Publications by authors named "Yoshinao Nakagawa"

54 Publications

Adsorption of Keggin-Type Polyoxometalates on Rh Metal Particles under Reductive Conditions.

Inorg Chem 2021 Aug 29;60(16):12413-12424. Epub 2021 Jul 29.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.

The adsorption of POMs on Rh/SiO in water solvent under strongly reductive conditions was investigated. Aqueous solutions of α-Keggin type silicotungstate and silicovanadotungstates were mixed with Rh/SiO at 393-473 K under 1 MPa of H. Monovanadium-substituted silicotungstate, α-SiVWO (SiVW), was more readily adsorbed than nonsubstituted silicotungstate, α-SiWO (SiW). After adsorption at 433 K, SiVW was desorbed from Rh/SiO by oxidation with Br water without change of the Keggin structure, as evidenced by V NMR. Trivanadium-substituted silicotungstate, α-1,2,3-SiVWO, was not stable, and the desorbed species from Rh/SiO by oxidation with Br did not maintain the Keggin structure. The very high temperature for adsorption (473 K) also led to the decomposition of the Keggin structure of SiVW. An increase in the concentration of SiVW in the liquid phase gave a saturation of the amount of desorbable SiVW, up to five SiVW anions per one Rh particle with a 3 nm size. The elemental analysis and W L-edge extended X-ray absorption fine structure of Rh/SiO after the adsorption of SiVW showed that a part of SiVW was decomposed and irreversibly adsorbed as metallic W species incorporated into the surface of Rh metal particles. The amount of decomposed SiVW was almost the same as that of SiVW adsorbed as the original Keggin structure. The desorbable SiVW was probably bonded on the W atom incorporated on the Rh metal particles as the two-electron-reduced form (α-SiVWO).
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http://dx.doi.org/10.1021/acs.inorgchem.1c01644DOI Listing
August 2021

Selective Hydrogenolysis of Erythritol over Ir-ReO /Rutile-TiO Catalyst.

ChemSusChem 2021 Jan 4;14(2):642-654. Epub 2020 Nov 4.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07, Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

Partial hydrogenolysis of erythritol, which can be produced at large scale by fermentation, to 1,4-butanediol (1,4-BuD) is investigated with Ir-ReO /SiO and Ir-ReO /rutile-TiO catalysts. In addition to the higher conversion rate over Ir-ReO /TiO than over Ir-ReO /SiO , which has been also reported for glycerol hydrogenolysis, Ir-ReO /TiO showed higher selectivity to 1,4-BuD than Ir-ReO /SiO , especially at low conversion levels, leading to high 1,4-BuD productivity of 20 mmol  g  h at 373 K (36 % conversion, 33 % selectivity). The productivity based on the noble metal amount is higher than those reported previously, although the maximum yield of 1,4-BuD (23 %) is not higher than the highest reported values. The reactions of various triols, diols and mono-ols are tested and the selectivity and the reaction rates are compared between catalysts and between substrates. The Ir-ReO /TiO catalyst showed about twofold higher activity than Ir-ReO /SiO in hydrogenolysis of the C-OH bond at the 2- or 3-positions in 1,2- and 1,3-diols, respectively, whereas the hydrogenolysis of C-OH at the 1-position is less promoted by the TiO support. Lowering the loading amount of Ir on TiO (from 4 wt % to 2 or 1 wt %) decreases the Ir-based activity and 1,4-BuD selectivity. Similarly, increasing the loading amount on SiO from 4 wt % to 20 wt % increases the Ir-based activity and 1,4-BuD selectivity, although they remain lower than those for TiO -supported catalyst with 4 wt % Ir. High metal loadings on the support seem to be important.
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http://dx.doi.org/10.1002/cssc.202002357DOI Listing
January 2021

Erythritol: Another C4 Platform Chemical in Biomass Refinery.

ACS Omega 2020 Feb 5;5(6):2520-2530. Epub 2020 Feb 5.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.

The potential of erythritol as a platform chemical in biomass refinery is discussed in terms of erythritol production and utilization. Regarding erythritol production, fermentation of sugar or starch has been already commercialized. The shift of the carbon source from glucose to inexpensive inedible waste glycerol is being investigated, which will decrease the price of erythritol. The carbon-based yield of erythritol from glycerol is comparable to or even higher than that from glucose. The metabolic pathway of erythritol biosynthesis has become clarified: erythrose-4-phosphate, which is one of the intermediates in the pentose phosphate pathway, is dephosphorylated and reduced to erythritol. The information about the metabolic pathway may give insights to improve the productivity by bleeding. Regarding erythritol utilization, chemical conversions of erythritol, especially deoxygenation, have been investigated in these days. Erythritol is easily dehydrated to 1,4-anhydroerythritol, which can be also used as the substrate for production of useful C4 chemicals. C-O hydrogenolysis and deoxydehydration using heterogeneous catalysts are effective reactions for erythritol/1,4-anhydroerythritol conversion.
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http://dx.doi.org/10.1021/acsomega.9b04046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7033684PMC
February 2020

A nickel-iridium alloy as an efficient heterogeneous catalyst for hydrogenation of olefins.

Chem Commun (Camb) 2019 Aug;55(71):10519-10522

Department of Applied Chemistry, School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.

Nickel and iridium supported on SiO2 (Ni-Ir/SiO2) acted as an effective and reusable heterogeneous catalyst for hydrogenation of olefins, and it showed higher activity and selectivity than the monometallic counterparts. The Ni-Ir/SiO2 catalyst has small Ni-Ir alloy and monometallic Ni particles, and the high catalytic performance can be attributed to the isolated Ni atom in the Ni-Ir alloys.
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http://dx.doi.org/10.1039/c9cc04822gDOI Listing
August 2019

Preparation of Highly Active Monometallic Rhenium Catalysts for Selective Synthesis of 1,4-Butanediol from 1,4-Anhydroerythritol.

ChemSusChem 2019 Aug 2;12(15):3615-3626. Epub 2019 Jul 2.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

1,4-Butanediol can be produced from 1,4-anhydroerythritol through the co-catalysis of monometallic mixed catalysts (ReO /CeO +ReO /C) in the one-pot reduction with H . The highest yield of 1,4-butanediol was over 80 %, which is similar to the value obtained over ReO -Au/CeO +ReO /C catalysts. Mixed catalysts of CeO +ReO /C showed almost the same performance, giving 89 % yield of 1,4-butanediol. The reactivity trends of possible intermediates suggest that the reaction mechanism over ReO /CeO +ReO /C is similar to that over ReO -Au/CeO +ReO /C: deoxydehydration (DODH) of 1,4-anhydroerythritol to 2,5-dihydrofuran over ReO species on the CeO support with the promotion of H activation by ReO /C, isomerization of 2,5-dihydrofuran to 2,3-dihydrofuran catalyzed by ReO on the C support, hydration of 2,3-dihydrofuran catalyzed by C, and hydrogenation to 1,4-butanediol catalyzed by ReO /C. The reaction order of conversion of 1,4-anhydroerythritol with respect to H pressure is almost zero and this indicates that the rate-determining step is the formation of 2,5-dihydrofuran from the coordinated substrate with reduced Re in the DODH step. The activity of ReO /CeO +ReO /C is higher than that of ReO -Au/CeO +ReO /C, which is probably related to the reducibility of ReO /C and the mobility of the Re species between the supports. High-valent Re species such as Re on the CeO and C supports are mobile in the solvent; however, low-valent Re species, including metallic Re species, have much lower mobility. Metallic Re and cationic low-valent Re species with high reducibility and low mobility can be present on the carbon support as a trigger for H activation and promoter of the reduction of Re species on CeO . The presence of noble metals such as Au can enhance the reducibility through the activation of H molecules on the noble metal and the formation of spilt-over hydrogen over noble metal/CeO , as indicated by H temperature-programmed reduction. The higher reducibility of ReO -Au/CeO lowers the DODH activity of ReO -Au/CeO +ReO /C in comparison with ReO /CeO +ReO /C by restricting the movement of Re species from C to CeO .
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http://dx.doi.org/10.1002/cssc.201900900DOI Listing
August 2019

Ring-opening polymerization of trimethylene carbonate to poly(trimethylene carbonate) diol over a heterogeneous high-temperature calcined CeO catalyst.

Chem Commun (Camb) 2018 Dec;54(99):14017-14020

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

CeO2 calcined at 1273 K showed higher activity per surface area than other metal oxides in the ring-opening polymerization of trimethylene carbonate under neat conditions without any additives, providing metal-free and additive-free poly(trimethylene carbonate) diols with no ether bonds with high selectivity. It was demonstrated that CeO2 was a robust and reusable heterogeneous catalyst.
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http://dx.doi.org/10.1039/c8cc08405jDOI Listing
December 2018

CO Conversion with Alcohols and Amines into Carbonates, Ureas, and Carbamates over CeO Catalyst in the Presence and Absence of 2-Cyanopyridine.

Chem Rec 2019 Jul 31;19(7):1354-1379. Epub 2018 Oct 31.

Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

Recent progress on the CeO catalyzed synthesis of organic carbonates, ureas, and carbamates from CO +alcohols, CO +amines, and CO +alcohols+amines, respectively, is reviewed. The reactions of CO with alcohols and amines are reversible ones and the degree of the equilibrium limitation of the synthesis reactions is strongly dependent on the properties of alcohols and amines as the substrates. When the equilibrium limitation of the reaction is serious, the equilibrium conversion of the substrate and the yield of the target product is very low, therefore, the shift of the equilibrium reaction to the product side by the removal of H O is essential in order to get the target product in high yield. One of the effective method of the H O removal from the related reaction systems is the combination with the hydration of 2-cyanopyridine to 2-picolinamide, which is also catalyzed by CeO .
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http://dx.doi.org/10.1002/tcr.201800117DOI Listing
July 2019

Selective hydrogenation of amides to alcohols in water solvent over a heterogeneous CeO-supported Ru catalyst.

Chem Commun (Camb) 2018 Jul;54(54):7503-7506

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

CeO2-supported Ru (Ru/CeO2) worked as an effective and reusable heterogeneous catalyst for the selective dissociation of the C-N bond in amides, particularly primary amides, with H2 in water solvent at low reaction temperature of 333 K, and high yields of the corresponding alcohols were obtained from primary amides.
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http://dx.doi.org/10.1039/c8cc02697aDOI Listing
July 2018

Transformation of Sugars into Chiral Polyols over a Heterogeneous Catalyst.

Angew Chem Int Ed Engl 2018 07 6;57(27):8058-8062. Epub 2018 Jun 6.

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan.

Transformation of sugars, while maintaining the intrinsic stereochemical structure, is desirable. However, such a transformation requires multistep synthesis with protection and deprotection of the OH groups. Herein, a new method for selective transformation of sugar derivatives into chiral building blocks and a diol synthon, with retention of the intrinsic configuration (stereo- and regioselectively), is demonstrated. The method is based on the selective recognition of cis-vicinal OH groups in sugars and leads to the one-pot removal of the cis-vicinal OH groups, without protection of OH groups (except the OH group of the hemiacetal group), over a heterogeneous CeO -supported ReO and Pd (ReO -Pd/CeO ) catalyst by using H as a reducing agent.
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http://dx.doi.org/10.1002/anie.201803043DOI Listing
July 2018

Formation of a New, Strongly Basic Nitrogen Anion by Metal Oxide Modification.

J Am Chem Soc 2017 08 17;139(34):11857-11867. Epub 2017 Aug 17.

Department of Applied Chemistry, Graduate School of Engineering, Tohoku University , 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.

Development of new hybrid materials having unique and unprecedented catalytic properties is a challenge for chemists, and heterogeneous-homogeneous hybrid catalysts have attracted much attention because of the preferable and exceptional properties that are highly expected to result from combination of the components. Base catalysts are widely used in organic synthesis as key materials, and a new class of base catalysts has made a large impact from academic and industrial viewpoints. Here, a principle for creating a new strong base by hybridization of homogeneous and heterogeneous components is presented. It is based on the modification of organic compounds with metal oxides by using the acid-base property of metal oxides. Based on kinetic and DFT studies, combination of CeO and 2-cyanopyridine drastically enhanced the basicity of 2-cyanopyridine by a factor of about 10 (∼9 by pK (in CHCN)), and the pK was estimated to be ∼21, which locates it in the superbase category. 2-Cyanopyridine and CeO formed a unique adsorption complex via two interaction modes: (i) coordinative interaction between the Ce atom of CeO and the N atom of the pyridine ring in 2-cyanopyridine, and (ii) covalent interaction between the surface O atom of CeO and the C atom of the CN group in 2-cyanopyridine by addition of the lattice oxygen of CeO to the CN group of 2-cyanopyridine. These interactions established a new, strongly basic site of N over the CeO surface.
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http://dx.doi.org/10.1021/jacs.7b05227DOI Listing
August 2017

Intramyocellular lipids of muscle type in athletes of different sport disciplines.

Open Access J Sports Med 2017 11;8:161-166. Epub 2017 Jul 11.

Department of Community Development, Tokai University, Sapporo, Japan.

The present study used magnetic resonance spectroscopy (H-MRS) to examine quantitative differences in intramyocellular lipid (IMCL) contents in various muscle types at rest for individual athletes from different sport disciplines. Five groups consisting of sprinters, alpine skiers, cross-country skiers, endurance runners and untrained healthy male subjects volunteered for this study. Data were acquired using H-MRS from the tibialis anterior (TA), medial gastrocnemius (MG) and soleus (SOL) muscles. No significant difference was found in the cross-sectional area (CSA) of the TA, MG and SOL muscles, whereas the CSA of subcutaneous fat was significantly lower (<0.01) for each athlete group compared with untrained subjects. In both TA and MG, IMCL concentrations in endurance runners were significantly higher than those of alpine skiers (<0.01), sprinters (<0.01) and untrained subjects (<0.05). The IMCL concentrations in TA and MG of cross-country skiers were significantly higher than those of alpine skiers (<0.05) and sprinters (TA, <0.01; MG, <0.05). There was no significant difference in the IMCL concentrations of TA and MG between alpine skiers or sprinters and untrained subjects. The IMCL concentration in SOL was significantly greater in endurance runners and showed no difference in cross-country skiers compared with that in alpine skiers and sprinters. There was no significant difference in the IMCL concentration of SOL between athletes and untrained subjects. These results suggest that differences in IMCL contents stored in various muscle types for athletes at rest are associated with the muscle cellular adaptation for differences in the type of exercise training and/or muscle fiber composition.
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http://dx.doi.org/10.2147/OAJSM.S139801DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513845PMC
July 2017

Selective hydrogenation of nitroarenes to aminoarenes using a MoO-modified Ru/SiO catalyst under mild conditions.

Chem Commun (Camb) 2017 Mar;53(23):3377-3380

Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, Aoba-ku, 6-6-07 Aoba, Aramaki, Sendai, 980-8579, Japan.

Modification of Ru/SiO with metal oxides (MoO, WO, and ReO) improved the activity and selectivity in the hydrogenation of 3-nitrostyrene to 3-aminostyrene under mild conditions such as 0.3 MPa H, 303 K, and no solvent. Ru-MoO/SiO(Mo/Ru = 1/2) catalyst was applicable to various substituted nitroarenes, providing the corresponding substituted aminoarenes in high yields (85-99%).
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http://dx.doi.org/10.1039/c7cc00653eDOI Listing
March 2017

Regioselectivity and Reaction Mechanism of Ru-Catalyzed Hydrogenolysis of Squalane and Model Alkanes.

ChemSusChem 2017 Jan 16;10(1):189-198. Epub 2016 Nov 16.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

The dependence of the C-C hydrogenolysis activity on reaction parameters and the structure of the substrate alkanes was investigated for Ru/CeO catalyst with very small (dispersion: H/Ru=0.89) Ru particles. The substrate concentration and reaction temperature did not have a significant effect on the selectivity pattern, except that methane production was promoted at high temperatures. However, the hydrogen pressure had a marked effect on the selectivity pattern. C -C bond dissociation, terminal C -C bond dissociation, and fragmentation to form excess methane had negative reaction order with respect to hydrogen partial pressure, whereas C -C bond dissociation had an approximately zero reaction order. Therefore, a high hydrogen pressure is essential for the regioselective hydrogenolysis of C -C bonds in squalane. Ru/SiO catalyst with larger Ru particles showed similar changes in the product distribution during the change in hydrogen pressure. The reaction mechanism for each type of C-C bond dissociation is proposed based on reactivity trends and DFT calculations. The proposed intermediate species for the internal C -C dissociation, terminal C -C dissociation, and C -C dissociation is alkyls, alkylidynes, and alkenes, respectively.
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http://dx.doi.org/10.1002/cssc.201601204DOI Listing
January 2017

Synthesis of 2-Butanol by Selective Hydrogenolysis of 1,4-Anhydroerythritol over Molybdenum Oxide-Modified Rhodium-Supported Silica.

ChemSusChem 2016 07 25;9(13):1680-8. Epub 2016 May 25.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07, Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

Rh-MoOx /SiO2 (Mo/Rh=0.13) is an effective catalyst for the hydrogenolysis of 1,4-anhydroerythritol (1,4-AHERY) and provides 2-BuOH in high yield of 51 %. This is the first report of the production of 2-BuOH from 1,4-AHERY by hydrogenolysis. 1,4-AHERY was more suitable as a starting material than erythritol because the 2-BuOH yield from erythritol was low (34 %). Based on the kinetics and comparison of reactivities of the related compounds using Rh-MoOx /SiO2 and Rh/SiO2 catalysts, the modification of Rh/SiO2 with MoOx leads to the high activity and high selectivity to 2-BuOH because of the generation of reactive hydride species and the strong adsorption of 1,4-AHERY on MoOx species. The reaction proceeds by main two routes, (I) the combination of single C-O hydrogenolysis with the desorption of intermediates, a usual route in hydrogenolysis, and (II) multiple C-O hydrogenolysis without the desorption of intermediates from the active site, and the reaction mechanism for Route (II) is proposed.
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http://dx.doi.org/10.1002/cssc.201600295DOI Listing
July 2016

Direct Copolymerization of CO2 and Diols.

Sci Rep 2016 Apr 14;6:24038. Epub 2016 Apr 14.

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

Direct polymerization of CO2 and diols is promising as a simple and environmental-benign method in place of conventional processes using high-cost and/or hazardous reagents such as phosgene, carbon monoxide and epoxides, however, there are no reports on the direct method due to the inertness of CO2 and severe equilibrium limitation of the reaction. Herein, we firstly substantiate the direct copolymerization of CO2 and diols using CeO2 catalyst and 2-cyanopyridine promotor, providing the alternating cooligomers in high diol-based yield (up to 99%) and selectivity (up to >99%). This catalyst system is applicable to various diols including linear C4-C10 α,ω-diols to provide high yields of the corresponding cooligomers, which cannot be obtained by well-known methods such as copolymerization of CO2 and cyclic ethers and ring-opening polymerization of cyclic carbonates. This process provides us a facile synthesis method for versatile polycarbonates from various diols and CO2 owing to simplicity of diols modification.
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http://dx.doi.org/10.1038/srep24038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831014PMC
April 2016

Self-assembled hybrid metal oxide base catalysts prepared by simply mixing with organic modifiers.

Nat Commun 2015 Oct 5;6:8580. Epub 2015 Oct 5.

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai 980-8579, Japan.

Multidentate materials formed by simply mixing heterogeneous and homogeneous components are promising for construction of versatile active sites on the surface of heterogeneous compounds, however, to the best of our knowledge, there are no reports on such materials. Self-assembly of hetero-hybrid catalytic materials occurs when heterogeneous catalysts having adjacent Lewis acid-Lewis base sites are mixed with an organic modifier that contains at least two Lewis base functional groups. Here we demonstrate the strategy by combining cerium oxide and 2-cyanopyridine that self-assembles to form a charge-transfer complex in methanol that exhibits a 2,000-fold increase in reaction rate for hydromethoxylation of acrylonitrile with high selectivity compared with cerium oxide or 2-cyanopyridine alone. The catalytic system is applied to the transesterification and Knoevenagel condensation affording 14-fold and 11-fold higher activity, respectively, than cerium oxide alone. These results demonstrate the potential versatility of the catalytic system and the generality of the catalyst preparation strategy.
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http://dx.doi.org/10.1038/ncomms9580DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4600743PMC
October 2015

Catalytic production of branched small alkanes from biohydrocarbons.

ChemSusChem 2015 Aug 11;8(15):2472-5. Epub 2015 Jun 11.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan).

Squalane, C30 algae-derived branched hydrocarbon, was successfully converted to smaller hydrocarbons without skeletal isomerization and aromatization over ruthenium on ceria (Ru/CeO2 ). The internal CH2 CH2 bonds located between branches are preferably dissociated to give branched alkanes with very simple distribution as compared with conventional methods using metal-acid bifunctional catalysts.
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http://dx.doi.org/10.1002/cssc.201500375DOI Listing
August 2015

Catalytic gasification of oil-extracted residue biomass of Botryococcus braunii.

Bioresour Technol 2015 Sep 13;191:452-9. Epub 2015 Mar 13.

Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8572, Japan.

Catalytic gasification of the oil-extracted residue biomass of Botryococcus braunii was demonstrated in a laboratory-scale continuous feeding dual bed reactor. Steam gasification at 1023 K over Ni-Fe/Mg/Al catalyst can completely reform tar derived from pyrolysis of the residue biomass into C1 gases and hydrogen, and has achieved 91%-C conversion to gaseous product (CO+CO2+CH4). Composition of product gas has higher contents of CO and H2 with their ratio (H2/CO) of around 2.4 which is slightly H2-rich syngas. Maximum hydrogen yield of 74.7 mmol g-biomass(-1) obtained in this work is much higher than that from gasification of other algal biomass reported in literature. The residue biomass of B. braunii can be a superior renewable source of syngas or hydrogen.
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http://dx.doi.org/10.1016/j.biortech.2015.03.034DOI Listing
September 2015

Catalytic total hydrodeoxygenation of biomass-derived polyfunctionalized substrates to alkanes.

ChemSusChem 2015 Apr 25;8(7):1114-32. Epub 2015 Feb 25.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan).

The total hydrodeoxygenation of carbohydrate-derived molecules to alkanes, a key reaction in the production of biofuel, was reviewed from the aspect of catalysis. Noble metals (or Ni) and acid are the main components of the catalysts, and group 6 or 7 metals such as Re are sometimes added as modifiers of the noble metal. The main reaction route is acid-catalyzed dehydration plus metal-catalyzed hydrogenation, and in some systems metal-catalyzed direct CO dissociation is involved. The appropriate active metal, acid strength, and reaction conditions depend strongly on the reactivity of the substrate. Reactions that use Pt or Pd catalysts supported on Nb-based acids or relatively weak acids are suitable for furanic substrates. Carbohydrates themselves and sugar alcohols undergo CC dissociation easily. The systems that use metal-catalyzed direct CO dissociations can give a higher yield of the corresponding alkane from carbohydrates and sugar alcohols.
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http://dx.doi.org/10.1002/cssc.201403330DOI Listing
April 2015

Combination of supported bimetallic rhodium-molybdenum catalyst and cerium oxide for hydrogenation of amide.

Sci Technol Adv Mater 2015 Feb 13;16(1):014901. Epub 2015 Jan 13.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.

Hydrogenation of cyclohexanecarboxamide to aminomethylcyclohexane was conducted with silica-supported bimetallic catalysts composed of noble metal and group 6-7 elements. The combination of rhodium and molybdenum with molar ratio of 1:1 showed the highest activity. The effect of addition of various metal oxides was investigated on the catalysis of Rh-MoO /SiO, and the addition of CeO much increased the activity and selectivity. Higher hydrogen pressure and higher reaction temperature in the tested range of 2-8 MPa and 393-433 K, respectively, were favorable in view of both activity and selectivity. The highest yield of aminomethylcyclohexane obtained over Rh-MoO /SiO + CeO was 63%. The effect of CeO addition was highest when CeO was not calcined, and CeO calcined at >773 K showed a smaller effect. The use of CeO as a support rather decreased the activity in comparison with Rh-MoO /SiO. The weakly-basic nature of CeO additive can affect the surface structure of Rh-MoO /SiO, i.e. reducing the ratio of Mo-OH/Mo-O sites.
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http://dx.doi.org/10.1088/1468-6996/16/1/014901DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5036504PMC
February 2015

Insight into the mechanism of hydrogenation of amino acids to amino alcohols catalyzed by a heterogeneous MoO(x) -modified Rh catalyst.

Chemistry 2015 Feb 29;21(7):3097-107. Epub 2014 Dec 29.

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai 980-8579 (Japan).

Hydrogenation of amino acids to amino alcohols is a promising utilization of natural amino acids. We found that MoOx -modified Rh/SiO2 (Rh-MoOx /SiO2 ) is an efficient heterogeneous catalyst for the reaction at low temperature (323 K) and the addition of a small amount of MoOx drastically increases the activity and selectivity. Here, we report the catalytic potential of Rh-MoOx /SiO2 and the results of kinetic and spectroscopic studies to elucidate the reaction mechanism of Rh-MoOx /SiO2 catalyzed hydrogenation of amino acids to amino alcohols. Rh-MoOx /SiO2 is superior to previously reported catalysts in terms of activity and substrate scope. This reaction proceeds by direct formation of an aldehyde intermediate from the carboxylic acid moiety, which is different from the reported reaction mechanism. This mechanism can be attributed to the reactive hydride species and substrate adsorption caused by MoOx modification of Rh metal, which results in high activity, selectivity, and enantioselectivity.
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http://dx.doi.org/10.1002/chem.201405769DOI Listing
February 2015

Hydrodeoxygenation of vicinal OH groups over heterogeneous rhenium catalyst promoted by palladium and ceria support.

Angew Chem Int Ed Engl 2015 Feb 17;54(6):1897-900. Epub 2014 Dec 17.

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan).

Heterogeneous ReOx-Pd/CeO2 catalyst showed excellent performance for simultaneous hydrodeoxygenation of vicinal OH groups. High yield (>99%), turnover frequency (300 h(-1)), and turnover number (10,000) are achieved in the reaction of 1,4-anhydroerythritol to tetrahydrofuran. This catalyst can be applied to sugar alcohols, and mono-alcohols and diols are obtained in high yields (≥85%) from substrates with even and odd numbers of OH groups, respectively. The high catalytic performance of ReOx-Pd/CeO2 can be assigned to rhenium species with +4 or +5 valence state, and the formation of this species is promoted by H2/Pd and the ceria support.
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http://dx.doi.org/10.1002/anie.201410352DOI Listing
February 2015

Selective hydrogenation of lactic acid to 1,2-propanediol over highly active ruthenium-molybdenum oxide catalysts.

ChemSusChem 2015 Apr 15;8(7):1170-8. Epub 2014 Dec 15.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan).

Modification of Ru/C with a small amount of MoOx (RuMoOx /C) enhanced the catalytic activity in the hydrogenation of L-lactic acid to form 1,2-propanediol and maintained high selectivity. The turnover frequency based on the amount of Ru over the optimized RuMoOx /C catalyst (Mo/Ru molar ratio=1:16) was 114 h(-1) at 393 K, which was about 4 times higher than that over Ru/C. The same effect of MoOx was obtained over RuMoOx /SiO2 , although RuMoOx /SiO2 showed slightly lower activity than that of RuMoOx /C. RuMoOx /C achieved a high yield of 95 % in 18 h at 393 K and was applicable to various carboxylic acids to provide the corresponding alcohols in high yields. Modification with MoOx also brought about suppression of racemization and (S)-1,2-propanediol was obtained in high enantiomeric excess at 353 K. Based on kinetic analysis and characterization data, such as XRD, TEM, CO adsorption by a volumetric method, FTIR spectroscopy, and X-ray absorption spectroscopy, for RuMoOx /C and RuMoOx /SiO2 , the catalyst structure and reaction mechanism are proposed.
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http://dx.doi.org/10.1002/cssc.201403011DOI Listing
April 2015

Metal catalysts for steam reforming of tar derived from the gasification of lignocellulosic biomass.

Bioresour Technol 2015 Feb 13;178:53-64. Epub 2014 Oct 13.

Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.

Biomass gasification is one of the most important technologies for the conversion of biomass to electricity, fuels, and chemicals. The main obstacle preventing the commercial application of this technology is the presence of tar in the product gas. Catalytic reforming of tar appears a promising approach to remove tar and supported metal catalysts are among the most effective catalysts. Nevertheless, improvement of catalytic performances including activity, stability, resistance to coke deposition and aggregation of metal particles, as well as catalyst regenerability is greatly needed. This review focuses on the design and catalysis of supported metal catalysts for the removal of tar in the gasification of biomass. The recent development of metal catalysts including Rh, Ni, Co, and their alloys for steam reforming of biomass tar and tar model compounds is introduced. The role of metal species, support materials, promoters, and their interfaces is described.
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http://dx.doi.org/10.1016/j.biortech.2014.10.010DOI Listing
February 2015

Production of renewable hexanols from mechanocatalytically depolymerized cellulose by using Ir-ReOx /SiO2 catalyst.

ChemSusChem 2015 Feb 3;8(4):628-35. Epub 2014 Nov 3.

Department of Applied Chemistry, School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan).

Hexanols were produced in high yield by conversion of cellulose over Ir-ReOx /SiO2 (molar ratio Re/Ir=2) catalyst in biphasic reaction system (n-decane+H2 O). The cellulose was depolymerized by mechanocatalysis with the aid of H2 SO4 . The influence of solvent amount, reaction temperature and hydrogen pressure was systematically investigated and the highest yield of hexanols reached 60 % under the conditions of n-decane/water ∼2 (v/v), 413 K, 10 MPa H2 for 24 h. Mechanocatalytic depolymerization of cellulose with the aid of H2 SO4 or HCl and the use of sufficient n-decane were very crucial for the production of hexanols. H2 SO4 not only catalyzed cellulose to water-soluble oligosaccharides but also promoted the hydrogenolysis activity of Ir-ReOx /SiO2 catalyst. The role of n-decane was to extract hexanols and to suppress over-hydrogenolysis of hexanols to n-hexane.
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http://dx.doi.org/10.1002/cssc.201403010DOI Listing
February 2015

Role of Re species and acid cocatalyst on Ir-ReOx /SiO2 in the C-O hydrogenolysis of biomass-derived substrates.

Chem Rec 2014 Dec 6;14(6):1041-54. Epub 2014 Aug 6.

Department of Applied Chemistry, School of Engineering, Tohoku University, Sendai, Japan.

The catalytic performance of ReOx -modified Ir metal catalyst in the hydrogenolysis of C-O bonds is strongly dependent on the choice of solvent. The acidic property of the Re species becomes obvious in the alkane solvent, and the hydrogenolysis reaction proceeds mainly by acid-catalyzed dehydration and the subsequent metal-catalyzed hydrogenation. The acidic property of the Re species is weakened in water; however, the hydrogenolysis reaction proceeds in water via a direct mechanism involving SN 2-like attack of a hydride species at the interface between Ir and ReOx on the adsorbed Re alkoxide species. This mechanism enabled the selective dissociation of the C-O bond neighboring the CH2 OH group.
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http://dx.doi.org/10.1002/tcr.201402026DOI Listing
December 2014

Selective hydrodeoxygenation of cyclic vicinal diols to cyclic alcohols over tungsten oxide-palladium catalysts.

ChemSusChem 2014 Aug 27;7(8):2185-92. Epub 2014 Jun 27.

Department of Applied Chemistry, School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan).

Hydrodeoxygenation of cyclic vicinal diols such as 1,4-anhydroerythritol was conducted over catalysts containing both a noble metal and a group 5-7 transition-metal oxide. The combination of Pd and WOx allowed the removal of one of the two OH groups selectively. 3-Hydroxytetrahydrofuran was obtained from 1,4-anhydroerythritol in 72 and 74% yield over WOx -Pd/C and WOx -Pd/ZrO2 , respectively. The WOx -Pd/ZrO2 catalyst was reusable without significant loss of activity if the catalyst was calcined as a method of regeneration. Characterization of WOx -Pd/C with temperature-programmed reduction, X-ray diffraction, and transmission electron microscopy/energy-dispersive X-ray spectroscopy suggested that Pd metal particles approximately 9 nm in size were formed on amorphous tungsten oxide particles. A reaction mechanism was proposed on the basis of kinetics, reaction results with tungsten oxides under an atmosphere of Ar, and density functional theory calculations. A tetravalent tungsten center (W(IV) ) was formed by reduction of WO3 with the Pd catalyst and H2 , and this center served as the reductant for partial hydrodeoxygenation.
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http://dx.doi.org/10.1002/cssc.201402188DOI Listing
August 2014

Catalytic hydrogenation of amino acids to amino alcohols with complete retention of configuration.

Chem Commun (Camb) 2014 Jun;50(50):6656-9

Graduate School of Engineering, Tohoku University, Aoba 6-6-07, Aramaki, Aoba-ku, Sendai, 980-8579, Japan.

Rh-MoOx/SiO2 is an effective heterogeneous catalyst for selective hydrogenation of amino acids to amino alcohols in a water solvent. MoOx modification of Rh drastically enhanced the activity and improved the selectivity and ee. Various amino alcohols were obtained in high yields (90-94%) with complete retention of configuration.
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http://dx.doi.org/10.1039/c4cc02675fDOI Listing
June 2014

Selective hydrogenolysis of C-O bonds using the interaction of the catalyst surface and OH groups.

Top Curr Chem 2014 ;353:127-62

Department of Applied Chemistry, School of Engineering, Tohoku University, Sendai, Japan,

Hydrogenolysis of C-O bonds is becoming more and more important for the production of biomass-derived chemicals. Since substrates originated from biomass usually have high oxygen content and various kinds of C-O bonds, selective hydrogenolysis is required. Rhenium or molybdenum oxide modified rhodium and iridium metal catalysts (Rh-ReO(x), Rh-MoO(x), and Ir-ReO(x)) have been reported to be effective for selective hydrogenolysis. This review introduces the catalytic performance and reaction kinetics of Rh-ReO(x), Rh-MoO(x), and Ir-ReO(x) in the hydrogenolysis of various substrates, where selectivity is especially characteristic. Based the model structure of the catalysts and the reaction mechanism, the role of the oxide components is to make the interaction between the OH groups in the substrates and the catalyst surface, and the role of metal components is to dissociate hydrogen molecule heterolytically to give hydride and proton.
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http://dx.doi.org/10.1007/128_2014_538DOI Listing
April 2015

Regenerability of hydrotalcite-derived nickel-iron alloy nanoparticles for syngas production from biomass tar.

ChemSusChem 2014 Feb 27;7(2):510-22. Epub 2013 Dec 27.

National Engineering Research Center of Chemical Fertilizer Catalyst (NERC), College of Chemistry and Chemical Engineering, Fuzhou University, Gongye Road 523, Fuzhou 350002, Fujian (P.R. China).

Nickel-iron/magnesium/aluminum bimetallic catalysts were prepared by the calcination and reduction of nickel-magnesium-iron-aluminum hydrotalcite-like compounds. Characterization suggests that, at iron/nickel≤0.5, both nickel and iron species are homogeneously distributed in the hydrotalcite precursor and incorporated into the Mg(Ni, Fe, Al)O periclase after calcination, giving rise to uniform nickel-iron alloy nanoparticles after reduction. Ni-Fe/Mg/Al (Fe/Ni=0.25) exhibits the best catalytic performance for the steam reforming of tar derived from the pyrolysis of biomass. It is suggested that the uniform nickel-iron alloy nanoparticles and the synergy between nickel and iron are responsible for the high catalytic performance. Moreover, the Ni-Fe/Mg/Al catalyst exhibits much better regenerability toward oxidation-reduction treatment for the removal of deposited coke than that of conventional Ni-Fe/α-Al2 O3 . This property can be attributed to the better regeneration of Ni-Fe alloy nanoparticles through the formation and reduction of Mg(Ni, Fe, Al)O.
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http://dx.doi.org/10.1002/cssc.201300855DOI Listing
February 2014
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