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Kiyotaka Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Effective Strategy for High-Yield Furan Dicarboxylate Production for Biobased Polyester Applications
2019Co-Authors: Minjune Kim, Atsushi Fukuoka, Emiel J M Hensen, Takayuki Aoshima, Kiyotaka NakajimaAbstract:A unique strategy for the formation of furan-2,5-dicarboxylic acid (FDCA)-derived esters with methanol and ethylene glycol in concentrated solutions was reported using a six-membered ring acetal of (5-hydroxymethyl)furfural (HMF) with 1,3-propanediol in order to improve the economics for the production of polyethylene 2,5-furandicarboxylate (PEF), a biobased polyester. Aerobic oxidative esterification with methanol and ethylene glycol in the presence of a CeO2-supported Au Catalyst gave 80–95% yields of methyl furan-2,5-dicarboxylate and bis(2-hydroxyethyl)furan-2,5-dicarboxylate from concentrated HMF-acetal solutions (10–20 wt %). Kinetic studies combined with density functional theory (DFT) calculations were used to identify two key steps for the conversion of the cyclic acetal ring to the corresponding methyl ester: (i) partial hydrolysis of the acetal ring by OH– ions and (ii) subsequent oxidation of the hemiacetal in solution by molecular O2 on Au nanoparticles. These results represent a significant contribution not only to cutting-edge conversion technology for renewable biomass feedstocks to PEF-based applications but also to opportunities for the efficient conversion of substrates with a reactive formyl group in high yield
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aerobic oxidation of hmf cyclic acetal enables selective fdca formation with ceo2 supported Au Catalyst
Angewandte Chemie, 2018Co-Authors: Minjune Kim, Atsushi Fukuoka, Emiel J M Hensen, Kiyotaka NakajimaAbstract:The utilization of 5‐(hydroxymethyl)furfural (HMF) for the large‐scale production of essential chemicals has been largely limited by the formation of solid humin as a by‐product, which prevents continuous operation of step‐wise batch‐type processes and continuous flow‐type processes. The reaction of HMF with 1,3‐propanediol produces an HMF‐acetal derivative that exhibits excellent thermal stability. Aerobic oxidation of the HMF‐acetal with a CeO2‐supported Au Catalyst and Na2CO3 in water gives a 90‐95% yield toward furan 2,5‐dicarboxylic acid, an increasingly important commodity chemical for the biorenewables industry, from concentrated HMF‐acetal solutions (10‐20 wt%) without humin formation. The stability of the six‐membered acetal ring suppresses thermal decomposition and self‐polymerization of HMF in concentrated solutions. Kinetic studies supported by density functional theory calculations identify two crucial steps in the reaction mechanism, i.e., the partial hydrolysis of the acetal into 5‐formyl‐2‐furan carboxylic acid involving OH‐ and Lewis acid sites on CeO2, and subsequent oxidative dehydrogenation of the in situ generated hemiacetal involving Au nanoparticles. The present results represent a significant advance over the current state of the art, overcoming an inherent limitation of the oxidation of HMF to an important monomer for biopolymer production.
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aerobic oxidation of 5 hydroxymethyl furfural cyclic acetal enables selective furan 2 5 dicarboxylic acid formation with ceo2 supported gold Catalyst
Angewandte Chemie, 2018Co-Authors: Minjune Kim, Atsushi Fukuoka, Emiel J M Hensen, Kiyotaka NakajimaAbstract:The utilization of 5-(hydroxymethyl)furfural (HMF) for the large-scale production of essential chemicals has been largely limited by the formation of solid humin as a byproduct, which prevents the operation of stepwise batch-type and continuous flow-type processes. The reaction of HMF with 1,3-propanediol produces an HMF acetal derivative that exhibits excellent thermal stability. Aerobic oxidation of the HMF acetal with a CeO2-supported Au Catalyst and Na2CO3 in water gives a 90–95 % yield of furan 2,5-dicarboxylic acid, an increasingly important commodity chemical for the biorenewables industry, from concentrated solutions (10–20 wt %) without humin formation. The six-membered acetal ring suppresses thermal decomposition and self-polymerization of HMF in concentrated solutions. Kinetic studies supported by DFT calculations identify two crucial steps in the reaction mechanism, that is, the partial hydrolysis of the acetal into 5-formyl-2-furan carboxylic acid involving OH− and Lewis acid sites on CeO2, and subsequent oxidative dehydrogenation of the in situ generated hemiacetal involving Au nanoparticles. These results represent a significant advance over the current state of the art, overcoming an inherent limitation of the oxidation of HMF to an important monomer for biopolymer production.
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selective synthesis of carbon monoxide via formates in reverse water gas shift reaction over alumina supported gold Catalyst
Journal of Energy Chemistry, 2016Co-Authors: Nobuhiro Ishito, Kiyotaka Nakajima, Kenji Hara, Atsushi FukuokaAbstract:Thermal decomposition of formic acid on SiO 2 , CeO 2 and γ-Al 2 O 3 was studied as an elementary step of reverse water-gas shit reaction (RWGS) over supported Au Catalysts. γ-Al 2 O 3 showed the highest CO selectivity among the tested oxides in the decomposition of formic acid. Infrared spectroscopy showed the formation of four formate species on γ-Al 2 O 3 : three η 1 -type and one μ 2 -type species, and these formates decomposed to CO at 473 K or higher. Au-loaded γ-Al 2 O 3 samples were prepared by a deposition-precipitation method and used as Catalysts for RWGS. The supported Au Catalyst gave CO with high selectivity over 99% from CO 2 and H 2 , which is attributed to the formation of formates on Au and subsequent decomposition to CO on γ-Al 2 O 3 .
Atsushi Fukuoka - One of the best experts on this subject based on the ideXlab platform.
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Effective Strategy for High-Yield Furan Dicarboxylate Production for Biobased Polyester Applications
2019Co-Authors: Minjune Kim, Atsushi Fukuoka, Emiel J M Hensen, Takayuki Aoshima, Kiyotaka NakajimaAbstract:A unique strategy for the formation of furan-2,5-dicarboxylic acid (FDCA)-derived esters with methanol and ethylene glycol in concentrated solutions was reported using a six-membered ring acetal of (5-hydroxymethyl)furfural (HMF) with 1,3-propanediol in order to improve the economics for the production of polyethylene 2,5-furandicarboxylate (PEF), a biobased polyester. Aerobic oxidative esterification with methanol and ethylene glycol in the presence of a CeO2-supported Au Catalyst gave 80–95% yields of methyl furan-2,5-dicarboxylate and bis(2-hydroxyethyl)furan-2,5-dicarboxylate from concentrated HMF-acetal solutions (10–20 wt %). Kinetic studies combined with density functional theory (DFT) calculations were used to identify two key steps for the conversion of the cyclic acetal ring to the corresponding methyl ester: (i) partial hydrolysis of the acetal ring by OH– ions and (ii) subsequent oxidation of the hemiacetal in solution by molecular O2 on Au nanoparticles. These results represent a significant contribution not only to cutting-edge conversion technology for renewable biomass feedstocks to PEF-based applications but also to opportunities for the efficient conversion of substrates with a reactive formyl group in high yield
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aerobic oxidation of hmf cyclic acetal enables selective fdca formation with ceo2 supported Au Catalyst
Angewandte Chemie, 2018Co-Authors: Minjune Kim, Atsushi Fukuoka, Emiel J M Hensen, Kiyotaka NakajimaAbstract:The utilization of 5‐(hydroxymethyl)furfural (HMF) for the large‐scale production of essential chemicals has been largely limited by the formation of solid humin as a by‐product, which prevents continuous operation of step‐wise batch‐type processes and continuous flow‐type processes. The reaction of HMF with 1,3‐propanediol produces an HMF‐acetal derivative that exhibits excellent thermal stability. Aerobic oxidation of the HMF‐acetal with a CeO2‐supported Au Catalyst and Na2CO3 in water gives a 90‐95% yield toward furan 2,5‐dicarboxylic acid, an increasingly important commodity chemical for the biorenewables industry, from concentrated HMF‐acetal solutions (10‐20 wt%) without humin formation. The stability of the six‐membered acetal ring suppresses thermal decomposition and self‐polymerization of HMF in concentrated solutions. Kinetic studies supported by density functional theory calculations identify two crucial steps in the reaction mechanism, i.e., the partial hydrolysis of the acetal into 5‐formyl‐2‐furan carboxylic acid involving OH‐ and Lewis acid sites on CeO2, and subsequent oxidative dehydrogenation of the in situ generated hemiacetal involving Au nanoparticles. The present results represent a significant advance over the current state of the art, overcoming an inherent limitation of the oxidation of HMF to an important monomer for biopolymer production.
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aerobic oxidation of 5 hydroxymethyl furfural cyclic acetal enables selective furan 2 5 dicarboxylic acid formation with ceo2 supported gold Catalyst
Angewandte Chemie, 2018Co-Authors: Minjune Kim, Atsushi Fukuoka, Emiel J M Hensen, Kiyotaka NakajimaAbstract:The utilization of 5-(hydroxymethyl)furfural (HMF) for the large-scale production of essential chemicals has been largely limited by the formation of solid humin as a byproduct, which prevents the operation of stepwise batch-type and continuous flow-type processes. The reaction of HMF with 1,3-propanediol produces an HMF acetal derivative that exhibits excellent thermal stability. Aerobic oxidation of the HMF acetal with a CeO2-supported Au Catalyst and Na2CO3 in water gives a 90–95 % yield of furan 2,5-dicarboxylic acid, an increasingly important commodity chemical for the biorenewables industry, from concentrated solutions (10–20 wt %) without humin formation. The six-membered acetal ring suppresses thermal decomposition and self-polymerization of HMF in concentrated solutions. Kinetic studies supported by DFT calculations identify two crucial steps in the reaction mechanism, that is, the partial hydrolysis of the acetal into 5-formyl-2-furan carboxylic acid involving OH− and Lewis acid sites on CeO2, and subsequent oxidative dehydrogenation of the in situ generated hemiacetal involving Au nanoparticles. These results represent a significant advance over the current state of the art, overcoming an inherent limitation of the oxidation of HMF to an important monomer for biopolymer production.
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selective synthesis of carbon monoxide via formates in reverse water gas shift reaction over alumina supported gold Catalyst
Journal of Energy Chemistry, 2016Co-Authors: Nobuhiro Ishito, Kiyotaka Nakajima, Kenji Hara, Atsushi FukuokaAbstract:Thermal decomposition of formic acid on SiO 2 , CeO 2 and γ-Al 2 O 3 was studied as an elementary step of reverse water-gas shit reaction (RWGS) over supported Au Catalysts. γ-Al 2 O 3 showed the highest CO selectivity among the tested oxides in the decomposition of formic acid. Infrared spectroscopy showed the formation of four formate species on γ-Al 2 O 3 : three η 1 -type and one μ 2 -type species, and these formates decomposed to CO at 473 K or higher. Au-loaded γ-Al 2 O 3 samples were prepared by a deposition-precipitation method and used as Catalysts for RWGS. The supported Au Catalyst gave CO with high selectivity over 99% from CO 2 and H 2 , which is attributed to the formation of formates on Au and subsequent decomposition to CO on γ-Al 2 O 3 .
Yasuhiro Iwasawa - One of the best experts on this subject based on the ideXlab platform.
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active oxygen species and mechanism for low temperature co oxidation reaction on a tio2 supported Au Catalyst prepared from Au pph3 no3 and as precipitated titanium hydroxide
Journal of Catalysis, 1999Co-Authors: Alexander I Kozlov, Anguelina P Kozlova, Takafumi Shido, Kiyotaka Asakura, Yasuhiro IwasawaAbstract:Abstract The active oxygen species and mechanism for catalytic CO oxidation with O 2 on a highly active TiO 2 -supported Au Catalyst (denoted as Au/Ti(OH) * 4 ), which was prepared by supporting a Au–phophine complex on as-precipitated wet titanium hydroxide followed by calcination at 673 K, have been studied by means of oxygen isotope exchange, O 2 temperature-programmed desorption (O 2 TPD), electron spin resonance (ESR), and Fourier-transformed infrared spectroscopy (FT-IR). Surface lattice oxygen atoms on the Au/Ti(OH) * 4 Catalyst were inactive for oxygen exchange with O 2 and CO and also for CO oxidation at room temperature. The surface lattice oxygen atoms were exchanged only with the oxygen atoms of CO 2 , probably via carbonates. O 2 did not dissociate to atomic oxygen on the Catalyst. The Catalyst showed a paramagnetic signal at g =2.002 due to unpaired electrons trapped at oxygen vacancies mainly at the surface. O 2 adsorbed on the oxygen vacancies to form superoxide O − 2 with g 1 =2.020, g 2 =2.010, and g 3 =2.005, which are characteristic of O − 2 with an angular arrangement. Upon CO exposure, all the adsorbed oxygen species disappeared. The adsorbed oxygen on Au/Ti(OH) * 4 desorbed below 550 K. O − 2 species were also observed on TiO * 2 prepared by calcination of as-precipitated wet titanium hydroxide at 673 K, but were unreactive with CO. FT-IR spectra revealed that CO reversibly adsorbed on both Au particles and Ti 4+ sites on the Au/Ti(OH) * 4 surface. No band for adsorbed CO was observed on the TiO * 2 , which indicates that the presence of Au particles has a profound effect on the surface state of Ti oxide. No shifts of ν CO peaks on Au/Ti(OH) * 4 occurred upon O 2 adsorption, suggesting that O 2 was not directly bound to the Au particles on which CO adsorbed. Annealing of Au/Ti(OH) * 4 under O 2 atmosphere significantly suppressed the O 2 adsorption and the CO oxidation due to a decrease in the amount of oxygen vacancies, while CO adsorption was not affected by annealing. From the systematic oxygen isotope exchange experiments along with O 2 -TPD, ESR, and FT-IR, it is most likely that CO adsorbed on Au metallic particles and O − 2 adsorbed on oxygen vacancies at the oxide surface adjacent to the Au particles contribute to the low-temperature catalytic CO oxidation. The mechanism for the catalytic CO oxidation on the active Au/Ti(OH) * 4 Catalyst is discussed in detail and compared with mechanisms reported previously.
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active oxygen species and reaction mechanism for low temperature co oxidation on an fe2o3 supported Au Catalyst prepared from Au pph3 no3 and as precipitated iron hydroxide
Physical Chemistry Chemical Physics, 1999Co-Authors: Haichao Liu, Alexander I Kozlov, Anguelina P Kozlova, Takafumi Shido, Yasuhiro IwasawaAbstract:Active oxygen species and the reaction mechanism for catalytic CO oxidation with O2 on a highly active Fe2O3-supported Au Catalyst (denoted as Au/Fe(OH)3*), which was prepared by supporting Au(PPh3)(NO3) on as-precipitated wet iron hydroxide followed by calcination at 673 K, have been studied by means of oxygen isotope exchange, O2-temperature programmed desorption (TPD) and FT-IR. Surface lattice oxygen atoms on the Au/Fe(OH)3* Catalyst were inactive for oxygen exchange with O2 and CO, and also for CO oxidation at room temperature. The surface lattice oxygen atoms were exchanged only with the oxygen atoms of CO2 probably via carbonates. There is no evidence that O2 dissociates to atomic oxygen on the Catalyst. TPD spectra following adsorption of 36O2 or a mixture of 32O2+36O2 showed no oxygen exchange, where the adsorbed oxygen on Au/Fe(OH)3* desorbed below 500 K. Upon CO exposure, all the adsorbed oxygen species disappeared. FT-IR spectra revealed that CO reversibly adsorbed on Au particles and irreversibly adsorbed on Fe3+ sites on the Au/Fe(OH)3* surface. Only CO molecules adsorbed on the Au particles were active for low-temperature CO oxidation. No band for adsorbed CO was observed on Fe2O3* prepared by calcination of the as-precipitated wet Fe(OH)3* at 673 K, which indicates that the presence of Au particles cAuses a profound effect on the surface state of Fe-oxide. Annealing of Au/Fe(OH)3* under an O2 atmosphere did not suppress the catalytic CO oxidation, unlike a remarkable suppression observed with Au/Ti(OH)4*. The presence of water vapor did not significantly decrease the CO oxidation rate due to the facile water gas shift reaction on Au/Fe(OH)3*, also unlike the case of Au/Ti(OH)4*. From the systematic oxygen isotope exchange experiments along with O2-TPD and FT-IR, it is most likely that CO adsorbed on Au metallic particles and O2 adsorbed on oxygen vacancies at the oxide surface adjacent to the Au particles contribute to the low-temperature catalytic CO oxidation on Au/Fe(OH)3*. The mechanism for the catalytic CO oxidation on the active Au/Fe(OH)3* Catalyst is discussed in detail and compared with those reported previously.
Xiuling Li - One of the best experts on this subject based on the ideXlab platform.
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Formation of high aspect ratio GaAs nanostructures with metal-assisted chemical etching
Nano Letters, 2011Co-Authors: Matt Dejarld, Winston Chern, Jae-cheol Shin, Karthik Balasundaram, John A Rogers, Debashis Chanda, Xiuling LiAbstract:Periodic high aspect ratio GaAs nanopillars with widths in the range of 500-1000 nm are produced by metal-assisted chemical etching (MacEtch) using n-type (100) GaAs substrates and Au Catalyst films patterned with soft lithography. Depending on the etchant concentration and etching temperature, GaAs nanowires with either vertical or undulating sidewalls are formed with an etch rate of 1-2 ?m/min. The realization of high aspect ratio III-V nanostructure arrays by wet etching can potentially transform the fabrication of a variety of optoelectronic device structures including distributed Bragg reflector (DBR) and distributed feedback (DFB) semiconductor lasers, where the surface grating is currently fabricated by dry etching.
Michael S Wong - One of the best experts on this subject based on the ideXlab platform.
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toward glucuronic acid through oxidation of methyl glucoside using pdAu Catalysts
Catalysis Communications, 2020Co-Authors: Ben Y Yin, Li Chen, Kimberly N Heck, Conrad Z Zhang, Michael S WongAbstract:Abstract The production of glucuronic acid via enzyme catalysis from biomass is slow. Here we studied the oxidation of methoxy-protected glucose (MG) using Pd-on-Au nanoparticle model Catalysts to generate methoxy-protected glucuronic acid (MGA), a precursor to glucuronic acid. Pd-on-Au showed volcano-shape activity dependence on calculated Pd surface coverage (sc). The 80 sc% Pd-on-Au Catalyst composition showed maximum initial turnover frequency (413 mol-MG mol-surface-atom−1 h−1) that was 5× higher than that of Au/C, while Pd/C was inactive. This Pd-on-Au composition gave the highest MGA yield (46%), supporting a bimetallic approach to glucuronic acid production.
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synergistic gold bismuth catalysis for non mercury hydrochlorination of acetylene to vinyl chloride monomer
ACS Catalysis, 2014Co-Authors: Kai Zhou, Michael S Wong, Wei Wang, Zhun Zhao, Guohua Luo, Jeffrey T Miller, Fei WeiAbstract:Gold has been proposed as an environmentally friendly Catalyst for acetylene hydrochlorination for vinyl chloride monomer synthesis by replacing the commercially used mercury Catalyst. However, long life with excellent activity is difficult to achieve becAuse gold is readily reduced to metallic nanoparticles. The stability of gold limits its industrial application. In this paper, we promoted gold with bismuth for the hydrochlorination of acetylene. It was found that the Bi promotion leads to partial reduction to AuCl, rather than the complete reduction of Au to metallic nanoparticles in the absence of Bi. The optimized Catalyst with a molar ratio of Bi/Au = 3:1 (0.3 wt % Au) showed comparable reactivity to 1.0 wt % Au Catalyst and significantly improved stability. Furthermore, the gold–bismuth Catalyst had higher activity and stability than the commercial mercury Catalyst, is less toxic and more environmental-friendly, making it a potentially green, mercury-free industrial Catalyst for acetylene hydrochlo...
