Catalysts For Deoxygenation Research Articles

Tungsten‐Based Catalysts for Selective Deoxygenation

Tungsten‐Based Catalysts for Selective Deoxygenation

Tungsten‐Based Catalysts for Selective Deoxygenation

On the tip of the tung(sten): The title catalysts selectively perform deoxygenation of vegetable-oil-based feeds by either decarboxylation/decarbonylation or hydrodeoxygenation (HDO) pathways, depending on the dominant tungsten phase (WO3 and W2C). The process upgrades vegetable-oil-based feeds, under a hydrogen atmosphere, to high-value olefinic products, thus providing a significant advantage over other types of deoxygenation catalysts.

Palladium Catalysts for Fatty Acid Deoxygenation: Influence of the Support and Fatty Acid Chain Length on Decarboxylation Kinetics

Supported metal catalysts containing 5 wt% Pd on silica, alumina, and activated carbon were evaluated for liquid-phase deoxygenation of stearic (octadecanoic), lauric (dodecanoic), and capric (decanoic) acids under 5 % H2 at 300 °C and 15 atm. On-line quadrupole mass spectrometry (QMS) was used to measure CO + CO2 yield, CO2 selectivity, H2 consumption, and initial decarboxylation rate. Post-reaction analysis of liquid products by gas chromatography was used to determine n-alkane yields. The Pd/C catalyst was highly active and selective for stearic acid (SA) decarboxylation under these conditions. In contrast, SA deoxygenation over Pd/SiO2 occurred primarily via decarbonylation and at a much slower rate. Pd/Al2O3 exhibited high initial SA decarboxylation activity but deactivated under the test conditions. Similar CO2 selectivity patterns among the catalysts were observed for deoxygenation of lauric and capric acids; however, the initial decarboxylation rates tended to be lower for these substrates. The influence of alkyl chain length on deoxygenation kinetics was investigated for a homologous series of C10–C18 fatty acids using the Pd/C catalyst. As fatty acid carbon number decreases, reaction time and H2 consumption increase, and CO2 selectivity and initial decarboxylation rate decrease. The increase in initial decarboxylation rates for longer chain fatty acids is attributed to their greater propensity for adsorption on the activated carbon support.

Integrated hydropyrolysis and hydroconversion (IH2) for the direct production of gasoline and diesel fuels or blending components from biomass, part 1: Proof of principle testing

AbstractCellulosic biomass can be directly converted to hydrocarbon transportation fuels through the use of hydropyrolysis or integrated hydropyrolysis plus hydroconversion (IH2). Hydropyrolysis performed in a fast fluidized bed under 14–35 bar of hydrogen pressure with an effective deoxygenation catalyst directly produces a fungible hydrocarbon product with less than 1 total acid number which can either be directly fed to a refinery or polished in an integrated hydroconversion reactor to produce gasoline and diesel with less than 1% oxygen. Experimental data from a 0.45 kg/h semi‐continuous IH2 pilot plant is presented. Economics and life cycle analysis data will be presented later in this series, and will show that by employing IH2 technology, biomass can be converted to gasoline and diesel fuels at delivered costs of less and in some cases significantly less than $1.80/gallon with greater than 90% reduction in greenhouse gas emissions. Larger (2.08 kg/h) long‐term continuous pilot‐scale testing of the IH2 process will commence in the near future. As a biomass‐to‐fuels conversion technology, IH2 has the potential to substantially reduce US dependence on foreign oil, thereby reducing the price of transportation fuels and significantly lowering worldwide greenhouse gas emissions. © American Institute of Chemical Engineers Environ Prog, 2011

Catalytic deoxygenation of oleic acid in continuous gas flow for the production of diesel-like hydrocarbons

Continuous gas phase deoxygenation of oleic acid in the presence of hydrogen employing a granular 2 wt% Pd/C catalyst was investigated under solvent free conditions. Conversion of oleic acid and selectivity to the desired diesel-like C17 hydrocarbons heptadecane and heptadecenes was studied at different reaction conditions such as temperature, gas flow and catalyst amount. The best hydrocarbon yield was achieved with low reaction temperatures, high catalyst amounts and high hydrogen flows. To further decrease the reaction temperature but yet maintain a pure gas phase reaction, reactions were conducted in vacuum. Furthermore, water was added in varying amounts to support desorption and to determine if catalyst deactivation could be overcome. The deoxygenation catalyst was characterized by nitrogen adsorption isotherms (BET; Brunauer–Emmet–Teller method), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM).

Stainless Steel As a Catalyst for the Total Deoxygenation of Glycerol and Levulinic Acid in Aqueous Acidic Medium

Exposing 316 Stainless Steel pressure reactor bodies to an aqueous Bronstedt acidic solution (trifluoromethane sulfonic acid) at elevated temperatures (100−250 °C) under reducing atmosphere (hydrogen gas at 800 psi) leads to the formation of insoluble inorganic precipitates, identified as mixed chromium oxides by scanning electron microscopy X-ray fluorescence (SEM-XRF). A catalytically active metal surface is generated, that is, under these conditions the <100 Ǻ thick chromium oxide layer that normally passivates 316 Stainless Steel (316SS) against corrosion is etched away, and the reactor body itself becomes an active hydrogenation catalyst. The effect is specific to aqueous acidic medium and therefore water-soluble substrates as encountered in biomass conversion, for example, sugar alcohols and levulinic acid, which can be deoxygenated to the corresponding alkanes and alkenes using only a Bronstedt acid and the reactor body as the catalyst. Control experiments in several different 316SS reactors built ...

Cyclopentadienyl and pentamethylcyclopentadienyl ruthenium complexes as catalysts for the total deoxygenation of 1,2-hexanediol and glycerol

The ruthenium aqua complexes [cp*Ru(OH2)(N–N)](OTf) (cp* = η5-pentamethylcyclopentadienyl, N–N = 2,2′-bipyridine, phen = 1,10-phenanthroline, OTf− = trifluoromethanesulfonate) and the acetonitrile complex [cpRu(CH3CN)(bipy)](OTf) (cp = η5-cyclopentadienyl) are water-, acid-, and thermally stable (>200 °C) catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOTf as a co-catalyst, they effect the deoxygenation of 1,2-hexanediol to 1-hexanol and hexane. Glycerol is deoxygenated to 1-propanol in up to 18% yield and under more forcing conditions completely deoxygenated to propene. The structure of the acetonitrile pro-catalyst [cpRu(CH3CN)(bipy)](OTf) has been determined by X-ray crystallography (space groupP (a = 9.3778(10) A; b = 10.7852(10) A; c = 11.1818(13) A; α = 101.718(5)°; β = 114.717(4)°; γ = 102.712(5)°; R = 3.95%).

Diesel-like Hydrocarbons from Catalytic Deoxygenation of Stearic Acid over Supported Pd Nanoparticles on SBA-15 Catalysts

Palladium catalysts with different loading on SBA-15 have been prepared using a direct synthesis method and characterized with X-ray diffraction, micrograph images, and X-ray photoelectron spectroscopy. Mesoporous Pd-SBA-15 was an active and selective catalyst for deoxygenation of stearic acid in dodecane as a solvent at 300 °C under 17 bar of 5 vol% H2 in argon as a carrier gas in a semibatch reactor. Palladium/SBA-15 catalysts have been prepared using a direct synthesis method and characterized with X-ray diffraction, micrograph images, and X-ray photoelectron spectroscopy. They were an active and selective catalyst for deoxygenation of stearic acid in dodecane as a solvent at 300 °C under 17 bar of 5 vol% H2 in argon as a carrier gas in a semibatch reactor.

Catalytic deoxygenation of terminal-diols under acidic aqueous conditions by the ruthenium complexes [(η 6-arene)Ru(X)(N ∩ N)](OTf) n, X = H 2O, H, η 6-arene = p-Me- iPr-C 6H 4, C 6Me 6, N ∩ N = bipy, phen, 6,6′-diamino-bipy, 2,9-diamino-phen, n = 1, 2) : Influence of the ortho-amine substituents on catalytic activity

A series of ruthenium complexes of the general composition [(η 6-arene)(N ∩ N)Ru(X)](Y) n , (arene = p-Me- i Pr-C 6H 4, C 6Me 6; N ∩ N = bipy, phen, 6,6′-diamino-2,2′-bipyridine, 2,9-diamino-1,10-phenanthroline; X = Cl, H, H 2O; Y = Cl, OTf) was synthesized and the new compounds exhaustively structurally characterized by standard techniques (NMR, IR, elemental analysis, single-crystal X-ray crystallography). The single-crystal X-ray structures of [( p-Me- i Pr-C 6H 4)Ru(dabipy)Cl][Cl] ( 3Cl[Cl]), [( p-Me- i Pr-C 6H 4)Ru(daphen)Cl][Cl] ( 4Cl[Cl]), [(C 6Me 6)Ru(dabipy)Cl][Cl] ( 7Cl[Cl]), [(C 6Me 6)Ru(daphen)Cl][Cl] ( 8Cl[OTf]), [( p-Me- i Pr-C 6H 4)Ru(bipy)(H 2O)][OTf] 2 ( 1O[OTf] 2 ), [( p-Me- i Pr-C 6H 4)Ru(dabipy)(H 2O)][OTf] 2 ( 3O[OTf] 2 ), [( p-Me- i Pr-C 6H 4)Ru(dabipy)(H 2O)][SO 4] ( 3O[SO 4 ]), [( p-Me- i Pr-C 6H 4)Ru(daphen)(H 2O)][OTf] 2 ( 4O[OTf] 2 ), [(C 6Me 6)Ru(daphen)(MeOH)][OTf] 2 ( 8(MeOH)[OTf] 2 ), [( p-Me- i Pr-C 6H 4)Ru(dabipy)(H)][OTf] ( 3H[OTf]), [( p-Me- i Pr-C 6H 4)Ru(daphen)(H)][OTf] ( 4H[OTf]), [(C 6Me 6)Ru(dabipy-BH 2-OTf)(H)] ( 7H[-NH 2 -BH 2 -OTf]) have been determined. Under 750–1100 psi (5–7.5 MPa) of hydrogen pressure at 110 °C in the presence of acid and water in sulfolane solvent the aquo complexes form active catalysts for the selective deoxygenation of terminal diols, notably 1,2-hexanediol, to the corresponding primary alcohol, i.e., 1-hexanol in up to 60% yield. The presence of amino functions on the ortho-positions of the chelating ligands results in lower catalyst activity. Under the same reaction conditions the catalysts fail to convert glycerol to GC-detectable products. At the higher temperatures ( T > 150 °C) possibly required for glycerol activation the catalysts show increasing decomposition with increasing temperature.

Catalytic deoxygenation of unsaturated renewable feedstocks for production of diesel fuel hydrocarbons

The liquid-phase deoxygenation reaction of unsaturated renewables has been investigated in a semi-batch reactor. The reactants examined were the monounsaturated fatty acid, oleic acid, the diunsaturated fatty acid, linoleic acid and the monounsaturated fatty acid ester, methyl oleate. The reactions were carried out over a Pd/C catalyst under constant pressure and temperature in the following domain, 15–27 bar and 300–360 °C, respectively. The influence of carrier gas was additionally investigated. The impact as solvent (mesitylene) was studied as well and reaction pathways were proposed. Furthermore, continuous deoxygenation experiments were conducted, facilitating understanding of the catalyst stability and catalyst deactivation. The deoxygenation catalyst was characterized by physisorption, temperature programmed desorption (TPD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).

ChemInform Abstract: Aminated Polystyrene‐Bound Carbonylrhodium Clusters as a Catalyst for Deoxygenation of Various N‐O Bonds.

AbstractPoly(p‐chloromethylstyrene) is partially aminated to yield ligands which form polymer‐bound carbonylrhodium amine complexes.

Investigation including ESCA analysis of Fe-Pd/ZSM-5 deoxygenation catalysts

This paper reports an investigation of Fe-Pd/ZSM-5 catalysts prepared by two different techniques, both using ferrocene and palladium allylcyclopentadienyl as sources of iron and palladium respectively. These catalysts are used for deoxygenation of organic compounds in the presence of CO. They were characterized using XRD, quantitative IR of adsorbed pyridine and quantitative ESCA (electron spectroscopy for chemical analysis). Catalytic tests including CO hydrogenation and methanol conversion in carbon monoxide are reported and discussed.

Aminated Polystyrene-Bound Rhodium Carbonyl Clusters as a Catalyst for Deoxygenation of Various N–O Bonds

Abstract Aminated polystyrene-bound rhodium carbonyl cluster complexes are prepared by treatment of Rh6(CO)16 with various aminated polystyrenes. The polymeric rhodium complexes show a catalytic activity for deoxygenation of nitro compounds, oximes, hydroxylamines, and N-oxides under the conditions using CO and H2O. The recovered rhodium complexes maintain the deoxygenation ability with a small loss of the selectivity.