hydrothermal system, approach employed in the present study show green characters such as conservation of energy and time, low cost of organic filler, and reducing wastewater discharge. Deoxygenation of stearic acid shows that Ni/SAPO-11 catalysts have a high selectivity to paraffin and a low yield to cracking products. Ni/SAPO-11G has a comparable activity (conversion> 95%) with Ni/SAPO-11H molecular sieves. Coke deposition in SAPO-11G is lower than that in SAPO-11H due to a lower concentration of extra-framework aluminum species (i.e., Lewis acid sites). These results propose a rapid way to prepare zeolites in an environmental friendly route and are important to produce bio-diesel fractions via a deoxygenation reaction. • A grinding synthesis method is employed to prepare water containing precursor. • SAPO-11 is prepared using dry gel conversion heated by microwave. • Ni/SAPO-11 catalysts exhibit a high selectivity to C15-18 paraffin in deoxygenation of stearic acid.

Magnetically separable Ru-containing catalysts in supercritical deoxygenation of fatty acids

Abstract In the current paper, the possibility of the use of magnetically separable catalysts containing ruthenium oxide species in the supercritical deoxygenation of stearic acid for producing of the second generation of biodiesel is reported. Three different supports (silica, ceria, and hypercrosslinked polystyrene) were used for the stabilization of magnetic nanoparticles (MNPs) and Ru-containing particles. The effect of support on the magnetic properties as well as the catalytic activity of the obtained systems was studied. All synthesized catalysts were shown to provide high stearic acid conversion (up to 95 %). The highest yield of C17+ hydrocarbons (up to 86 %) was observed while using the Ru–Fe3O4-HPS system. Ru–Fe3O4-HPS was characterized by the high values of the specific surface area (364 m2/g) and saturation magnetization (4.5 emu/g). The chosen catalytic system was found to maintain its catalytic activity for a minimum of 10 consecutive cycles.

Полимерный магнитоотделяемый катализатор для сверхкритического деоксигенирования жирных кислот

In this paper, the possibility of using a magnetically separated ruthenium-containing catalyst based on a polymer matrix of hypercrosslinked polystyrene in the supercritical deoxygenation of stearic acid to produce a second-generation biodiesel fuel is studied. The catalyst was synthesized by a successive deposition of iron and ruthenium oxides to the polymeric support. The resulting catalytically active Ru-Fe3O4-HPS system is characterized by high specific surface area (364 m2/g) and magnetization (4.5 emu/g). This catalyst allows obtaining a high (up to 86%) yield of hydrocarbons C17+ and exhibits high activity in the process of deoxygenation in supercritical n-hexane. It was found that the selected catalytic system retains its catalytic activity for at least 10 consecutive cycles.

Decarboxylation of stearic acid over Ni/MOR catalysts

AbstractBACKGROUNDOils derived from plants, animal fats, and algae contain both saturated and unsaturated fatty acids. These fatty acids can be converted into liquid fuels and chemicals in the presence of active solid catalysts.RESULTSNickel‐based catalysts were supported on mordenite via ion exchange synthesis and evaluated for the deoxygenation of stearic acid to diesel fuels. By tuning the synthesis pH, loadings of over 20 wt% Ni were obtained. Catalysts synthesized at pH 8.5 displayed the highest Ni loading and the highest activity for the decarboxylation/decarbonylation of stearic acid under inert nitrogen gas atmospheres, yielding 47% heptadecane. Characterization included scanning transmission electron microscopy‐energy‐dispersive spectroscopy (STEM‐EDS), X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), inductively coupled plasma atomic emission spectroscopy (ICP‐AES), N2 physisorption and thermogravimetric analysis (TGA), providing new insights into the recyclability of the catalyst. The observed loss of catalytic activity upon recycling was attributed to the agglomeration of Ni nanoparticles and the accumulation of carbonaceous coke.CONCLUSIONThis work demonstrates that Ni‐based catalysts supported on mordenite zeolite can effectively convert stearic acid into heptadecane. Yields to heptadecane were as high as 47%. Mechanistically, the reaction proceeds by decarboxylation and decarbonylation pathways. © 2019 Society of Chemical Industry

Novel Catalyst Synthesized by Hydrothermal Method for Fatty Acid Conversion Into Hydrocarbons

Here, the novel method for the conversion of fatty acids into hydrocarbon fuel without hydrogen consumption is reported. The deoxygenation of stearic acid as a model compound was performed in the medium of supercritical n-hexane in the presence of Ni-containing catalysts synthesized by a hydrothermal deposition method. We studied the influence of the support as well as the metal loading on the yield of target products of stearic acid conversion into hydrocarbons. Ni was supported on the three different supports: anhydrous microporous silica, anhydrous alumina, and non-functionalized hypercrosslinked polystyrene. The hydrothermal synthesis of the catalysts leads to the changes in the porosity and structure of the supports increasing the number of mesopores. The active phase of the catalysts was found to be deposited on the internal surface of the supports as a thin layer of ?-NiOOH. Ni/HPS catalyst was found to be the most active in the stearic acid deoxygenation process in supercritical n-hexane. The study of the influence of the metal loading on the conversion of the substrate and the target product yield showed that 10 wt. % of Ni is more favorable for the production of high yield of C16-C17 hydrocarbons.

Catalytic deoxygenation of stearic acid and waste cooking oil over Pd/SBA-15 for obtaining hydrocarbons with potential as renewable liquid fuels

It has been found that catalytic deoxygenation of triglycerides is a viable pathway for obtaining renewable liquid fuels to contribute to meet the global energy demand. In this study, SBA-15 mesoporous silica was synthesized in a pure form and modified with mesitylene (TMB) as a swelling molecule (SBA15-TMB). Catalysts with 0.5, 1.5 and 3.0 wt% Pd were synthesized and tested by deoxygenation of stearic acid (SA), obtaining initial conversions of 68–98% that decreased to 36–73% after 6 h time-on-stream. The most abundant product was n-heptadecane, with a selectivity of ~ 90%. The most active catalyst evaluated with SA was 3.0 wt% Pd over unmodified SBA-15 (30Pd/SBA-15). Subsequently, fresh and regenerated 30Pd/SBA-15 catalysts were tested with waste cooking oil (WCO) feed, obtaining conversions of 74 and 72%, respectively, but the fresh catalyst allowed a better oxygen removal (91%. Additionally, commercial Pd(10wt %)/C catalyst was evaluated, obtaining results comparable to those for the regenerated 30Pd/SBA-15 catalyst. The main WCO reaction product for all catalysts was a diesel fraction (C12-C21), and the quality of the products was not very different, following the order: Pd(10wt %)/C > 3.0Pd/SBA-15-regenerated > 3.0Pd/SBA-15-fresh. The results obtained indicate that shynthetized catalysts of this study are promising for obtaining renewable diesel from low-cost feeds while using low hydrogen consumption.

Improved conversion of stearic acid to diesel-like hydrocarbons by carbon nanotubes-supported CuCo catalysts

In this study, a novel carbon nanotube (CNT)-supported CuCo catalyst was successfully synthesized by wet impregnation. Experimental and theoretical results on catalytic deoxygenation of stearic acid, a model compound of microalgal bio-oil, revealed that the CuCo catalyst can effectively inhibit cracking reactions and promote production of diesel-like hydrocarbons. CuCo particles in the pores of CNTs were conducive to conversion of stearic acid to long-chain alkanes, featuring a high selectivity of 94.82% at 100% conversion. CuCo catalyst in oxidation state underwent fast in-situ reduction at the beginning of deoxygenation reaction, and its catalytic performance was comparable to that of reduced CuCo catalyst. The improved catalytic conversion of stearic acid to diesel-like hydrocarbons can be achieved at a high ratio of Cu0/(Cu++Cu0) and lattice Co atoms. In addition, the reduced H2 pressure and amounts of catalysts show potential for large-scale industrial applications.

Fatty Acid Deoxygenation in Supercritical Hexane over Catalysts Synthesized Hydrothermally for Biodiesel Production

AbstractDeposition of catalytically active metal‐containing compounds on solid porous supports by using superheated (subcritical) water is a promising way to produce materials with unique physicochemical and catalytic properties. The hydrothermal method has been found to give catalysts with high surface area, fine distribution of the active phase, and high catalytic activity. In the current work, the catalytic activities of 10 % Ni and 10 % Co deposited on hyper‐cross‐linked polystyrene (HPS) by the hydrothermal method in the supercritical deoxygenation of fatty acids were compared. 10 % Ni/HPS was found to be the most active catalyst in the deoxygenation of stearic acid in supercritical n‐hexane.

Deoxygenation of Stearic Acid over Cobalt-Based NaX Zeolite Catalysts

For the production of sustainable biofuels from lipid biomass it is essential to develop non-noble metal catalysts with high conversion and selectivity under inert gas atmospheres. Herein, we report a novel cobalt-based catalyst supported on zeolite NaX via ion-exchange synthesis. The resultant bifunctional cobalt-based NaX zeolite catalyst displayed high conversion of stearic acid to liquid fuels. In addition, the effect of reaction temperature and catalyst loading was studied to evaluate the order of reaction and activation energy. Decarboxylation and decarbonylation were the dominant deoxygenation pathways. Stearic acid was successfully deoxygenated in N2 atmospheres using Co/NaX catalysts with a conversion as high as 83.7% and a yield to heptadecane up to ~28%. Furthermore, we demonstrate that higher reaction temperatures resulted in competing pathways of decarboxylation and decarbonylation. Finally, the fresh and recycled catalysts were characterized showing modest recyclability with a ~12.5% loss in catalytic activity.

Role of Sn promoter in Ni/Al2O3 catalyst for the deoxygenation of stearic acid and coke formation: experimental and theoretical studies

The effect of Sn promoter on a Ni/γ-Al2O3 catalyst towards the deoxygenation of stearic acid has been investigated.

Effect of Cu-Ce/γ-Al2O3 catalyst on bio-oil production by hydrothermal deoxygenation of stearic acid

In order to improve the hydrothermal deoxygenation of organic acids as well as to reduce the cost, we prepared a Cu-Ce/γ-Al2O3 catalyst to study the hydrothermal deoxygenation of stearic acid in the absence of H2. The Brunauer-Emmett-Teller surface area and X-ray diffraction pattern suggest that both CuO and CeO2 exist in the Cu-Ce/γ-Al2O3 catalyst. The crystals of Cu-Ce/γ-Al2O3 were more stable compared with those of the Cu/γ-Al2O3 catalyst after 12 h of hydrothermal liquefaction at 300℃, thereby indicating a better thermal stability of the former. The presence of Cu-Ce/γ-Al2O3 catalyst could greatly improve the conversion of stearic acid (94.71%) and the yield of hydrocarbon (81.41%). A preliminary analysis of the mechanism suggests that decarboxylation is the main step in the deoxygenation during the hydrothermal liquefaction of stearic acid. The addition of Cu/γ-Al2O3 and Cu-Ce/γ-Al2O3 decreased the yield of n-heptadecane and increased the yield of n-octadecane. Besides, the yields of n-paraffins increased drastically from 0.45% to 49.72% along the series from n-nonane to n-hexadecane. Thus, the cracking reactions could be improved in the presence of Cu-Ce/γ-Al2O3, suggesting that it is an efficient deoxygenation catalyst in the hydrothermal liquefaction of organic acid. In addition, the Cu-Ce/γ-Al2O3 catalyst could help in removing the carbonyl groups, and this effectively reduced the amounts of aldehydes and ketones in the bio-oil.

Production of bio-jet fuel range alkanes from catalytic deoxygenation of Jatropha fatty acids on a WOx/Pt/TiO2 catalyst

Bio-jet fuel range alkanes were prepared by catalytic deoxygenation reaction of non-edible acid oils with no added hydrogen. A WOx[6]/Pt[1.6]/TiO2 was used for the deoxygenation of stearic acid and Jatropha fatty acid derived from Jatropha oil by hydrolysis. Tungsten addition to the Pt/TiO2 showed remarkably enhanced performance, a degree of deoxygenation of 86%, which is more than two times higher than that of the Pt/TiO2, even though the WOx/TiO2 had almost no activity for deoxygenation reaction. The enhanced Pt-related hydrogen uptake, measured by H2-TPR, and XPS analysis showed the intimate contact of tungsten with Pt nanoparticles supported on TiO2. This tight contact allows for easier CC cleavage over Pt nanoparticles and this is assisted by the strong bonding between tungsten and oxygen in the reactant, resulting in more C17 hydrocarbon production on the WOx/Pt/TiO2.

Catalytic deoxygenation of C18 fatty acids over HAlMCM-41 molecular sieve

The large demand for energy combined with ecological, economic, and social reasons encouraged the studies for alternative sources of fuel. The deoxygenation process of oils and fatty acids has emerged as a promising resource in obtaining fuels. This paper studied the deoxygenation process of oleic and stearic acids carried out in a distillation system, under the temperature of 450 °C over MCM-41, AlMCM-41-41, and HAlMCM-41 molecular sieves, which were synthesized by direct hydrothermal synthesis method and characterized by X-ray diffraction (XRD) spectroscopy in the infrared site (FTIR), adsorption and desorption of N2, and scanning electron microscopy (SEM). The products were analyzed by gas chromatography (GC) and acid-base titration. The results showed that stearic acid deoxygenates more than the oleic acid, and that the performance of HAlMCM-41 was superior to AlMCM-41, indicating that the total acidity positively influenced the process. Furthermore, from the stearic acid deoxygenation, it obtained mainly heptadecanes (C17:0) structures, while the oleic acid produces heptadecenes (C17:1).