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Mark Crocker - One of the best experts on this subject based on the ideXlab platform.
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Effect of Pt Promotion on the Ni-Catalyzed Deoxygenation of Tristearin to Fuel-Like Hydrocarbons
Catalysts, 2019Co-Authors: Ryan Loe, Robert Pace, Tonya Morgan, Eduardo Santillan-jimenez, Kelsey Huff, Morgan Walli, Mark A Isaacs, Yang Song, Dali Qian, Mark CrockerAbstract:Pt represents an effective promoter of supported Ni catalysts in the transformation of tristearin to green diesel via decarbonylation/Decarboxylation (deCOx), conversion increasing from 2% over 20% Ni/Al2O3 to 100% over 20% Ni-0.5% Pt/Al2O3 at 260 °C. Catalyst characterization reveals that the superior activity of Ni-Pt relative to Ni-only catalysts is not a result of Ni particle size effects or surface area differences, but rather stems from several other phenomena, including the improved reducibility of NiO when Pt is present. Indeed, the addition of a small amount of Pt to the supported Ni catalyst dramatically increases the amount of reduced surface metal sites, which are believed to be the active sites for deCOx reactions. Further, Pt addition curbs the adsorption of CO on the catalyst surface, which decreases catalyst poisoning by any CO evolved via decarbonylation, making additional active sites available for deoxygenation reactions and/or preventing catalyst coking. Specifically, Pt addition weakens the Ni-CO bond, lowering the binding strength of CO on surface Ni sites. Finally, analysis of the spent catalysts recovered from deCOx experiments confirms that the beneficial effect of Pt on catalyst performance can be partially explained by decreased coking and fouling.
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catalytic deoxygenation of fatty acids and their derivatives to hydrocarbon fuels via Decarboxylation decarbonylation
Journal of Chemical Technology & Biotechnology, 2012Co-Authors: Eduardo Santillanjimenez, Mark CrockerAbstract:Fatty acids and their derivatives can be converted to renewable and carbon-neutral fuel-like hydrocarbons that are entirely fungible with fossil fuels. Typically, these hydrocarbon-based biofuels are obtained through hydrotreating, a method which has the significant disadvantages of requiring problematic sulfided catalysts and high pressures of hydrogen. In recent years, Decarboxylation/decarbonylation has been proposed as an alternative method, as this approach has the advantages of permitting the use of simpler catalysts and requiring less hydrogen than hydrotreating. In this contribution, the deoxygenation of fatty acids and their derivatives to fuel-like hydrocarbons via Decarboxylation/decarbonylation is critically reviewed. The main aspects discussed include the influence of the feed, catalyst, reactor system and reaction conditions on the Decarboxylation/decarbonylation reaction, as well as the reaction mechanism and catalyst deactivation/regeneration. Copyright © 2012 Society of Chemical Industry
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Catalytic deoxygenation of fatty acids and their derivatives to hydrocarbon fuels via Decarboxylation/decarbonylation.
Journal of Chemical Technology & Biotechnology, 2012Co-Authors: Eduardo Santillan-jimenez, Mark CrockerAbstract:Fatty acids and their derivatives can be converted to renewable and carbon-neutral fuel-like hydrocarbons that are entirely fungible with fossil fuels. Typically, these hydrocarbon-based biofuels are obtained through hydrotreating, a method which has the significant disadvantages of requiring problematic sulfided catalysts and high pressures of hydrogen. In recent years, Decarboxylation/decarbonylation has been proposed as an alternative method, as this approach has the advantages of permitting the use of simpler catalysts and requiring less hydrogen than hydrotreating. In this contribution, the deoxygenation of fatty acids and their derivatives to fuel-like hydrocarbons via Decarboxylation/decarbonylation is critically reviewed. The main aspects discussed include the influence of the feed, catalyst, reactor system and reaction conditions on the Decarboxylation/decarbonylation reaction, as well as the reaction mechanism and catalyst deactivation/regeneration. Copyright © 2012 Society of Chemical Industry
Yoshihisa Watanabe - One of the best experts on this subject based on the ideXlab platform.
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Ruthenium complex catalyzed benzylation of arenes with benzyl formates; decarbonylation and Decarboxylation of alkyl formates
Tetrahedron Letters, 2001Co-Authors: Teruyuki Kondo, Yasushi Tsuji, Supawan Tantayanon, Yoshihisa WatanabeAbstract:Abstract Ru 3 (CO) 12 -(CH 3 ) 3 NO·2H 2 O showed high catalytic activity for the decarbonylation of alkyl formates to the corresponding alcohols at 150 – 200 °C under an argon atmosphere. Decarbonylation of β-phenetyl formate afforded β-phenetyl alcohol in 82 % yield. On the other hand, when decarbonylation of benzyl formate was performed in the absence of (CH 3 ) 3 NO·2H 2 O, benzylation of arenes, which were employed as a solvent, proceeded via catalytic Decarboxylation of benzyl formate. For the reaction of toluene with benzyl formate, phenyltolylmethane ( o -, m -, and p -mixture) was obtained in total 77 % yield.
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ruthenium complex catalyzed novel transformation of alkyl formates
Journal of Organometallic Chemistry, 1995Co-Authors: Teruyuki Kondo, Satoshi Kajiya, Supawan Tantayanon, Yoshihisa WatanabeAbstract:Abstract The following ruthenium-catalyzed novel transformations of alkyl formates have been developed: (1) selective decarbonylation of alkyl formates to the corresponding alcohols; (2) alkylation of arenes and alkenes using alkyl formates as an alkylating reagent via Decarboxylation. Also the ruthenium-catalyzed addition of alcohols to alkenes has been developed as an appendant reaction, providing an effective method for the protection of alcohols.
Andreas Heyden - One of the best experts on this subject based on the ideXlab platform.
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Theoretical investigation of the Decarboxylation and decarbonylation mechanism of propanoic acid over a Ru(0 0 0 1) model surface
Journal of Catalysis, 2015Co-Authors: Jianmin Lu, Sina Behtash, Muhammad Faheem, Andreas HeydenAbstract:Abstract The hydrodeoxygenation of organic acids is often found to be a rate-controlling process during upgrading of biomass feedstocks into fuels. We developed a microkinetic model based on data obtained from density functional theory calculations for the Decarboxylation and decarbonylation mechanisms of propanoic acid (CH 3 CH 2 COOH) over a Ru(0 0 0 1) model surface. The model predicts that the decarbonylation mechanism is two orders of magnitude faster than the Decarboxylation mechanism. The most favorable decarbonylation pathway proceeds via removal of the acid –OH group to produce propanoyl (CH 3 CH 2 CO) followed by C–CO bond scission of propanoyl to produce CH 3 CH 2 and CO. Finally, CH 3 CH 2 is hydrogenated to CH 3 CH 3 . Dehydrogenation reactions that have been observed to be important over Pd catalysts play no role over Ru(0 0 0 1), and a sensitivity analysis indicates that removal of the acid –OH group is the rate-controlling step in the deoxygenation. Overall, our results suggest that to improve the Ru catalyst performance for the decarbonylation of organic acids, the free site coverage needs to be increased by, for example, adding a catalyst promoter that decreases the hydrogen and CO adsorption strength (without significantly affecting the C–OH bond scission rate), or by raising the reaction temperature and operating at relatively low CO and H 2 partial pressures.
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solvent effects on the hydrodeoxygenation of propanoic acid over pd 111 model surfaces
Green Chemistry, 2014Co-Authors: Sina Behtash, Muhammad Faheem, Andreas HeydenAbstract:The effects of liquid water, n-octane, and n-butanol on the hydrodeoxygenation of propanoic acid over Pd(111) model surfaces have been studied from first principles. We developed a microkinetic model for the hydrodeoxygenation and studied the reaction mechanism at a temperature of 473 K. Our model predicts that for all reaction media, decarbonylation pathways are favored over Decarboxylation pathways. However, in the presence of polar solvents like water, Decarboxylation routes become competitive with decarbonylation routes. The activity of the Pd surface varies as a function of the environment as follows: water > n-butanol > octane ≈ gas phase. Finally, a sensitivity analysis of our models suggests that both C–OH and C–H bond cleavages control the overall rate of the catalyst in all environments and are likely to be activity descriptors for the hydrodeoxygenation of organic acids.
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microkinetic modeling of the Decarboxylation and decarbonylation of propanoic acid over pd 111 model surfaces based on parameters obtained from first principles
Journal of Catalysis, 2013Co-Authors: Jianmin Lu, Sina Behtash, Muhammad Faheem, Andreas HeydenAbstract:We have studied the reaction mechanism of deoxygenation of propanoic acid to alkanes over Pd(1 1 1) model surfaces by a combination of microkinetic modeling and density functional theory calculations. Approximate, coverage-dependent adsorption energies of CO and H have been implemented in a microkinetic model that shows that the decarbonylation mechanism is slightly preferred over the Decarboxylation mechanism at various H2 partial pressures. The most significant decarbonylation pathway proceeds via dehydrogenation of the acid to yield CH3CHCOOH which illustrates the important role of α-carbon dehydrogenation steps, followed by dehydroxylation to yield CH3CHCO which further dehydrogenates to CHCHCO. Finally, facile C–CO bond scission occurs to yield CO and acetylene which gets hydrogenated to ethane. Overall, the dehydroxylation of CH3CHCOOH and to a lower degree the removal of the hydrocarbon pool from the surface and the dehydrogenation of the α-carbon of the reactant are found to be the rate-controlling steps.
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Theoretical Investigation of the Reaction Mechanism of the Decarboxylation and Decarbonylation of Propanoic Acid on Pd(111) Model Surfaces
Journal of Physical Chemistry C, 2012Co-Authors: Jianmin Lu, Sina Behtash, Andreas HeydenAbstract:Conversion of biomass into fuels or chemicals often requires a processing step limited by hydrodeoxygenation of organic acids. Various pathways have been proposed for the deoxygenation of these acids into hydrocarbons, with the Decarboxylation and decarbonylation requiring less hydrogen than the reductive deoxygenation without C–C bond cleavage. In this paper, we present the reaction mechanism for the Decarboxylation and decarbonylation of propanoic acid over Pd(111) model surfaces determined by first-principles electronic structure calculations based on density functional theory. Our calculations suggest that the most significant decarbonylation pathways proceed via a dehydroxylation of the acid to produce propanoyl (CH3CH2CO) followed by either full α-carbon dehydrogenation and CH3C–CO bond scission to produce CH3C and CO, or first α-carbon dehydrogenation followed by β-carbon dehydrogenation and CH2CH–CO bond scission to produce CH2CH and CO. The Decarboxylation mechanism starts with O–H bond cleavage ...
Johannes H. Bitter - One of the best experts on this subject based on the ideXlab platform.
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deoxygenation of biobased molecules by Decarboxylation and decarbonylation a review on the role of heterogeneous homogeneous and bio catalysis
Green Chemistry, 2015Co-Authors: Gwen J S Dawes, Jérôme Le Nôtre, Elinor L Scott, Johan P M Sanders, Johannes H. BitterAbstract:Use of biomass is crucial for a sustainable supply of chemicals and fuels for future generations. Compared to fossil feedstocks, biomass is more functionalized and requires defunctionalisation to make it suitable for use. Deoxygenation is an important method of defunctionalisation. While thermal deoxygenation is possible, high energy input and lower reaction selectivity makes it less suitable for producing the desired chemicals and fuels. Catalytic deoxygenation is more successful by lowering the activation energy of the reaction, and when designed correctly, is more selective. Catalytic deoxygenation can be performed in various ways. Here we focus on Decarboxylation and decarbonylation. There are several classes of catalysts: heterogeneous, homogeneous, bio- and organocatalysts and all have limitations. Homogeneous catalysts generally have superior selectivity and specificity but separation from the reaction is cumbersome. Heterogeneous catalysts are more readily isolated and can be utilised at high temperatures, however they have lower selectivity in complex reaction mixtures. While bio-catalysts can operate at ambient temperatures, the volumetric productivity is lower. Therefore it is not always apparent in advance which catalyst is the most suitable in terms of conversion and selectivity under optimal process conditions. Here we compare classes of catalysts for the Decarboxylation and decarbonylation of biobased molecules and discuss their limitations and advantages. We mainly focus on the activity of the catalysts and find there is a strong correlation between specific activity (turn over frequency) and temperature for metal based catalysts (homogeneous or heterogeneous). Thus one is not more active than the other at the same temperature. Alternatively, enzymes have a higher turnover frequency but drawbacks (low volumetric productivity) should be overcome.
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Deoxygenation of biobased molecules by Decarboxylation and decarbonylation – a review on the role of heterogeneous, homogeneous and bio-catalysis
Green Chemistry, 2015Co-Authors: Gwen J S Dawes, Jérôme Le Nôtre, Elinor L Scott, Johan P M Sanders, Johannes H. BitterAbstract:Use of biomass is crucial for a sustainable supply of chemicals and fuels for future generations. Compared to fossil feedstocks, biomass is more functionalized and requires defunctionalisation to make it suitable for use. Deoxygenation is an important method of defunctionalisation. While thermal deoxygenation is possible, high energy input and lower reaction selectivity makes it less suitable for producing the desired chemicals and fuels. Catalytic deoxygenation is more successful by lowering the activation energy of the reaction, and when designed correctly, is more selective. Catalytic deoxygenation can be performed in various ways. Here we focus on Decarboxylation and decarbonylation. There are several classes of catalysts: heterogeneous, homogeneous, bio- and organocatalysts and all have limitations. Homogeneous catalysts generally have superior selectivity and specificity but separation from the reaction is cumbersome. Heterogeneous catalysts are more readily isolated and can be utilised at high temperatures, however they have lower selectivity in complex reaction mixtures. While bio-catalysts can operate at ambient temperatures, the volumetric productivity is lower. Therefore it is not always apparent in advance which catalyst is the most suitable in terms of conversion and selectivity under optimal process conditions. Here we compare classes of catalysts for the Decarboxylation and decarbonylation of biobased molecules and discuss their limitations and advantages. We mainly focus on the activity of the catalysts and find there is a strong correlation between specific activity (turn over frequency) and temperature for metal based catalysts (homogeneous or heterogeneous). Thus one is not more active than the other at the same temperature. Alternatively, enzymes have a higher turnover frequency but drawbacks (low volumetric productivity) should be overcome.
Teruyuki Kondo - One of the best experts on this subject based on the ideXlab platform.
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Ruthenium complex catalyzed benzylation of arenes with benzyl formates; decarbonylation and Decarboxylation of alkyl formates
Tetrahedron Letters, 2001Co-Authors: Teruyuki Kondo, Yasushi Tsuji, Supawan Tantayanon, Yoshihisa WatanabeAbstract:Abstract Ru 3 (CO) 12 -(CH 3 ) 3 NO·2H 2 O showed high catalytic activity for the decarbonylation of alkyl formates to the corresponding alcohols at 150 – 200 °C under an argon atmosphere. Decarbonylation of β-phenetyl formate afforded β-phenetyl alcohol in 82 % yield. On the other hand, when decarbonylation of benzyl formate was performed in the absence of (CH 3 ) 3 NO·2H 2 O, benzylation of arenes, which were employed as a solvent, proceeded via catalytic Decarboxylation of benzyl formate. For the reaction of toluene with benzyl formate, phenyltolylmethane ( o -, m -, and p -mixture) was obtained in total 77 % yield.
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ruthenium complex catalyzed novel transformation of alkyl formates
Journal of Organometallic Chemistry, 1995Co-Authors: Teruyuki Kondo, Satoshi Kajiya, Supawan Tantayanon, Yoshihisa WatanabeAbstract:Abstract The following ruthenium-catalyzed novel transformations of alkyl formates have been developed: (1) selective decarbonylation of alkyl formates to the corresponding alcohols; (2) alkylation of arenes and alkenes using alkyl formates as an alkylating reagent via Decarboxylation. Also the ruthenium-catalyzed addition of alcohols to alkenes has been developed as an appendant reaction, providing an effective method for the protection of alcohols.
