Publications

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2021

  • Simultaneously enhanced activity and selectivity for C(sp3)–H bond oxidation under visible light by nitrogen doping

    Tingting Hou, Zhuyan Gao, Jian Zhang, Nengchao Luo, and Feng Wang*

    Trans. Tianjin Univ., 2021, 27, 331–337

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    Herein, we constructed N-doped TiO2 nanotubes (N-TNTs) that exhibited remarkable activity and selectivity for toluene oxidation under visible light, delivering the conversion of toluene and selectivity of benzaldehyde of 32% and > 99%, respectively. Further mechanistic studies demonstrated that the incorporation of nitrogen induced the generation of N-doping level above the O 2p valance band, directly contributing to the visible-light response of TiO2. Furthermore, hydroxyl radicals generated by photogenerated holes at the orbit of O 2p were found to be unselective for the oxidation of toluene, affording both benzaldehyde and benzoic acid. The incorporation of nitrogen was able to inhibit the generation of hydroxyl radicals, terminating the formation of benzoic acid.

  • Oxygen-controlled photo-reforming of biopolyols to CO over Z-scheme CdS@g-C3N4

    Hongru Zhou, Min Wang*, and Feng Wang*

    Chem., 2021, DOI: 10.1016/j.chempr.2021.10.021

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    Carbon monoxide (CO) is a large-scale feedstock and fuel, which is industrially produced from steam reforming of coal and methane at high temperatures. Photocatalytic CO production from biomass at room temperature is a promising route but still shows low activity. Targeting this problem, we propose an oxygen-controlled photo-reforming method to promote CO evolution from biopolyols and sugars. Appropriate O2 content turns the reaction into thermodynamically favorable, thus accelerating the CO generation rate. A core-shell structure Z-scheme CdS@g-C3N4 was prepared as the photocatalyst. The particular catalyst structure facilitates the adsorption and activation of dioxygen, thus accelerating the CO evolution.

  • Photocatalytic conversion of waste plastics to low carbon number organic products

    Kaiyi Su, Huifang Liu, Chaofeng Zhang, and Feng Wang*

    Chin. J. Catal., 2021, DOI: 10.1016/S1872-2067(21)63885-8

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    As a great threat to all livings on earth, waste artificial plastics now are everywhere, from oceans to our cells. The world cannot withstand the growing waste plastic in million tonnes every year, which has already caused environmental pollution and economic losses. Besides the efforts for preparing novel plastics with the self-decomposition ability, the world needs methods to clear away these waste plastics leftover from history or recycle well this organic carbon resource. Photocatalysis is a potential solution for the conversion of waste plastics under mild conditions. In this perspective, we highlight the effect of photocatalytic approaches toward the generation of low carbon number organic products (Cn products, n ≤ 8) from waste plastics, which can proceed under an inert or aerobic atmosphere. Notably, critical analysis of the carbon source in products is necessary to reveal the active species for the C–X bonds (X = C, N, and O) cleavage of plastics... ...

  • Catalysis of positively charged Ru species stabilized by hydroxyapatite in amine formylation

    Yehong Wang*, Dongxia Jiao, Zhixin Zhang, Jian Zhang, Lijun Lei, and Feng Wang*

    ChemCatChem, 2021, DOI: 10.1002/cctc.202100937

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    Formamide is an important solvent and synthetic intermediate. Herein, we designed a hydroxyapatite (HAP)-stabilized, positively charged Ru-based catalysts which can efficiently catalyze the formylation reaction of amines with CO for the synthesis of formamide. The Ru-HAP showed excellent catalytic performance in N,N-Dimethylformamide (DMF) synthesis, with about 75% DMA (dimethylamine) conversion and >99% DMF selectivity at 300 h of continuous reaction. The combination of characterization results and control experiments showed that positively charged Ru species, including hydrated RuO x and Ru 3+ species, were catalytically active. In particular, the surface RuO x species were more active than the Ru 3+ species located within the HAP framework.

  • Oxygen-vacancy-mediated catalytic methanation of lignocellulose at temperatures below 200 °C

    Hongru Zhou, Min Wang*, and Feng Wang*

    Joule, 2021, DOI: 10.1016/j.joule.2021.07.001

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    Biomethane is a clean energy and a key platform chemical for modern chemical industries. The conversion of biomass, especially the most abundant lignocellulose, into biomethane is challenging and shows low selectivity either in chemical or biological processes. Herein, we report the direct methanation of biomass at temperatures below 200°C with >95% selectivity using interfacial oxygen-vacancy (VO)-mediated catalysis over Ru/TiO2. The biomass feedstock is oxidized by TiO2 to form CO2 and VO, and CO2 is then in situ reduced on Ru sites to CH4, restoring the oxygen to VO simultaneously. Various biomass resources were converted into methane with 82%–99% yields. Even lowering the temperature to 120°C, about 0.24 mmol g−1 h−1 of CH4 with >99% selectivity was steadily produced from 50 wt % aqueous glycerol for 432 h. In situ X-ray photoelectron spectroscopy, infrared spectrometry, and DFT calculation confirm the VO-mediated catalysis process over Ru/TiO2.

  • Tuning the Pt species on Nb2O5 by support-induced modification in the photocatalytic transfer hydrogenation of phenylacetylene

    Kaiyi Su, Yehong Wang, Chaofeng Zhang, Zhuyan Gao, Jianyu Han, and Feng Wang*

    Appl. Catal. B-Environ., 2021, 298, 120554

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    Herein, we reported the tuning of dominant products in the photocatalytic hydrogen transfer reaction over Pt/Nb2O5 photocatalysts, using a support-induced modification strategy. In the photocatalytic conversion of phenylacetylene with ethanol as a probe reaction, the dominant product was styrene over Pt/2D Nb2O5 nanoplates; in contrast, H2 was the main product over the Pt/bulk Nb2O5. Compared to the metallic Pt species over bulk Nb2O5, the positively charged Pt (Ptδ+) species over 2D Nb2O5 nanoplates contributed to the reduction of phenylacetylene, which was revealed by CO adsorbed Fourier transform infrared spectra.

  • Ceria-based materials for thermocatalytic and photocatalytic organic synthesis

    Xiubing Huang*, Kaiyue Zhang, Baoxiang Peng, Ge Wang*, Martin Muhler*, and Feng Wang*

    ACS Catal., 2021, 11, 9618-9678

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    Value-added chemicals, fuels, and pharmaceuticals synthesized by organic transformation from raw materials via catalytic techniques have attracted enormous attention in the past few decades. Heterogeneous catalysts with high stability, long cycling life, good environmental-friendliness, and economic efficiency are greatly desired to accomplish the catalytic organic transformations. With the advantages of reversible Ce3+/Ce4+ redox pairs, tailorable oxygen vacancies, and surface acid–base properties, ceria-based catalysts have been actively investigated in the fields of catalytic organic synthesis. In this Review, we summarize the fundamentals and latest applications of ceria-based heterogeneous catalysts for organic transformations via thermocatalytic and photocatalytic routes.

  • Surface sulfate ion on CdS catalyst enhances syngas generation from biopolyols

    Zhe Zhang, Min Wang*, Hongru Zhou, and Feng Wang*

    J. Am. Chem. Soc., 2021, 143, 6533-6541

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    Photocatalytic biomass conversion represents an ideal way of generating syngas because of the sustainable use of biomass carbon and solar energy. However, the lack of efficient electron–proton transfer limits its efficiency. We here report an unprecedented method to simultaneously increase both the electron and proton transfer by creating surface sulfate ions on the CdS catalyst ([SO4]/CdS). Surface sulfate ion [SO4] is bifunctional, serving as the proton acceptor to promote proton transfer, and increasing the oxidation potential of the valence band to enhance electron transfer...

  • Controlling radical intermediates in photocatalytic conversion of low-carbon-number alcohols

    Zhuyan Gao, Nengchao Luo*, Zhipeng Huang, Stuart H. Taylor, and Feng Wang*

    ACS Sustain. Chem. Eng., 2021, 9, 6188-6202

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    Low-carbon number alcohols (LCNAs) are important platform molecules that can be derived from many resources, such as coal, oil, natural gas, biomass, and CO2, creating a route to value-added chemicals and fuels. Semiconductor photocatalysis provides a novel method for converting LCNAs into a variety of downstream products. Photocatalysis is initiated by light-excited charge carriers that are highly oxidative and reductive. The polarity and bond dissociation energy (BDE) of Cα–H bonds are small for alcohols, so it can be homolytically dissociated by the participation of photogenerated holes. Consequently, photocatalytic LCNA conversion overcomes the challenge of Cα–H bond activation in thermocatalysis. Apart from carbon radicals generated from Cα–H bond cleavage, many other radicals are formed during photocatalysis, which are active and have multiple conversion pathways, resulting in complex product distributions...

  • New advances in catalytic synthesis of acrylic acid

    Zhixin Zhang*, Yehong Wang, Chaofeng Zhang, Feng Wang*

    Chem. Ind.& Eng. Prog., 2021, 40, 2016-2033

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    Acrylic acid (AA) is an important industrial chemical intermediate and polymer monomer, which is in great demand. The rich coal resources and renewable biomass resources in China provide a solid material guarantee for the coal-based and biomass-based synthesis routes of acrylic acid. The two main routes were reviewed, including the synthesis routes of acrylic acid from coal-based chemicals, such as CO, low carbon alcohols (methanol and ethanol), formaldehyde, acetic acid, ethylene, and so on, and the synthesis routes of acrylic acid using glycerol, 3-hydroxypropionic acid, lactic acid, fumaric acid, and muconic acid. These routes are compared to provide a reference for the route selection...

  • Heterogeneous Ru/TiO2 for hydroaminomethylation of olefins: multicomponent synthesis of amines

    Jinghua An, Zhuyan Gao, Yehong Wang, Zhixin Zhang, Jian Zhang, Lu Li, Bo Tang, Feng Wang*

    Green Chem., 2021, doi: 10.1039/d1gc00113b.

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    Synthesizing amines via the hydroaminomethylation (HAM) reaction of olefins, a multicomponent reaction, has been regarded as one of the most attractive methods compared with the traditional methods considering the atom economy and environmental friendliness. However, the use of homogeneous catalysts, complex ligands containing diphosphine or nitrogen, and base or acid additives has severely hampered the utilization of these methods. Herein, an efficient heterogeneous Ru/TiO2-catalyzed HAM reaction of olefins is developed without any additives. Various amines, including secondary and tertiary amines, can be successfully obtained from olefins including aromatic and aliphatic olefins. Systematic studies demonstrate the lower electron density of Ruδ+ and the higher number of acid sites of Ru/TiO2, leading to the high HAM reaction activity of olefins. Most importantly, nitrobenzene derivatives can also be transformed to the corresponding products over Ru/TiO2 in excellent yields.

  • Catalytic cleavage of lignin C-O and C-C bonds

    Chaofeng Zhang, Feng Wang*

    Elsevier, 2021, 77, 175-218

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    In this chapter, focusing on lignin catalytic depolymerization to aromatic chemicals, we herein first provide our understanding about the scientific question and strategic foundation process in lignin depolymerization, and then clarify them by mainly presenting our recent studies. Firstly, we introduce our research on direct protolignin depolymerization via a fragmentation–hydrogenolysis process in alcohol solvents. Then, focusing on the catalytic cleavage of lignin C-C and C-O bonds, we shed light on a recapitulative adjacent functional group modification (AFGM) strategy for the conversion of lignin models and apply the established methods in the real lignin conversion via a bottom-up research approach......

  • Guidelines for performing lignin-first biorefining

    Mahdi M. Abu-Omar, Katalin Barta, Gregg T. Beckham*, Jeremy S. Luterbacher*, John Ralph*, Roberto Rinaldi, Yuriy Román-Leshkov, Joseph S. M. Samec*, Bert F. Sels, Feng Wang.

    Green Chem., 2021, 23, 2722-2728

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    We present herein a set of guidelines for analysing critical data from lignin-first approaches, including feedstock analysis and process parameters, with the ambition of uniting the lignin-first research community around a common set of reportable metrics. These guidelines comprise standards and best practices or minimum requirements for feedstock analysis, stressing reporting of the fractionation efficiency, product yields, solvent mass balances, catalyst efficiency, and the requirements for additional reagents such as reducing, oxidising, or capping agents. Our goal is to establish best practices for the research community at large primarily to enable direct comparisons between studies from different laboratories. The use of these guidelines will be helpful for the newcomers to this field and pivotal for further progress in this exciting research area.

  • Nb2O5‐based photocatalysts

    Kaiyi Su, Huifang Liu, Zhuyan Gao, Paolo Fornasiero*, Feng Wang*

    Adv. Sci., 2021, 8, 2003156

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    Niobium pentoxide (Nb2O5), a typically nontoxic metal oxide, is eco‐friendly and exhibits strong oxidation ability, and has attracted considerable attention from researchers. Furthermore, unique Lewis acid sites (LASs) and Brønsted acid sites (BASs) are observed on Nb2O5 prepared by different methods. Herein, the recent advances in the synthesis and application of Nb2O5‐based photocatalysts, including the pure Nb2O5, doped Nb2O5, metal species supported on Nb2O5, and other composited Nb2O5 catalysts, are summarized. An overview is provided for the role of size and crystalline phase, unsaturated Nb sites and oxygen vacancies, LASs and BASs, dopants and surface metal species, and heterojunction structure on the Nb2O5‐based catalysts in photocatalysis. Finally, the challenges are also presented, which are possibly overcome by integrating the synthetic methodology, developing novel photoelectric characterization techniques, and a profound understanding of the local structure of Nb2O5.

  • Advancing development of biochemicals through the comprehensive evaluation of bio-ethylene glycol

    Zhitong Zhao, Jingyang Jiang, Mingyuan Zheng, Feng Wang*

    Chem. Eng. J., 2021, 411, 128516

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    To achieve the economic benefits of bio-EG, research strategies, such as raising the product yield, changing hydrogen sources, increasing feedstock collection efficiency, and lowing water consumption were explored and proved to be effective measures. In addition, a carbon tax of 184 and 598 CNY·t-1 CO2eq are the breakeven points to reach economic benefits of bio-EG compared to petro-EG and coal-EG, respectively. This work aims at conducting a comprehensive evaluation of bio-EG to promote its practical application, and also shedding light on bright prospects and general approaches to develop lignocellulosic biochemicals.

  • Understanding the interaction between active sites and sorbents during the integrated carbon capture and utilization process

    Hongman Sun, Yehong Wang, Shaojun Xu, Ahmed I. Osman, Gavin Stenning, Jianyu Han, Shuzhuang Sun, David Rooney, Paul T. Williams*, Feng Wang*, Chunfei Wu*

    Fuel, 2021, doi:10.1016/j.fuel.2020.119308

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    The distance between catalytic sites (Ni) and sorbents (CaO) on the performance of integrated CO2 capture and utilization (ICCU) process is crucial important because the sorbents demonstrate a dramatic volume increase during carbonation reaction (1st stage of ICCU) and sequentially cover the catalytic sites and retard the CO2 conversion (2nd stage of ICCU). Herein, we synthesized various Ni/CaO-based dual functional materials (DFMs) with different distances between active sites and sorbents to provide different volume spaces for the growth of CaCO3 during the carbonation reaction. It is found that both 1%NiCaO and 10%NiCaO synthesized by a one-pot method exhibited a low CO2 conversion (38% and 45%, respectively) and CH4 selectivity (58% and 69%, respectively) as the distance between catalytic sites and sorbents was so close that the Ni active sites were covered by the formed CaCO3 during carbonation reaction......

  • An economic analysis of twenty light olefin production pathways

    Zhitong Zhao, Jingyang Jiang*, Feng Wang*

    J. Energy Chem., 2021, 56, 193-202

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    A comprehensive economic analysis of twenty light olefin production pathways has been performed, covering current and promising processes from fossil (petroleum, coal and natural gas) and renewable resources (biomass and CO2). Taking steam cracking of naphtha as the benchmark, this study gives an economic perspective and points out the bottleneck in different olefin production pathways. The assessment indicates that nearly all renewable pathways are economically unattractive currently and the raw material cost accounts for dominant contribution in most pathways, especially in the oil-, natural gas- and CO2-derived pathways. More details......

2020

  • Catalytic hydrodeoxygenation of methyl stearate and microbial lipids to diesel-range alkanes over Pd/HPA-SiO2 catalysts

    Huifang Liu, Jianyu Han, Qitian Huang, Hongwei Shen, Lijun Lei, Zhipeng Huang, Zhixin Zhang, Zongbao K. Zhao*, Feng Wang*

    Ind. Eng. Chem. Res., 2020, 59, 17440-17450

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    Catalytic hydrotreating of renewable oils is a promising way to get diesel alkanes, with the use of microbial lipids further facilitating scalable production of green diesel. The core issue of triglyceride hydrodeoxygenation (HDO) research is still to develop efficient catalysts under mild reaction conditions. Herein, we demonstrate that the heteropolyacid (HPA)-modified SiO2 supported Pd catalysts showed high activity for the HDO reaction of methyl stearate and soybean oil to diesel alkanes (C15∼C18, >90 wt % at 200 °C). Characterizations show that the Brønsted acid sites introduced by grafting heteropolyacid on SiO2 and metal sites of small Pd particles contribute to the high HDO activity of this bifunctional catalyst. Additionally, lipids produced by Rhodosporidium toruloides Y4 from glucose or corn stover were also transformed to about 75 wt % of diesel-range alkane products......

  • Photocatalytic transformations of lignocellulosic biomass into chemicals

    Xuejiao Wu, Nengchao Luo, Shunji Xie*, Haikun Zhang, Qinghong Zhang, Feng Wang*, Ye Wang*

    Chem. Soc. Rev., 2020, 49, 6198-6223

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    As the largest renewable carbon resource, lignocellulosic biomass has great potential to replace fossil resources for the production of high-value chemicals, in particular organic oxygenates. Catalytic transformations of lignocellulosic biomass using solar energy have attracted much recent attention, because of unique reactive species and reaction patterns induced by photo-excited charge carriers or photo-generated reactive species as well as the mild reaction conditions, which may enable the precise cleavage of target chemical bonds or selective functionalisation of specific functional groups with other functional groups kept intact. Here, we present a critical review on recent advances in the photocatalytic transformation of lignocellulosic biomass with an emphasis on photocatalytic cleavage of C–O and C–C bonds in major components of lignocellulosic biomass, including polysaccharides and lignin, and the photocatalytic valorisation of some key platform molecules......

  • Transformations of biomass, its derivatives and downstream chemicals over ceria catalysts

    Lijun Lei, Yehong Wang, Zhixin Zhang, Jinghua An, Feng Wang*

    ACS Catal., 2020, 10, 8788-8814

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    In the past two decades, on account of the energy and environmental crisis brought by the decline in fossil resources, price volatility, and climate change, the high-value utilization of biomass feedstocks has gradually attracted widespread attention. The reversible Ce3+/Ce4+ redox pairs and the existence of oxygen vacancies improve its redox ability and thus catalytic activity. Besides, the acid-base properties enable its use in acid-base catalytic reactions. The strength or concentration of acid-base sites is tailorable. The water-tolerance character is unique and thus can be employed in the conversion of dilute aqueous biomass solutions. In this perspective, we summarize the latest research progress in the high-value utilization of biomass feedstocks, including biomass raw materials, platform molecules originated from biomass as well as its derivatives and downstream chemicals over pure CeO2, doped-CeO2 and CeO2 supported metal catalysts.

  • Amine‐mediated bond cleavage in oxidized lignin models

    Hongji Li‡, Meijiang Liu‡, Huifang Liu, Nengchao Luo, Chaofeng Zhang, Feng Wang*

    ChemSusChem, 2020, 13, 4660-4665

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    Introducing amines/ammonia into lignin cracking will allow novel bond cleavage pathways. Herein, a method of amines/ammonia-mediated bond cleavage in oxidized lignin β-O-4 models was studied using a copper catalyst at room temp., demonstrating the effect of the amine source on the selectivity of products. For primary and secondary aliph. amines, lignin ketone models underwent oxidative Cα-Cβ bond cleavage and Cα-N bond formation to generate arom. amides. For ammonia, the competition between oxygen and ammonia detd. the selectivity between Cα-N and Cβ-N bond formation, generating amides and α-keto amides, resp. For tertiary amines, the lignin models underwent oxidative Cα-Cβ bond cleavage to benzoic acids. Control expts. indicated that amines act as nucleophiles attacking at the Cα or Cβ position of the oxidized β-O-4 linkage to be cleaved. This study represents a novel example that the breakage of oxidized lignin model can be regulated by amines with a copper catalyst.

  • Heteroatom-participated lignin cleavage to functionalized aromatics

    Hongji Li, Anon Bunrit, Ning Li, Feng Wang*

    Chem. Soc. Rev., 2020, 49, 3748-3763

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    Lignin, the most abundant aromatic polymer in nature, enables sustainable supply of miscellaneous aromatics as green fuels and chemicals. Obtaining the value-added aromatics from lignin, though subjected to enormous research efforts, mainly relies on depolymerization induced by activated hydrogen species or oxygen species, delivering hydrocarbons and oxygenates. The future bio-refinery demands a broad spectrum of fine chemicals, especially those containing elements other than C, H and O. Heteroatom-containing compounds have emerged as powerful reagents to participate in the bond cleavage in lignin; meanwhile, the obtained heteroatom-containing aromatics, which could be used as dye precursors, pharmaceutical precursors, hydrogen storage materials, etc., extend the application of lignin-derived products...

  • Photocatalytic transfer hydrogenolysis of aromatic ketones using alcohols

    Hongji Li, Zhuyan Gao, Lijun Lei, Huifang Liu, Jianyu Han, Feng Hong, Nengchao Luo, Feng Wang*

    Green Chem., 2020, 22, 3802-3808

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    A mild method of photocatalytic deoxygenation of aromatic ketones to alkyl arenes was developed, which utilized alcohols as green hydrogen donors. No hydrogen evolution during this transformation suggested a mechanism of direct hydrogen transfer from alcohols. Control experiments with additives indicated the role of acid in transfer hydrogenolysis, and catalyst characterization confirmed a larger number of Lewis acidic sites on the optimal Pd/TiO2 photocatalyst. Hence, a combination of hydrogen transfer sites and acidic sites may be responsible for efficient deoxygenation without additives. The photocatalyst showed reusability and achieved selective reduction in a variety of aromatic ketones.

  • Linear-regioselectivitive hydromethoxycarbonylation of styrene using Ru-clusters/CeO2 catalyst.

    Jinghua An, Yehong Wang, Zhixin Zhang, Jian Zhang, Feng Wang*

    Chin. J. Catal., 2020, 41(6), 963-969

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    Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods to synthesize esters. Controlling the regioselectivities of linear esters (L) and branched esters (B) is a challenging project for researchers working in this reaction. Although most of the attention has been paid to control the regioselectivity through ligand design in homogeneous catalytic sy...

  • Photo splitting of bio-polyols and sugars to methanol and syngas

    Min Wang, Meijiang Liu, Jianmin Lu, Feng Wang*

    Nat. Commun., 2020, 11, 1083

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    We report the conversion of biomass-derived polyols and sugars into methanol and syngas (CO+H2) via UV light irradiation under room temperature, and the bio-syngas can be further used for the synthesis of methanol. The cellulose and even raw wood sawdust could be converted into methanol or syngas after hydrogenolysis or hydrolysis pretreatment. We find Cu dispersed on titanium oxide nanorod (TNR) rich in defects is effective for the selective C−C bond cleavage to methanol. Methanol is obtained from glycerol with a co-production of H2. A syngas with CO selectivity up to 90% in the gas phase is obtained via controlling the energy band structure of Cu/TNR.

  • Enhanced photocatalytic alkane production from fatty acid decarboxylation via inhibition of radical oligomerization

    Zhipeng Huang‡, Zhitong Zhao‡, Chaofeng Zhang, Jianmin Lu, Huifang Liu, Nengchao Luo, Jian Zhang, Feng Wang*

    Nat. Catal., 2020, 3, 170-178

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    Here we demonstrate that photogenerated radicals can be rapidly terminated by surface hydrogen species during photocatalytic decarboxylation of fatty acids on a hydrogen-rich surface that is constructed by the interactions between H2 and Pt/TiO2 catalyst, thereby greatly inhibiting oligomerization; Cn–1 alkanes can therefore be obtained from bio-derived C12–C18 fatty acids in high yields (≥90%) under mild conditions (30 °C, H2 pressure ≤0.2 MPa) and 365 nm light-emitting dode irradiation. Industrial low-value fatty acid mixtures (namely, soybean and tall oil fatty acids) can be transformed into alkane products in high yields (up to 95%). Our research introduces an efficient biomass-upgrading approach that is enabled by subtle control of the radical intermediate conversion on a heterogeneous surface.

  • Visible-light-driven selective oxidation of toluene into benzaldehyde over nitrogen-modified Nb2O5 nanomeshes

    Kaiyi Su, Huifang Liu, Bin Zeng, Zhixin Zhang, Nengchao Luo, Zhipeng Huang, Zhuyan Gao, Feng Wang*

    ACS Catal., 2020, 10(2), 1324-1333

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    Photocatalytic selective oxidation of hydrocarbons to oxygenated chemicals greatly relies on catalytic materials that show high efficiency of photogenerated holes and electrons separation and visible light absorption capacity. We, herein, report one facile calcination approach with ammonium chloride and melamine as the template to synthesize nitrogen-modified Nb2O5 nanomeshes material (Nb2O5-N), which exhibits a 37-fold reaction rate larger than its commercial counterpart in photocatalytic oxidation of toluene into benzaldehyde under visible light irradiation. The reactivity is ascribed to an extended absorption spectrum within 700 nm by nitrogen modification. In addition, photocurrent response results suggest that a relaxation effect induced by nanomesh structure is beneficial for the separation of charge carriers for enhanced reactivity.

  • Photocatalytic coproduction of deoxybenzoin and H2 through tandem redox reactions

    Nengchao Luo, Tingting Hou, Shiyang Liu, Bin Zeng, Jianmin Lu, Jian Zhang, Hongji Li, Feng Wang*

    ACS Catal., 2020, 10(1), 762-769

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    Photocatalytic H2 evolution from organic feedstocks with simultaneous utilization of photogenerated holes achieves solar energy storage and coproduces value-added chemicals. Here we show visible-light H2 production from benzyl alcohol (BAL) with controllable generation of deoxybenzoin (DOB) or benzoin (BZ) through tandem redox reactions. Particularly, DOB synthesis circumvents the use of expensive feedstocks and environmentally unfriendly catalysts that are required previously. Under the irradiation of blue LEDs, the key of steering the major product to DOB rather than BZ is to decrease the conduction band bottom potentials of the ZnIn sulfide catalysts by increasing the Zn/In ratio, which results in the dehydration of intermediate hydrobenzoin (HB) to DOB proceeding in a redox-neutral mechanism and consuming an electron–hole pair. As a proof of concept, this method is used to synthesize DOB derivatives in gram scale.

  • Catalytic lignin depolymerization to aromatic chemicals

    Chaofeng Zhang, Feng Wang*

    Acc. Chem. Res., 2020, 53(2), 470-484

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    We present our recent studies on lignin's catalytic conversion to aromatic chemicals. First, we introduce our research on protolignin depolymerization via a fragmentation–hydrogenolysis process in alcohol solvents. Then, focusing on the catalytic cleavage of lignin C–C and C–O bonds, we shed light on a recapitulative adjacent functional group modification (AFGM) strategy for the conversion of lignin models. AFGM strategy begins with the adjacent functional group modification of the target C–C or C–O bond to directly decrease the bond dissociation enthalpy (BDE) of targeted bonds or generate new substrate sites to introduce the cleavage reagent for further conversion. Subsequently, on the basis of these two concepts from AFGM, we summarize our strategies on lignin depolymerization, which highlight the effects of lignin structure, catalyst character, and reaction conditions on the efficiency of strategies.

  • Visible-light-induced oxidative lignin C–C bond cleavage to aldehydes using vanadium catalysts

    Huifang Liu, Hongji Li, Nengchao Luo, Feng Wang*

    ACS Catal., 2020, 10(1), 632-643

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    Using vanadium catalysts under visible light, we selectively cleave the C–C bonds in β-1 and β-O-4 interlinkages occluded in lignin models and extracts by an oxidative protocol. Visible light irradiation triggered single electron transfer between the substrate and the catalyst, which further induced the selective Cα–Cβ bond cleavage and generated the final aromatic products through radical intermediates. Using this photocatalytic chemistry, the reactivity of lignin models and the selectivity of Cα–Cβ bond cleavage were significantly improved. More importantly, this protocol affords aromatic monomers through the fragmentation of organosolv lignins even at room temperature, indicating the potential of photocatalytic C–C bond cleavage of lignin linkages under ambient conditions.

2019

  • Selective reduction of CO2 to CO under visible light by controlling coordination structures of CeOX-S/ZnIn2S4 hybrid catalysts

    Tingting Hou, Nengchao Luo, Yi-Tao Cui, Jianmin Lu, Lei Li, Katherine E MacArthur, Marc Heggen, Ruotian Chen, Fengtao Fan, Wenming Tian, Shengye Jin, Feng Wang*

    Appl. Catal. B-Environ., 2019, 245, 262-270

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    Engineering the electronic properties of heterogeneous catalysts is an important strategy to enhance their activity towards CO2 reduction. Herein, we prepared partially sulfurized cerium oxide (CeOx-S) nanoclusterswith the size less than 2 nm on the surface of ZnIn2S4 layers. Surface electronic properties of CeOx-S nanoclusters are facilely modulated by cerium coordination to sulfur, inducing ...

  • Functionalized spirolactones by photoinduced dearomatization of biaryl compounds

    Hongji Li‡, Elena Subbotina‡, Anon Bunrit, Feng Wang*, Joseph S. M. Samec*

    Chem. Sci., 2019, 10, 3681-3686

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    The idea of using biaryl structures to generate synthetic building blocks such as spirolactones is attractive because biaryl structures are abundant in biomass waste streams. However, the inertness of aromatic rings of biaryls makes it challenging to transform them into functionalized structures. In this work, we developed photoinduced dearomatization of nonphenolic biaryl compounds to generate...

  • Single atom alloy preparation and applications in heterogeneous catalysis

    Jianyu Han, Jianmin Lu, Min Wang, Yehong Wang, Feng Wang*

    Chin. J. Chem., 2019, 37(9), 977-988

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    There have been remarkable progresses in manipulating heterogeneous catalysts' nanostructures in the past decade. The concept of single atom alloy (SAA) was firstly proposed in 2012 when researchers successfully stabilized single Pd atoms on the Cu(111) surface. However, earlier work in 2009, which focused on replacing one Au atom with a Pd atom in thiolate protected Au25 nanoclusters, cou...

  • Catalytic scissoring of lignin into aryl monomers

    Min Wang, Feng Wang*

    Adv. Mater., 2019, 1901866

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    Lignin is an aromatic polymer, which is the biggest and most sustainable reservoir for aromatics. The selective conversion of lignin polymers into aryl monomers is a promising route to provide aromatics, but it is also a challenging task. Compared to cellulose, lignin remains the most poorly utilized biopolymer due to its complex structure. Although harsh conditions can degrade lignin, the...

  • Effectiveness of metal oxide catalysts for the degradation of 1,4-dioxane

    Kimberly N. Heck, Yehong Wang, Gang Wu, Feng Wang, Ah-Lim Tsai, David T. Adamsond, Michael S. Wong*

    RSC Adv., 2019, 9, 27042-27049

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    ​1,4-dioxane, commonly used as a solvent stabilizer and industrial solvent, is an environmental contaminant and probable carcinogen. In this study, we explored the concept of using metal oxides to activate H2O2 catalytically at neutral pH in the dark for 1,4-dioxane degradation. Based on batch kinetics measurements, materials that displayed the most suitable characteristics (high 1,4-dioxane d...

  • Microreactor-assisted synthesis of a nickel-based infinite coordination polymer and its application in the selective adsorption of alcohols

    Jian Zhang, Yehong Wang, FengWang*

    Inorg. Chem. Commun., 2019, 109, 107566

    Full-text linkage

    Here, we report the synthesis of an infinite coordination polymer (ICP) with 2,5-furan dicarboxylic acid (FDCA) and nickel acetate as precursors in a flow tubular microreactor in a continuous mode. Compared with the available synthesis methods, which usually span hours to days at elevated temperature, this strategy remarkably saves time and energy, and greatly increases the efficiency of s...

  • Photocatalytic cleavage of aryl ether in modified lignin to non-phenolic aromatics

    Hongji Li, Anon Bunrit, Jianmin Lu, Zhuyan Gao, Nengchao Luo, Huifang Liu, Feng Wang*

    ACS Catal., 2019, 9, 8843-8851

    Full-text linkage

    Depolymerization of lignin meets the difficulty in cleaving the robust aryl ether bond. Herein, through installing an internal nucleophile in the β-O-4′ linkage, the selective cleavage of aryl ether was realized by the intramolecular substitution on aryl rings affording non-phenolic arylamine products. In particular, nitrogen-modified lignin models and lignin samples were employed to generate the iminyl radical under photocatalytic reduction, which acted as the internal nucleophile inducing aryl migration from O to the N atom. The following hydrolysis released primary arylamines and α-hydroxy ketones. Mechanism studies including electron spin resonance (ESR), fluorescence quenching experiments, and density functional theory (DFT) calculations proved the aryl migration pathway. This method enables access to non-phenolic arylamine products from lignin conversion.

  • Visible-light-driven coproduction of diesel precursors and hydrogen from lignocellulose-derived methylfurans

    Nengchao Luo, Tiziano Montini, Jian Zhang, Paolo Fornasiero, Emiliano Fonda, Tingting Hou, Wei Nie, Jianmin Lu, Junxue Liu, Marc Heggen, Long Lin, Changtong Ma, Min Wang, Fengtao Fan, Shengye Jin & Feng Wang*

    Nat. Energy, 2019, 4(7), 575-584

    Full-text linkage

    We demonstrate the coproduction of H2 and diesel fuel precursors from lignocellulose-derived methylfurans via acceptorless dehydrogenative C−C coupling, using a Ru-doped ZnIn2S4 catalyst a​nd driven by visible light. With this chemistry, up to 1.04 g /g catalyst/h of diesel fuel precursors (~41% of which are precursors of branched-chain alkanes) are produced with selectivity higher than 96%, together with 6.0  mmol/ g catalyst/ h of H2. Subsequent hydrodeoxygenation reactions yield the desired diesel fuels comprising straight- and branched-chain alkanes. We suggest that Ru dopants, substituted in the position of indium ions in the ZnIn2S4 matrix, improve charge separation efficiency, thereby accelerating C−H activation for the coproduction of H2 and diesel fuel precursors.

2018

  • Selective production of phase-separable product from a mixture of biomass-derived aqueous oxygenates

    Yehong Wang, Mi Peng, Jian Zhang, Zhixin Zhang, Jinghua An, Shuyan Du, Hongyu An, Fengtao Fan, Xi Liu, Peng Zhai, Ding Ma*, Feng Wang*

    Nat. Commun., 2018, 9, 5183

    Full-text linkage

    Selective conversion of an aqueous solution of mixed oxygenates produced by biomass fermentation to a value-added single product is pivotal for commercially viable biomass utilization. However, the efficiency and selectivity of the transformation remains a great challenge. Herein, we present a strategy capable of transforming ~70% of carbon in an aqueous fermentation mixture (ABE: acetone–butanol–ethanol–water) to 4-heptanone (4-HPO), catalyzed by tin-doped ceria (Sn-ceria), with a selectivity aas high as 86%. Water (up to 27 wt%), detrimental to the reported catalysts for ABE conversion, was beneficial for producing 4-HPO, highlighting the feasibility of the current reaction system. In a 300 h continuous reaction over 2 wt% Sn-ceria catalyst, the average 4-HPO selectivity is maintained at 85% with 50% conversion and > 90% carbon balance. This strategy offers a route for highly efficient organic-carbon utilization, which can potentially integrate biological and

  • Low-carbon roadmap of chemical production: A case study of ethylene in China

    Zhitong Zhao, Katie Chong, Jingyang Jiang, Karen Wilson, Xiaochen Zhang, Feng Wang*

    Renew. Sustain. Energy Rev., 2018, 97, 580-591

    Full-text linkage

    The increasing emissions of carbon dioxide (CO2) are primarily driven by the rapid expansion of energy-intensive sectors such as the chemical industry. This work selects ethylene, one of the most important chemicals, as a model study to represent the low-carbon roadmap of chemical production. Four strategies improving the efficiency of fossil resource usage, developing the technology for carbon capture and storage (CCS), CO2 chemical conversion, and converting biomass resources into chemicals, are used to reduce CO2 emissions. A comprehensive analysis of the life cycle CO2 emissions of different ethylene production routes has been performed to compare their emission reduction potential. The results indicate that the BMTO (biomass to olefins via methanol-to-olefins) pathway releases the least CO2 (− 1.3 t CO2/t ethylene)

  • The synthesis of quinazolinones from olefins, CO and amines over heterogeneous Ru-clusters/ceria catalyst

    Jinghua An, Yehong Wang, Zhixin Zhang, Zhitong Zhao, Jian Zhang, Feng Wang*

    Angew. Chem. Int. Ed., 2018, 57(38), 12308-12312

    Full-text linkage

    Quinazolinones, an important class of heterocyclic compounds, have been widely used in pharmaceuticals because of their biological activity. However, the efficient and economical synthesis of quinazolinones has remained a challenge. A novel synthetic approach has now been developed to produce quinazolinones from olefins, CO, and amines over heterogeneous Ru‐clusters/ceria catalyst in the absence of acids, bases, and oxidants. Furthermore, H2O is generated as the only by‐product. A series of quinazolinones with aromatic or non‐aromatic substituents can be obtained in yields of up to 99 %. The Ru‐clusters/ceria can be reused at least four times. The analysis of the E‐factor (environmental impact factor) for the synthesis of 2‐ethyl quinazolinone suggests that this system is more environmentally friendly than other processes reported previously.

  • Dealkylation of lignin to phenol via oxidation–hydrogenation strategy

    Min Wang, Meijiang Liu, Hongji Li, Zhitong Zhao, Xiaochen Zhang, Feng Wang*

    ACS Catal., 2018, 8(8), 6837-6843

    Full-text linkage

    Lignin is a renewable and abundant aromatic polymer found in plants. We herein propose a "cutting tail" methodology to produce phenol from lignin, which is achieved by combining Ru/CeO2 catalyst and CuCl2 oxidant via an oxidation–hydrogenation route. Phenol was obtained from separated poplar lignin with 13 wt % yield. Even raw biomass, such as poplar, birch, pine, peanut, bamboo willow, and straw, could be converted into phenol in 1–33 mg per gram of biomass.

  • Photocatalytic cleavage of C–C bond in lignin models under visible light on mesoporous graphitic carbon nitride through π-π stacking interaction

    Huifang Liu, Hongji Li, Jianmin Lu, Shu Zeng, Min Wang, Nengchao Luo, Shutao Xu, Feng Wang*

    ACS Catal., 2018, 8(6), 4761-4771

    Full-text linkage

    Photocatalysis is a potentially promising approach to harvest aromatic compounds from lignin. However, the development of an active and selective solid photocatalyst is still challenging for lignin transformation under ambient conditions. We herein report a mild photocatalytic oxidative strategy for C–C bond cleavage of lignin β-O-4 and β-1 linkages using a mesoporous graphitic carbon nitride catalyst. Identifications by solid-state NMR techniques and density functional theory (DFT) calculations indicate that π–π stacking interactions are most likely present between the flexible carbon nitride surface and lignin model molecule. Besides, low charge recombination efficiency and high specific surface area (206.5 m2 /g) of the catalyst also contribute to its high catalytic activity. Mechanistic investigations reveal that photogenerated holes, as the main active species, trigger the oxidation and C–C bond cleavage of lignin models.

  • Synthesis of 1,4-cyclohexanedimethanol, 1,4-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylates from formaldehyde, crotonaldehyde and acrylate

    Yancheng Hu‡, Zhitong Zhao‡, Yanting Liu, Guangyi Li, Aiqin Wang, Yu Cong, Tao Zhang, Feng Wang*, Ning Li*

    Angew. Chem. Int. Ed., 2018, 57(23), 6901-6905

    Full-text linkage

    Valuable polyester monomers and plasticizers—1,4‐cyclohexanedimethanol (CHDM), 1,4‐cyclohexanedicarboxylic acid (CHDA), and 1,2‐cyclohexanedicarboxylates—have been prepared by a new strategy. The synthetic processes involve a proline‐catalyzed formal [3+1+2] cycloaddition of formaldehyde, crotonaldehyde, and acrylate (or fumarate). CHDM is produced after a subsequent hydrogenation step over a commercially available Cu/Zn/Al catalyst and a one‐pot hydrogenation/oxidation/hydrolysis process yields CHDA, whereas 1,2‐cyclohexanedicarboxylate is obtained by a Pd/C‐catalyzed tandem decarbonylation/hydrogenation step.

  • Pr-doped CeO2 catalyst in the prins condensation–hydrolysis reaction: Are all of the defect sites catalytically active?

    Zhixin Zhang, Yehong Wang, Jianmin Lu, Jian Zhang, Mingrun Li, Xuebin Liu, Feng Wang*

    ACS Catal., 2018, 8(4), 2635-2644

    Full-text linkage

    Defect chemistries of metal-doped CeO2 catalysts have attracted extensive scientific interests in heterogeneous catalysis. Here, we report the structure–activity relationship of CeO2 catalysts doped ...

  • Acid-promoter-free ethylene methoxycarbonylation over Ru-clusters/Ceria: the catalysis of interfacial lewis acid-base pair

    Jinghua An‡, Yehong Wang‡, Jianmin Lu, Jian Zhang, Zhixin Zhang, Shutao Xu, Xiaoyan Liu, Tao Zhang, Martin Gocyla, Marc Heggen, Rafal E. Dunin-Borkowski, Paolo Fornasiero, Feng Wang*

    J. Am. Chem. Soc., 2018, 140(11), 4172-4181

    Full-text linkage

    The interface of metal-oxide plays pivotal roles in catalytic reactions, but its catalytic function is still not clear. In this study, we report the high activity of nanostructured Ru/ceria (Ru-cluste...

  • The in situ transformation of the co-product formaldehyde in the reversible hydrolysis of 1,3-dixoane to obtain 1,3-propanediol efficiently

    Yehong Wang, Jian Zhang, Zhixin Zhang, Tingting Hou, Chaofeng Zhang, Jinghua An, Feng Wang*

    Green Chem., 2018, 20, 1455-1458

    Full-text linkage

    Herein, a strategy is developed for efficient production of 1,3-propanediol via the hydrolysis of 1,3-dioxane by the in situ transformation of the co-product formaldehyde (HCHO) in the presence of Eu(...

  • Carbon modification of nickel catalyst for depolymerization of oxidized lignin to aromatics

    Min Wang, Xiaochen Zhang, Hongji Li, Jianmin Lu, Meijiang Liu, Feng Wang*

    ACS Catal., 2018, 8(2), 1614-1620

    Full-text linkage

    Catalytic valorization of lignin is a sustainable way to provide aromatics for the human society, which depends on the electronic structure of catalytic sites. We herein report the preparation of a carbon-modified nickel catalyst via carbothermal reduction of Ni-doped layered double hydroxides. Lignosulfonate (LS), a lignin resource from the pulp industry, was used as a renewable carbon precursor. The carbon residues in the nickel surface layer changed the 3d electron distribution of nickel, whi

  • Sustainable productions of organic acids and their derivatives from biomass via selective oxidative cleavage of C-C bond

    Min Wang, Jiping Ma, Huifang Liu, Nengchao Luo, Zhitong Zhao, Feng Wang

    ACS Catal., 2018, 8(3), 2129-2165

    Full-text linkage

    The use of biomass as a resource has developed rapidly in recent years, and various kinds of chemicals could be produced from biomass. Although biomass is annually renewable and abundant, it is important to process it in the most efficient way. Before rushing into biomass conversion, it is necessary to consider what chemicals are reasonably and economically produced from biomass. In this Review, we first analyzed the products from biomass based on the structural properties and economics. Taking

  • NH2OH-mediated lignin conversion to isoxazole and nitrile

    Hongji Li, Min Wang, Huifang Liu, Nengchao Luo, Jianmin Lu, Chaofeng Zhang, Feng Wang*

    ACS Sustainable Chem. Eng., 2018, 6(3), 3748-3753

    Full-text linkage

    Conversion of lignin to aromatic compounds via C–C/C–O bond cleavage has been an attractive but challenging subject in recent years. We herein report the first protocol that converts lignin models and preoxidized lignin to isoxazole and aromatic nitrile. The isoxazole motif is constructed by condensation of β-hydroxyl ketone with hydroxylamine. Magnesium oxide promotes an oximation reaction and an intramolecular condensation. Aromatic nitriles and esters are obtained via Beckmann rearrangement o

  • Generation and confinement of long-lived N-Oxyl radical and its photocatalysis

    Chaofeng Zhang, Zhipeng Huang, Jianmin Lu, Nengchao Luo, Feng Wang*

    J. Am. Chem. Soc., 2018, 140(6), 2032-2035

    Full-text linkage

    Generation of controllable carbon radical under the assistance of N-oxyl radical is an efficient method for the activation of C–H bonds in hydrocarbons. We herein report that irradiation of α-Fe2O3 and N-hydroxyphthalimide (NHPI) under 455 nm light generates phthalimide-N-oxyl radical (PINO*), which after being formed by oxidation with holes, is confined on α-Fe2O3 surface. The half-life time of the confined radical reaches 22 s as measured by in situ electron paramagnetic resonance (EPR) after

2017

  • Synthesis of 1,3-diols from isobutene and HCHO via Prins condensation-hydrolysis using CeO2 catalysts: effects of crystal plane and oxygen vacancy

    Zhixin Zhang, Yehong Wang, Jianmin Lu, Min Wang, Jian Zhang, Xuebin Liu, Feng Wang*

    Inorganics, 2017, 5(4), 75

    Full-text linkage

    We herein report the synthesis of 3-methyl-1,3-butanediol from isobutene and HCHO in water via a Prins condensation-hydrolysis reaction over CeO2, which is a water-tolerant Lewis acid catalyst. The CeO2 exhibits significant catalytic activity for the reaction, giving 95% HCHO conversion and 84% 3-methyl-1,3-butanediol selectivity at 150 °C for 4 h. The crystal planes of CeO2 have a signific...

  • Life cycle assessment of primary energy demand and greenhouse gas (GHG) emissions of four propylene production pathways in China

    Zhitong Zhao, Yong Liu, Feng Wang, Xuekuan Li, Shuping Deng, Jie Xu*, Wei Wei, Feng Wang*

    J. Clean. Prod., 2017, 163, 285-292

    Full-text linkage

    Life cycle primary energy demand (PED) and greenhouse gas (GHG) emissions for the production of propylene in China (year 2013) have been carried out by considering several propylene production routes into account, such as catalytic cracking (CC), stream cracking (SC), coal-to-olefins (CTO) and coal-to-propylene (CTP), which cover the entire life cycle including: extraction and transportation...

  • Sell a dummy: Adjacent functional group modification strategy for the catalytic cleavage of lignin β-O-4 linkage

    Chaofeng Zhang, Feng Wang*

    Chin. J. Catal., 2017. 38(7), 1102-1107

    Full-text linkage

    This perspective highlights recent progress on lignin β-O-4 conversion, which focuses on the combinatorial strategies leading to lignin β-O-4 cleavage beginning with adjacent fmunctional group modification, and provides insight into the challenges unexplored in this area.

  • Metal-free protocol for the synthesis of N-arylpyrrolidines catalyzed by hydrogen iodine

    Tingting Hou, Chaofeng Zhang, Yehong Wang, Zhenting Liu, Zhixin Zhang, Feng Wang*

    Catal. Commun., 2017, 94(5), 56-59

    Full-text linkage

    A metal-free and efficient approach to N-arylpyrrolidines from arylamines and cyclic ethers catalyzed by hydrogen iodine is described. In this protocol, no additive is added and a wide range of N-arylpyrrolidines are synthesized with up to 99% yield. Reaction mechanism involving iodine radical is proposed.

  • Visible light gold nanocluster photocatalyst: selective aerobic oxidation of amines to imines

    Haijun Chen, Chao Liu, Min Wang, Chaofeng Zhang, Nengchao Luo, Yehong Wang, Hadi Abroshan, Gao Li*, Feng Wang*

    ACS Catal., 2017, 7(5), 3632–3638

    Full-text linkage

    This work demonstrates the synthesis of an efficient photocatalyst, Au25(PPh3)10Cl2(SC3H6SiO3)5/TiO2, for selective oxidation of amines to imines. The photocatalyst is prepared via hydrolysis of Au25(PPh3)10Cl2[(SC3H6Si(OC2H5)3]5 nanoclusters in the presence of TiO2 support. The gold nanoclusters exhibit good photocatalytic activity using visible light and under mild thermal conditions for the selective oxidation with molecular oxygen (O2). The turnover frequency (TOF) of 4-methylbenzylamine oxi

  • Photocatalytic coupling of amines to imidazoles using a Mo–ZnIn2S4 catalyst

    Min Wang, Lihua Li, Jianmin Lu, Nengchao Luo, Xiaochen Zhang, Feng Wang*

    Green Chem., 2017, 19(21), 5172-5177

    Full-text linkage

    Substituted imidazoles are traditionally synthesized by co-condensation of multiple feedstocks. Herein, we report a new route for the synthesis of substituted imidazoles via photocyclization of readily available amines at room temperature. The reaction is achieved by the visible-light-induced C–C/C–N bond coupling and subsequent dehydrogenation reaction over Mo–ZnIn2S4 as a heterogeneous photocatalyst. A wide range of amines were converted into the corresponding tri- and tetra-substituted imidaz

  • Peculiar hydrogenation reactivity of Ni–Niδ+ clusters stabilized by ceria in reducing nitrobenzene to azoxybenzene

    Tingting Hou, Yehong Wang, Jian Zhang, Mingrun Li, Jianmin Lu, Marc Heggen, Carsten Sievers, Feng Wang*

    J. Catal., 2017, 353, 107-115

    Full-text linkage

    In many catalytic processes, metastable reaction intermediates are more valuable and desirable than final products. Here, we report Ni–Niδ+ clusters on ceria where the extent of reduction of nickel oxide/ceria in H2 has been optimized. This catalyst shows high selectivity in reducing nitrobenzene to azoxybenzene, the latter usually being metastable. Due to strong electronic metal–support interactions between Ni and ceria, mixed Ni–Niδ+ clusters are formed on ceria even after reduction at 500 °C

  • Promoting lignin depolymerization and restraining the condensation via an oxidation-hydrogenation strategy

    Chaofeng Zhang, Hongji Li, Jianmin Lu, Xiaochen Zhang, Katherine E MacArthur, Marc Heggen, Feng Wang*

    ACS Catal., 2017, 7(5), 3419–3429

    Full-text linkage

    For lignin valorization, simultaneously achieving the efficient cleavage of ether bonds and restraining the condensation of the formed fragments represents a challenge thus far. Herein, we report a two-step oxidation–hydrogenation strategy to achieve this goal. In the oxidation step, the O2/NaNO2/DDQ/NHPI system selectively oxidizes CαH–OH to Cα═O within the β-O-4 structure. In the subsequent hydrogenation step, the α-O-4 and the preoxidized β-O-4 structures are further hydrogenated over a NiMo

  • Visible-light-driven self-hydrogen transfer hydrogenolysis of lignin models and extracts into phenolic products

    Nengchao Luo, Min Wang, Hongji Li, Jian Zhang, Tingting Hou, Haijun Chen, Xiaochen Zhang, Jianmin Lu, Feng Wang*

    ACS Catal., 2017, 7(7), 4571-4580

    Full-text linkage

    Obtaining high selectivity of aromatic monomers from renewable lignin has been extensively pursued but is still unsuccessful, hampered by the need to efficiently cleave C–O/C–C bonds and inhibit lignin proliferation reactions. Herein, we report a transfer hydrogenolysis protocol using a heterogeneous ZnIn2S4 catalyst driven by visible light. In this process, alcoholic groups (CαH–OH) of lignin act as hydrogen donors. Proliferation of phenolic products to dark substances is suppressed under visib

  • Yin and yang dual characters of CuOx clusters for C–C bond oxidation driven by visible light

    Tingting Hou, Nengchao Luo, Hongji Li, Marc Heggen, Jianmin Lu, Yehong Wang, Feng Wang*

    ACS Catal., 2017, 7(6), 3850–3859

    Full-text linkage

    Selective cleavage of C–C bonds is pursued as a useful chemical transformation method in biomass utilization. Herein, we report a hybrid CuOx/ceria/anatase nanotube catalyst in the selective oxidation of C–C bonds under visible light irradiation. Using the lignin β-1 model as a substrate offers 96% yields of benzaldehydes. Characterization results by high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy element (EDX) mapping

  • Ru/ceria-catalyzed direct formylation of amines and CO to produce formamides

    Yehong Wang, Jian Zhang, Haijun Chen, Zhixin Zhang, Chaofeng Zhang, Mingrun Li, Feng Wang*

    Green Chem., 2017,19(1), 88-92

    Full-text linkage

    We herein report a new strategy of directly converting amines and CO to formamides with 100% atom utilization efficiency. It is suitable for up to 25 amine substrates with no additives. Ru/ceria is found to be an excellent catalyst for this reaction due the efficient co-activation of CO and amine on Ru species.

  • New protocol of copper-catalyzed oxidative C(CO)-C bond cleavage of aryl and aliphatic ketones to organic acids using O2 as the terminal oxidant

    Huifang Liu, Min Wang, Hongji Li, Nengchao Luo, Shutao Xu, Feng Wang*

    J. Catal., 2017, 346, 170-179

    Full-text linkage

    Catalytic oxidation of C-C bond is a key technology to transform petroleum-based as well as sustainable biomass feedstock into more valuable oxygenates. We herein describe a convenient and useful oxidation strategy of converting ketones into carboxylic acids using homogeneous copper catalyst without additives and with O2 as the terminal oxidant. A wide range of aryl and aliphatic ketones as well as β–O–4 lignin models were selectively oxidized to acids via C-C bond cleavage. Mechanism studies by

  • Oxidative C(OH)-C bond cleavage of secondary alcohols to acids over a copper catalyst with molecular oxygen as the oxidant

    Min Wang, Jianmin Lu, Lihua Li, Hongji Li, Huifang Liu, Feng Wang*

    J. Catal., 2017, 348, 160-167

    Full-text linkage

    Selective oxidative cleavage of C-C bond is pivotal for producing functionalized molecules, useful for organic synthesis and biomass utilization. We herein report the oxidative C(OH)-C bond cleavage of secondary alcohols to acids over a copper/1, 10-phenanthroline complex with molecular oxygen as the oxidant. A wide range of secondary alcohols are converted into acids with up to 98% yields. More interestingly, it is effective for breaking up lignin model systems into acids, which is rarely achie

  • Acid promoted C–C bond oxidative cleavage of β-O-4 and β-1 lignin models to esters over copper catalyst

    Min Wang, Lihua Li, Jianmin Lu, Hongji Li, Xiaochen Zhang, Huifang Liu, Nengchao Luo, Feng Wang*

    Green Chem., 2017, 19(3), 702-706

    Full-text linkage

    Depolymerisation of lignin to aromatics is a challenging task. We herein report that a Cu(OAc)2/BF3·OEt2 catalyst is effective in simultaneously cleaving C–C bonds in β-1 and β-O-4 ketones, yielding esters and phenols. In-depth studies show that C–H bond activation is the rate determining step for C–C bond cleavage. BF3·OEt2 promotes the reaction via activating the β-C–H bond. This study offers the potential to obtain aromatic esters from lignin.

2016

  • The cascade synthesis of α,β-unsaturated ketones via oxidative C–C coupling of ketones and primary alcohols over a ceria catalyst

    Zhixin Zhang, Yehong Wang, Min Wang, Jianmin Lu, Chaofeng Zhang, Lihua Li, Jingyang Jiang, Feng Wang*

    Catal. Sci. Technol., 2016, 6(6), 1693-1700

    Full-text linkage

    We herein report the oxidative C–C coupling of ketones and primary alcohols to produce α,β-unsaturated ketones in the absence of base additives. This cascade synthetic reaction was conducted at 150 °C in 12 h using a heterogeneous CeO2 catalyst. The conversion of acetophenone reached 74% with 89% selectivity to chalcone. A correlation between the CeO2 crystal plane and catalytic performance is established as the catalytic activities decrease in the sequence of (110) > (111) > (100). Characterization using Raman spectroscopy, CO2 temperature-programmed desorption (CO2-TPD), and in situ active site-capping tests has shown that the unusual catalysis of the CeO2 catalyst is attributed to the coexistence of basic and redox active sites. These sites synergistically catalyze the oxidation of alcohols to aldehydes and the aldol condensation to ketones. Moreover, the CeO2 catalyst can be reused several times after calcination to remove the surface-adsorbed substances.

  • Conversion of isobutene and formaldehyde to diol using praseodymium-doped ceria catalyst

    Zhixin Zhang, Yehong Wang, Jianmin Lu, Chaofeng Zhang, Min Wang, Mingrun Li, Xuebin Liu, Feng Wang*

    ACS Catal., 2016, 6(12), 8248–8254

    Full-text linkage

    Conversion of low-carbon olefins to higher alcohols or olefins via the formation of C–C bonds is an increasingly important topic. We herein report an example of converting isobutene and formaldehyde (38 wt % aqueous solution) to 3-methyl-1,3-butanediol (MBD), a precursor for isoprene. The reaction occurs through a Prins condensation–hydrolysis reaction over a praseodymium (Pr)-doped CeO2 catalyst. The best MBD yield (70%) is achieved over the Pr-doped CeO2 catalyst. Catalyst characterizations wi

  • Photocatalytic oxidation–hydrogenolysis of lignin β-O-4 models via a dual light wavelength switching strategy

    Nengchao Luo, Min Wang, Hongji Li, Jian Zhang, Huifang Liu, Feng Wang*

    ACS Catal., 2016, 6(11), 7716–7721

    Full-text linkage

    One of the challenges of depolymerizing lignin to valuable aromatics lies in the selective cleavage of the abundant C–O bonds of β-O-4 linkages. Herein we report a photocatalytic oxidation–hydrogenolysis tandem method for cleaving C–O bonds of β-O-4 alcohols. The Pd/ZnIn2S4 catalyst is used in the aerobic oxidation of α-C–OH of β-O-4 alcohols to α-C═O with 455 nm light, and then a TiO2–NaOAc system is employed for cleaving C–O bonds neighboring the α-C═O bonds through a hydrogenolysis reaction b

  • Cleavage of lignin β-O-4 ether bond via dehydroxylation-hydrogenation strategy over a NiMo sulfide catalyst

    Chaofeng Zhang, Jianmin Lu, Xiaochen Zhang, Katherine E MacArthur, Marc Heggen, Hongji Li, Feng Wang*

    Green Chem., 2016,18(24), 6545-6555

    Full-text linkage

    Efficient cleavage of lignin β-O-4 ether bonds to produce aromatics is a challenging and attractive topic. Recently a growing number of studies reveal the initial oxidation of CαHOH to Cα=O can decrease the β-O-4 bond dissociation energy (BDE) from 274.0 kJ•mol-1 to 227.8 kJ•mol-1, and thus the β-O-4 bond is more readily cleaved in the subsequent transfer hydrogenation, or acidolysis. Here we show that the first reaction step, except in the above-mentioned pre-oxidation methods, can be a Cα-OH b

  • Two-step, catalytic C–C bond oxidative cleavage process converts lignin models and extracts to aromatic acids

    Min Wang, Jianmin Lu, Xiaochen Zhang, Lihua Li, Hongji Li, Nengchao Luo, Feng Wang*

    ACS Catal., 2016, 6(9), 6086–6090

    Full-text linkage

    We herein report a two-step strategy for oxidative cleavage of lignin C–C bond to aromatic acids and phenols with molecular oxygen as oxidant. In the first step, lignin β-O-4 alcohol was oxidized to β-O-4 ketone over a VOSO4/TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl)oxyl)] catalyst. In the second step, the C–C bond of β-O-4 linkages was selectively cleaved to acids and phenols by oxidation over a Cu/1,10-phenanthroline catalyst. Computational investigations suggested a copper-oxo-bridged dimer w

  • β-O-4 bond cleavage mechanism for lignin model compounds over Pd catalysts identified by combination of first-principles calculations and experiments

    Jianmin Lu, Min Wang, Xiaochen Zhang, Andreas Heyden, Feng Wang*

    ACS Catal., 2016, 6(8), 5589–5598

    Full-text linkage

    Lignin in lignocellulosic biomass is the only renewable source for aromatic compounds, and effective valorization of lignin remains a significant challenge in biomass conversion processes. We have performed density functional theory calculations and experiments to investigate the cleavage mechanism of the C–O ether bond in the lignin model compound 2-phenoxy-1-phenylethanol with a β-O-4 linkage over a Pd(111) catalyst surface model. We propose the favorable reaction pathway to proceed as follows

  • Thermally robust silica-enclosed Au25 nanocluster and its catalysis

    Haijun Chen, Chao Liu, Min Wang, Chaofeng Zhang, Gao Li*, Feng Wang*

    Chin. J. Catal., 2016, 37(10), 1787-1793

    Full-text linkage

    Well-defined gold nanoclusters with average size less than 2 nm have emerged as a new and novel catalyst. The gold nanocluster loaded on the oxide surface usually aggregates to larger particles at high temperature (> 300 °C), which is caused by the removal of the surface ligands. We herein present a novel method to prepare Au25 cluster catalyst (∼1.3 nm) with high thermal stability (up to...

  • Epoxides hydrolysis and alcoholysis reactions over crystalline Mo–V–O oxide

    Xiaochen Zhang, Min Wang, Chaofeng Zhang, Jianmin Lu, Yehong Wang, Feng Wang*

    RSC Adv., 2016, 6, 70842-70847

    Full-text linkage

    ​Crystalline Mo–V–O oxides have been used as a catalyst for the hydrolysis and alcoholysis of propylene oxide to diols and ethers, respectively. Relationships between the active crystal facet, the acidity of Mo–V–O catalysts and the activity have been established. Our results indicate that the a–b plane is the active facet for the hydrolysis reaction.

  • Chemoselective transfer hydrogenation to nitroarenes mediated by oxygen-implanted MoS2

    Chaofeng Zhang, Xu Wang, Mingrun Li, Zhixin Zhang, Yehong Wang, Rui Si, Feng Wang

    Chin. J. Catal., 2016, 37(9), 1569-1577

    Full-text linkage

    We present an efficient approach for the chemoselective synthesis of arylamines from nitroarenes and formate over an oxygen-implanted MoS2 catalyst (O-MoS2). O-MoS2 was prepared by incomplete sulfidation and reduction of an ammonium molybdate precursor. A number of Mo–O bonds were implanted in the as-synthesized ultrathin O-MoS2 nanosheets. As a consequence of the different coordination ge...

  • Transfer hydrogenation of nitroarenes to arylamines catalysed by an oxygen-implanted MoS2 catalyst

    Chaofeng Zhang, Zhixin Zhang, Xu Wang, Mingrun Li, Jianmin Lu, Rui Si, Feng Wang*

    Appl. Catal. A: Gen., 2016, 525, 85-93

    Full-text linkage

    We present an efficient approach for chemoselective synthesis of various functionalized arylamines from nitroarenes over an oxygen-implanted MoS2 catalyst (O-MoS2). The HRTEM, XRD, XPS, Raman, EXAFS and NH3-TPD characterizations show the existence of MoIVOx structure and abundant coordinative unsaturated (CUS) Mo sites in the 2D-layer structure of O-MoS2. In the transfer hydrogenation of nitro...

  • Transfer hydrogenation of nitroarenes with hydrazine at near-room temperature catalysed by a MoO2 catalyst

    Chaofeng Zhang, Jianmin Lu, Mingrun Li, Yehong Wang, Zhe Zhang, Haijun Chen, Feng Wang*

    Green Chem., 2016, 18(8), 2435-2442

    Full-text linkage

    We present an experimental and computational study of the elementary steps of hydrazine hydrogen transfer on crystalline MoO2, and demonstrate its unique bifunctional metallic-basic properties in a catalytic hydrogenation reaction. Density functional theory (DFT) calculations suggest that the stepwise hydrogen transfer via the prior cleavage of the N–H bond rather than the N–N bond, is the key step to create the dissociated hydride and proton species on the dual Mo and O sites, marking its diffe

  • Oxidative coupling of anilines to azobenzenes using heterogeneous manganese oxide catalysts

    Min Wang, Jiping Ma, Miao Yu, Zhe Zhang, Feng Wang*

    Catal. Sci. Technol., 2016, 6, 1940-1945

    Full-text linkage

    We herein report the transition metal oxide-catalyzed synthesis of azobenzenes through the oxidative coupling of anilines. An octahedral molecular sieve of manganese oxide, OMS-2, exhibited the best activity and selectivity. Nine examples of symmetric azobenzenes and twenty unsymmetric ones were synthesized with 62–99% conversion and 64–99% selectivity. In the aniline cross-coupling reactions...

  • The cascade synthesis of quinazolinones and quinazolines using an α-MnO2 catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant

    Zhe Zhang, Min Wang, Chaofeng Zhang, Zhixin Zhang, Jianmin Lua, Feng Wang*

    Chem. Commun., 2015,51(44), 9205-9207

    Full-text linkage

    Heterogeneously catalyzed synthesis of quinazolinones or quinazolines is reported in this study. An α-MnO2 catalyst is found to be highly active and selective in the oxidative cyclization of anthranilamides or aminobenzylamines with alcohols using TBHP as an oxidant. This protocol exhibits a broad substrate scope, and is operationally simple without an additive.

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