- Bio-diesel production from deoxygenation reaction over Ce0.6Zr0.4O2 supported transition metal (Ni, Cu, Co, and Mo) catalysts
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Ce0.6Zr0.4O2 supported transition metal (Me = Ni, Cu, Co, and Mo) catalysts have been investigated to screen for the catalytic activity and selectivity for deoxygenation reaction of oleic acid. Me - Ce0.6Zr0.4O2 catalysts were prepared by a co-precipitation method. Ni - Ce0.6Zr0.4O2 catalyst exhibited much higher oleic acid conversion, selectivity for C9 to C17 compounds, and oxygen removal efficiency than the others. This is mainly ascribed to the presence of free Ni species, synergy effects between Ni and Ce0.6Zr0.4O2, and the highest BET surface area.
- Shim, Jae-Oh,Jeong, Dae-Woon,Jang, Won-Jun,Jeon, Kyung-Won,Jeon, Byong-Hun,Kim, Seong-Heon,Roh, Hyun-Seog,Na, Jeong-Geol,Han, Sang Sup,Ko, Chang Hyun
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- Revealing the Influence of Silver in Ni–Ag Catalysts on the Selectivity of Higher Olefin Synthesis from Stearic Acid
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Results on the conversion of stearic acid to olefins over Ni–Ag/γ-Al2O3 catalysts are presented. XANES and EXAFS experiments in situ and DFT calculations were applied to reveal the structure of active sites therein. It is shown that the introduction of Ag to Ni catalysts leads to an increase in the olefin yield. After a reduction in hydrogen (350°C, 3 h) alumina-supported nanoparticles of nickel sulfides and metallic Ag are formed. The role of metal hydrides formed during the reaction is extensively discussed.
- Danyushevsky, V. Ya.,Murzin, V. Yu.,Kuznetsov,Shamsiev,Katsman,Khramov,Zubavichus,Berenblyum
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- Insights into substrate and metal binding from the crystal structure of cyanobacterial aldehyde deformylating oxygenase with substrate bound
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The nonheme diiron enzyme cyanobacterial aldehyde deformylating oxygenase, cADO, catalyzes the highly unusual deformylation of aliphatic aldehydes to alkanes and formate. We have determined crystal structures for the enzyme with a long-chain water-soluble aldehyde and medium-chain carboxylic acid bound to the active site. These structures delineate a hydrophobic channel that connects the solvent with the deeply buried active site and reveal a mode of substrate binding that is different from previously determined structures with long-chain fatty acids bound. The structures also identify a water channel leading to the active site that could facilitate the entry of protons required in the reaction. NMR studies examining 1-[13C]-octanal binding to cADO indicate that the enzyme binds the aldehyde form rather than the hydrated form. Lastly, the fortuitous cocrystallization of the metal-free form of the protein with aldehyde bound has revealed protein conformation changes that are involved in binding iron.
- Buer, Benjamin C.,Paul, Bishwajit,Das, Debasis,Stuckey, Jeanne A.,Marsh, E. Neil G.
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- Effect of promotion of nickel sulfide catalyst with silver on kinetics of decarbonilation of stearic acid
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The kinetics of liquid-phase decarbonylation of stearic acid in n-dodecane on γ-Al2O3 supported nickel sulfide catalyst promoted with silver was experimentally studied at 350 °C. The parameters of the reaction steps were determined and a structural kinetic model was developed. The model was compared with an earlier developed kinetic model for the unpromoted catalyst. It was suggested that an increased reaction selectivity in the presence of silver promoted catalyst was caused by a change in the composition of the adsorption complexes formed by the active sites of the catalyst. This change in the composition of the complexes is probably associated with an increase in the average size of the surface active particles of the catalyst.
- Katsman,Berenblyum,Danyushevsky, V. Ya.,Karpov,Kuznetsov,Leont′eva,Flid
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- Engineering Fatty Acid Photodecarboxylase to Enable Highly Selective Decarboxylation of trans Fatty Acids
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Due to the high risk of heart disease caused by the intake of trans fatty acids, a method to eliminate trans fatty acids from foods has become a critical issue. Herein, we engineered fatty acid photo-decarboxylase from Chlorella variabilis (CvFAP) to selectively catalyze the decarboxylation of trans fatty acids to yield readily-removed hydrocarbons and carbon dioxide, while cis fatty acids remained unchanged. An efficient protein engineering based on FRISM strategy was implemented to intensify the electronic interaction between the residues and the double bond of the substrate that stabilized the binding of elaidic acid in the channel. For the model compounds, oleic acid and elaidic acid, the best mutant, V453E, showed a one-thousand-fold improvement in the trans-over-cis (ToC) selectivity compared with wild type (WT). As the first report of the direct biocatalytic decarboxylation resolution of trans/cis fatty acids, this work offers a safe, facile, and eco-friendly process to eliminate trans fatty acids from edible oils.
- Han, Tao,Li, Danyang,Wu, Qi,Xu, Jian,Xu, Weihua,Xue, Jiadan
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- The Effect of the Active Component Content on the Catalytic Activity of Nickel Sulfide Catalysts in Olefin Synthesis from Stearic Acid
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Abstract: The effect of active component content on the catalytic activity of supported sulfide catalysts in the synthesis of C17 olefins from stearic acid has been studied. It has been shown that an increase in the nickel content leads to a decrease in the catalyst activity; in addition, there is a negative correlation between the activity and the fraction of large particles on the support surface. The highest heptadecene selectivity (50–60%) is observed for alumina-supported catalysts owing to the higher degree of dispersion of the active component.
- Katsman,Danyushevsky, V. Ya.,Karpov,Kuznetsov,Shishilov,Berenblyum
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- Hydrothermal conversion of linoleic acid and ethanol for biofuel production
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The catalytic conversion of linoleic acid in ethanol/water mixtures (1:1 vol. ratio) was explored in a batch reactor using a Pt/C catalyst. Linoleic acid was converted into heptadecane with high yields (>80%) after 6?h at 350?°C under autogenous pressure. The reaction proceeded through consecutive steps: linoleic acid?→?stearic acid?→?ethyl stearate?→?heptadecane. Hydrogen was generated in-situ by oxidation of ethanol into acetaldehyde. A moderate sintering of platinum was evidenced after hydrothermal reaction. A reaction network based on products distribution and kinetic studies was proposed. It was found that the hydrogenation route proceeds via the free acids whereas the hydrogenation of the ethyl esters was negligible. The formation of heptadecane, on the other hand, proceeded via ethyl stearate and not via stearic acid.
- Besse, Xavier,Schuurman, Yves,Guilhaume, Nolven
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- Light-Driven Enzymatic Decarboxylation of Dicarboxylic Acids
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Photodecarboxylase from Chlorella variabillis (CvFAP) is one of the three known light-activated enzymes that catalyzes the decarboxylation of fatty acids into the corresponding C1-shortened alkanes. Although the substrate scope of CvFAP has been altered by protein engineering and decoy molecules, it is still limited to mono-fatty acids. Our studies demonstrate for the first time that long chain dicarboxylic acids can be converted by CvFAP. Notably, the conversion of dicarboxylic acids to alkanes still represents a chemically very challenging reaction. Herein, the light-driven enzymatic decarboxylation of dicarboxylic acids to the corresponding (C2-shortened) alkanes using CvFAP is described. A series of dicarboxylic acids is decarboxylated into alkanes in good yields by means of this approach, even for the preparative scales. Reaction pathway studies show that mono-fatty acids are formed as the intermediate products before the final release of C2-shortened alkanes. In addition, the thermostability, storage stability, and recyclability of CvFAP for decarboxylation of dicarboxylic acids are well evaluated. These results represent an advancement over the current state-of-the-art.
- Chen, Bi-Shuang,Liu, Lan,Zeng, Yong-Yi,Zhang, Wuyuan
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p. 553 - 559
(2021/06/25)
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- Highly stable and selective catalytic deoxygenation of renewable bio-lipids over Ni/CeO2-Al2O3 for N-alkanes
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Ni-based catalysts are easy deactivated in bio-lipids deoxygenation due to metal aggregation and Ni leaching. They also suffer from the hydrocracking of C–C bonds due to strong acidity at high reaction temperature (≥ 300 ℃). Herein, a series of Ni/CeO2-Al2O3 catalysts with different Ce/Al ratio were prepared by one-pot sol-gel method. The characteristic results showed that an appropriate addition of Ce both increase the catalytic activity and stability in bio-lipids deoxygenation. The oxygen vacancies formed by Ce introduction weaken the strong interaction of Ni-Al, thus improving Ni sites dispersion. Additional, Ce-addition in NiCeAl system increases weak and medium acidity and decreases strong acidity, preventing the C–C bond cleavage of hydrocarbon. As the result, the Ni/CeAl-3.0 catalyst afforded a 97.1 % n-C17 yield at 99.9 % MO conversion under 2.5 MPa H2 at 300 ℃ for 6 h. Minor C15-16 alkanes (17 yield). After simple regeneration, n-C17 yield was recovered to 95 %. Furthermore, non-edible bio-lipids (JO and WCO) can be converted to C13-18 alkanes with 95.2 % and 93.8 % yields, respectively.
- Ba, Wenxia,Cui, Huamin,Fu, Lin,Li, Yongfei,Liu, Yuejin
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- A Reconstructed Common Ancestor of the Fatty Acid Photo-decarboxylase Clade Shows Photo-decarboxylation Activity and Increased Thermostability
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Light-dependent enzymes are a rare type of biocatalyst with high potential for research and biotechnology. A recently discovered fatty acid photo-decarboxylase from Chlorella variabilis NC64A (CvFAP) converts fatty acids to the corresponding hydrocarbons only when irradiated with blue light (400 to 520 nm). To expand the available catalytic diversity for fatty acid decarboxylation, we reconstructed possible ancestral decarboxylases from a set of 12 extant sequences that were classified under the fatty acid decarboxylases clade within the glucose-methanol choline (GMC) oxidoreductase family. One of the resurrected enzymes (ANC1) showed activity in the decarboxylation of fatty acids, showing that the clade indeed contains several photo-decarboxylases. ANC1 has a 15 °C higher melting temperature (Tm) than the extant CvFAP. Its production yielded 12-fold more protein than this wild type decarboxylase, which offers practical advantages for the biochemical investigation of this photoenzyme. Homology modelling revealed amino acid substitutions to more hydrophilic residues at the surface and shorter flexible loops compared to the wild type. Using ancestral sequence reconstruction, we have expanded the existing pool of confirmed fatty acid photo-decarboxylases, providing access to a more robust catalyst for further development via directed evolution.
- Sun, Yue,Calderini, Elia,Kourist, Robert
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p. 1833 - 1840
(2021/04/05)
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- An unconventional DCOx favored Co/N-C catalyst for efficient conversion of fatty acids and esters to liquid alkanes
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Cobalt (Co) catalysis has recently attracted significant attention in the field of biomass conversion. However, the fabrication of highly dispersive Co nanoparticles at high metal loading with selective facet exposure to achieve specific selectivity is still questionable. In this work, a nitrogen-doped carbon-supported Co catalyst is fabricated for efficient conversion of fatty acids and esters to liquid alkanes. Nitrogen-doping facilitates a highly uniform dispersion of Co nanoparticles even at a high Co loading of 10 wt% and after recycling for 5 runs. The Co/N-C catalyst affords an unconventional decarbonylation/decarboxylation (DCOx) dominant selectivity probably due to partial reduction of cobalt oxides to α-Co0 with only exposure of the (111) facet. Co-existence of Co and N-C leads to strong Lewis acidity and basicity, facilitating the interaction between catalyst and –COOH group, and some important acid-catalyzed step-reactions. The versatility of the Co/N-C catalyst is demonstrated through conversion of various fatty acids and esters.
- Li, Jiang,Liu, Jiaxing,Zhang, Junjie,Wan, Tong,Huang, Lei,Wang, Xintian,Pan, Runze,An, Zhidong,Vlachos, Dionisios G.
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- An efficient hydrogenation catalytic model hosted in a stable hyper-crosslinked porous-organic-polymer: From fatty acid to bio-based alkane diesel synthesis
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In this study, a Pd-based catalytic model over a nitrogen enriched fibrous Porous-Organic-Polymer (POP) is established to execute hydrodeoxygenation of various vegetable oils in producing potential large-scale renewable diesel. Here we report a cost-effective synthesis strategy for a new microporous hypercrosslinked POP through the FeCl3 assisted Friedel-Crafts alkylation reaction, followed by fabrication of Pd0-NPs (2-3 nm) using a solid gas phase hydrogenation route to deliver a novel catalytic system. This catalyst (called Pd@PPN) exhibits versatile catalytic performance for different types of vegetable oils including palm oil, soybean oil, sunflower oil and rapeseed oil to furnish long chain diesel range alkanes. The catalyst is comprehensively characterized using various spectroscopic tools and it shows high stability during five runs of recycling without leaching of Pd. Our results further reveal that a direct decarbonylation (DCN) pathway of fatty acids to produce alkanes with one fewer carbon is the dominant mechanism. Under optimized conditions, using stearic acid to represent the long linear carboxylic acids in the vegetable oils, up to 90% conversion with 83% selectivity of C17-alkane has been achieved on our fabricated catalyst. Density functional theory (DFT) calculations are performed to provide insights into the electronic properties of the catalyst, the mechanistic reaction pathway, the crucial role of the catalyst surface and the product selectivity trend. The strong interaction between the corrugated polymer-frame-structure and the Pd-NPs suggests the presence of high density step sites on the fabricated Pd-NP anchored within the cage of the polymer structure. DFT calculations also reveal the strong promotional effect of step sites and charge transfer in facilitating rate-limiting steps during the decarbonylation (DCN) pathway and removal of strongly bound intermediates formed during the process, therefore explaining the high activity of the fabricated Pd@PPN catayst for the hydrodeoxygenation (HDO) conversion to produce bio-based alkane diesel.
- Sarkar, Chitra,Shit, Subhash Chandra,Dao, Duy Quang,Lee, Jihyeon,Tran, Ngoc Han,Singuru, Ramana,An, Kwangjin,Nguyen, Dang Nam,Le, Quyet Van,Amaniampong, Prince Nana,Drif, Asmaa,Jerome, Francois,Huyen, Pham Thanh,Phan, Thi To Nga,Vo, Dai-Viet N.,Thanh Binh, Nguyen,Trinh, Quang Thang,Sherburne, Matthew P.,Mondal, John
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supporting information
p. 2049 - 2068
(2020/04/09)
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- Production of Bio Hydrofined Diesel, Jet Fuel, and Carbon Monoxide from Fatty Acids Using a Silicon Nanowire Array-Supported Rhodium Nanoparticle Catalyst under Microwave Conditions
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Biodiesel was efficiently produced from biomass fatty acids using renewable gas H2 and a reusable heterogeneous catalyst under low-energy-consumption microwave conditions. As the decarboxylation of fatty acids to alkanes is an important transformation in the production of bio hydrofined diesel (BHD) and jet fuel, we herein report the development of a highly active and reusable Rh nanoparticle catalyst supported by a silicon nanowire array (SiNA-Rh) and its application in the decarboxylation of fatty acids to alkanes under mild conditions. More specifically, SiNA-Rh (500 mol ppm) selectively promoted the hydrogenative decarboxylation reaction at 200 °C under microwave irradiation (~40 W) in a H2 atmosphere (10 bar) to afford the corresponding alkanes in high yields selectively. The only coproduct observed was carbon monoxide, an important and essential staple for the chemical industry. Importantly, carbon dioxide formation was not observed. Moreover, the aldehydes were efficiently converted to alkanes by SiNA-Rh, and this catalyst was reused 20 times without any loss in catalytic activity. Finally, to investigate the effects of microwave irradiation on the enhancement of this chemical transformation based on the Si nanorod structures present in the SiNA-Rh catalyst, the effect of the microwave electric field and magnetic field in the microwave to the reaction was experimentally investigated, and the spatial distribution of the electric field intensity around the surface of the Si nanostructure was simulated using the finite element method.
- Baek, Heeyoel,Fujii, Takashi,Fujikawa, Shigenori,Kashimura, Keiichiro,Sato, Takuma,Tsubaki, Shuntaro,Uozumi, Yasuhiro,Wada, Yuji,Yamada, Yoichi M. A.
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p. 2148 - 2156
(2020/02/11)
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- Hydrodeoxygenation of Palmitic and Stearic Acids on Phosphide Catalysts Obtained In Situ in Reaction Medium
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Abstract: Unsupported phosphide catalysts of composition Ni2P and CoP are prepared in situ in the reaction medium from oil-soluble precursors in the course of hydrodeoxygenation of palmitic and stearic acids. The obtained catalysts are characterized by X-ray powder diffraction and X-ray photoelectron spectroscopy; they show high activity in the hydrodeoxygenation of model substrates. After 6 h of the hydrodeoxygenation reactions, the conversion of palmitic acid reaches 93 and 92% and the conversion of stearic acid is as high as 94 and 91% in the presence of nickel phosphide and cobalt phosphide, respectively. It is shown that the catalyst formed in situ can be isolated and recycled.
- Golubeva,Maksimov
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p. 1326 - 1330
(2019/12/30)
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- Catalyst-free Decarboxylation and Decarboxylative Giese Additions of Alkyl Carboxylates through Photoactivation of Electron Donor-Acceptor Complex
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We report herein a catalyst-free method to perform decarboxylative conjugated addition and hydrodecarboxylation of aliphatic N-(acyloxy)phthalimides (redox active esters, RAEs) through photoactivation of electron-donor-acceptor (EDA) complex with Hantzsch ester (HE) in N,N-dimethylacetamide (DMA) solution. The reactions present a green method to decarboxylatively construct carbon-carbon bond and to perform hydrodecarboxylation with broad substrate scope and functional group tolerance under mild blue light irradiation condition without recourse of popularly used photoredox catalysts. (Figure presented.).
- Zheng, Chao,Wang, Guang-Zu,Shang, Rui
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p. 4500 - 4505
(2019/08/26)
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- Esters as Radical Acceptors: β-NHC-Borylalkenyl Radicals Induce Lactonization by C?C Bond Formation/Cleavage on Esters
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Substituted propargyl acetates are converted into 4-boryl-2(5H)-furanones upon thermolysis in the presence of an N-heterocyclic carbene borane (NHC-borane) and di-tert-butyl peroxide. The acetyl methyl group is lost during the reaction as methane. Evidence suggests that the reaction proceeds by a sequence of radical events including: 1) addition of an NHC-boryl radical to the triple bond; 2) cyclization of the resultant β-borylalkenyl radical to the ester carbonyl group; 3) β-scission of the so-formed alkoxy radical to provide the 4-boryl-2(5H)-furanone and a methyl radical; and 4) hydrogen abstraction from the NHC-borane to return the initial NHC-boryl radical and methane.
- Shimoi, Masaki,Maeda, Katsuhiro,Geib, Steven J.,Curran, Dennis P.,Taniguchi, Tsuyoshi
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p. 6357 - 6361
(2019/04/13)
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- Photocatalytic degradation of benzothiophene by a novel photocatalyst, removal of decomposition fragments by MCM-41 sorbent
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In this study, a catalyst was synthesized by introduction of ZnO onto the surface of FSM-16 catalyst support (ZnO/FSM-16). Impregnation of catalyst support by ZnO proceeded through reacting of FSM-16 nanoparticles with Zn(CH3COO)2 solution followed by calcination of the product. The synthesized photocatalyst was then identified by different methods, and the optical property of the photocatalyst was studied by the DRS method. The results showed that after deposition of photocatalyst on FSM-16 support, the photocatalyst band gap was shifted to the visible region. The photoluminescence studies revealed lower recombination of electron–holes of the photocatalyst after immobilization on FSM-16. The influence of different variables on the photocatalytic performance of the samples was studied. Under optimized conditions, the high degradation efficiency of 97% was obtained by ZnO/FSM-16. The compounds produced from degradation of benzothiophene were recognized by the GC–MS method, and the products containing sulfur were properly adsorbed by MCM-41 sorbent. The photocatalyst showed high regeneration capability, and its activity was mostly preserved after six regeneration cycles.
- Hosseini, Asma,Faghihian, Hossein
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p. 2383 - 2401
(2019/01/29)
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- Chemoselective Hydrodeoxygenation of Carboxylic Acids to Hydrocarbons over Nitrogen-Doped Carbon-Alumina Hybrid Supported Iron Catalysts
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The establishment of catalyst systems for the chemoselective hydrodeoxygenation (HDO) of carboxylic acids to hydrocarbons, such as the HDO of long-chain fatty acids to alkanes, is important for biomass to biofuel conversion. As the most abundant and probably the cheapest transition metal on the earth, iron is a promising non-noble-metal alternative to precious metals for large-scale conversion of biomass. However, it usually suffers from unsatisfactory activity. In this work, a nitrogen-doped carbon-alumina hybrid supported iron (Fe-N-C@Al2O3) catalyst is established for chemoselective HDO of carboxylic acids to hydrocarbons. By using stearic acid HDO as the model reaction, n-octadecane and n-heptadecane are produced with yields of 91.9% and 6.0%, respectively. Triglycerides can also be converted into liquid alkanes with a total molar yield of >92%. In addition, the iron catalyst can chemoselectively catalyze the HDO of the carboxylic acid group in the presence of other functional groups such as an aromatic ring. This chemoselectivity has rarely been seen before because the aromatic ring is usually more easily hydrogenated in comparison to HDO of the carboxylic acid group. The characterization results showed that both the formation of a nitrogen-doped carbon-alumina hybrid and the iron loading are important for the Lewis basicity of these catalysts, in order to adsorb the acid substrates. The addition of melamine as the nitrogen precursor during pyrolysis eliminates undesired reactions between the iron precursor and alumina support to form an inactive hercynite phase, leading to the formation of an Fe3C active phase for the hydrogenation of -COOH to -CH2OH and the hybrid of N-C and alumina for the HDO of -CH2OH to -CH3.
- Li, Jiang,Zhang, Junjie,Wang, Shuai,Xu, Guangyue,Wang, Hao,Vlachos, Dionisios G.
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p. 1564 - 1577
(2019/02/03)
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- Catalytic deoxygenation of C18 fatty acid over supported metal Ni catalysts promoted by the basic sites of ZnAl2O4 spinel phase
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Highly active Zn-Al composite oxides were synthesized via a hydrothermal process followed by thermal treatment and were used as supports to prepare Ni-based hydrogenation catalysts for catalytic deoxygenation of oleic acid, stearic acid, and 1-octadecanol. The results showed that increasing the temperature of hydrothermal synthesis changed the morphology of the Zn-Al composite oxides from sheet-like structures to spheroidal structures. High hydrothermal synthesis temperatures enhanced the interaction between Zn and Al atoms, resulting in more ZnAl2O4 spinel phase. This phase not only improved the chemical stability of the support but also supplied strong basic sites which efficiently inhibited the formation of by-products and increased the yield of heptadecane in the catalytic deoxygenation of oleic acid. Stearic acid and 1-octadecanol could be readily transformed to alkanes in the presence of metallic Ni and ZnAl2O4 phase. Decarbonylation of the octadecanal intermediate and dehydrogenation of 1-octadecanol were key reaction pathways to produce heptadecane, in which decarbonylation was catalyzed by metallic Ni, while the dehydrogenation was attributed to synergistic catalysis between metallic Ni and the strong basic sites of the support. Individual metallic Ni only catalyzed the cleavage of C-H bonds but did not affect the O-H bond of 1-octadecanol.
- Li, Guangci,Chen, Lei,Fan, Ruikun,Liu, Di,Chen, Song,Li, Xuebing,Chung, Keng H.
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p. 213 - 222
(2019/01/14)
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- In situ hydrogenation and decarboxylation of oleic acid into heptadecane over a Cu-Ni alloy catalyst using methanol as a hydrogen carrier
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In this work, supported Cu-Ni bimetallic catalysts were synthesized and evaluated for the in situ hydrogenation and decarboxylation of oleic acid using methanol as a hydrogen donor. The supported Cu-Ni alloy exhibited a significant improvement in both activity and selectivity towards the production of heptadecane in comparison with monometallic Cu and Ni based catalysts. The formation of the Cu-Ni alloy is demonstrated by high-angle annular dark-field scanning transmission electron microscopy (HADDF-STEM), energy dispersive X-ray spectroscopy (EDS-mapping), X-ray diffraction (XRD) and temperature programmed reduction (TPR). A partially oxidized Cu in the Cu-Ni alloy is revealed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) following CO adsorption and X-ray photoelectron spectroscopy (XPS). The temperature programmed desorption of ethylene and propane (ethylene/propane-TPD) suggested that the formation of the Cu-Ni alloy inhibited the cracking of C-C bonds compared to Ni, and remarkably increased the selectivity to heptadecane. The temperature programmed desorption of acetic acid (acetic acid-TPD) indicated that the bimetallic Cu-Ni alloy and Ni catalysts had a stronger adsorption of acetic acid than that of the Cu catalyst. The formation of the Cu-Ni alloy and a partially oxidized Cu facilitates the decarboxylation reaction and inhibits the cracking reaction of C-C bonds, leading to enhanced catalytic activity and selectivity.
- Zhang, Zihao,Yang, Qiwei,Chen, Hao,Chen, Kequan,Lu, Xiuyang,Ouyang, Pingkai,Fu, Jie,Chen, Jingguang G.
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p. 197 - 206
(2018/01/12)
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- Construction of bifunctional co/h-zsm-5 catalysts for the hydrodeoxygenation of stearic acid to diesel-range alkanes
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Bifunctional Co/H-ZSM-5 zeolites were prepared by a surface organometallic chemistry grafting route, namely, by the stoichiometric reaction between cobaltocene and the Br?nsted acid sites in zeolites. The catalyst was applied to a model reaction of the catalytic hydrodeoxygenation of stearic acid (SA). The cobalt species existed in the form of isolated Co2 + ions at the exchange positions after grafting, transformed to CoO species on the surface of the zeolite, stabilized inside the zeolite channels upon calcination in air, and finally reduced by hydrogen to homogeneous clusters of metallic cobalt species approximately 1.5 nm in size. During this process, the Br?nsted acid sites of the H-ZSM-5 zeolites were preserved with a slight-ly reduced acid strength. The as-prepared bifunctional catalyst exhibited an approximately 16 times higher activity for the hydrodeoxygenation of SA (2.11 gSA gcat1 h1) than the reference catalyst (0.13 gSA gcat1 h1) prepared by solid-state ion exchange and a high C18 /C17 ratio of approximately 24. The remarkable hydrodeoxygenation performance of the bifunctional Co/H-ZSM-5 was owed to the effective synergy between the uniformed metallic cobalt clusters and the Br?nsted acid sites in H-ZSM-5. The simplified reaction network and kinetics of the SA hydrodeoxygenation catalyzed by the as-prepared bifunctional Co/H-ZSM-5 zeolites were also investigated.
- Wu, Guangjun,Zhang, Nan,Dai, Weili,Guan, Naijia,Li, Landong
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- Selective Hydrodeoxygenation of Vegetable Oils and Waste Cooking Oils to Green Diesel Using a Silica-Supported Ir–ReOx Bimetallic Catalyst
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High yields of diesel-range alkanes are prepared by hydrodeoxygenation of vegetable oils and waste cooking oils over ReOx-modified Ir/SiO2 catalysts under mild reaction conditions. The catalyst containing a Re/Ir molar ratio of 3 exhibits the best performance, achieving 79–85 wt % yield of diesel-range alkanes at 453 K and 2 MPa H2. The yield is nearly quantitative for the theoretical possible long-chain alkanes on the basis of weight of the converted oils. The catalyst retains comparable activity upon regeneration through calcination. Control experiments using probe molecules as model substrates suggest that C=C bonds of unsaturated triglycerides and free fatty acids are first hydrogenated to their corresponding saturated intermediates, which are then converted to aldehyde intermediates through hydrogenolysis of acyl C?O bonds and subsequently hydrogenated to fatty alcohols. Finally, long-chain alkanes without any carbon loss are formed by direct hydrogenolysis of the fatty alcohols. Small amounts of alkanes with one carbon fewer are also formed by decarbonylation of the aldehyde intermediates. A synergy between Ir and partially reduced ReOx sites is discussed to elucidate the high activity of Ir–ReOx/SiO2.
- Liu, Sibao,Simonetti, Trent,Zheng, Weiqing,Saha, Basudeb
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p. 1446 - 1454
(2018/04/30)
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- Light-Driven Enzymatic Decarboxylation of Fatty Acids
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The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their triglycerides are converted by CvFAP in near-quantitative yield and exclusive selectivity upon illumination with blue light. Very promising turnover numbers of up to 8000 were achieved in this proof-of-concept study.
- Huijbers, Mieke M. E.,Zhang, Wuyuan,Tonin, Fabio,Hollmann, Frank
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supporting information
p. 13648 - 13651
(2018/09/21)
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- Petroleum like biodiesel production by catalytic decarboxylation of oleic acid over Pd/Ce-ZrO2 under solvent-free condition
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The Ce/Zr ratio of Pd/Ce-ZrO2 catalysts was systematically changed in order to investigate the effect of oxygen vacancy concentration on their decarboxylation activityunder solvent-free conditions for potential sustainable petroleum like biodiesel production. Pd/Ce0.5Zr0.5O2 exhibited the highest catalytic activity from all other tested catalysts because it contained the highest oxygen vacancy concentration and Pd dispersion, as shown by the X-ray photoelectron spectroscopy, Raman spectroscopy, and CO-chemisorption data. A catalyst deactivation study also showed that both the Pd dispersion and the oxygen vacancy concentration influences the catalytic activity.The catalyst deactivation was found to occur mainly due to Pd sintering, decreases in the BET surface area and Pd dispersion, and partially due to the loss of oxygen vacancies.
- Shim, Jae-Oh,Jang, Won-Jun,Jeon, Kyung-Won,Lee, Da-We,Na, Hyun-Suk,Kim, Hak-Min,Lee, Yeol-Lim,Yoo, Seong-Yeun,Jeon, Byong-Hun,Roh, Hyun-Seog,Ko, Chang Hyun
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p. 163 - 169
(2018/07/25)
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- Insight into forced hydrogen re-arrangement and altered reaction pathways in a protocol for CO2 catalytic processing of oleic acid into C8-C15 alkanes
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A new vision of using carbon dioxide (CO2) catalytic processing of oleic acid into C8-C15 alkanes over a nano-nickel/zeolite catalyst is reported in this paper. The inherent and essential reasons which make this achievable are clearly resolved by using totally new catalytic reaction pathways of oleic acid transformation in a CO2 atmosphere. The yield of C8-C15 ingredients reaches 73.10 mol% in a CO2 atmosphere, which is much higher than the 49.67 mol% yield obtained in a hydrogen (H2) atmosphere. In the absence of an external H2 source, products which are similar to aviation fuel are generated where aromatization of propene (C3H6) oxidative dehydrogenation (ODH) involving CO2 and propane (C3H8) and hydrogen transfer reactions are found to account for hydrogen liberation in oleic acid and achieve its re-arrangement in the final alkane products. The reaction pathway in the CO2 atmosphere is significantly different from that in the H2 atmosphere, as shown by the presence of 8-heptadecene, γ-stearolactone, and 3-heptadecene as reaction intermediates, as well as a CO formation pathway. Because of the highly dispersed Ni metal center on the zeolite support, H2 spillover is observed in the H2 atmosphere, which inhibits the production of short-chain alkanes and reveals the inherent disadvantage of using H2. The CO2 processing of oleic acid described in this paper will significantly contribute to future CO2 utilization chemistry and provide an economical and promising approach for the production of sustainable alkane products which are similar to aviation fuel.
- Xing, Shiyou,Lv, Pengmei,Yuan, Haoran,Yang, Lingmei,Wang, Zhongming,Yuan, Zhenhong,Chen, Yong
-
p. 4157 - 4168
(2017/09/07)
-
- Noble metal-free catalytic decarboxylation of oleic acid to n-heptadecane on nickel-based metal-organic frameworks (MOFs)
-
Nickel based metal organic frameworks (Ni-MOFs) were successfully synthesized using new conjugated carboxylic acid linkers. These conjugated carboxylic acid linkers were synthesized using mild Heck coupling that led to the incorporation of functional groups not possible by traditional synthetic methods. Control of linker size allows for porosity tuning of the crystalline network and high surface area, that, in theory, results in the increased accessibility to Ni metal centers for catalysis. The resultant crystalline Ni-MOFs displayed BET areas as high as ~314 m2 g-1. To investigate their catalytic activity for conversion of oleic acid to liquid hydrocarbons, Ni-MOFs were grown on zeolite 5A beads that served as catalytic supports. The resultant catalysts displayed heptadecane selectivity as high as ~77% at mild reaction conditions, one of the highest yields for non-noble metal containing catalysts. The catalytic activity correlated to the concentration of acid sites. A slight decrease in catalytic activity was observed after catalysts recycling.
- Yang,McNichols,Davidson,Schweitzer,Gómez-Gualdrón,Trewyn,Sellinger,Carreon
-
p. 3027 - 3035
(2017/08/01)
-
- One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways
-
For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
- Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong
-
p. 2961 - 2973
(2017/02/05)
-
- Controlling Hydrodeoxygenation of Stearic Acid to n-Heptadecane and n-Octadecane by Adjusting the Chemical Properties of Ni/SiO2–ZrO2 Catalyst
-
A series of SiO2–ZrO2 mixed oxides with varying SiO2 concentrations were hydrothermally synthesized and used as support for Ni in the hydrodeoxygenation of stearic acid. ZrO2 provides a relatively low surface area and only Lewis acid sites, and Ni supported on ZrO2 produces n-heptadecane from stearic acid through hydrogenation and decarbonylation. The SiO2–ZrO2 mixed oxides have a higher specific surface area than ZrO2 as well as an unprecedented spherical and nanolayered morphology. Br?nsted acid sites were created by the incorporation of SiO2 into ZrO2, promoting the hydrodeoxygenation activity of Ni and specifically opening a new reaction route to n-octadecane through the dehydration of 1-octadecanol intermediate into 1-octadecene with subsequent hydrogenation.
- Foraita, Sebastian,Liu, Yue,Haller, Gary L.,Baráth, Eszter,Zhao, Chen,Lercher, Johannes A.
-
p. 195 - 203
(2017/01/17)
-
- Effect of Zn/Al ratio of Ni/ZnO-Al2O3 catalysts on the catalytic deoxygenation of oleic acid into alkane
-
Ni-based catalysts supported on Zn-Al composite oxides have been prepared for the catalytic deoxygenation of oleic acid into diesel-ranged alkanes, and the effects of the Zn/Al ratio on the physico-chemical properties of the supports and the deoxygenation activity of the final catalyst were investigated in detail. The results showed that higher Zn/Al ratios led to lower specific surface area of the supports and weakening of the interaction between Ni species and supports thereby improving the reducibility of Ni species. However, higher Zn/Al ratios may limit the dispersion of Ni species, leading to a decrease in the exposure of metallic Ni. Because the conversion and deoxygenation of the reactants mainly depended on the hydrogenation capability of the catalysts which was controlled by the amount of exposed metallic Ni, the catalyst with a Zn/Al ratio of 2/1 showed the highest hydrogenation rate and alkane yield. Further decreasing the Zn/Al ratio led to strong metal-support interaction, making the Ni species difficult to reduce, which may also inhibit the formation of alkane products. In addition, the change in Zn/Al ratio affected intermediate type, which could affect the yield of alkane products.
- Chen, Lei,Zhang, Feng,Li, Guangci,Li, Xuebing
-
p. 175 - 184
(2016/11/23)
-
- Kinetics and mechanism of the production of higher olefins from stearic acid in the presence of an alumina-supported nickel sulfide catalyst
-
A nickel sulfide catalyst which efficient in the decarbonylation of fatty acids to olefins and dienes has been obtained for the first time by treating alumina-supported nickel sulfate with hydrogen, and its properties have been studied. In its presence, the olefin selectivity of the reaction can exceed 90%. The kinetics of stearic acid deoxygenation to heptadecenes has been investigated, a kinetic model has been constructed, and a mechanism has been proposed for the reaction over this catalyst. Olefin oligomerization is the dominant side reaction. Kinetic evidence for the catalytic inhibition of oligomerization by nickel hydrides formed on the catalyst has been obtained. The compositions of active site–reactant adsorption complexes have been discussed.
- Katsman,Danyushevsky, V. Ya.,Kuznetsov,Shamsiev,Berenblyum
-
p. 147 - 155
(2017/04/24)
-
- The influence of the support on activity and selectivity of nickel sulfide catalysts in the decarbonylation of stearic acid to heptadecenes
-
The influence of the support nature on the performance of nickel sulfide catalyst in the decarbonylation of stearic acid to heptadecenes was investigated. The catalyst supported on silica demonstrated higher activity and selectivity in comparison with the catalyst on γ-Al2O3 used as a reference. The reaction schemes over these catalysts are nearly the same; however, the contributions from the side reactions of hydrogenation and oligomerization are reasonably different. Introduction of the products of decarbonylation (CO and water vapor) decreases the stearic acid conversion; and in the case of the catalyst supported on silica, the addition of CO strongly reduces the rate of hydrogenation of heptadecenes. The reasons for the observed differences were discussed. It was suggested that the dispersion of the nickel component as well as the nature of support acidity played a significant role.
- Danyushevsky, V. Ya.,Kuznetsov,Katsman,Kupriyanov,Flid,Berenblyum
-
p. 463 - 467
(2017/09/15)
-
- Effective conversion of heteroatomic model compounds in microalgae-based bio-oils to hydrocarbons over β-Mo2C/CNTs catalyst
-
Hydrotreatment of heteroatomic model compounds in microalgae-based bio-oils into diesel-like hydrocarbons was carried out over carbon nanotubes (CNTs)-supported β-Mo2C catalyst with superior activity and selectivity under a mild condition (≤200 °C). The results show that stearic acid and hexadecanamide can be completely converted into n-C15-C18 alkanes over β-Mo2C/CNTs catalyst. The β-Mo2CC/CNTs favors the pathway of hydrogenation-dehydration-hydrogenation to produce n-octadecane with an optimal yield of 91.24% at a lower temperature of 180 °C during hydrotreating process of stearic acid. The recycle tests demonstrate that the β-Mo2CC/CNTs exhibits excellent stability, and can be reused for seven times consecutively without reduction of catalytic stability. Based on the determined products, a brief reaction pathway is proposed. Therefore, a novel approach to produce diesel-like hydrocarbons via catalytic hydrotreatment of microalgae-based bio-oils over β-Mo2C/CNTs is introduced, which provides a basic research as well as technical parameters for its further industrialization.
- Liang, Junmei,Ding, Ranran,Wu, Yulong,Chen, Yu,Wu, Kejing,Meng, Yongqiang,Yang, Mingde,Wang, Yaowu
-
-
- Hydrodeoxygenation (HDO) of methyl palmitate over bifunctional Rh/ZrO2 catalyst: Insights into reaction mechanism via kinetic modeling
-
Hydrodeoxygenation (HDO) of triglycerides into hydrocarbons is a novel catalytic process for the production of green biofuels. In this work, the HDO reaction mechanism over Rh/ZrO2 catalyst was studied by selecting methyl palmitate as a model compound. HDO of methyl palmitate proceeded initially via the hydrogenolysis into palmitic acid intermediate, followed by sequential hydrogenation-decarbonylation reaction into pentadecane via aldehyde intermediate. Bifunctional mechanism of the Rh/ZrO2 catalyst is advocated for the HDO process, in which both Rh sites and oxygen vacancy sites on ZrO2 synergistically contribute to the catalysis. The interface between Rh nanoparticle and support was proposed to host the most active sites. Based on our earlier work, a surface reaction mechanism was proposed and slightly modified to develop a set of mechanistic kinetic models. The mechanistic model consisting of two distinct types of adsorption sites for oxygenated components and H2, gave a good fitting to the kinetic data over a broad range of reaction conditions and conversion levels.
- Bie, Yuwei,Lehtonen, Juha,Kanervo, Jaana
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p. 183 - 190
(2016/09/13)
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- Catalytic decarboxylation of non-edible oils over three-dimensional, mesoporous silica-supported Pd
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Deoxygenation of fatty acids (oleic and stearic acids) and non-edible oil (jatropha oil) over Pd(1-5 wt%) supported on two structurally different, three-dimensional, mesoporous silica (SBA-12 and SBA-16) catalysts was investigated. Pd/SBA-16 (cubic mesoporous structure with space group Im3ˉm) showed higher catalytic activity than Pd/SBA-12 (hexagonal mesoporous structure with space group p63/mmc). The influence of reaction parameters like temperature, H2 pressure and Pd content as well as the nature of the feedstock on catalytic activity and product selectivity was studied. A temperature of above 320 °C, reaction time of 5 h and Pd content (on silica surface) of 3 wt% enabled complete conversion of the fatty compounds into diesel-range hydrocarbons. Deoxygenation proceeded through hydrodeoxygenation and decarboxylation mechanisms when a saturated (stearic) acid was used as a feed while it advanced mainly through decarboxylation route when an unsaturated (oleic) acid was employed. Higher surface hydrophobicity and smaller size particles of Pd are the possible causes for the superior catalytic activity of Pd/SBA-16.
- Raut, Ravindra,Banakar, Vikram V.,Darbha, Srinivas
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p. 126 - 134
(2016/03/30)
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- Impact of the oxygen defects and the hydrogen concentration on the surface of tetragonal and monoclinic ZrO2 on the reduction rates of stearic acid on Ni/ZrO2
-
The role of the specific physicochemical properties of ZrO2 phases on Ni/ZrO2 has been explored with respect to the reduction of stearic acid. Conversion on pure m-ZrO2 is 1.3 times more active than on t-ZrO2, whereas Ni/m-ZrO2 is three times more active than Ni/t-ZrO2. Although the hydrodeoxygenation of stearic acid can be catalyzed solely by Ni, the synergistic interaction between Ni and the ZrO2 support causes the variations in the reaction rates. Adsorption of the carboxylic acid group on an oxygen vacancy of ZrO2 and the abstraction of the a-hydrogen atom with the elimination of the oxygen atom to produce a ketene is the key to enhance the overall rate. The hydrogenated intermediate 1-octadecanol is in turn decarbonylated to heptadecane with identical rates on all catalysts. Decarbonylation of 1-octadecanol is concluded to be limited by the competitive adsorption of reactants and intermediate. The substantially higher adsorption of propionic acid demonstrated by IR spectroscopy and the higher reactivity to O2 exchange reactions with the more active catalyst indicate that the higher concentration of active oxygen defects on m-ZrO2 compared to t-ZrO2 causes the higher activity of Ni/m-ZrO2.
- Foraita, Sebastian,Fulton, John L.,Chase, Zizwe A.,Vjunov, Aleksei,Xu, Pinghong,Barth, Eszter,Camaioni, Donald M.,Zhao, Chen,Lercher, Johannes A.
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p. 2423 - 2434
(2015/02/05)
-
- Decarboxylation of Oleic Acid to Heptadecane over Pt Supported on Zeolite 5A Beads
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The synthesis of Pt supported on zeolite 5A beads for the decarboxylation of oleic acid to heptadecane is demonstrated. The use of a microporous ZIF-67 crystalline layer on zeolite 5A beads not only improved the heptadecane selectivity but also, most importantly, improved the stability of the resultant catalyst. Heptadecane yields as high as ~81% were observed for the fresh catalysts. The catalysts displayed only low to moderate loss of catalytic activity after two rounds of recycle. To our best knowledge, the catalytic performance of these catalysts is superior to those of the state-of-the-art catalysts at mild reaction conditions. In addition, as compared to powders, beads are much easier to recycle, can be fully recovered, and are more amenable for potential scale-up. The resultant catalysts are promising for the catalytic conversion of fatty acid molecules into gasoline/diesel-range hydrocarbons.
- Yang, Liqiu,Tate, Kirby L.,Jasinski, Jacek B.,Carreon, Moises A.
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p. 6497 - 6502
(2015/11/23)
-
- Catalytic conversion of Jatropha oil to alkanes under mild conditions with a Ru/La(OH)3 catalyst
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The long-chain alkanes obtained from the hydrodeoxygenation of plant oils are ideal substitutes for diesel. In this work, a new efficient catalytic system was established for the conversion of plant oil to long-chain alkanes under mild conditions with a bi-functional Ru/La(OH)3 catalyst. The hydrodeoxygenation of stearic acid was performed in an autoclave with Ru-based catalysts with different supports (HZSM-5, ZSM-5, SiO2-Al2O3, SiO2, ZrO2, Mg(OH)2, La(OH)3, and La2O3). Among these catalysts, Ru supported on basic La(OH)3 showed a remarkable catalytic performance for the reaction. Over 98% of long-chain alkanes were obtained with 100% conversion of stearic acid at 200 °C and 4 MPa H2. When crude Jatropha oil was hydrogenated, about 80.7 wt% of long chain alkanes were obtained under the optimized conditions (200 °C, 4 MPa H2, 8 h). The high efficiency of the Ru/La(OH)3 catalyst could be due to a co-effect of the high hydrogenation activity of Ru and the basic La(OH)3 support which can attract the acidic raw material. Additionally, the Ru/La(OH)3 catalyst was recycled four times and maintained a good activity and stability. The reaction pathway was also explored by using stearic acid as a model compound. Hydrogenation-decarbonylation could be the main pathway to produce n-heptadecane, which has one carbon atom less than stearic acid.
- Guo, Jian-Hua,Xu, Guang-Yue,Shen, Fei,Fu, Yao,Zhang, Ying,Guo, Qing-Xiang
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p. 2888 - 2895
(2015/05/27)
-
- Selective Catalytic Hydrogenolysis of Carbon-Carbon σ Bonds in Primary Aliphatic Alcohols over Supported Metals
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The selective scission of chemical bonds is always of great significance in organic chemistry. The cleavage of strong carbon-carbon σ bonds in the unstrained systems remains challenging. Here, we report the selective hydrogenolysis of carbon-carbon σ bonds in primary aliphatic alcohols catalyzed by supported metals under relatively mild conditions. In the case of 1-hexadecanol hydrogenolysis over Ru/TiO2 as a model reaction system, the selective scission of carbon-carbon bonds over carbon-oxygen bonds is observed, resulting in n-pentadecane as the dominant product with a small quantity of n-hexadecane. Theoretical calculations reveal that the 1-hexadecanol hydrogenolysis on flat Ru (0001) undergoes two parallel pathways: i.e. carbon-carbon bond scission to produce n-pentadecane and carbon-oxygen bond scission to produce n-hexadecane. The removal of adsorbed CO on a flat Ru (0001) surface is a crucial step for the 1-hexadecanol hydrogenolysis. It contributes to the largest energy barrier in n-pentadecane production and also retards the rate for n-hexadecane production by covering the active Ru (0001) surface. The knowledge presented in this work has significance not just for a fundamental understanding of strong carbon-carbon σ bond scission but also for practical biomass conversion to fuels and chemical feedstocks.
- Di, Lu,Yao, Sikai,Li, Mengru,Wu, Guangjun,Dai, Weili,Wang, Guichang,Li, Landong,Guan, Naijia
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p. 7199 - 7207
(2015/12/11)
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- Highly Selective Hydrodecarbonylation of Oleic Acid into n-Heptadecane over a Supported Nickel/Zinc Oxide-Alumina Catalyst
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The production of second-generation biodiesel with triglycerides or their derivatives through hydroprocessing is considered as a promising approach to make transportation fuels. In this study, a series of Ni-based catalysts supported on basic composite oxides (MO-Al2O3, M=Mg, Ca, Ni, Cu, Zn) were prepared for the catalytic deoxygenation of oleic acid in the presence of H2. Ni/ZnO-Al2O3 exhibited the highest deoxygenation activity and alkane selectivity, which depended on its moderate basicity. Investigations of the reaction conditions, which include reaction time, reaction temperature, H2 pressure, and Ni loading, suggested that n-heptadecane was the predominant product and its content increased with reaction temperature. The reaction temperature was more important than H2 pressure in the catalytic deoxygenation of oleic acid. Additionally, the overall reaction pathways for the conversion of oleic acid were proposed based on the product distribution for different durations and reaction rates of stearic acid, 1-octadecanol, and stearyl stearate, in which the oxygen atoms in the oleic acid were mainly removed in the form of CO through a hydrogenation-dehydrogenation-decarbonylation reaction route. If glycerol trioleate was used instead of oleic acid, Ni/ZnO-Al2O3 exhibited a high hydrodecarbonylation activity and selectivity to n-heptadecane.
- Li, Guangci,Zhang, Feng,Chen, Lei,Zhang, Chuanhui,Huang, He,Li, Xuebing
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p. 2646 - 2653
(2015/09/15)
-
- Effective deoxygenation of fatty acids over Ni(OAc)2 in the absence of H2 and solvent
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Different metal acetate salts were systematically examined for the catalytic deoxygenation of stearic acid in the absence of H2 and solvent for the first time. Ni(OAc)2 exhibited the highest activity with 62% yield achieved at 350°C for 4.5 h with only 1 mol% (0.2 wt%) of the catalyst. Even with 0.25 mol% (0.05 wt%) catalyst, around 28% yield was achieved within 2 h at 350°C with 89% selectivity to C17 hydrocarbons. The activity based on C17 yields per Ni was 14.5 mol mol-1 h-1, considerably higher than that in previous reports. The catalytically active species were identified to be in situ generated Ni nanoparticles (8-10 nm) formed from the decomposition of the metal precursor with stearic acid as a stabilizer. A new reaction pathway of alkane formation from stearic acid via anhydride intermediate decarbonylation under an inert gas atmosphere was proposed. The excellent stability of the catalyst was demonstrated by re-adding a substrate to the system, during which the activity remained constant through four consecutive runs. The novel catalytic system was found to be applicable to a range of fatty acids and triglycerides with varying activities.
- Li, Wenjing,Gao, Yongjun,Yao, Siyu,Ma, Ding,Yan, Ning
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p. 4198 - 4205
(2015/08/11)
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- Cu, Al and Ga based metal organic framework catalysts for the decarboxylation of oleic acid
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Herein we demonstrate the catalytic decarboxylation and conversion of oleic acid to paraffins and hydrocarbons over bare and Pt supported Cu, Al and Ga based metal organic frameworks. Moderate degrees of decarboxylation were observed for all metal organic framework catalysts. The incorporation of Pt with the porous frameworks resulted in high degrees of decarboxylation. All MOF catalysts showed high thermal stability, resulting in recyclable catalysts displaying low catalytic activity loss. Of all studied catalysts, Ga-MOF catalysts were the most effective catalysts, displaying moderate to high degrees of decarboxylation. In addition, the Pt-Ga-MOF catalyst displayed selectivity to heptadecane, an important industrial chemical. Octadecane, heptadecane, dodecane, undecane, decane, nonane, octane, and heptane were observed as the main side products. To our best knowledge, the catalytic ability of a metal organic framework both as catalyst and support for the decarboxylation of a model fatty acid molecule is reported for the first time.
- Yang,Ruess,Carreon
-
p. 2777 - 2782
(2015/07/22)
-
- Optimization of unsupported CoMo catalysts for decarboxylation of oleic acid
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Hydrodeoxygenation (HDO) processes have been developed to remove the oxygenated compounds in lipids. However, the HDO process consumes excess hydrogen. As opposed to the HDO process, decarboxylation does not require hydrogen. In this study, decarboxylation of oleic acid without hydrogen was carried out over unsupported CoMo catalysts. Unsupported CoMo catalysts were prepared by a co-precipitation method. The Co/Mo ratio was systematically varied to optimize unsupported CoMo catalyst. The catalyst properties were studied using various characterization techniques and related to the activity results in decarboxylation.
- Shim, Jae-Oh,Jeong, Dae-Woon,Jang, Won-Jun,Jeon, Kyung-Won,Kim, Seong-Heon,Jeon, Byong-Hun,Roh, Hyun-Seog,Na, Jeong-Geol,Oh, You-Kwan,Han, Sang Sup,Ko, Chang Hyun
-
-
- One-pot synthesized hierarchical zeolite supported metal nanoparticles for highly efficient biomass conversion
-
Hierarchically porous zeolite supported metal nanoparticles are successfully prepared through a base-assisted chemoselective interaction between the silicon species on the zeolite crystal surface and metal salts, in which in situ construction of mesopores and high dispersion of metal species are realized simultaneously.
- Wang, Darui,Ma, Bing,Wang, Bo,Zhao, Chen,Wu, Peng
-
supporting information
p. 15102 - 15105
(2015/10/12)
-
- Light-mediated deoxygenation of alcohols with a dimeric gold catalyst
-
A new protocol for the reductive deoxygenation of primary alcohols was explored. This photo-mediated method combines a novel approach to bromination of alcohols merged with the powerful reducing capability of [Au2(dppm)2]Cl2 [dppm = 1,1-bis(diphenylphosphino)methane] as a photoredox catalyst. The highly efficient methods discussed are marked by the use of UVA light-emitting diodes, which have significantly reduced reaction times and lowered setup cost.
- McCallum, Terry,Slavko, Ekaterina,Morin, Mathieu,Barriault, Louis
-
supporting information
p. 81 - 85
(2015/02/18)
-
- PROCESS FOR ISOMERIZATION AND DECARBOXYLATION OF UNSATURATED ORGANIC COMPOUNDS WITH A METAL CATALYST OR CATALYST PRECURSOR
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Disclosed is the use of a metal catalyst or catalyst precursor that catalyzes the isomerization of an unsaturated fatty acid, unsaturated fatty acid derivative, or an unsaturated triglyceride. Also disclosed is the use of a metal catalyst or catalyst precursor that catalyzes the decarboxylation of an unsaturated organic compound. Also disclosed is the use of a catalyst or catalyst precursor for the dual function isomerization and decarboxylation of an unsaturated fatty acid to an unsaturated organic compound.
- -
-
Paragraph 0130; 0133
(2014/09/30)
-
- Supported iron nanoparticles for the hydrodeoxygenation of microalgal oil to green diesel
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Iron nanoparticles supported on mesoporous silica nanoparticles (Fe-MSN) catalyze the hydrotreatment of fatty acids with high selectivity for hydrodeoxygenation over decarbonylation and hydrocracking. The catalysis is likely to involve a reverse Mars-Van Krevelen mechanism, in which the surface of iron is partially oxidized by the carboxylic groups of the substrate during the reaction. The strength of the metal-oxygen bonds that are formed affects the residence time of the reactants facilitating the successive conversion of carboxyl first into carbonyl and then into alcohol intermediates, thus dictating the selectivity of the process. The selectivity is also affected by the pretreatment of Fe-MSN, the more reduced the catalyst the higher the yield of hydrodeoxygenation product. Fe-MSN catalyzes the conversion of crude microalgal oil into diesel-range hydrocarbons.
- Kandel, Kapil,Anderegg, James W.,Nelson, Nicholas C.,Chaudhary, Umesh,Slowing, Igor I.
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p. 142 - 148
(2014/05/20)
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- Kinetics of hydrodeoxygenation of stearic acid using supported nickel catalysts: Effects of supports
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The hydrodeoxygenation of fatty acids derived from vegetable and microalgal oils is a novel process for production of liquid hydrocarbon fuels well-suited with existing internal combustion engines. The hydrodeoxygenation of stearic acid was investigated in a high pressure batch reactor using n-dodecane as solvent over nickel metal catalysts supported on SiO2, γ-Al2O3, and HZSM-5 in the temperature range of 533-563 K. Several supported nickel oxide catalysts with nickel loading up to 25 wt.% were prepared by incipient wetness impregnation method and reduced using hydrogen. The catalysts were then characterized by BET, TPR, H2 pulse chemisorption, TPD, XRD, and ICP-AES. Characterization studies revealed that only dispersed nickel oxide was present up to 15 wt.% nickel loading on γ-Al2O3. The acidity of the supports depends on nickel loading of oxidized catalysts and increases with increasing nickel loading up to 15 wt.%. n-Pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and l-octadecanol were identified as products of hydrodeoxygenation of stearic acid with n-heptadecane being primary product. The catalytic activity and selectivity to products for hydrodeoxygenation of stearic acid depends strongly on acidity of the supports. The maximum selectivity to n-heptadecane was observed with nickel supported γ-Al2O3 catalyst. A suitable reaction mechanism of hydrodeoxygenation of stearic acid was delineated based on products distribution. The conversion of stearic acid was increased with increasing reaction time, nickel loading on γ-Al2O 3, temperature, and catalyst loading. Complete conversion of stearic acid was accomplished with more than 80% selectivity to n-heptadecane at reasonable reaction temperature of 563 K after 240 min of reaction using 15 wt.% Ni/γ-Al2O3 catalyst. An empirical kinetic model was also developed to correlate the experimental data.
- Kumar, Pankaj,Yenumala, Sudhakara Reddy,Maity, Sunil K.,Shee, Debaprasad
-
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- Hydrothermal catalytic processing of saturated and unsaturated fatty acids to hydrocarbons with glycerol for in situ hydrogen production
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Lipids are a promising feedstock to produce renewable hydrocarbon fuels and H2via catalytic hydrothermal processing. Upon exposure to hydrothermal media (e.g., 300 °C, 8-11 MPa), lipids rapidly hydrolyze to produce saturated and unsaturated free fatty acids in varying ratios, depending on the feedstock, as well as glycerol. This report demonstrates the potential of Pt-Re/C for the hydrothermal conversion of saturated and unsaturated fatty acids to hydrocarbons, using glycerol reforming for in situ H2 production to meet process demands. Experiments showed that deoxygenation of stearic acid, a model saturated fatty acid, was significantly enhanced with Pt-Re/C under a reducing atmosphere compared to Pt/C. The coupled hydrogenation and deoxygenation (HYD-DOX) of oleic aid, a model unsaturated fatty acid, was also moderately enhanced under an inert atmosphere using glycerol for in situ H2 production, with DOX as the rate-limiting step. Characterization of Pt-Re/C showed that Re had a significant effect on CO:H uptake ratio (2.2) compared to commercial Pt/C (1.3), with the metals dispersed as small crystallites (~3-4 nm) throughout carbon support. Experiments revealed that the initial system H2 headspace loading 2 consumption. At higher initial H2 loadings (≥3.45 MPa), fatty acid reduction was also observed as a minor DOX pathway. Experiments also showed that oleic acid HYD-DOX and glycerol reforming are affected by initial glycerol concentration and catalyst loading. Under optimized process conditions, complete HYD-DOX of oleic acid to heptadecane was achieved within 2 h with a net-zero H2 consumption using a 1:3 glycerol-to-fatty acid ratio (i.e., the native ratio in triacylglycerides). X-ray photoelectron spectroscopy showed that H2 in the reactor headspace results in lower oxidation states of Pt and Re, suggesting a possible mechanism for enhanced DOX kinetics. This approach holds promise for overcoming the high external H 2 demands of conventional lipid hydrotreatment processes.
- Vardon, Derek R.,Sharma, Brajendra K.,Jaramillo, Humberto,Kim, Dongwook,Choe, Jong Kwon,Ciesielski, Peter N.,Strathmann, Timothy J.
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p. 1507 - 1520
(2014/03/21)
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- Hydrothermal deoxygenation of triglycerides over Pd/C aided by in situ hydrogen production from glycerol reforming
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A one-pot catalytic hydrolysis-deoxygenation reaction for the conversion of unsaturated triglycerides and free fatty acids to linear paraffins and olefins is reported. The hydrothermal deoxygenation reactions are performed in hot compressed water at 250 °C over a Pd/C catalyst in the absence of external H2. We show that aqueous-phase reforming (APR) of glycerol and subsequent water-gas-shift reaction result in the in situ formation of H 2. While this has a significant positive effect on the deoxygenation activity, the product selectivity towards high-value, long-chain olefins remains high. With a little H2elp from my friends: A one-pot hydrolysis-deoxygenation reaction for triglycerides and free fatty acids, which is of particular interest for the production of biofuels and value-added chemicals from nonedible or waste fats and oils, is reported. The reaction is performed over palladium on carbon (Pd/C) at 250 °C without additional H2. Instead, in situ H2 production occurs through glycerol reforming and subsequent water-gas-shift reaction with a positive effect on the deoxygenation activity.
- Hollak, Stefan A. W.,Ari?ns, Maxim A.,De Jong, Krijn P.,Van Es, Daan S.
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p. 1057 - 1062
(2014/05/06)
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- Role of support in deoxygenation and isomerization of methyl stearate over nickel-molybdenum catalysts
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Microporous SAPO-11 and highly ordered mesoporous AlSBA-15 with different aluminum contents (with Si/Al ratio of 5 and 10) were synthesized. Thus prepared samples were characterized by BET, pyridine-FTIR and NH3-TPD to investigate their structural and acidic properties. The samples were then transformed into bifunctional catalysts by loading with molybdenum and nickel. Their activities were tested in the hydroconversion of methyl stearate using a fixed bed flow reactor system. The sulfided NiMo catalysts exhibited high conversion and deoxygenation activities. High isomerization activities observed for both NiMo/SAPO-11 and NiMo/AlSBA-15 catalysts, similar to the isomerization of light naphtha, was attributed to the acidity of supports. However, the acidity of supports was not the only factor influencing the isomerization of long chain molecules. AlSBA-15 had a large specific surface area that contained more acidic sites inside of its channels, promoting the formation of cracking products; SAPO-11 had a suitable pore size and contained fewer acidic sites inside the pore channels, promoting the formation of mono-branched isomers while suppressing cracking reactions.
- Qian, Eika W.,Chen, Ning,Gong, Shaofeng
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- Catalytic deoxygenation of fatty acids: Elucidation of the inhibition process
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Catalytic 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.
- Hollak, Stefan A. W.,De Jong, Krijn P.,Van Es, Daan S.
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p. 2648 - 2655
(2015/04/14)
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