Hydrodeoxygenation Of Oleic Acid Research Articles

Novel monolithic catalysts for the hydrotreating of oleic acid

Alumina-supported palladium and molybdenum carbide monolithic catalysts were tested in the hydrodeoxygenation of oleic acid. Anodized aluminum monoliths were used as the substrate of the structured catalysts. The Pd catalyst was synthetized by wet impregnation, and the Mo2C sample was prepared in situ using the temperature-programmed carburization methodology. The monolithic catalysts were characterized by X-ray diffraction, N2 sorption analysis, CO chemisorption and scanning electron microscopy. The catalytic tests were carried out in a continuous tubular reactor at temperatures between 553 and 633 K, with a hydrogen pressure of 30 atm. Both catalysts showed to be active, reaching a conversion of oleic acid higher than 92% at 633 K. The deoxygenation reactions using the Mo2C catalyst were suppressed, favoring the saturation of carbon-carbon double bonds and the stearic acid formation. On the other hand, oleic acid hydrodeoxygenation was promoted when using the palladium-based catalyst, forming undecane and tridecane alkanes.

Toward maximizing the selectivity of diesel-like hydrocarbons from oleic acid hydrodeoxygenation using Ni/Co-Al2O3 embedded mesoporous silica nanocomposite catalysts: An experimental and DFT approach

The development of an effective hydrodeoxygenation (HDO) catalyst is crucial for controlling product selectivity and catalyst stability. In this study, we synthesized monometallic (Ni and Co), as well as a bimetallic, NiCo embedded mesoporous composite catalysts using a simple one-step method involving meso-macroporous silica, boehmite, nickel acetate, and cobalt acetate. The synthesized range of catalysts (5, 10, 15 wt% Ni, 10 wt% Co, 10 wt% NiCo) were thoroughly characterized by various techniques. The characterization results showed that the present method leads to the growth of nano-catalyst on porous silica surface (M−Al2O3/SiO2, M = Ni, Co, NiCo). These composites exhibited strong metal-support interaction, improved surface and texture properties and significant amount of weak to medium acid sites. The M−Al2O3/SiO2 composite catalysts demonstrated improved catalytic performance in the HDO of oleic acid. At temperature of 375 °C, the conversion trend of catalysts followed the order; 10NiCo-Al2O3/SiO2 (89%) > 10Ni-Al2O3/SiO2 (87%) > 10Co-Al2O3/SiO2 (85%) > 10Ni/SiO2 (81%). Moreover, the yield of C15-C18 hydrocarbons was substantially enhanced at moderate temperature compared to unmodified silica support. Time-on-stream experiments further confirmed the relative stability of the composite catalysts over a period of 20 h. Furthermore, density functional theory (DFT) ab initio calculations were performed where the adsorption of oleic acid on icosahedral monometallic M13 (M = Co or Ni) and bimetallic Ni2Co2 nanocluster deposited on γ-Al2O3 (110) support was investigated. The adsorption strength for the most stable conformations followed the order: Ni13/amorphous SiO2 >Ni2Co2/Al2O3 >Co13/Al2O3 >Ni13/Al2O3. Bader charge transfer analysis indicated higher charge transfer at the interfaces of γ-Al2O3Al2O3(110) supported catalysts compared to Ni13/amorphous SiO2 surface.

Hydrodeoxygenation of oleic acid over NiMo bimetallic catalysts supported on niobium phosphate

The properties of the support have profound effects on the catalytic performance of the supported catalyst.

Metal Phase, Electron Density, Textural Properties, and Catalytic Activity of CoMo Based Catalyst Applied in Hydrodeoxygenation of Oleic Acid

Metal Phase, Electron Density, Textural Properties, and Catalytic Activity of CoMo Based Catalyst Applied in Hydrodeoxygenation of Oleic Acid

Hydrodeoxygenation of oleic acid for effective diesel-like hydrocarbon production using zeolite-based catalysts

Hydrodeoxygenation of oleic acid for effective diesel-like hydrocarbon production using zeolite-based catalysts

Hydrodeoxygenation of oleic acid using γ-Al2O3 supported transition metallic catalyst systems: Insight into the development of novel FeCu/γ-Al2O3 catalyst

Hydrodeoxygenation of oleic acid was performed using NiMo-based catalyst supported on several mesoporous supports such as γ-Al2O3, SBA-15 and hexagonal mesoporous silica (HMS) in batch mode at 350−410 °C under H2 pressure of 6.9 MPa. The catalysts were synthesized using incipient wet impregnation with approximately 12 wt.% Mo and 4 wt.% Ni loadings. Among the synthesized catalysts, NiMo/SBA-15 demonstrated the highest surface area (484 m2/g) and average pore diameter (9.4 nm). Moreover, γ-Al2O3 showed better catalytic activity during hydrodeoxygenation compared to SBA-15 and HMS supports. At hydrotreating conditions (390 °C and 6.9 MPa), NiMo/γ-Al2O3 showed 77 % oxygen removal and 42 % selectivity towards C16-C18 alkanes during 8 h of batch reaction. To elucidate the promotional effects, bimetallic catalyst (NiMo/γ-Al2O3) promoted with Cu, Cr and Fe (CuNiMo/γ-Al2O3, CrNiMo/γ-Al2O3 and FeNiMo/γ-Al2O3) catalysts were used for hydrodeoxygenation of oleic acid. CuNiMo/γ-Al2O3 gave the highest conversion (ca. 92 %) during hydrodeoxygenation at 300 °C, 6.9 MPa H2 pressure and 600 rpm agitation speed.

Evaluation of the performance and atmospheric emissions in a diesel engine of the biofuel obtained by hydrodeoxygenation of oleic acid with Pt/γ‐Al2O3 catalysts

AbstractPt/γ‐Al2O3 catalysts were prepared by incipient wet impregnation and tested in hydrodeoxygenation reactions for conversion of oleic acid to n‐C17 alkanes at optimal conditions. The high conversion of 96.5% to renewable biodiesel (RD) is justified with the characterization results, showing that the catalyst has good texture properties, presence of metallic Pt evidenced by 2θ reflections and binding energies, as well as adequate dispersion of active phase and nanoparticle size. 20% and 40% mixtures of RD with diesel were used. At full load a slight decrease in potency was observed when using RD mixtures and comparing them with petrodiesel; fortunately, the RD mixtures showed significant reductions in air pollutants, RD40 achieved reductions greater than 22% for CO, HC, and near 43% in emissions of smoke when compared to diesel.

Controlled Evaluation in a Diesel Engine of the Biofuel Obtained with Ni/γ-Al2O3 Nanoparticles in the Hydrodeoxygenation of Oleic Acid

AbstractRenewable biodiesel with a high content of n-C17 alkanes was prepared through the catalytic hydrodeoxygenation of oleic acid under optimum conditions of temperature, reaction time and weight percentage of Ni deposited in γ-Al2O3. The hydrotreated vegetable oil (HVO) was blended with petrodiesel (20 % and 40 % of HVO) to evaluate its behaviour in a diesel engine. Comparative studies of power and emission of atmospheric pollutants such as NOx, CO, HC and smoke were evaluated under prepared blends and petrodiesel. The presence of HVO biodiesel at full load generated a slight decrease in power compared to petrodiesel; however, the decrease in emission of pollutants when using the blends containing HVO was significant. In the case of 40 % HVO were able to reduce more of 20 % of CO and HC emissions, and more than 40 % reduction in smoke when compared with petrodiesel. The NOx emissions of the blends with HVO had a significant slightly decrease. Further, the properties of Ni/γ-Al2O3 catalysts are justified by the results of EDS characterization, surface area (SBET), XRD, XPS, HR-TEM and it’s capacity to produce biodiesel.

Monometallic and bimetallic catalysts based on Pd, Cu and Ni for hydrogen transfer deoxygenation of a prototypical fatty acid to diesel range hydrocarbons

Bimetallic PdxNi(100-x) and PdxCu(100-x) structures of a wide compositional range supported on activated carbon were synthesised via a simple, cheap and commercially relevant method. The surface and bulk properties of both the bimetallic structures and their monometallic counterparts were determined via STEM-EDS, TEM, XPS, powder XRD, N2 porosimetry and ICP-OES. A close correlation between the XRD patterns and EDS elemental composition mapping of individual metal particles established the extent of palladium-base metal interaction in each sample. The performance of the different structures as catalysts for the selective hydrogenation and hydrodeoxygenation of oleic acid, a prototypical fatty acid, was evaluated using tetralin as a hydrogen donor. Catalysts displaying true bimetallic/alloy formation were found to improve the conversion of tetralin as compared to catalysts in which compositional segregation was observed. The PdxNi(100-x) series was found to outperform the PdxCu(100-x) catalysts in terms of hydrogen production via the dehydrogenation of tetralin, mirroring the fact that compositional segregation occurs more for the PdxCu(100-x) series than PdxNi(100-x). The hydrogen transfer deoxygenation of oleic acid over the monometallic and bimetallic catalysts was found to mirror the availability of hydrogen with those catalysts liberating more hydrogen also favouring the formation of C17 and C18 alkanes.

Hydrodeoxygenation of oleic acid and palmitic acid to hydrocarbon-like biofuel over unsupported Ni-Mo and Co-Mo sulfide catalysts

Second generation biodiesel, so-called bio-hydrogenated diesel (BHD), can be produced from hydrotreatment of vegetable oils. The hydrogenation (HDO) of oleic acid and palmitic acid as model compounds of palm oil over unsupported Ni-Mo and Co-Mo sulfide catalysts was performed in a Parr reactor to produce BHD. The effects of reaction parameters: temperature, hydrogen pressure and the atomic ratio of catalysts (Ni/(Ni + Mo) or Co/(Co + Mo)) on the conversion and product yields (mainly n-C15, n-C16, n-C17 and n-C18 hydrocarbons) were evaluated. The results show that the high pressure favored HDO pathway, while high temperature strongly affected the decarboxylation and decarbonylation pathways. At optimal conditions for oleic acid HDO, the efficient catalyst was NiMoS2 catalyst (Ni/(Ni + Mo) = 0.2) which gave high oleic acid conversion (100%), n-C18 selectivity (78.8%) and n-C18 yield (70.3%) whereas, for palmitic acid HDO, NiMoS2 catalyst (Ni/(Ni + Mo) = 0.2) also gave high palmitic acid conversion (95.2%), n-C16 selectivity (78.5%) and n-C16 yield (65.6%).

Hydrodeoxygenation of Oleic Acid on Supported and Unsupported MoS2 and NiMoS2 Catalysts for the Production of Green Diesel Fuel

MoS2/Al2O3 and NiMoS2/Al2O3 catalysts were prepared by incipient wetness impregnation of alumina using aqueous solutions of 12-molybdophosphoric heteropolyacid and nickel citrate. Unsupported catalysts were prepared by etching a support made from MoS2/Al2O3 using hydrofluoric acid (Et-MoS2) and thermal decomposition of aluminum tetrathiomolybdate (Ref-MoS2). The activity of the catalysts in hydrodeoxygenation decreases in the series NiMoS2/Al2O3 = Et-MoS2 > MoS2/Al2O3 > Ref-NiS2. On the other hand, the selectivity relative hydrogenation of oleic acid has a different order: Et-MoS2 > MoS2/Al2O3 > Ref-MoS2 > NiMoS2/Al2O3. The unsupported Et-MoS2 catalyst has similar activity to NiMoS2/Al2O3 in hydrodeoxygenation and the highest selectivity, which indicates virtually completion of the hydrodeoxygenation reaction through a hydrogenation pathway without the formation of CO or CO2. These gases display strong inhibiting properties and have a detrimental eject on the environment.

Influence of oxalate ligand functionalization on Co/ZSM-5 activity in Fischer Tropsch synthesis and hydrodeoxygenation of oleic acid into hydrocarbon fuels

Achieving high degree of active metal dispersions at the highest possible metal loading and high reducibility of the metal remains a challenge in Fischer Tropsch synthesis (FTS) as well as in hydrogeoxygenation (HDO).This study therefore reports the influence of oxalic acid (OxA) functionalization on the metal dispersion, reducibility and activity of Co supported ZSM-5 catalyst in FTS and HDO of oleic acid into paraffin biofuel. The Brunauer–Emmett–Teller (BET) results showed that cobalt oxalate supported ZSM-5 catalyst (CoOx/ZSM-5) synthesized from the incorporation of freshly prepared cobalt oxalate complex into ZSM-5 displayed increase in surface area, pore volume and average pore size while the nonfunctionalized cobalt supported on ZSM-5 (Co/ZSM-5) catalyst showed reduction in those properties. Furthermore, both XRD and XPS confirmed the presence of Co° formed from the decomposition of CoOx during calcination of CoOx/ZSM-5 under inert atmosphere. The HRTEM showed that Co species average particle sizes were smaller in CoOx/ZSM-5 than in Co/ZSM-5, and in addition, CoOx/ZSM-5 shows a clear higher degree of active metal dispersion. The FTS result showed that at CO conversion over Co/ZSM-5 and CoOx/ZSM-5 catalysts were 74.28% and 94.23% and their selectivity to C5+ HC production were 63.15% and 75.4%, respectively at 4 h TOS. The HDO result also showed that the CoOx/ZSM-5 has higher OA conversion of 92% compared to 59% over Co/ZSM-5. In addition CoOx/ZSM-5 showed higher HDO and isomerization activities compared to Co/ZSM-5.

Effect of Dimethyl Disulfide on Activity of NiMo Based Catalysts Used in Hydrodeoxygenation of Oleic Acid

Alumina supported NiMo catalysts were synthesized. The prepared NiMo catalysts were activated by DMDS in a sulfidation process and characterized. The sulfided NiMo catalysts were next used in hydrodeoxygenation (HDO) of oleic acid in a batch reactor. Afterward, the NiMo catalysts were recovered and used in another set of HDO reactions of oleic acid under the same conditions used in the previous HDO reactions. After the HDO experiments, the active phase and deposited coke on spent catalysts were characterized. The results indicated that higher concentrations of DMDS promoted the production of heptadecane (C17) but had no effect on the production of octadecane (C18). Moreover, the XPS results revealed the promotional effect of DMDS concentration on maintenance of the sulfidity of the catalysts. In addition, the results for the experiments with the second run catalyst revealed a clear deactivation due to increased coke depositions. Furthermore, after two repeated experiments with first run and second run catalysts, it was observed that coke formation decreased when the concentration of DMDS was increased. These results clearly indicate a correlation between the concentration of DMDS and coke formation.

NiMo nitride supported on γ-Al2O3 for hydrodeoxygenation of oleic acid: Novel characterization and activity study

Oxide and nitride phases of NiMo supported on Al2O3 were employed for hydrodeoxygenation (HDO) of oleic acid. Synthesized catalysts were characterized using Raman Spectroscopy, X-ray absorption near edge structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). Raman spectroscopy was employed to understand the active-site distribution in NiMo catalysts and elucidate the relation between distribution of active species and catalytic activity. Catalyst evaluation studies showed that NiMo supported on γ-Al2O3 has higher conversion (80%) in comparison to NiMo supported on SBA-15 and HMS during the HDO of oleic acid. Raman maps were obtained for the oxide phase of catalyst and it indicates that the Mo supported on Al2O3 is present as polyanions ([Mo7O24]6− or [Mo8O26]4−). XANES and EXAFS analyses were carried out to understand the oxidation state and co-ordination environment of the catalyst. Occurrence of Mo-Ni and Mo-Mo interactions were proved by the Mo K-edge EXAFS spectra and the bond lengths were determined. The presence of the promoter metal (Nickel) aids in the hydrogenation of oleic acid to stearic acid and direct hydrodeoxygenation, decarboxylation and decarboxylation reactions were observed. The occurrence of polymeric molybdates as confirmed by the Raman spectroscopy leads to the decrease in the availability of active metals for the selective removal of water without breaking the carbon bond leading to the formation of C18H38.

Hydrodeoxygenation of oleic acid in hexane containing pressurized CO2 using Fe/SBA-15 as catalyst

The hydrotreatment of oleic acid in a green reaction media to produce the major hydrodeoxygenation product octadecane using a 6 wt% nano Fe loaded Fe/SBA-15 as catalyst was demonstrated in this study. The data show that hexane containing pressurized CO2 could dictate the selectivity of the hydrotreatment of oleic acid with high selectivity for hydrodeoxygenation over decarboxylation/decarbonylation. In addition, hexane containing pressurized CO2 could offer beneficial effects including reduction of viscosity of the solution and increase of H2 solubility. As a result, uniform dispersion of the catalyst occurred in the solution and the diffusion resistances were reduced as well due to the increase in mass transfer. At the best operating condition of 290 °C, 6 h, 30 bars H2 and 40 bars CO2, an octadecane yield of 83.3% and a heptadecane yield of 8.7% were observed when compared to 65% and 15%, which were the yields in the absence of CO2. The effects of three independent operation variables namely, temperature, CO2 pressure and time and their interactions on the hydrotreatment of oleic acid were studied using a central composite design and response surface methodology. The results showed that all these three variables were significant factors for increasing the yield of octadecane while CO2 pressure was the most significant variable in decreasing the yield of heptadecane, the major decarboxylation/decarbonylation product.

Hydrodeoxygenation of oleic acid into n- and iso-paraffin biofuel using zeolite supported fluoro-oxalate modified molybdenum catalyst: Kinetics study

The activity of zeolite supported fluoride-ion functionalized molybdenum-oxalate catalyst (FMoOx/Zeol) and its kinetic study on the hydrodeoxygenation (HDO) of oleic acid (OA) is presented in this report. The FMoOx/Zeol was synthesized via simple dissolution method and characterized. The results revealed formation of highly reactive octahedral Mo species with enhanced textural and morphological properties. The FMoOx/Zeol activity on the HDO of OA at the best observed experimental conditions of 360°C, 30 mg FMoOx/Zeol and 20 bar produces 64% n-C18H38 and 30% iso-C18H38 in 60 min. The acidity of FMoOx/Zeol was responsible for the production of the iso-C18H38. The kinetic data showed that sequential hydrogenation of OA into stearic acid (SA) was faster than the HDO of SA into biofuel with activation energies of 98.7 and 130.3 kJ/mol, respectively. The reusability studies showed consistency after three consecutive runs amounting to 180 min reaction time. The results are encouraging towards industrial application.

Optimization of catalytic hydrodeoxygenation of oleic acid into biofuel using fluoroplatinum oxalate zeolite supported catalyst

Optimization of hydrodeoxygenation (HDO) of oleic acid (OA) into paraffinic biofuel using zeolite supported fluoroplatinum oxalate (FPtOx/Zeol) catalyst is reported in this study. FPtOx/Zeol was synthesized via incorporation of HF modified oxalic acid (OxA) functionalized K2PtCl4 into zeolite A support. FPtOx/Zeol was characterized and the results showed highly dispersed tetrahedral and octahedral Pt species which are effective for sequential hydrogenation of the unsaturated OA bond and the HDO of OA, respectively. Furthermore, there was increase in Si/Al ratio of FPtOx/Zeol leading to loss of crystallinity due to dealumination of the extra framework and framework alumina as a result of acid attacks and calcination, respectively. FPtOx/Zeol activity was tested on the HDO of OA in a semi-batch reactor and the process parameters were optimized using validated quadratic models. The optimum conditions were 364°C, 18bar and 27.8mg FPtOx/Zeol loading under reaction time of 58min to produce 28.39% iso-C18H38 and 68.93% n-C18H38. The presence of the isomerized product was due to the combine effect of fluoride ion and oxalic acid functionalization on the catalyst. FPtOx/Zeol reusability studies showed consistency after three consecutive runs. These results are promising for further research toward commercialization of biofuel production.

Synthesis of Renewable Diesel through Hydrodeoxygenation Using Pd/zeolite Catalysts

Hydrodeoxygenation of oleic acid as model compound of vegetable oils over Pd/zeolite catalysts was investigated under conditions of 375−400°C and 15bar in a semi batch stirred autoclave reactor. Pd/zeolite-1 and Pd/zeolite-2 catalysts were prepared using microwave polyol method with different treatment conditions. The liquid hydrocarbon products named Renewable Diesel have suitable density and viscosity, and quite high cetane index in accordance with standard commercial diesel and ASTM D-975. The IR spectrum of Renewable Diesel products have similarities with commercial diesel. The oxygenation removal pathway of oleic acid over Pd/zeolite 1 catalyst was primarily compiled through decarboxylation at 375°C.