Conversion Of Stearic Acid Research Articles

Simulation of a catalytic deoxygenation reaction of fatty acids to produce biohydrocarbons and evaluation of the influence of reaction parameters on the conversion and selectivity of products

Nowadays, there has been an urgency in the search for sustainable energy sources, such as those derived from biomass. This search is not only limited to minimizing greenhouse gas emissions but is also related to the increasing scarcity of fossil fuels. This work aims to investigate and analyze the production of bio-hydrocarbons from fatty acids through the simulation of the deoxygenation reaction by the DWSim software. In this simulation, a continuous catalytic deoxygenation reactor of the stirred tank with fluidized bed type was selected, aiming to understand the influence of operating parameters on this reaction. The parameters evaluated were temperature, pressure, hydrogen feed, and catalyst mass. For this simulation, hydrogen and stearic acid were chosen as feedstocks, focusing on the heptadecane and octadecane production. The rate law was chosen based on an extensive literature review, as well as reaction conditions. The kinetic model used as a reference was based on reactions of stearic acid and hydrogen in the presence of NiMo/Al2O3 as a catalyst. A stearic acid feed of 2.4 x 104 m3 year-1 was used as a base, representing the average feed of fatty raw material practiced in biodiesel plants located in the state of Minas Gerais, Brazil. From the variation of these parameters for a sensitivity analysis, with conversion as the key response, the following optimal operating conditions were defined: temperature of 650 K, pressure of 50 bar, molecular hydrogen feed of 4.1 x 10-3 m³ s-1, and catalyst mass of 8 kg. Under these new circumstances, the conversion of stearic acid reached a value of 99.23 %. The simulation of this reaction allowed us to understand the effect of the main reaction parameters on the reaction products, proved to be an important and robust tool to be used in projects and feasibility analyses of plants and biorefineries.

Synthesis of fatty amides from lauric acid and stearic acid for pharmaceutical and cosmetic applications

The research relates to developing a process for making fatty acid-based surfactants from renewable natural resources. At this stage, the potential of stearic acid and lauric acid to be synthesized into fatty amide surfactants was observed using monoethanolamine and urea as an amine source. In this study, the potential utilization of two types of fatty acids, namely lauric acid and stearic acid, was reacted with monoethanolamine using CaO and hexane-isopropanol solvent in a stirred tank reactor. For this reason, the research was planned to study the effect of reaction time, stirring speed, and temperature on the amide recovery. The success of the process is measured by the best conversion of fatty acids produced, as well as observing the effect of the three reaction variables on the conversion of fatty acids. Furthermore, structural tests were carried out with FT-IR spectroscopy. As a result, the lauric acid conversion was 83.33%, and the stearic acid conversion was 82.38%, obtained at a substrate (fatty acid: MEA) ratio of 1:8, a catalyst weight of 5%, and a solvent ratio of 2:1.

Hierarchical porous honeycomb NiCo/C catalyst for decarboxylation of fatty acids and upgrading of sludge bio-crude

Honeycomb NiCo/C-Na catalyst featured with a micro-meso-macroporous structure is fabricated and shows a significantly higher catalytic activity for decarboxylation of fatty acid compared to a series of other carbon-based catalysts. A 100 % conversion of stearic acid and a C15-18 alkane total yield of 70 % is achieved at 280 °C for 3 h under 1 MPa H2 with heptadecane as the main product. NiCo/C-Na also achieves a complete conversion of monoglyceride into heptadecane when using edible oil as reactant. The catalyst is further evaluated for upgrading of sludge HTL bio-crude and proves to be highly efficient. The obtained upgraded biofuel exhibits a decreased viscosity and an increased density. Specifically, the higher heating value (HHV) increases to 47.32 MJ/kg. This result is attributed to the easier desorption of CO2, better H2 activation capacity and the unique hierarchical pore structure of the catalyst, which allows faster mass transfer and reaction rate.

Fabrication of NiZn bimetallic oxides catalysts supported on carbon black waste for catalytic pyrolysis of fatty acid

Herein, NiZn bimetallic oxides derived from calcination treatment of metal-organic frameworks (MOFs) were successfully loaded onto the carbon black waste as support obtained from the oil refinery. The resulting hybrids could serve as environmentally friendly and cost-effective catalysts for the deoxygenation of biomass-derived fatty acids under an inert atmosphere. An online pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) system was employed to evaluate their deoxygenation performance. The optimized catalysts demonstrated remarkably high stearic acid conversion of 99.6% and selectivity towards C8-C17 olefins of 57.2%. Furthermore, these catalysts with varying metal loadings also exhibited excellent efficiency in deoxygenation reactions of other types of fatty acids, such as myristic acid and palmitic acid, achieving conversion exceeding 85% and selectivities towards olefins of ca. 50%. When converting coconut oil, the supported NiZn bimetallic oxides showed excellent selectivity towards olefins (>60%). Furthermore, in-situ DRIFTS results suggest that fatty alcohols might be the key intermediates in the deoxidation reactions of fatty acid. This study not only demonstrates the great potential for obtaining valuable chemicals from biomass but also provides some insights into the fabrication of catalyst materials by using industrial solid waste.

NiCo/SiO2 nanospheres for efficient synergetic decarboxylation of fatty acids and upgrading of municipal sludge HTL bio-crude to biofuels

Municipal sludge (MS) and derived HTL (hydrothermal liquefaction) bio-crude contains a large quantity of organics, including fatty acids, which may be a potential resource for producing biofuels via catalytic treatment. Herein, decarboxylation of fatty acids is chosen as the model reaction to screen a series of nickel-based bimetallic catalysts supported on homemade SiO2 nanospheres to investigate the synergetic effect. NiCo/SiO2 turned out with the best performance compared to NiCu-, NiZn-, NiMo- and NiFe/SiO2. An 83% conversion of stearic acid and an 84% selectivity of heptadecane via hydrothermal decarboxylation were achieved at 280 °C under 1 MPa H2. XPS results revealed the electron transfer from Co to Ni, leading to the formation of Niδ-, which is more accessible to bond with Cδ+ in the carboxyl group of fatty acids, thus facilitating the decarboxylation reaction. Compared to commercial SiO2, our homemade SiO2 showed a stronger carbon accumulation resistance, indicating a medium specific surface area was essential. Both the synergetic effect of NiCo bimetal and the carbon accumulation resistance of homemade SiO2 nanospheres contributed to the efficient hydrothermal decarboxylation. The NiCo/SiO2 catalyst was further applied for upgrading of MS HTL bio-crude to biofuels, and the theoretical higher heating value (HHV) was significantly improved from 34.4 to 37.2 MJ/kg, suggesting the potential application of converting MS bio-crude to biofuels.

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.

Bioinformatics and Functional Analysis of High Oleic Acid-Related Gene GmSAM22 in Soybean [Glycine max (L.) Merr.

High yield, high quality, stable yield, adaptability to growth period, and modern mechanization are the basic requirements for crops in the 21st century. Soybean oleic acid is a natural unsaturated fatty acid with strong antioxidant properties and stability. Known as a safe fatty acid, it has the ability to successfully prevent cardiovascular and cerebrovascular disorders. Improving the fatty acid composition of soybean seeds, can not only speed up the breeding process of high-quality high-oil and high-oleic soybeans, but also have important significance in human health, and provide the possibility for the development of soybean oil as a new energy source. Hence, the aim of this study was to analyze the high oleic acid elated gene GmSAM22 in soybean. In this research the soybean oleic acid-related gene GmSAM22 was screened out by Genome-wide association analysis, a 662 bp fragment was acquired by specific PCR amplification, and the pMD18T cloning vector was linked by the use of a seamless cloning technique. Bioinformatics analysis of the signal peptide prediction, subcellular localization, protein hydrophobicity, transmembrane region analysis, a phosphorylation site, protein secondary and tertiary structure and protein interaction analysis of the protein encoded by the SAM22 gene was carried out. The plasmid of the gene editing vector is pBK041. The overexpression vector was transformed from pCAMBIA3301 as the base vector, and overexpression vector were designed. Positive plants were obtained by genetic transformation by the pollen tube channel method. Fluorescence quantitative PCR was performed on the T2 generation plants to detect the relative expression levels in different tissues. Southern Blot was used to detect the presence of hybridization signal. Screening genes BAR, 35S, and NOS in plants were identified by conventional PCR. 10 seeds with high and low oleic acid content were chosen for quantitative PCR identification, and finally, the concentration and morphology of soybean fatty acids were identified by near-far infrared spectroscopy. On 10 seeds with an upper and lower oleic acid content, a quantitative fluorescence analysis was done. In Southern blot hybridization, the SAM22 gene was integrated into the recipient soybean plant in hands of a sole copy. Fluorescence quantitative PCR appeared that the average relative expression of the SAM22 gene in roots, stems, leaves, and seeds was 1.70, 1.67, 3.83, and 4.41, respectively. Positive expression seeds had a 4.77% increase in oleic acid content. The level of oleic acid in the altered seeds was reduced by 4.13% when compared to CK, and it was discovered that the GmSAM22 gene could be a regulatory and secondary gene that promotes the conversion of stearic acid to oleic acid in soybean. There has not been a discussion of gene cloning or functional verification. The cloning and genetic transformation of the soybean SAM22 gene can effectively increase the content of oleic acid, which lays a foundation for the study of soybean with high oleic acid.

Esterification of stearic acid using novel protonated and crosslinked amidoximated polyacrylonitrile ion exchange fibres

This study will demonstrate the conversion of stearic acid to methyl stearate (biodiesel) using for the first time crosslinked amidoximated polyacrylonitrile ion-exchanged mesh protonated by sulphuric acid. Quantitative analysis of conversion was by GC-FID, 1H NMR and ATR-FT-IR with GC-FID the most reliable. A molar ratio of methanol to stearic acid of 35.5: 1 gave 94 % conversion to the ester at 90 °C. At 65 °C and a greater ratio of 87.1:1 conversion was 94.1 % comparable to the 98 % yield obtained with 1wt% H2SO4. Re-use at 65 °C gently dropped to 57 % on the 13th cycle. Regeneration by washing with dichloromethane and re-acidification achieved 84 % conversion but quickly deactivated due to blocking of sites by methyl stearate as shown by ATR-FTIR. This protonated amidoxime PAN catalyst (distinct from sulfonated fibres) exhibited higher stability than other heterogeneous protonated catalysts (ion-exchange resins, zeolites, clays) used lower temperatures and shorter reaction times. Advantages of using a mesh in place of powders are its ease of removal/replacement for continuous flow reactors promoting quick changes in process parameters. This study is promising as providing a sustainable protonated catalyst for use in converting Fats, Oils and Greases (FOG’s) in waste oils and wastewater to biodiesel.

Environmental impact assessment of sustainable methyl stearate (biodiesel) synthesis employing fly ash supported tin oxide catalyst

Management of Fly ash (FA), a thermal power plant waste, is a major global issue since a sizeable fraction of fly ash's annual generation is not effectively valorised. FA is a heterogeneous mix of crystalline and amorphous phases containing significant amounts of aluminium and silicon elements alongside high surface energy, making FA an economically suitable catalyst support framework. Accordingly, the development of a low-cost, recyclable fly ash-supported tin oxide solid acid catalyst has been investigated for esterification of stearic acid (SA) with methanol to produce methyl stearate (MS); which is regarded as biodiesel and is presently being blended with petro-diesel as a cleaner fuel substitute. The characterisations of the prepared SnO2-FA catalyst (SFC) have been performed through TGA, XRD, BET-BJH and FESEM-EDS analyses. The optimal process conditions (assessed through response surface methodology (RSM)) viz. 475.06 °C calcination temperature, 3.39:1 weight ratio of SnCl4.5H2O: FA and 73.16 °C esterification temperature rendered a significant 85.734% SA conversion. The optimal mesoporous SFC comprising SnO2 active phase possessed 11 m2/g specific surface area (much greater than that of the support material, FA: 0.60 m2/g); 0.0109 cc/g pore volume and 2.9 nm modal pore size. Important fuel properties of the optimally produced MS conformed to the ASTM biodiesel (B100) standards. The overall environmental sustainability of the process assessed through the openLCA platform (ecoinvent database 3.8) revealed lower environmental impacts of the developed process. The LCA study divulges the fossil depletion potential and the global warming potential of the overall process to be 4.34 kg oil Eq. and 4.03 kg CO2-Eq. respectively. The present study could establish a green and effective FA valorisation avenue through a sustainable methyl stearate (biodiesel) production process.

MOF-Derived Co3O4 Nanoparticles Catalyzing Hydrothermal Deoxygenation of Fatty Acids for Alkane Production

Designing economical and nonprecious catalysts with a catalytic performance as good as that of noble metals is of great importance in future renewable bioenergy production. In this study, the metal–organic framework (MOF) was applied as a precursor template to synthesize Co3O4 nanoparticles with a carbon matrix shell (denoted as M-Co3O4). To select the synthesized optimal catalyst, stearic acid was chosen as the model reactant. The effects of catalyst dosage, methanol dosage, water dosage, temperature, and reaction time on catalytic efficiency were examined. Under the designed condition, M-Co3O4 exhibited high catalytic performance and the catalyst showed higher conversion of stearic acid (98.7%) and selectivity toward C8–C18 alkanes (92.2%) in comparison with Pt/C (95.8% conversion and 93.2% selectivity toward C8–C18). Furthermore, a series of characterization techniques such as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption isotherms (Brunauer–Emmett–Teller (BET) method), and thermogravimetric analysis (TGA) was applied to investigate the physicochemical properties of the catalysts. Finally, we proposed that decarbonization (deCO) could be the presumably mechanistic pathway for the production of C8–C18 alkanes from the decomposition of stearic acid.

Catalytic hydrogenation of stearic acid to 1-octadecanol using supported bimetallic Pd–Sn(3.0)/γ–Al2O3 catalyst

Supported bimetallic palladium-tin catalyst on gamma-alumina (γ-Al2O3) (denoted as Pd–Sn(3.0)/γ-Al2O3; Pd = 5%wt and Pd/Sn molar ratio is 3.0) has been synthesized via the hydrothermal method at a temperature of 423 K for 24 h and reduced with H2 at 673 K for 3 h. The XRD patterns of the samples showed typical diffraction peaks of support γ-Al2O3, metallic Pd, Sn, and Pd–Sn alloy phases. Diffraction peaks of metallic Pd were observed at 2θ = 39.8°; 46.6°; and 68.0°, which can be attributed to the Pd(111), Pd(200), and Pd(220), respectively, while the diffraction peaks at 2θ = 39.8° and 41.0° can be attributed to Pd2Sn and Pd3Sn2, respectively, which may overlap with the Pd(111) species. The ammonia desorption and pyridine adsorption profiles showed Lewis and Brönsted acid sites. The specific surface area (SBET) of Pd–Sn(3.0)/γ-Al2O3 catalyst was 117.83 m2/g which is dominated by a micropore structure. The highest conversion of stearic acid was 99.1% with a yield of 1-octadecanol 43.2% was obtained at temperature 513 K, initial H2 pressure of 2.0 MPa, a reaction time of 13 h, and in 2-propanol/water (4.0:1.0 v/v) solvent.

Catalytic deoxygenation of carboxyl compounds in the hydrothermal liquefaction crude bio-oil via in-situ hydrogen supply by CuO-CeO2/[formula omitted]-Al2O3 catalyst

Hydrothermal liquefaction (HTL) has drawn great attention as a potential method to produce bio-oil from biomass waste. However, bio-crude from HTL shows undesired high-oxygen content and needs further deoxygenation upgrading. Herein, stearic acids as a model carboxylic compounds in HTL bio-crude was employed to investigate catalytic deoxygenation performance. Results showed that (CuO)10-CeO2/γ-Al2O3 had the most superior catalytic deoxygenation performance for the stearic acids. The maximum stearic acid conversion rate (96.36%) and total hydrocarbon yield (88.79%) were obtained at 300°C, 12h, ratio of stearic acid to water 1:4. The main catalytic deoxygenation pathways were proposed: carbon monoxide generation (decarbonylation) – in-situ hydrogen generation (water–gas shift) – short-chain fatty acid generation (hydrogenolysis) – n-alkanes generation (decarboxylation, hydrodeoxygenation and hydrogenation). DFT calculation elucidated that CuO-CeO2 reduced the activation energy from 24.8kcalmol−1 (vacuum) to 15.0kcalmol−1 (catalytic). Thus, deoxygenation via CuO-CeO2/γ-Al2O3 would be an effective method for upgrading HTL bio-crude.

Selective Hydrogenation of Stearic Acid to 1-Octadecanol Using Bimetallic Palladium-Tin Supported on Carbon Catalysts at Mild Reaction Conditions

Bimetallic palladium-tin catalysts supported on microporous carbon (denoted as Pd-Sn(x)/C, loading amount of Pd = 5 wt% and x = Pd/Sn molar ratio; c.a. 3.0; 1.5; and 1.0) showed high selectivity in the hydrogenation of stearic acid towards 1-octadecanol (stearyl alcohol) under mild reaction conditions. Pd-Sn(x)/C catalysts were synthesized via the hydrothermal method at temperature of 150 °C for 24 h, and reduced with H2 at 400 °C for 3 h. Pd-Sn(1.5)/C catalyst exhibited the highest yield of stearyl alcohol (1-octadecanol) (up to 73.2%) at 100% conversion of stearic acid at temperature 240 °C, initial H2 pressure of 3.0 MPa, a reaction time of 13 h, and in 2-propanol/water solvent. The high selectivity of alcohols over Pd-Sn(1.5)/C catalyst can be attributed to the formation of bimetallic Pd-Sn alloy phases (e.g. Pd3Sn and Pd3Sn2) as obviously depicted by XRD analysis. The presence of co-promotor Sn and the formation of bimetallic may play a pivotal role in the high selectivity of 1-octadecanol. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Preparation of palladium catalysts using the strong electrostatic adsorption technique for stearic acid conversion via the deoxygenation process

Preparation of palladium catalysts using the strong electrostatic adsorption technique for stearic acid conversion via the deoxygenation process

Novel SnZr oxides nanomaterials synthesized by ultrasonic-assisted co-precipitation method: Application in biodiesel production and DFT study

Novel solids as Sn2O3-ZrSnO4 nanoparticles were prepared by ultrasonic- assisted co-precipitation method and were characterized by several techniques. The catalytic efficiency of the sonicated SnZr oxide catalysts was evaluated by biodiesel production through a stearic acid esterification reaction with methanol. Also, the optimization conditions and the kinetic study for the esterification reaction were practically implemented. The optimized catalyst (SnZr15m) gave stearic acid conversion of 88.5% at the optimum conditions with pseudo- first order kinetic reaction and the thermodynamic parameters of the esterification reaction were inspected theoretically and compared with the practical data. Furthermore, the recycling experimental results and the theoretically DFT data proved that the stability of the SnZr15m catalyst in the esterification process was reasonable and possess useful quality. The different phases for tin zirconium oxides have been studied using density functional theory (DFT) calculations at the DFT/B3LYP level of theory, using the GENECP basis set in the gas phase. DFT modeling indicated that the stability of the Sn2O3-ZrSnO4 (Sn3ZrO7) phase is higher than the other phases of SnZr oxide which catalyzed the esterification process. The electronic parameters; dipole moment of these compounds in the ground state theoretically were analyzed by computing HOMO and LUMO pictures. Using frontier molecular orbital (FMO) analysis, non-linear optical (NLO) properties and quantum chemical parameters were evaluated. The charge transfer of the electron density in the studied compounds was characterized by natural bond orbital analysis (NBO). For understanding of the reactivity points, the molecular electrostatic potential surfaces (MEPS) plots have been computed. Finally, Illustration for the proposed interaction between stearic acid, the catalyst (Sn3ZrO7), and methanol to produce the biodiesel was proposed.

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.

Catalytic hydrodeoxygenation of waste cooking oil and stearic acid over reduced nickel-basded catalysts

Waste cooking oil (WCO) and stearic acid (SA) were considered to be renewable and readily available bio-oil resources to produce bio-fuel via catalytic hydrodeoxygenation. The most often used catalysts for hydrodeoxygenation were the vulcanized NiMo catalysts, however, the vulcanized catalysts tend to deactivate due to the loss and oxidation of sulfur upon treating bio-oil with high oxygen content. Therefore, it is necessary to develop sulfur-free catalysts. In present study, the reduced NiMo catalysts were prepared by loading Ni and Mo on different supports (γ-Al2O3, HZSM-5, β-zeolite, activated carbon and bentonite) using incipient-wetness impregnation method, and followed by H2 reduction. The effects of the properties of supports (acidity, porosity) and H2 reduction on the dispersity and valence state of metal components were investigated. The hydrodeoxygenation activities of the reduced catalysts were evaluated by catalytic WCO and SA. It was found that when Ni2+ was loaded on a slightly acidic supports such as γ-Al2O3 and activated carbon, Ni2+ was easier to be reduced, and aggregate to form larger particles. When Ni2+ was loaded on a strongly acid supports e.g. HZSM-5, β-zeolite or bentonite, Ni2+ was more difficult to be reduced but could uniformly disperse on the supports. The aggregated Ni atoms could promote the formation of C17, while the dispersed Ni atoms could promote the formation of C18. γ-Al2O3 supported catalyst achieved the highest SA (97.9%) and WCO (80%) conversion under the mild reaction conditions of 300 °C and 2 MPa H2 for 3 h, exhibiting the superior catalytic activity.

Enhancement of fatty acids hydrodeoxygenation selectivity to diesel-range alkanes over the supported Ni-MoOx catalyst and elucidation of the active phase

Metal oxide modified nickel catalysts are highly desirable for the conversion of biomass-derived compounds to biofuels and valuable chemicals because of their low-cost and unique synergistic effects in catalytic reaction. Herein, a series of metal oxide modified nickel catalysts were scrutinized in the hydrodeoxygenation of steatic acid to diesel-range alkanes without any carbon loss as a model reaction. The results showed that MoOx modified Ni/SiO2 catalyst was the most active and selective for the hydrodeoxygenation of stearic acid under mild reaction conditions (260 °C and 3.0 MPa H2 partial pressure). The catalyst with an Ni/Mo molar ratio of 1, and that was reduced at an optimized temperature (500 °C), exhibited the best performance; this catalyst achieved a high selectivity (>95%) to diesel-range alkanes at 100% stearic acid conversion. A high selectivity (>60%) to C18 alkane and a less than 30% selectivity to C17 alkane were observed at 260 °C and 3.0 MPa H2 partial pressure. By selecting an appropriate support, the selectivity to C18 alkane can reach 95% at 100% stearic acid conversion over Ni–Mo/H-ZSM-5 catalysts. In contrast to Ni/SiO2, Ni–Mo/SiO2 was more efficient for CO hydrogenation and less active for C–C bond cleavage, which afforded a higher selectivity to long-chain hydrocarbons without any carbon loss. Detailed characterization, control experiments, and kinetic studies indicate that the high activity and selectivity to the C18 alkane arises from a synergy between Ni and MoOx. The Ni sites at the interface between the Ni metal and MoOx species play a role in the generation of hydride (Hδ−) species from H2 dissociation, and MoOx plays a role in promotion of fatty acids adsorption through adsorbing carboxylic groups at the oxygen vacancy of MoOx. The deep understanding of such synergic catalysis will provide significant clues for the rational design of bimetallic catalysts towards the production of diesel-range alkanes without any carbon loss from the hydrodeoxygenation of fatty acids/esters.

Unprecedented green chemistry approach: tungstophosphoric acid encapsulated in MOF 199 as competent acid catalyst for some significant organic transformations

In the work, a series of new 12-tungstophosphoric acid (HPW) encapsulated MOF 199 catalysts were synthesized by simple and convenient one step method. The structural and textural properties of the synthesized catalysts were fully characterized by using different techniques such as FTIR, XRD, N2 adsorption–desorption, TEM and SEM. The acidic properties were also studied by using nonaqueous potentiometric titration and FTIR spectra of chemisorbed pyridine techniques. The efficacy of the newly synthesized acid catalysts was tested in the production of 3,4-dihydropyrimidin-2(1H)-one through three-component coupling based Biginelli reaction and biodiesel production through stearic acid esterification reaction. The obtained results indicate that the MOF 199 preserves its structure without any noteworthy changes after the fruitful incorporation of HPW crystals within its cavities. Furthermore, an extraordinary improvement in both Lewis and Bronsted acid sites is observed as a result of the HPW encapsulation process. The catalytic activity results showed that the catalyst displayed excellent performance, where 98.3% of 3,4-dihydropyrimidin-2(1H)-one was obtained over 0.02 g of 50HPWMOF 199 after 2 h at 80 °C using benzaldehyde: ethyl acetoacetate: urea molar ratios of 1:1:1.5. Additionally, 94.1% conversion of stearic acid was observed after 3 h over 0.05 g of 50HPWMOF 199 at ~ 80 °C using stearic acid: ethanol molar ratio of 1:8. Moreover, the catalysts also demonstrated excellent reusability in the investigated organic reactions which can be used many consecutive eras without meaningful loss of their catalytic performance. The achieved high catalytic performance of the synthesized catalysts in the Biginelli and esterification reactions are attributed to uniform HPW distribution inside MOF 199 cavities as well as the Lewis acidity property of MOF 199. The results also demonstrated that the incorporation of HPW crystals within MOF 199 cavities through the encapsulation process is more efficient than the impregnation method.

Heterogeneous Non-noble Catalyst for Highly Selective Production of Linear α-Olefins from Fatty Acids: A Discovery of NiFe/C.

Catalytic deoxygenation of even-numbered fatty acids into odd-chain linear α-olefins (LAOs) has emerged as a complementary strategy to oligomerization of ethylene, which only affords even-chain LAOs. Although enzymes and homogeneous catalysts have shown promising potential for this application, industrial production of LAOs through these catalytic systems is still very difficult to accomplish to date. A recent breakthrough involves the use of an expensive noble-metal catalyst, Pd/C, through a phosphine ligands-assisted method for LAOs production from fatty acid conversion. This study presents a unique, cost-friendly, non-noble bimetallic NiFe/C catalyst for highly selective LAOs production from fatty acids through decarbonylative dehydration. In the presence of acetic anhydride and phosphine ligand, a remarkable improvement in the yield of 1-heptadecene from the conversion of stearic acid was found over the supported bimetallic catalyst (NiFe/C) as compared to corresponding monometallic counterparts (Ni/C and Fe/C). Through optimization of the reaction conditions, a 70.1 % heptadecene yield with selectivity to 1-heptadecene as high as 92.8 % could be achieved over the bimetallic catalyst at just 190 °C. This unique bimetallic NiFe/C catalyst is composed of NiFe alloy in the material bulk phase and a surface mixture of NiFe alloy and oxidized NiFeδ+ species, which offer a synergized contribution towards decarbonylative dehydration of stearic acid for 1-heptadecene production.