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Johannes A. Lercher - One of the best experts on this subject based on the ideXlab platform.
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controlling Hydrodeoxygenation of stearic acid to n heptadecane and n octadecane by adjusting the chemical properties of ni sio2 zro2 catalyst
Chemcatchem, 2017Co-Authors: Sebastian Foraita, Johannes A. Lercher, Yue Liu, Gary L Haller, Eszter Barath, Chen ZhaoAbstract:A series of SiO2-ZrO2 mixed oxide with varying SiO2 concentrations was 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 via hydrogenation and decarbonylation. The SiO2-ZrO2 mixed oxides have a higher specific surface area as well as a novel spherical and nano-layer shaped morphology. Bronsted acid sites are created by incorporation of SiO2 into ZrO2 promoting the Hydrodeoxygenation activity of Ni and specifically opening a new reaction route to n-octadecane via the dehydration of 1 octadecanol intermediate into 1-octadecene with subsequent hydrogenation.
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Deoxygenation of Palmitic Acid on Unsupported Transition-Metal Phosphides
2017Co-Authors: Marco Peroni, Insu Lee, Xiaoyang Huang, Eszter Baráth, Oliver Y. Gutiérrez, Johannes A. LercherAbstract:Highly active bulk transition-metal phosphides (WP, MoP, and Ni2P) were synthesized for the catalytic Hydrodeoxygenation of palmitic acid, hexadecanol, hexadecanal, and microalgae oil. The specific activities positively correlated with the concentration of exposed metal sites, although the relative rates changed with temperature due to activation energies varying from 57 kJ mol–1 for MoP to 142 kJ mol–1 for WP. The reduction of the fatty acid to the aldehyde occurs through a Langmuir–Hinshelwood mechanism, where the rate-determining step is the addition of the second H to the hydrocarbon. On WP, the conversion of palmitic acid proceeds via R-CH2COOH → R-CH2CHO → R-CH2CH2OH → R-CHCH2 → R-CH2CH3 (Hydrodeoxygenation). Decarbonylation of the intermediate aldehyde (R-CH2COOH → R-CH2CHO → R-CH3) was an important pathway on MoP and Ni2P. Conversion via dehydration to a ketene, followed by its decarbonylation, occurred only on Ni2P. The rates of alcohol dehydration (R-CH2CH2OH → R-CHCH2) correlate with the concentrations of Lewis acid sites of the phosphides
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synergistic effects of ni and acid sites for hydrogenation and c o bond cleavage of substituted phenols
Green Chemistry, 2015Co-Authors: Wenji Song, Johannes A. Lercher, Eszter Barath, Chen Zhao, Yuanshuai LiuAbstract:The cleavage of C–O bonds in phenol, catechol, and guaiacol has been explored with mono- and dual-functional catalysts containing Ni and/or HZSM-5 in the aqueous phase. The aromatic ring of phenol is hydrogenated in the first step, and the C–O bond of the resulting cyclohexanol is dehydrated in sequence. The initial turnover frequency (TOF) of phenol Hydrodeoxygenation increases in parallel with the acid site concentration irrespective of the concentration of the accessible surface Ni atoms. For catechol and guaiacol conversion, Ni catalyzes the hydrogenolysis of the C–O bonds in addition to arene hydrogenation. For catechol, the hydrogenation of the aromatic ring and the hydrogenolysis of the phenolic –OH group occur in parallel with a ratio of 8:1. The saturated cyclohexane-1,2-diol can be further dehydrated over HZSM-5 or hydrogenolyzed on Ni to complete Hydrodeoxygenation. Guaiacol undergoes primarily hydrogenolysis (75%) to phenol via demethoxylation, and the hydrogenation route accounts for only 25%. This is attributed to the steric effects arising from the adjacent sp3 hybrid O–CH3 group. 2-Methoxycyclohexanol (from guaiacol hydrogenation) reacts further either via hydrogenolysis by Ni to cyclohexanol or via acid catalyzed demethoxylation and rearrangement steps followed by the subsequent hydrogenation of the intermediately formed olefins. On Ni/HZSM-5, the Hydrodeoxygenation activities are much higher for the phenolic monomers than for their respective saturated analogues, pointing to the importance of sp2 orbitals. The presence of proximal acid sites increases the activities of Ni in the presence of H2 by a synergistic action.
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Importance of Size and Distribution of Ni Nanoparticles for the Hydrodeoxygenation of Microalgae Oil
Chemistry (Weinheim an der Bergstrasse Germany), 2013Co-Authors: Wenji Song, Chen Zhao, Johannes A. LercherAbstract:Improved synthetic approaches for preparing small-sized Ni nanoparticles (d=3nm) supported on HBEA zeolite have been explored and compared with the traditional impregnation method. The formation of surface nickel silicate/aluminate involved in the two precipitation processes are inferred to lead to the stronger interaction between the metal and the support. The lower BrOnsted acid concentrations of these two Ni/HBEA catalysts compared with the parent zeolite caused by the partial exchange of BrOnsted acid sites by Ni2+ cations do not influence the Hydrodeoxygenation rates, but alter the product selectivity. Higher initial rates and higher stability have been achieved with these optimized catalysts for the Hydrodeoxygenation of stearic acid and microalgae oil. Small metal particles facilitate high initial catalytic activity in the fresh sample and size uniformity ensures high catalyst stability.
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comparison of kinetics activity and stability of ni hzsm 5 and ni al2o3 hzsm 5 for phenol Hydrodeoxygenation
Journal of Catalysis, 2012Co-Authors: Chen Zhao, Stanislav Kasakov, Johannes A. LercherAbstract:Abstract We have investigated the detailed kinetics of phenol Hydrodeoxygenation in liquid aqueous medium over Ni supported on HZSM-5 or HZSM-5 with 19.3 wt.% γ-Al2O3 binder. The individual reaction steps on two Ni catalysts followed the rate order r1 (phenol hydrogenation)
George W Huber - One of the best experts on this subject based on the ideXlab platform.
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supercritical methanol depolymerization and Hydrodeoxygenationof maple wood and biomass derived oxygenates into renewable alcoholsin a continuous flow reactor
ACS Sustainable Chemistry & Engineering, 2019Co-Authors: Peter H Galebach, Ashley M Wittrig, Jimmy K Soeherman, Michael P Lanci, George W HuberAbstract:Supercritical methanol depolymerization and Hydrodeoxygenation (SCM-DHDO) of biomass is a technology to produce C2–C9 alcohols in a single reaction step. Previous research has shown that this techn...
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production of alcohols from cellulose by supercritical methanol depolymerization and Hydrodeoxygenation
ACS Sustainable Chemistry & Engineering, 2018Co-Authors: Peter H Galebach, Daniel J Mcclelland, Nathaniel M Eagan, Ashley M Wittrig, Scott J Buchanan, James A Dumesic, George W HuberAbstract:The reaction pathway and products of cellulose supercritical methanol depolymerization and Hydrodeoxygenation (SCM-DHDO) were investigated. Monoalcohols, diols, alcohol ethers, and methyl esters we...
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Hydrodeoxygenation of sorbitol to monofunctional fuel precursors over co tio2
Joule, 2017Co-Authors: Nathaniel M Eagan, Ashley M Wittrig, Scott J Buchanan, James A Dumesic, Joseph P Chada, George W HuberAbstract:Summary Hydrodeoxygenation of sugar alcohols can be tuned to produce monofunctional oxygenates for use as jet or diesel fuel precursors. However, the catalysts typically utilize precious metals and are not highly selective. Here, the Hydrodeoxygenation of aqueous sorbitol was studied over a Co/TiO 2 catalyst to produce monofunctionals at a 56 C% yield. The majority of these species are alcohols (69%) or heterocycles (23%) while ketones and aldehydes are readily hydrogenated. 67% of the monofunctionals are C 5 -C 6 . Fourier transform ion cyclotron resonance mass spectrometry provided evidence for the coupling of C 3 and C 6 oxygenates to C 9+ oligomeric species, which likely fragment and deoxygenate to form C 1 -C 6 monofunctionals and gases. Co/TiO 2 deactivation occurred irreversibly due to sintering and leaching promoted by oxygenated species. Our results suggest that low-cost base metal catalysts can be as effective as many precious metal catalysts for monofunctional production from sorbitol toward heavy fuels if catalyst deactivation issues can be overcome.
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aqueous phase Hydrodeoxygenation of sorbitol with pt sio2 al2o3 identification of reaction intermediates
Journal of Catalysis, 2010Co-Authors: Ning Li, George W HuberAbstract:Aqueous-phase Hydrodeoxygenation of sugar and sugar-derived molecules can be used to produce a range of alkanes and oxygenates. In this paper, we have identified the reaction intermediates and reaction chemistry for the aqueous-phase Hydrodeoxygenation of sorbitol over a bifunctional catalyst (Pt/SiO2–Al2O3) that contains both metal (Pt) and acid (SiO2–Al2O3) sites. A wide variety of reactions occur in this process including CC bond cleavage, CO bond cleavage, and hydrogenation reactions. The key CC bond cleavage reactions include: retro-aldol condensation and decarbonylation, which both occur on metal catalytic sites. Dehydration is the key CO bond cleavage reaction and occurs on acid catalytic sites. Sorbitol initially undergoes dehydration and ring closure to produce cyclic C6 molecules or retro-aldol condensation reactions to produce primarily C3 polyols. Isosorbide is the major final product from sorbitol dehydration. Isosorbide then undergoes ring opening hydrogenation reactions and a dehydration/hydrogenation step to form 1,2,6-hexanetriol. The hexanetriol is then converted into hexanol and hexane by dehydration/hydrogenation. Smaller oxygenates are produced by CC bond cleavage. These smaller oxygenates undergo dehydration/hydrogenation reactions to produce alkanes from C1–C5. The results from this paper suggest that Hydrodeoxygenation chemistry can be tuned to make a wide variety of products from biomass-derived oxygenates.
Chen Zhao - One of the best experts on this subject based on the ideXlab platform.
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controlling Hydrodeoxygenation of stearic acid to n heptadecane and n octadecane by adjusting the chemical properties of ni sio2 zro2 catalyst
Chemcatchem, 2017Co-Authors: Sebastian Foraita, Johannes A. Lercher, Yue Liu, Gary L Haller, Eszter Barath, Chen ZhaoAbstract:A series of SiO2-ZrO2 mixed oxide with varying SiO2 concentrations was 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 via hydrogenation and decarbonylation. The SiO2-ZrO2 mixed oxides have a higher specific surface area as well as a novel spherical and nano-layer shaped morphology. Bronsted acid sites are created by incorporation of SiO2 into ZrO2 promoting the Hydrodeoxygenation activity of Ni and specifically opening a new reaction route to n-octadecane via the dehydration of 1 octadecanol intermediate into 1-octadecene with subsequent hydrogenation.
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synergistic effects of ni and acid sites for hydrogenation and c o bond cleavage of substituted phenols
Green Chemistry, 2015Co-Authors: Wenji Song, Johannes A. Lercher, Eszter Barath, Chen Zhao, Yuanshuai LiuAbstract:The cleavage of C–O bonds in phenol, catechol, and guaiacol has been explored with mono- and dual-functional catalysts containing Ni and/or HZSM-5 in the aqueous phase. The aromatic ring of phenol is hydrogenated in the first step, and the C–O bond of the resulting cyclohexanol is dehydrated in sequence. The initial turnover frequency (TOF) of phenol Hydrodeoxygenation increases in parallel with the acid site concentration irrespective of the concentration of the accessible surface Ni atoms. For catechol and guaiacol conversion, Ni catalyzes the hydrogenolysis of the C–O bonds in addition to arene hydrogenation. For catechol, the hydrogenation of the aromatic ring and the hydrogenolysis of the phenolic –OH group occur in parallel with a ratio of 8:1. The saturated cyclohexane-1,2-diol can be further dehydrated over HZSM-5 or hydrogenolyzed on Ni to complete Hydrodeoxygenation. Guaiacol undergoes primarily hydrogenolysis (75%) to phenol via demethoxylation, and the hydrogenation route accounts for only 25%. This is attributed to the steric effects arising from the adjacent sp3 hybrid O–CH3 group. 2-Methoxycyclohexanol (from guaiacol hydrogenation) reacts further either via hydrogenolysis by Ni to cyclohexanol or via acid catalyzed demethoxylation and rearrangement steps followed by the subsequent hydrogenation of the intermediately formed olefins. On Ni/HZSM-5, the Hydrodeoxygenation activities are much higher for the phenolic monomers than for their respective saturated analogues, pointing to the importance of sp2 orbitals. The presence of proximal acid sites increases the activities of Ni in the presence of H2 by a synergistic action.
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Importance of Size and Distribution of Ni Nanoparticles for the Hydrodeoxygenation of Microalgae Oil
Chemistry (Weinheim an der Bergstrasse Germany), 2013Co-Authors: Wenji Song, Chen Zhao, Johannes A. LercherAbstract:Improved synthetic approaches for preparing small-sized Ni nanoparticles (d=3nm) supported on HBEA zeolite have been explored and compared with the traditional impregnation method. The formation of surface nickel silicate/aluminate involved in the two precipitation processes are inferred to lead to the stronger interaction between the metal and the support. The lower BrOnsted acid concentrations of these two Ni/HBEA catalysts compared with the parent zeolite caused by the partial exchange of BrOnsted acid sites by Ni2+ cations do not influence the Hydrodeoxygenation rates, but alter the product selectivity. Higher initial rates and higher stability have been achieved with these optimized catalysts for the Hydrodeoxygenation of stearic acid and microalgae oil. Small metal particles facilitate high initial catalytic activity in the fresh sample and size uniformity ensures high catalyst stability.
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comparison of kinetics activity and stability of ni hzsm 5 and ni al2o3 hzsm 5 for phenol Hydrodeoxygenation
Journal of Catalysis, 2012Co-Authors: Chen Zhao, Stanislav Kasakov, Johannes A. LercherAbstract:Abstract We have investigated the detailed kinetics of phenol Hydrodeoxygenation in liquid aqueous medium over Ni supported on HZSM-5 or HZSM-5 with 19.3 wt.% γ-Al2O3 binder. The individual reaction steps on two Ni catalysts followed the rate order r1 (phenol hydrogenation)
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Aqueous-phase Hydrodeoxygenation of bio-derived phenols to cycloalkanes
Journal of Catalysis, 2011Co-Authors: Chen Zhao, Angeliki A Lemonidou, Johannes A. LercherAbstract:The kinetics of the catalytic Hydrodeoxygenation of phenol and substituted phenols has systematically been investigated on the dual-functional catalyst system Pd/C and H(3)PO(4) in order to better understand the elementary steps of the overall reaction. The reaction proceeds via stepwise hydrogenation of the aromatic ring, transformation of the cyclic enol to the corresponding ketone, hydrogenation of the cycloalkanone to the cycloalkanol and its subsequent dehydration as well as the hydrogenation of the formed cycloalkene. The presence of dual catalytic functions is indispensible for the overall Hydrodeoxygenation. The dehydration reaction is significantly slower than the hydrogenation reaction and the keto/enol transformation, requiring a significantly larger concentration of Bronsted acid sites compared to the available metal sites for hydrogenation. (C) 2011 Published by Elsevier Inc.
Yushuai Sang - One of the best experts on this subject based on the ideXlab platform.
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catalytic conversion of enzymatic hydrolysis lignin into cycloalkanes over a gamma alumina supported nickel molybdenum alloy catalyst
Bioresource Technology, 2021Co-Authors: Qingfeng Liu, Yunfei Bai, Hong Chen, Mengmeng Chen, Yushuai SangAbstract:Abstract The efficient depolymerization and Hydrodeoxygenation of enzymatic hydrolysis lignin are achieved in cyclohexane solvents over a gamma-alumina supported nickel molybdenum alloy catalyst in a single step. Under initial 3 MPa hydrogen at 320 °C, the highest overall cycloalkane yield of 104.4 mg/g enzymatic hydrolysis lignin with 44.4 wt% selectivity of ethyl-cyclohexane was obtained. The reaction atmosphere and temperature have significant effects on enzymatic hydrolysis lignin conversion, product type and distribution. The conversion of enzymatic hydrolysis lignin was also investigated over different nickel and molybdenum-based catalysts, and the gamma-alumina supported nickel molybdenum alloy catalyst exhibited the highest activity among those catalysts. To reveal the reaction pathways of alkylphenol Hydrodeoxygenation, 4-ethylphenol was tested as a model compound. Complete conversion of 4-ethylphenol into cycloalkanes was achieved. A two-step mechanism of 4-ethylphenol dihydroxylation – hydrogenation is proposed, in which the benzene ring saturation is deemed as the rate-determining step.
Martin Schmal - One of the best experts on this subject based on the ideXlab platform.
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influence of acid sites on the Hydrodeoxygenation of anisole with metal supported on sba 15 and sapo 11
Renewable Energy, 2018Co-Authors: Thiago L R Hewer, Adriana Galdino Figueira De Souza, Karina Tamiao De Campos Roseno, Paulo F Moreira, Rodrigo De Paiva Floro Bonfim, Rita M B Alves, Martin SchmalAbstract:Abstract Nickel and molybdenum nanoparticles were prepared on silicon aluminum phosphate (SAPO-11) and mesoporous silica (SBA-15), respectively, and compared with γ-Al2O3 support. Results showed that the nickel and molybdenum nanoparticles were located inside the pores of the SBA-15 structure with particles sizes around 7 nm. However, for the SAPO-11 support the nanoparticles are dispersed outside the support surface. These catalysts were tested for Hydrodeoxygenation (HDO) and exhibited excellent catalytic activity. The catalytic reaction had been carried out in a fixed bed flow reactor at 200–300 °C. It is noteworthy that the Turnover Frequencies (TOF) obtained for of NiMoSAPO was 2 times greater than NiMoSBA-15 catalyst. The products formed on NiMoSAPO and NiMoSBA were completely different from the NiMoAl2O3 catalyst used as reference. IR of Pyridine suggested that the Hydrodeoxygenation and hydrodearomatization reaction is strongly affected by the support nature, specifically, due to the relation between Bronsted and Lewis acid sites present at the surface of these materials. The low surface area, dispersion of the metallic sites and the proportion of Lewis/Bronsted acid sites have had strong influence on the selectivity of the Hydrodeoxygenation reaction.
