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Mild-temperature hydrodeoxygenation of vanillin over porous nitrogen-doped carbon black supported nickel nanoparticles
Porous nitrogen-doped carbon black (NCB) was synthesized by facile carbonization of carbon black (CB) coated with polypyrrole (CB@polypyrrole) and used as a support for Ni nanoparticles (NPs). The microstructure, reducibility and crystallinity of the as-synthesized materials were investigated by transmission electron microscopy (TEM), H2-TPR/TPD, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was found that surface nitrogen species on NCB significantly promote the decomposition of the nickel precursor and the reduction of nickel oxide, and improve the stability of metallic Ni in ambient atmosphere. In the selective hydrodeoxygenation (HDO) of vanillin in the aqueous phase at low hydrogen pressure (0.5 MPa) and mild temperature (150 °C), Ni/NCB shows much higher activity than N-free catalysts. This is ascribed to the higher reducibility, the lower oxidation state of Ni NPs and the enhanced hydrogen spillover of Ni to the support. Moreover, the Ni/NCB catalyst is relatively cheap and easy to scale-up the production of, thus achieving a low-cost transformation of biomass to bio-oils.
Nie, Renfeng,Yang, Huanhuan,Zhang, Haifu,Yu, Xiaolong,Lu, Xinhuan,Zhou, Dan,Xia, Qinghua
p. 3126 - 3134
(2017)
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Hydrogenation of biofuels with formic acid over a palladium-based ternary catalyst with two types of active sites
A composite catalyst including palladium nanoparticles on titania (TiO 2) and on nitrogen-modified porous carbon (Pd/TiO2@N=C) is synthesized from palladium salts, tetrabutyl titanate, and chitosan. N 2 sorption isotherms show that the catalyst has a high BET surface area (229 m2 g-1) and large porosity. XPS and TEM characterization of the catalyst shows that palladium species with different chemical states are well dispersed across the TiO2 and nitrogen-modified porous carbon, respectively. The Pd/TiO2@N=C catalyst is very active and shows excellent stability towards hydrogenation of vanillin to 2-methoxy-4-methylphenol using formic acid as hydrogen source. This activity can be attributed to a synergistic effect between the Pd/TiO 2 (a catalyst for dehydrogenation of formic acid) and Pd/N=C (a catalyst for hydrogenation of vanillin) sites. Triple play: A ternary Pd/TiO2@N=C catalyst is developed by supporting palladium nanoparticles onto a composite support of titania (TiO2) and nitrogen-modified porous carbon. The catalyst is able to fully hydrogenate vanillin, using formic acid, available from biomass, as hydrogen source. Its unique catalytic properties for hydrogenation are due to a synergistic effect between two different types of palladium sites in the catalyst: one for formic acid dehydrogenation and on for vanillin hydrogenation.
Wang, Liang,Zhang, Bingsen,Meng, Xiangju,Su, Dang Sheng,Xiao, Feng-Shou
p. 1537 - 1541
(2014)
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Silica/titania composite-supported NiCo catalysts with combined catalytic effects for phenol hydrogenation under fast and mild conditions
The effect of titanium as a promoter for the nickel-cobalt/silica-titania (NiCo/Si-Ti) catalyst in the hydrogenation of phenol was comparatively studied. In the phenol hydrogenation under mild reaction conditions (1 MPa H2 pressure and 100 °C), the Ti-promoter induces the formation of the Coδ??OV?Ti3+ active sites and enhances the hydrogenation activity of the NiCo/Si catalyst to convert phenol to cyclohexanol. The catalytic hydrogenation with the optimal composition of the NiCo/Si-1.0Ti (Si:Ti ratio of 8.5:1) catalyst was completed within 1 h (conversion 98.2 % and selectivity >99 %), which was more efficiently than that with other Ti-doped catalysts and NiCo/Si as baseline, indicating a strong positive synergistic effect between the metal (Ni-Co) and support (Ti-Si) components of the catalyst in this reaction. Additionally, the kinetics, pathway and catalytic mechanism of the hydrogenation of phenol are also examined. Furthermore, the NiCo/Si-1.0Ti catalysts also showed a good performance at reducing the unstable oxygenated compounds in the bio-oil.
Li, Yucheng,Liu, Jing,He, Jing,Wang, Luying,Lei, Jiandu
(2020)
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Visible light mediated upgrading of biomass to biofuel
Pd and Ag nanoparticles over graphitic carbon nitride (g-C3N4) surface, AgPd@g-C3N4, serve as an efficient catalyst for upgrading of biofuel via hydrodeoxygenation of vanillin under visible light.
Verma, Sanny,Nasir Baig,Nadagouda, Mallikarjuna N.,Varma, Rajender S.
p. 1327 - 1331
(2016)
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Method for catalyzing hydrodeoxygenation of vanillin by using MOF-based nano composite material
The invention discloses a method for catalyzing hydrodeoxygenation of vanillin by using an MOF-based nano composite material, which is characterized in that a UiO-series MOFs material with relatively good hydrothermal stability is used as a carrier and is combined with metal nanoparticles to catalyze hydrodeoxygenation of vanillin. The method solves some problems of a traditional catalyst carrier in the hydrodeoxygenation reaction of vanillin, such as self-sintering, carbon deposition, leaching of active components, and great influence on activity in the reaction process. According to the invention, the active component can be well anchored, the performance of the active component can be promoted, the high yield of the target deoxidation product can be achieved, and the excellent catalysis effect can be achieved.
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Paragraph 0024; 0031-0033; 0040-0042; 0049-0050

(2021/07/31)

Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information
p. 9029 - 9039
(2021/06/28)

In situhydrodeoxygenation of vanillin over Ni-Co-P/HAP with formic acid as a hydrogen source
A new noble metal-free Ni-Co-P/HAP (hydroxyapatite) amorphous alloy catalyst was synthesized by an impregnation-chemical reduction method; the structure and properties of the catalysts were characterized by XRD, SEM, BET, XPS and DSC. Based on the model of the hydrodeoxygenation (HDO) of vanillin to 2-methoxy-4-methylphenol (MMP) with formic acid as a hydrogen source, the catalytic performance of the catalyst was studied. The results found that the Ni-Co-P/HAP catalyst exhibited excellent catalytic activity for thein situHDO reaction of vanillin compared with Ni-P and Ni-Co-P. The conversion of vanillin could be high to 97.86% with MMP selectivity of 93.97% under optimized reaction conditions. In addition, mechanism studies have shown that the side reaction of carbocation and vanillyl alcohol (HMP) condensation can be effectively reduced with increasing the hydrogenation rate, thereby the selectivity of MMP was effectively increased.
Duan, Mingxing,Cheng, Qingyan,Wang, Mingming,Wang, Yanji
p. 10996 - 11003
(2021/03/23)

Ceria-promoted Co@NC catalyst for biofuel upgrade: synergy between ceria and cobalt species
Ceria-promoted Co@NC (NC, N doped carbon) catalysts are prepared by pyrolysis of biomass materials. Characterization results indicate that ceria and Co species facilitate the distribution of each other due to the formation of a Ce-O-Co solid solution. The specific surface area of the catalyst increased from 378.77 to 537.7 m2g?1viathe introduction of ceria. The electron transfer from Co to Ce further enhanced their interaction, and Co species facilitate the formation of more defective oxygen vacancies on ceria, which are beneficial to the activities of catalytic hydrogenation and catalytic transfer hydrogenation (CTH), respectively. Thus, Co/Ce@NC (0.99% Co loading) pyrolyzed at 850 °C exhibits excellent performance in the hydrodeoxygenation (HDO) of vanillin with high metal utilization. Catalytic hydrogenation and CTH coexisted in the presence of H2and ethanol, and >99% yield of creosol can be obtained in each of them. The reaction processes are monitored. No intermediate is found in aqueous media, while ethoxymethyl-4-methoxy-2-phenol is detected in ethanol. Moreover, Co/Ce@NC presents outstanding stability and general applicability. This work provides new insights into the construction of M@NC (M, metal) catalysts and the HDO process of biofuel upgrade.
Wang, Bowei,Gao, Ruixiao,Zhang, Dan,Zeng, Yuyao,Zhang, Fangying,Yan, Xilong,Li, Yang,Chen, Ligong
supporting information
p. 8541 - 8553
(2021/04/12)

Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water
Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.
Chen, Chun,Gong, Wanbing,Han, Miaomiao,Wang, Dongdong,Wang, Guozhong,Zhang, Haimin,Zhang, Jifang,Zhang, Yunxia,Zhao, Huijun
p. 2027 - 2037
(2021/09/02)

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions
Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (～10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.
Chen, Yuzhuo,Chen, Zhirong,Gong, Yutong,Mao, Shanjun,Ning, Honghui,Wang, Yong,Wang, Zhenzhen
supporting information
p. 3069 - 3084
(2021/11/16)

SELECTIVE HYDRODEOXYGENATION OF AROMATIC COMPOUNDS
Disclosed are methods of selective hydrodeoxygenation of aromatic compounds by using catalyst systems comprising N-heterocyclic carbene (NHC) and 4-pyridinol-derived pincer ligands and metal complexes containing these ligands.
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Paragraph 0228-0231; 0235-02360238; 0249-0254

(2021/07/02)

Resin-supported iridium complex for low-temperature vanillin hydrogenation using formic acid in water
Biorefinery seeks to utilize biomass waste streams as a source of chemical precursors with which to feed the chemical industry. This goal seeks to replace petroleum as the main feedstock, however this task requires the development of efficient catalysts capable of transforming substances derived from biomass into useful chemical products. In this study, we demonstrate that a highly-active iridium complex can be solid-supported and used as a low-temperature catalyst for both the decomposition of formic acid (FA) to produce hydrogen, and as a hydrogenation catalyst to produce vanillyl alcohol (VA) and 2-methoxy-4-methylphenol (MMP) from vanillin (V); a lignin-derived feedstock. These hydrogenation products are promising precursors for epoxy resins and thus demonstrate an approach for their production without the need for petroleum. In contrast to other catalysts that require temperatures exceeding 100 °C, here we accomplish this at a temperature of 50 °C in water under autogenous pressure. This approach provides an avenue towards biorefinery with lower energy demands, which is central to the decentralization and broad implementation. We found that the high activity of the iridium complex transfers to the solid-support and is capable of accelerating the rate determining step; the decomposition of FA into hydrogen and carbon dioxide. The yield of both VA and MMP can be independently tuned depending on the temperature. The simplicity of this approach expands the utility of molecular metal complexes and provides new catalyst opportunities in biorefinery.
Smith, Christene A.,Brandi, Francesco,Al-Naji, Majd,Guterman, Ryan
p. 15835 - 15840
(2021/05/19)

Controlled lignosulfonate depolymerization: Via solvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor
Sodium lignosulfonate (LS) was valorized to low molecular weight (Mw) fractions by combining solvothermal (SF) and catalytic hydrogenolysis/hydrogenation fragmentation (SHF) in a continuous flow system. This was achieved in either alcohol/H2O (EtOH/H2O or MeOH/H2O) or H2O as a solvent and Ni on nitrogen-doped carbon as a catalyst. The tunability according to the temperature of both SF and catalytic SHF of LS has been separately investigated at 150 °C, 200 °C, and 250 °C. In SF, the minimal Mw was 2994 g mol-1 at 250 °C with a dispersity (?) of 5.3 using MeOH/H2O. In catalytic SHF using MeOH/H2O, extremely low Mw was found (433 mg gLS-1) with a ? of 1.2 combined with 34 mg gLS-1. The monomer yield was improved to 42 mg gLS-1 using dual catalytic beds. These results provide direct evidence that lignin is an unstable polymer at elevated temperatures and could be efficiently deconstructed under hydrothermal conditions with and without a catalyst. This journal is
Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco
supporting information
p. 9894 - 9905
(2021/12/24)

Hollow, mesoporous, eutectic Zn1?xMgxO nano-spheres as solid acid-base catalysts for the highly regio-selectiveO-methylation of 1,2-diphenols
The highly regio-selectiveO-methylation of catechol with dimethyl carbonate (DMC), catalyzed by a solid acid-base catalyst, is an environmentally friendly chemical process for industrial production of guaiacol. However, a guaiacol yield below 84% and high reaction temperature above 280 °C limit its industrial application. Here, hollow, mesoporous Zn1?xMgxO nano-spheres with a eutectic structure, denoted as Zn1?xMgxO HMNSs (x= 0.012-0.089), are facilely fabricatedviathe calcination of Mg2+/Zn2+ion-adsorbing carbon spheres at 500 °C in air. In theO-methylation of catechol with DMC at 180 °C, Zn1?xMgxO HMNSs (x= 0.052) afford guaiacol in 95.5% yield with a complete catechol conversion. Furthermore, 89.0-95.3% mono-ether yields with high 1,2-diphenol conversions (94.5-100%) are also obtained for the other 1,2-diphenols bearing -CH3and -Br groups. Moreover, a plausible mechanism for highly selectiveO-methylation of catechol with DMC is proposed, in which the single-site activation and double-site activation of phenolic hydroxyls by the basic oxygen of Mg-O afford guaiacol and veratrole, respectively.
Liu, Jie,Ma, Xuebing,Wang, Xuri,Xie, Guangxin,Yin, Zuyong,Zhang, Jianing
p. 7454 - 7466
(2021/11/23)

Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals
With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
Jiang, Huifang,Lu, Rui,Luo, Xiaolin,Si, Xiaoqin,Xu, Jie,Lu, Fang
supporting information
p. 1292 - 1296
(2020/12/09)

Copper-nickel mixed oxide catalysts from layered double hydroxides for the hydrogen-transfer valorisation of lignin in organosolv pulping
Copper and nickel mixed catalysts obtained by calcination of iron and aluminium hydrotalcites (layered double hydroxides, LDH) have been tested in the conversion of a lignin model dimer in subcritical methanol. Phase distribution and textural properties of the catalysts were characterized by X-ray diffraction Rietveld analysis and N2 physisorption. The presence of copper was critical for effective hydrogenation, both by direct hydrogen transfer from methanol to aldehyde groups and by reactivity of products from methanol reforming. TPR experiments showed that the hydrogenation activity was promoted by an enhanced reducibility of the Cu-catalysts, related to the presence of other oxide components. Characterisation of the catalysts after reaction indicated that metallic copper was formed by the reduction of CuO by methanol and that modifications of the oxide catalysts in the reaction medium played a major role in the formation of active sites.
Albonetti, Stefania,Awan, Iqra Zubair,Beltrami, Giada,Bonincontro, Danilo,Cacciaguerra, Thomas,Cavani, Fabrizio,Di Renzo, Francesco,Gimello, Olinda,Martucci, Annalisa,Tanchoux, Nathalie
(2020/12/02)

Atomically Dispersed Co Catalyst for Efficient Hydrodeoxygenation of Lignin-Derived Species and Hydrogenation of Nitroaromatics
Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co1?NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.
Du, Congcong,Gao, Shutao,Gao, Yongjun,Huang, Jianyu,Meng, Tao,Qiao, Yuqing,Shang, Ningzhao,Shen, Tongde,Wang, Chun,Wang, Haijun,Wang, Junmin,Wang, Zhi,Wu, Qiuhua,Zhang, Longkang
p. 8672 - 8682
(2020/09/18)

Improved Pd/Ru metal supported graphene oxide nano-catalysts for hydrodeoxygenation (HDO) of vanillyl alcohol, vanillin and lignin
Pd and Ru nanoparticles supported on graphene oxide (GO) [Pd?GO and Ru?GO] and bimetallic [Pd/Ru?GO] were prepared and well characterized by XRD, FT-IR, EDS, TEM, XPS and ICP-AES analyses. The prepared nano-catalysts were tested for hydrodeoxygenation (HDO) of lignin monomer molecules-vanillyl alcohol and vanillin. In comparison with previously reported methods, Ru?GO and bimetallic Pd/Ru?GO catalysts showed high activity and selectivity, under milder conditions, at room temperature and 145 psi H2 pressure, for the formation of p-creosol, a value added product, as a potential future biofuel with antibacterial and anti-insecticidal properties. The multifold advantages of both these catalysts are in terms of reduced catalyst loading with a lower metal content and ambient temperture conditions resulting in higher conversion of the starting material. Furthermore, the efficacy of the developed methodology using Ru?GO and bimetallic Pd/Ru?GO catalysts under the optimized conditions was tested on the phenolic components of commercial lignin obtained by photo-catalytic fragmentation using TiO2, to obtain a mixture after HDO which contained vanillyl alcohol and p-creosol among others, as indicated by HPLC-MS analysis.
Arora, Shalini,Gupta, Neeraj,Singh, Vasundhara
supporting information
p. 2018 - 2027
(2020/04/07)

Biomimetic Design of a 3 D Transition Metal/Carbon Dyad for the One-Step Hydrodeoxygenation of Vanillin
Enzyme catalysts always show an excellent catalytic selectivity, which is important in biochemistry, especially in catalytic synthesis and biopharming. This selectivity is achieved by combining the binding effect induced by the electrostatic effect of the enzyme to attract a specific substrate and then the prearrangement of the substrates inside the enzyme pocket. Herein, we report a proof-of-concept application of an interfacial electrostatic field induced by constructing Schottky heterojunctions to mimic the electrostatic catalysis of an enzyme. In combination with the 3 D structure, a transition metal/carbon dyad was designed by nanoconfinement methods to promote the differential binding effect and the space-induced organization of the reaction intermediate (vanillyl alcohol) to develop a new one-step hydrogenolysis of vanillin for the production of 2-methoxy-4-methylphenol with a remarkably high selectivity (>99 %).
Chen, Jie-Sheng,Li, Xin-Hao,Su, Juan,Wang, Hong-Hui,Zhang, Jun-Jun,Zhao, Tian-Jian
(2020/03/30)

Highly dispersed nickel anchored on a N-doped carbon molecular sieve derived from metal-organic frameworks for efficient hydrodeoxygenation in the aqueous phase
ZIF-8 was employed as a template to synthesize HD-Ni/N-CMS containing highly dispersed Ni at the atomic level anchored on a N-doped carbon molecular sieve for vanillin hydrodeoxygenation. The ZIF-8 structure was inherited and Ni-N bonds were formed by the coordination of Ni with N-rich defects, therefore it exhibited a high turnover frequency (1047.1 h-1) and good stability.
Fan, Ruoyu,Fan, Ruoyu,Hu, Zhi,Hu, Zhi,Chen, Chun,Zhu, Xiaoguang,Zhang, Haimin,Zhang, Yunxia,Zhao, Huijun,Zhao, Huijun,Wang, Guozhong
supporting information
p. 6696 - 6699
(2020/07/03)

Efficient heterogeneous palladium-catalyzed transfer hydrogenolysis of benzylic alcohols by formic acid
An efficient heterogeneous palladium-catalyzed transfer hydrogenolysis- of primary, secondary, and tertiary benzylic alcohols using formic acid as hydrogen source has been developed. The resulting hydrocarbon products were obtained in excellent yields. Moreover, the system exhibits high chemoselectivity, reacting only with the hydroxy groups in the presence of other functional groups, and excellent re-cyclability.
Afewerki, Samson,Córdova, Armando,Palo-Nieto, Carlos
supporting information
p. 2330 - 2336
(2020/08/19)

Determining the Catalyst Properties That Lead to High Activity and Selectivity for Catalytic Hydrodeoxygenation with Ruthenium Pincer Complexes
Ten ruthenium pincer complexes were evaluated as catalysts for the hydrodeoxygenation (HDO) reaction on a lignin monomer surrogate, vanillyl alcohol. Four of these complexes are reported herein with the synthesis and full characterization data for all and single-crystal X-ray diffraction data for three complexes bearing OH/O-, NMe2, and Me substituents on the pincer. A systematic study of these CNC pincer complexes revealed that the π-donor substituent on the pyridine ring plays a key role in enhancing the yield of the desired deoxygenated product. While OMe, OH, and NMe2 are all effective as π-donor substituents on the central pyridine ring in the pincer, the highest conversion to products and the best selectivity was observed with OH substituents and added sodium carbonate as a base. Base serves to deprotonate the OH group and form 1O- as observed spectroscopically. Furthermore, efforts to use other catalysts have revealed that free or labile sites are needed on the ruthenium center and an electronically rich and nonbulky CNC pincer is optimal. At low catalyst loadings (0.01 mol %), the OH-substituted catalyst 1OH in the presence of base serves as a homogeneous catalyst and is able to achieve quantitative and selective conversion of vanillyl alcohol to desired the HDO product, creosol, with up to 10000 turnovers. With this knowledge in hand, we can design the next generation of homogeneous catalysts with increased reactivity toward all of the oxygenated sites on lignin-derived monomers.
Boudreaux, Chance M.,Das, Sanjit,Delucia, Nicholas A.,Papish, Elizabeth T.,Qu, Fengrui,Vannucci, Aaron K.,Yao, Wenzhi
supporting information

(2020/03/13)

Oxygen-Free Regioselective Biocatalytic Demethylation of Methyl-phenyl Ethers via Methyltransfer Employing Veratrol- O-demethylase
The cleavage of aryl methyl ethers is a common reaction in chemistry requiring rather harsh conditions; consequently, it is prone to undesired reactions and lacks regioselectivity. Nevertheless, O-demethylation of aryl methyl ethers is a tool to valorize natural and pharmaceutical compounds by deprotecting reactive hydroxyl moieties. Various oxidative enzymes are known to catalyze this reaction at the expense of molecular oxygen, which may lead in the case of phenols/catechols to undesired side reactions (e.g., oxidation, polymerization). Here an oxygen-independent demethylation via methyl transfer is presented employing a cobalamin-dependent veratrol-O-demethylase (vdmB). The biocatalytic demethylation transforms a variety of aryl methyl ethers with two functional methoxy moieties either in 1,2-position or in 1,3-position. Biocatalytic reactions enabled, for instance, the regioselective monodemethylation of substituted 3,4-dimethoxy phenol as well as the monodemethylation of 1,3,5-trimethoxybenzene. The methyltransferase vdmB was also successfully applied for the regioselective demethylation of natural compounds such as papaverine and rac-yatein. The approach presented here represents an alternative to chemical and enzymatic demethylation concepts and allows performing regioselective demethylation in the absence of oxygen under mild conditions, representing a valuable extension of the synthetic repertoire to modify pharmaceuticals and diversify natural products.
Grimm, Christopher,Lazzarotto, Mattia,Pompei, Simona,Schichler, Johanna,Richter, Nina,Farnberger, Judith E.,Fuchs, Michael,Kroutil, Wolfgang
p. 10375 - 10380
(2020/10/02)

Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
p. 4348 - 4358
(2020/09/22)

Regioselectivity of Cobalamin-Dependent Methyltransferase Can Be Tuned by Reaction Conditions and Substrate
Regioselective reactions represent a significant challenge for organic chemistry. Here the regioselective methylation of a single hydroxy group of 4-substituted catechols was investigated employing the cobalamin-dependent methyltransferase from Desulfitobacterium hafniense. Catechols substituted in position four were methylated either in meta- or para-position to the substituent depending whether the substituent was polar or apolar. While the biocatalytic cobalamin dependent methylation was meta-selective with 4-substituted catechols bearing hydrophilic groups, it was para-selective for hydrophobic substituents. Furthermore, the presence of water miscible co-solvents had a clear improving influence, whereby THF turned out to enable the formation of a single regioisomer in selected cases. Finally, it was found that also the pH led to an enhancement of regioselectivity for the cases investigated.
Pompei, Simona,Grimm, Christopher,Farnberger, Judith E.,Schober, Lukas,Kroutil, Wolfgang
p. 5977 - 5983
(2020/10/06)

Selective catalytic transformation of lignin with guaiacol as the only liquid product
Guaiacol is an important feedstock for producing various high-value chemicals. However, the current production route of guaiacol relies heavily on fossil resources. Using lignin as a cheap and renewable feedstock to selectively produce guaiacol has great potential, but it is a challenge because of its heterogeneity and inert reactivity. Herein, we discovered that La(OTf)3 could catalyze the transformation of lignin with guaiacol as the only liquid product. In the reaction, La(OTf)3 catalyzed the hydrolysis of lignin ether linkages to form alkyl-syringol and alkyl-guaiacol, which further underwent decarbonization and demethoxylation to produce guaiacol with a yield of up to 25.5 wt%, and the remaining residue was solid. In the scale-up experiment, the isolated yield of guaiacol reached up to 21.2 wt%. To our knowledge, this is the first work to produce pure guaiacol selectively from lignin. The bio-guaiacol may be considered as a platform to promote lignin utilization.
Shen, Xiaojun,Meng, Qinglei,Mei, Qingqing,Liu, Huizhen,Yan, Jiang,Song, Jinliang,Tan, Dongxing,Chen, Bingfeng,Zhang, Zhanrong,Yang, Guanying,Han, Buxing
p. 1347 - 1352
(2020/02/15)

Decyanation method of nitrile organic compound
The invention provides a decyanation method of a nitrile organic compound. The nitrile organic compound shown in a general formula (1), a sodium reagent, crown ether and a proton donor are subjected to decyanation reaction in an organic solvent I to generate an organic compound shown in a general formula (2). According to the method, a Na/15-crown-5/H2O system is adopted, so that nitrile organic matters can be converted into a decyanation product, and the generation of amine byproducts is inhibited. The new method does not need to use liquid ammonia as a solvent, and is safer and more convenient to operate. The required sodium dispersoid is low in price; and the 15-crown-5 can be recycled and repeatedly used. The method has the advantages of good chemical selectivity, wide substrate application range, good functional group compatibility and the like.
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Paragraph 0075-0078

(2020/02/10)

Soft template-based bismuth doped zinc oxide nanocomposites for photocatalytic depolymerization of lignin
Lignin depolymerization is a growing research area for the synthesis of aromatic molecules. In current studies, photocatalytic lignin depolymerization has been investigated by designing a series of soft template-based Zn0.95Bi0.05O nano-materials (SK1-SK5). Synthesized nano-materials were characterized by PXRD, SEM/EDX, BET, FTIR and utilized for photocatalytic lignin depolymerization in the presence of direct sunlight. Lignin depolymerization was monitored by UV–Visible Spectroscopy and catalytic pathway analyzed by different kinetic models. Percent depolymerization was studied for the effect of catalyst dose, starting lignin concentration and different temperatures. Pseudo second order was found the best fitted kinetic model indicating chemically rate controlled mechanism. Activation energy (Ea) for the reaction was found to be 11 kJ/mol that is remarkably lower than conventional lignin depolymerization i.e. 59.75 kJ/mol depicting better catalytic efficiencies of tested materials. Lignin depolymerization products were characterized by HPLC and FTIR Spectroscopy and their analysis indicated the conversion of lignin into smaller subunits like syringaldehyde, sinapyl alcohol, phthalates, and 4-hydroxy-benzoic acid. Specifically, phenol (21%) and 2-methoxy-4-methylphenol (16%) were detected by GCMS analysis in the products of lignin depolymerization by SK2.
Kausar, Samia,Ali Altaf, Ataf,Hamayun, Muhammad,Danish, Muhammad,Zubair, Muhammad,Naz, Sumbal,Muhammad, Shabbir,Zaheer, Muhammad,Ullah, Shafiq,Badshah, Amin
(2020/01/02)

Scale-up biopolymer-chelated fabrication of cobalt nanoparticles encapsulated in N-enriched graphene shells for biofuel upgrade with formic acid
Exploring both high-performance catalytic materials from non-edible lignocellulosic biomass and selective hydrodeoxygenation of bioderived molecules will enable value-added utilization of renewable feedstocks to replace rapidly diminishing fossil resources. Herein, we developed a scale-up and sustainable method to fabricate gram-quantities of highly dispersed cobalt nanocatalysts sheathed in multilayered N-doped graphene (Co@NG) by using a biomacromolecule carboxymethyl cellulose (CMC) as a raw material. The ionic gelation of CMC, urea and Co2+ ions leads to uniform dispersion and chelation of different species, consequently resulting in the formation of highly distributed Co nanoparticles (NPs) (10.91 nm) with N-enriched graphene shells in the solid-state thermolysis process. The usage of urea as a non-corrosive activation agent can introduce a porous belt-like nanostructure and abundant doped nitrogen. Among all the prepared catalysts in this work, the optimized Co@NG-6 with the largest specific surface area (627 m2 g-1), the most and strongest basic sites, and the highest proportion of pyridinic-N (37.6%) and mesopores exhibited excellent catalytic activity (99% yield of 2-methoxy-p-cresol) for base-free transfer hydrodeoxygenation (THD) of vanillin using bioderived formic acid (FA) as a H source at 160 °C for 6 h. The poisoning tests and electron paramagnetic resonance (EPR) spectra verified that the strong interaction between N atoms and encapsulated Co NPs provided synergistic effects, which were essential for the outstanding catalytic performance of Co@NG-6. The deuterium kinetic isotope effect study clearly demonstrated that the formation of Co-H-via β-hydride elimination and protonation was the rate-determining step, and protic N-H+ and hydridic Co-H- were considered to be active intermediate species in the THD reaction. Furthermore, Co@NG-6 was highly stable for recycling owing to the graphene shells preventing Co NPs from corrosion and aggregation.
Zhou, Shenghui,Dai, Fanglin,Dang, Chao,Wang, Ming,Liu, Detao,Lu, Fachuang,Qi, Haisong
p. 4732 - 4747
(2019/09/16)

Nickel-catalyzed intelligent reductive transformation of the aldehyde group using hydrogen
The selective transformation of the aldehyde group (-CHO) in multifunctional oxygenates is a key challenge in the development of sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst was developed from a 2D Ni-based metal-organic framework (MOF), which efficiently promoted the transformation of -CHO in the presence of H2 to a methyl group (-CH3) via the reductive etherification and hydrogenolysis of the C-O ether bond in methanol. Moreover, the catalytic process could be controlled to directionally produce methyl ether (-CH2OR) using the reductive etherification protocol. For the catalytic reduction of vanillin, the Ni-MFC-700 catalyst guaranteed the full conversion of vanillin and 96.5% yield of the desired 2-methoxy-4-methylphenol (MMP), while the Ni-MFC-500 catalyst afforded about 82.7% yield of 4-(methoxymethyl)-2-methoxyphenol in methanol solvent. This is a novel and promising approach for the valorization of multifunctional oxygenates and biomass-derived platform compounds.
Tong, Xinli,Guo, Pengfei,Liao, Shengyun,Xue, Song,Zhang, Haigang
p. 5828 - 5840
(2019/11/11)

Cooperative catalysis at the metal-MOF interface: Hydrodeoxygenation of vanillin over Pd nanoparticles covered with a UiO-66(Hf) MOF
Cooperative catalysis has been demonstrated over metal-MOF hybrids for the conversion of vanillin (biomass based platform molecules) into value-added 2-methoxy-4-methylphenol. Over a Pd@UiO-66(Hf) core-shell catalyst, cooperativity between Br?nsted acidic μ3-OH groups and Pd active sites present at the interface has rendered a catalytic performance of >99% vanillin conversion and >99% 2-methoxy-4-methylphenol selectivity at 90 °C under 3 bar H2 in water. An enhanced cooperative effect has been observed over a core-shell catalyst compared to a support catalyst.
Bakuru, Vasudeva Rao,Davis, Deljo,Kalidindi, Suresh Babu
p. 8573 - 8577
(2019/06/24)

Influence of Carbon Supports on Palladium Nanoparticle Activity toward Hydrodeoxygenation and Aerobic Oxidation in Biomass Transformations
Three palladium catalysts at similar loadings supported on few-layers graphene (FLG), carbon nanotubes (CNT) and carbon nanofibers (CNF) have been prepared by wet impregnation of palladium nitrate with the purpose of determine the influence of the support on Pd catalytic activity. The supports and catalysts have been characterized by chemical analysis, Raman spectroscopy, XRD, electron microscopy and XPS. The average Pd particle size depends on the carbon support, ranging from 1.6 nm for CNF to 2.6 nm for FLG. The catalytic activity of these catalysts was evaluated for two different reactions of interest for biomass transformations, namely hydrodeoxygenation of vanillin to 2-methoxy-4-methyl-phenol (creosol) that requires a bifunctional catalyst with hydrogenating and Lewis acid sites, and aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Both compounds have application either as food flavouring additive and polyester co-monomer. For the two reactions the activity order of the fresh catalyst was Pd/FLG > Pd/CNF > Pd/CNT, indicating that FLG contributes favorably to the activity in spite of the larger Pd size of the nanoparticles on this support, a fact that has been attributed to the interaction with the prismatic planes on where Pd nanoparticles are located.
Espinosa, Juan C.,Contreras, Rubén Castro,Navalón, Sergio,Rivera-Cárcamo, Camila,álvaro, Mercedes,Machado, Bruno F.,Serp, Philippe,Garcia, Hermenegildo
p. 1979 - 1987
(2019/04/01)

Reductive Cleavage of Unactivated Carbon-Cyano Bonds under Ammonia-Free Birch Conditions
A general protocol for the reductive cleavage of unactivated carbon-cyano bonds in aliphatic nitriles has been achieved under single-electron-transfer conditions using Na/15-crown-5/H2O. Electron is supplied by the electride derived from bench-stable sodium dispersions and recoverable 15-crown-5. H2O provides the proton source and suppresses the reduction of aromatic moieties. Compared with the Na/NH3 electride system generated under traditional Birch conditions, this ammonia-free electride system is more practical and features better reactivity and chemoselectivity for the decyanations of a broad range of aliphatic nitriles.
An, Jie,Ding, Yuxuan,Luo, Shihui,Ma, Lifu
(2019/11/29)

Role of copper- or cerium-promoters on NiMo/Γ-Al2O3 catalysts in hydrodeoxygenation of guaiacol and bio-oil
Effect of copper (Cu) or cerium (Ce) as promoters for nickel-molybdenum/γ-alumina (NiMo/γ-Al2O3) catalyst on the hydrodeoxygenation (HDO) of guaiacol (GUA), a model oxygenated compound found in a bio-oil derived from woody biomass, was comparatively investigated. The addition of Cu- or Ce-promoters affected the physicochemical properties of the NiMo catalyst. The NiMo catalyst promoted by Cu showed the higher reducibility, whilst the Ce-promoter (2–8 wt% based on γ-Al2O3 content) provided the NiMo catalyst with a higher distribution of active metals and induced a greater difficulty in the reduction under hydrogen (H2) atmosphere. For the HDO of GUA at a mild reaction condition (10 bar initial H2 pressure and 300 °C) in the absence of solvent, the Cu-promoter enhanced the hydrogenation activity of the NiMo catalyst to convert GUA to phenol and methylphenols, one-atomic oxygen species. Whereas, the addition of Ce obviously inhibited the formation of coke on the catalyst surface after a long reaction period (6 h) and gave a higher GUA conversion level with increasing yield of phenols. For the HDO of real bio-oil obtained from the fast pyrolysis of cassava rhizome, the NiMo catalysts promoted by Cu or Ce at 4 wt% based on the γ-Al2O3 content showed a higher performance at eliminating the oxygenated compounds in the bio-oil, reducing the oxygen/carbon (O/C) molar ratio by over seven-fold from 1.75 to 0.24–0.25. Moreover, the gross heating value of the bio-oil was improved from 21.5 to ca. 29.0 MJ/kg after the HDO process. However, the addition of the Cu or Ce promoter did not inhibit coke deposition, possibly due to the acidic properties of the bio-oil that deteriorated the catalyst performance by metal leaching.
Sangnikul, Patiphat,Phanpa, Chanisara,Xiao, Rui,Zhang, Huiyan,Reubroycharoen, Prasert,Kuchonthara, Prapan,Vitidsant, Tharapong,Pattiya, Adisak,Hinchiranan, Napida
p. 151 - 160
(2019/02/17)

Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)
Catalytic hydrogenolysis of diaryl ethers is achieved by using ruthenium nanoparticles immobilized on an acidic supported ionic liquid phase (Ru@SILP-SO 3 H) as a multifunctional catalyst. The catalyst components are assembled through a molecular approach ensuring synergistic action of the metal and acid functions. The resulting catalyst is highly active for the hydrogenolysis of various diaryl ethers. For symmetric substrates such as diphenyl ether, hydrogenolysis is followed by full hydrodeoxygenation producing the corresponding cycloalkanes as the main products. For unsymmetric substrates, the cleavage of the C-O bond is regioselective and occurs adjacent to the unsubstituted phenyl ring. As hydrogenation of benzene is faster than hydrodeoxygenation over the Ru@SILP-SO 3 H catalyst, controlled mixtures of cyclohexane and substituted phenols are accessible with good selectivity. Application of Ru@SILP-SO 3 H catalyst in continuous-flow hydrogenolysis of 2-methoxy-4-methylphenoxybenzene is demonstrated with use of commercial equipment.
Rengshausen, Simon,Etscheidt, Fabian,Gro?kurth, Johannes,Luska, Kylie L.,Bordet, Alexis,Leitner, Walter
p. 405 - 412
(2019/02/26)

Catalytic activation of unstrained C(aryl)–C(aryl) bonds in 2,2′-biphenols
Transition metal catalysis has emerged as an important means for C–C activation that allows mild and selective transformations. However, the current scope of C–C bonds that can be activated is primarily restricted to either highly strained systems or more polarized C–C bonds. In contrast, the catalytic activation of non-polar and unstrained C–C moieties remains an unmet challenge. Here we report a general approach for the catalytic activation of the unstrained C(aryl)–C(aryl) bonds in 2,2′-biphenols. The key is to utilize the phenol moiety as a handle to install phosphinites as a recyclable directing group. Using hydrogen gas as the reductant, monophenols are obtained with a low catalyst loading and high functional group tolerance. This approach is also applied to the synthesis of 2,3,4-trisubstituted phenols. A further mechanistic study suggests that the C–C activation step is mediated by a rhodium(i) monohydride species. Finally, a preliminary study on breaking the inert biphenolic moieties in lignin models is illustrated.
Zhu, Jun,Wang, Jianchun,Dong, Guangbin
p. 45 - 51
(2018/11/23)

Cobalt Nanoparticles Supported on Nitrogen-Doped Carbon: An Effective Non-Noble Metal Catalyst for the Upgrade of Biofuels
A new method has been developed for the deoxygenation of vanillin to produce 2-methoxy-4-methylphenol (MMP) as a promising liquid fuel over a heterogeneous non-noble metal catalyst. Cobalt nanoparticles supported on nitrogen-doped carbon (Co/N-C-600) exhibit high activity and stability for the deoxygenation of vanillin into MMP under mild conditions (150 °C, 10 bar H2). Nearly quantitative MMP yield is obtained in isopropanol after 8 h at 150 °C and 10 bar H2 pressure. According to the distribution of products with time, the deoxygenation of vanillin into MMP mainly proceeds through the hydrogenation of vanillin into vanillyl alcohol and the subsequent hydrogenolysis of vanillyl alcohol into MMP, of which the latter is the rate-determining step, owing to a much higher activation energy. Moreover, after being recycled several times, the loss of catalytic activity is negligible, which demonstrates that the Co/N-C-600 catalyst shows good resistance to deactivation.
Jiang, Liang,Zhou, Peng,Liao, Chanjuan,Zhang, Zehui,Jin, Shiwei
p. 959 - 964
(2018/02/16)

Phosphonic acid promotion of supported Pd catalysts for low temperature vanillin hydrodeoxygenation in ethanol
Bifunctional catalysts with activity for both hydrogenation and dehydration have been frequently investigated for hydrodeoxygenation (HDO). Here, we report the application of organophosphonic acids (PAs) to Pd/Al2O3 catalysts for low-temperature vanillin HDO. Reaction studies indicated that PA-modification significantly improved the liquid-phase HDO activity; the yield to the desirable product, p-creosol (CR), increased from 2.5% to 87% at 50 °C. This improvement was attributed to the creation of metal/acid bifunctional sites upon PA modification. In addition, HDO activity positively correlated with the Br?nsted acidity of the PA modifier, which could be tuned by adjusting the PA tail functionality.
Hao, Pengxiao,Schwartz, Daniel K.,Medlin, J. Will
p. 1 - 6
(2018/05/24)

Pd Nanoparticles Supported on Cellulose as a Catalyst for Vanillin Conversion in Aqueous Media
Palladium nanoparticles were first anchored on modified biopolymer as an efficient catalyst for a biofuel upgrade. Fluorinated compounds was grafted onto cellulose to obtain amphiphilic supports for on water reactions. Pd catalyst was prepared by straightforward deposition of metal nanoparticles on modified cellulose. The catalyst exhibited excellent catalytic activity and selectivity in hydrodeoxygenation of vanillin (a typical model compound of lignin) to 2-methoxy-4-methylphenol under atmospheric hydrogen pressure in neat water without any other additives under mild conditions.
Li, Dan-Dan,Zhang, Jia-Wei,Cai, Chun
p. 7534 - 7538
(2018/05/29)

Highly Dispersed Copper Nanoparticles Supported on Activated Carbon as an Efficient Catalyst for Selective Reduction of Vanillin
Highly dispersed copper nanoparticles (Cu NPs) supported on activated carbon (AC) are effectively synthesized by one-pot carbothermal method at temperature range of 400–700 °C. The X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis reveal that Cu NPs with diameters of 20–30 nm are evenly anchored in carbon matrix. The 15 wt%-Cu/AC-600 catalyst (derived at 600 °C) exhibits best bifunctional catalysis of aqueous-phase hydrodeoxygenation (HDO) and organic-phase transfer-hydrogenation reaction (THR) to selectively transform vanillin to 2-methoxy-4-methylphenol (MMP). In HDO of vanillin, the as-prepared catalyst achieves a 99.9% vanillin conversion and 93.2% MMP selectivity under 120 °C, 2.0 MPa H2 within 5 h. Meanwhile, near-quantitative vanillin conversion and 99.1% MMP selectivity are also obtained under 180 °C within 5 h in THR of vanillin by using 2-propanol as hydrogen donor. The transforming pathways of vanillin are also proposed: vanillin is transformed into MMP via intermediate of 4-hydroxymethyl-2-methoxyphenol in HDO case and by direct hydrogenolysis of vanillin in THR course. More importantly, the activity and the selectivity do not change after 5 cycles, indicating the catalyst has excellent stability. The Cu-based catalyst is relatively cheap and preparation method is facile, green, and easy scale-up, thus achieving a low-cost transformation of biomass to bio-oils and chemicals.
Fan, Ruoyu,Chen, Chun,Han, Miaomiao,Gong, Wanbing,Zhang, Haimin,Zhang, Yunxia,Zhao, Huijun,Wang, Guozhong
(2018/08/11)

RETRACTED ARTICLE: Room-temperature hydrogenation of levulinic acid by uniform nano-TiO2 supported Ru catalysts
Uniform TiO2 nanoparticles (NPs) is synthesized by a facile hydrothermal approach and used as support for Ru NPs. It is found that HF amount has a considerable influence in the size and uniformity of TiO2 NPs, and the optimized Ru/TiO2-0.4 is highly efficient for fast room-temperature hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in water. For example, Ru/TiO2-0.4 Exhibits 5.1 times higher activity in comparison with commercial TiO2 supported Ru (Ru/TiO2-C), and affords 97.4% LA conversion and >99% GLV selectivity at 30 °C and 1 MPa H2 for 30 min. In particular, Ru/TiO2-0.4 can even reach 88.5% LA conversion at lower temperature to 10 °C. This catalyst is stable for recycle and also affords good conversion as well as high selectivity for hydrodeoxygenation (HDO) of biomass-derived vanillin, attributed to smaller sized TiO2 NPs, easier electron donation from TiO2 to Ru and higher reducibility of Ru species.
Li, Guoqiang,Yang, Huanhuan,Cheng, Mei,Hu, Wei,Tian, Lihong,Mao, Wuxiang,Nie, Renfeng
p. 95 - 102
(2018/06/19)

Selective C-C Bond Cleavage of Methylene-Linked Lignin Models and Kraft Lignin
Biorefinery and paper pulping lignins, referred hereto as technical lignins, contain condensed C-C interunit linkages. These robust C-C linkages with higher bond dissociation energies are difficult to disrupt under hydrogenolysis conditions, which are gen
Shuai, Li,Sitison, Jake,Sadula, Sunitha,Ding, Junhuan,Thies, Mark C.,Saha, Basudeb
p. 6507 - 6512
(2018/06/13)

A High Mobility Reactor Unit for R&D Continuous Flow Transfer Hydrogenations
A suitcase sized mobile reactor unit (MRU) weighing in at less than 10 kg was designed for laboratory scale transfer hydrogenations in continuous flow. Simple cyclohexene and a cosolvent in combination with a palladium-on-charcoal packed bed reactor provided a setup with isolation of nearly all products without the need for further purification. Several functional groups including olefins, triple bonds, nitro-groups, carbonyls, and so forth were effectively reduced with retention times as low as 2 min. Additionally, standard protection groups such as Cbz, benzyl, and allyl ether or esters were removed in high yields. To prove the flexibility of the setup an example of the Mizoroki-Heck reaction was also performed on the MRU. Finally, two scale-up transfer hydrogenation experiments were performed affording isolation of the desired target compounds in 0.5 and 0.8 mol scales with less than 4 h of continuous operation on the MRU.
Jensen, Rasmus K.,Thykier, Nikolaj,Enevoldsen, Martin V.,Lindhardt, Anders T.
supporting information
p. 370 - 376
(2017/03/24)

Auto-Tandem Catalysis with Frustrated Lewis Pairs for Reductive Etherification of Aldehydes and Ketones
Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H2, R-OH or H2O generates the required Br?nsted acid in a reversible, “turn on” manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.
Bakos, Mária,Gy?m?re, ádám,Domján, Attila,Soós, Tibor
supporting information
p. 5217 - 5221
(2017/04/27)

Transfer hydrogenation of bio-fuel with formic acid over biomass-derived N-doped carbon supported acid-resistant Pd catalyst
Nitrogen-enriched highly mesoporous carbons (NMCs) are synthesized via the one-pot carbonization of biomass-derived glucose and harmless melamine with ZnCl2 as the porogen agent and catalyst. NMC contains an N content of 15.4 wt% and specific surface area of 1017 m2 g-1 with the mesopore volume proportion of 92.1%. Owing to its rich N species and high mesoporosity, NMC can be adapted as a proper support for the fabrication of well-dispersed Pd catalysts for the transfer hydrogenation of vanillin in the water phase with formic acid (FA) as the hydrogen donor. For example, Pd/NMC exhibits 2.9 times higher activity in comparison to nitrogen-free catalysts, and affords 100% vanillin conversion with 2-methoxy-4-methylphenol (MMP) as the sole product. The Pd/NMC catalyst demonstrates enhanced acid-resistance in acid media and adsorption of substrates. It is found that the electron-deficient Pd (Pdδ+) percentage is affected by the N species, and the strong Pd-N interaction generates the co-existence of Pdδ+ and metallic Pd (Pd0), which results in Pd/NMC as a novel bifunctional nanocatalyst for both FA dehydrogenation and vanillin hydrogenation.
Nie, Renfeng,Peng, Xiaolun,Zhang, Haifu,Yu, Xiaolong,Lu, Xinhuan,Zhou, Dan,Xia, Qinghua
p. 627 - 634
(2017/03/01)

Method for reducing carbonyl into methylene at normal temperature and normal pressure
The invention discloses a method for reducing carbonyl into methylene at normal temperature and normal pressure. The method includes the following steps that a carbonyl compound, a nitrogen doped carbon material loaded palladium catalyst and a solvent are added into a reaction container, the ratio of the carbonyl compound to the nitrogen doped carbon material loaded palladium catalyst is (1-5) mol:(10-40) g, hydrogen is introduced, reacting is carried out for 0.5-20 h at normal temperature and normal pressure, and carbonyl can be reduced into methylene through catalytic hydrogenation. The reaction formula of the reaction is shown in the specification. The method is simple, easy to operate, mild in condition, high in conversion rate, good in selectivity, low in cost and free of pollution to the environment.
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Paragraph 0031; 0032; 0033; 0034; 0036; 0037; 0038

(2017/04/29)

A sustainable approach to empower the bio-based future: Upgrading of biomass via process intensification
An economically viable and environmentally benign continuous flow intensified process has been developed that demonstrates its ability to upgrade biomass into potential biofuels, solvents, and pharmaceutical feedstocks using a bimetallic AgPd@g-C3N4 catalyst.
Tadele, Kidus,Verma, Sanny,Gonzalez, Michael A.,Varma, Rajender S.
supporting information
p. 1624 - 1627
(2017/05/16)

Co embedded within biomass-derived mesoporous N-doped carbon as an acid-resistant and chemoselective catalyst for transfer hydrodeoxygenation of biomass with formic acid
An N-doped Co@C catalyst (Co@NC) is synthesized by a one-pot carbonization of biomass-derived glucose and harmless melamine with CoCl2 as the catalyst, where C and N resources could be transformed into highly graphitic N-doped carbon, while the coordinated Co2+ ions are reduced to uniform Co nanoparticles (NPs), which are embedded in N-doped graphitic structures. Under base-free conditions with formic acid (FA) as a hydrogen donor, the optimized Co@NC-700 (pyrolyzed at 700 °C) shows a highly efficient H2 generation from FA and the best activity for vanillin hydrodeoxygenation (HDO) with FA. For example, Co@NC-700 exhibits 15.4 times higher activity in comparison with uncovered Co on AC (Co/AC), and affords >95% vanillin conversion with 2-methoxy-4-methylphenol (MMP) as the sole product at 180 °C for 4 h. Compared with molecular hydrogen, Co@NC-700 gives a much higher activity and MMP selectivity for vanillin HDO with FA. The Co@NC-700 demonstrates enhanced acid resistance in acidic medium and adsorption of vanillin, and is recyclable and versatile for hydrogenating various unsaturated compounds. The superior performance of Co@NC-700 could be ascribed to N-derived defective sites on Co@NC, which could play multiple roles as base additives in FA dehydrogenation and as a metal-like active center in vanillin HDO.
Yang, Huanhuan,Nie, Renfeng,Xia, Wang,Yu, Xiaolong,Jin, Dingfeng,Lu, Xinhuan,Zhou, Dan,Xia, Qinghua
p. 5714 - 5722
(2017/12/06)

Method of synthesizing 2-alkoxyl-4-methylphenol with 2-bromine-4-methylphenol
The invention provides a method of synthesizing 2-alkoxyl-4-methylphenol with 2-bromine-4-methylphenol. The method comprises the step of allowing alkyl sodium alkoxide to react with 2-bromine-4-methylphenol in the presence of alkanol and in a near-critical state of alkanol. According to the method, a reaction condition of alkanol in the near-critical state is adopted; a catalyst and a promoter are substituted for catalyzed synthesis of 2-alkoxyl-4-methylphenol; the method is a green reaction technology; alkanol can be recovered in a simple distillation manner after reaction; an atom utilization ratio is higher; a conversion rate of the reactor, 2-bromine-4-methylphenol, can reach above 97.9% and 100% at most; and the selectivity of the product, 2-alkoxyl-4-methylphenol, can reach above 93.4%.
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Paragraph 0042-0072

(2017/07/22)

Selective hydrogenolysis of carbon-oxygen bonds with formic acid over a Au-Pt alloy catalyst
We reported selective hydrogenolysis of carbon-oxygen species over a CeO2-supported Au-Pt alloy catalyst (Au-Pt/CeO2) using biomass-derived formic acid as the hydrogen source. The success of this reaction is reasonably attributed to the high efficiency of Au-Pt/CeO2 in the tandem steps of formic acid dehydrogenation and carbon-oxygen species hydrodeoxygenation.
Wang, Liang,Zhang, Jian,Wang, Guoxiong,Zhang, Wei,Wang, Chengtao,Bian, Chaoqun,Xiao, Feng-Shou
supporting information
p. 2681 - 2684
(2017/03/10)

Examination of Selectivity in the Oxidation of ortho- and meta-Disubstituted Benzenes by CYP102A1 (P450 Bm3) Variants
Cytochrome P450 CYP102A1 (P450 Bm3) variants were used to investigate the products arising from the P450 catalysed oxidation of a range of disubstituted benzenes. The variants used all generated increased levels of metabolites compared to the wild-type enzyme. With ortho-halotoluenes up to six different metabolites could be identified whereas the oxidation of 2-methoxytoluene generated only two aromatic oxidation products. Addition of an ethyl group markedly shifted the selectivity for oxidation to the more reactive benzylic position. Epoxidation of an alkene was also preferred to aromatic oxidation in 2-methylstyrene. Significant minor products arising from the migration of one substituent to a different position on the benzene ring were formed during certain P450-catalysed substrate turnovers. For example, 2-bromo-6-methylphenol was formed from the turnover of 2-bromotoluene and the dearomatisation product 6-ethyl-6-methylcyclohex-2,4-dienone was generated from the oxidation of 2-ethyltoluene. The RLYF/A330P variant altered the product distribution enabling the generation of certain metabolites in higher quantities. Using this variant produced 4-methyl-2-ethylphenol from 3-ethyltoluene with ≥90 % selectivity and with a biocatalytic activity suitable for scale-up of the reaction.
Munday, Samuel D.,Dezvarei, Shaghayegh,Lau, Ian C.-K.,Bell, Stephen G.
p. 2512 - 2522
(2017/07/12)

Palladium Nanoparticles Encaged in a Nitrogen-Rich Porous Organic Polymer: Constructing a Promising Robust Nanoarchitecture for Catalytic Biofuel Upgrading
Robust nanoarchitectures based on surfactant-free ultrafine Pd nanoparticles (NPs) (2.7–8.2±0.5 nm) have been developed by using the incipient wetness impregnation method with subsequent reduction of PdII species encaged in the 1,3,5-triazine-functionalized nitrogen-rich porous organic polymer (POP) by employing NaBH4, HCHO, and H2 reduction routes. The Pd-POP materials prepared by the three different synthetic methods consist of virtually identical chemical compositions but have different physical and texture properties. Strong metal–support interactions, the nanoconfinement effect of POP, and the homogeneous distribution of Pd NPs have been investigated by performing 13C cross-polarization (CP) solid-state magic angle spinning (MAS) NMR, FTIR, and X-ray photoelectron spectroscopy (XPS), along with wide-angle powder XRD, N2 physisorption, high-resolution (HR)-TEM, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray (EDX) mapping spectroscopic studies. The resulting Pd-POP based materials exhibit highly efficient catalytic performance with superior stability in promoting biomass refining (hydrodeoxygenation of vanillin, a typical compound of lignin-derived bio-oil). Outstanding catalytic performance (≈98 % conversion of vanillin with exclusive selectivity for hydrogenolysis product 2-methoxy-4-methylphenol) has been achieved over the newly designed Pd-POP catalyst under the optimized reaction conditions (140 °C, 10 bar H2 pressure), affording a turnover frequency (TOF) value of 8.51 h?1 and no significant drop in catalytic activity with desired product selectivity has been noticed for ten successive catalytic cycles, demonstrating the excellent stability and reproducibility of this catalyst system. A size- and location-dependent catalytic performance for the Pd NPs with small size (1.31±0.36 and 2.71±0.25 nm) has been investigated in vanillin hydrodeoxygenation reaction with our newly designed Pd-POP catalysts. The presence of well-dispersed electron-rich metallic Pd sites and highly rigid cross-linked amine-functionalized POP framework with high surface area is thought to be responsible for the high catalytic activity and improvement in catalyst stability.
Singuru, Ramana,Dhanalaxmi, Karnekanti,Shit, Subhash Chandra,Reddy, Benjaram Mahipal,Mondal, John
p. 2550 - 2564
(2017/07/12)