JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Huihuang Fang,Alberto Roldan,Chenchen Tian,Yanping Zheng,Xinping Duan,Kun Chen,Linmin Ye,Stefano Leoni,Youzhu Yuan
Tungsten carbides exhibit excellent performance in many heterogeneous processes because of their distinctive catalytic properties. Preparation of tungsten carbides with controllable phase composition relevant to their catalytic behavior is essential yet challenging. In this study, tungsten carbides embedded in carbon spheres (W x C@CS) were fabricated through carburization of organic–inorganic hybrid precursors. W 1.25 C@CS with rational structure-tuning properties exhibits promising regioselectivity (reaching 91.5%) toward aryl C O bond cleavage, specifically during hydrogenolysis of guaiacol to phenol. A structure reconstruction strategy was adopted to elucidate structure–performance relationship by transforming commercially available bulk WC from inert phase to composition-dependent active catalysts. Combined catalytic and characteristic analyses illustrate that the catalyst performance is dependent on the C-defect structure. The intimate connection between the phenol space time yield and the C/W atomic ratio on the exterior interface of the catalyst was verified. The C/W atomic ratio of 7.2 leads to the optimal catalytic performance. Density functional theory calculations were performed to define the catalytic mechanism at the atomic level. The theoretical analysis suggests an appropriate configuration of surface W and C atoms for activation of hydrogen and guaiacol molecules, rendering the intrinsic active sites for phenol production. This work provides insights into controlling the surface compositions of tungsten carbides to develop efficient C O bond cleavage catalysts, which verifies the importance of hydrogenolysis catalysis in lignin-derived compounds involving complex O-containing guaiacols and phenolics.
研究领域:
化学工程
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催化科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2023
·
IF 7.5
Fa-Peng Wu,Yun-Peng Zhao,Zong-Pin Fu,Le-Le Qiu,Jian Xiao,Jian Li,Fang-Jing Liu,Jing-Pei Cao
Efficient transfer hydrogenolysis of benzyl phenyl ether (BPE) was accomplished over Ni 1.5 Cu 1.5 /Al 2 O 3 using isopropanol as hydrogen source . The characterization results demonstrated that the formation of NiCu alloy and electron transfer between Ni and Cu were responsible for the excellent catalytic performance. Isopropanol displayed better hydrogen-donating ability than other low-carbon alcohols because of its unique dehydrogenation pathway and small steric hindrance . The results of isotopic experiments elucidated that active hydrogen species for the C O bond cleavage originated from isopropanol rather than H 2 , while both isopropanol and H 2 were responsible for hydrogenation of phenol to cyclohexanol when reaction was conducted with mixed hydrogen sources. A mechanism study illustrated that transfer hydrogenolysis of BPE proceeded through direct cleavage of C O bond followed by phenol hydrogenation, in which the active hydrogen species were in the form of H + and H − .
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2018
·
IF 3.024
Jun Hu,Shiliang Wu,Xiaoxiang Jiang,Rui Xiao
The structure–reactivity relationship in fast pyrolysis of lignin for monomeric phenolic compounds was studied on seven lignins from hardwood, softwood, and grass. The distribution of elements, functional groups, phenylpropane units, and interunit linkage bonds varied greatly across the lignins. Lignins from hardwood and grass prepared with mild conditions presented more C–O linkages. Pyrolysis–gas chromatography/mass spectrometry showed that the cleavage of unstable C–O linkages dominated the pyrolysis reaction at low temperatures, and the total yields of monomers peaked at 700 °C for most lignins. 4-Vinylphenol produced from acid extracted corn stalk lignin reached up to 4.77 wt % at 700 °C. Pyrolysis of grass lignins and woody lignins, which had more unstable C–O linkages, exhibited higher total yields of monomers. The pyrolysis behavior of lignin at low temperatures is closely related to its structural characteristics. Pyrolyzed at 500 °C, the total yields of monomeric aromatics were highly linearly correlated with the frequencies of C–O linkages (R2 = 0.86). This work demonstrates the significance of selecting the right lignin for producing monomeric aromatic compounds.
研究领域:
生物质能
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化学工程
·
植物化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
·
IF 16.744
Jinglin Zou,Xinping Duan,Xu Liu,Lele Huang,Xiaoying Liu,Jiachang Zuo,Weizhou Jiao,Haiqiang Lin,Linmin Ye,Youzhu Yuan
Deciphering intrinsic reactive sites of metal–oxide catalysts, where the outer surface and/or interfaces coupled with oxygen species in the vicinity of nanoparticles concurrently work, remains a challenge. Given the extreme complexity of heterogeneous catalysis ( e.g. , metal catalysts for preliminary hydrogenation process), catalytically active sites, the activity origin, and reaction mechanism generally present a so-called 'black box'. Herein, Ag/ZrO 2−x achieves a higher intrinsic hydrogenation rate for selective scission of C O bond per mass Ag than the reference Ag/SiO 2 catalyst, as illustrated by the preliminary hydrogenation of dimethyl oxalate to methyl glycolate. The in-depth characterization revealed that the Ag δ+ –O v –Zr 3+ (Ag δ+ –O–Zr 4+ , O v refers to as oxygen vacancy) structure could be engineered owing to the higher affinity of Ag for the partially reduced ZrO 2 surface and heteroatom junctions (in preference to the inert support, such as SiO 2 and Al 2 O 3 ). Furthermore, the local environment of different crystallite phases (tetragonal or monoclinic ZrO 2 ) induced tunable (electronic) metal–support interactions (EMSIs), resulting in enhanced catalytic activity and ultra-stability for C O bond hydrogenation. XPS, methyl acetate-TPD, and in situ DRIFTS results unveiled the activity origin of silver–oxide systems, where the location of active metal sites for distinct functionalities over superficial and interfacial phases was validated. The mediated O v was verified to stabilize the thermodynamically unstable metallic (Ag 0 ) and charged silver species (Ag + or Ag n δ+ ). More importantly, time-resolved DRIFTS confirmed the crucial interfacial sites of Ag–ZrO 2−x for regioselective C O bond adsorption and activation. Further, the distinct active sites over Ag–ZrO 2−x may release the altered reaction mechanisms, i.e. , conventional Langmuir–Hinshelwood (LH) on Ag/SiO 2 versus quasi Mars–Van Krevelen process (Ag–ZrO 2−x ), which presents the new pathway for regioselective C O bond hydrogenation. The coordinated EMSIs were proposed as the origin of the catalytic activity caused by the synergistic catalysis of the interfacial/superficial sites. These findings rationalize the underlying understanding of the EMSI and highlight the instructive role for perceiving the structure-performance relationships and the activity origin in heterogeneous catalysts, thus moving away from the 'black-box' cognition.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2017
·Vol. 36
·期 2
·147-152
·
IF 1.852
Qing-Wen Song,Ping Liu,Li-Hua Han,Kan Zhang,Liang-Nian He
One-pot two-step stepwise reaction of terminal propargylic alcohols, carbon dioxide, and primary/secondary amines for the effective synthesis of various urethanes through robust silver-catalysed C-O/C-N bond formation is reported. Catalytic activities were investigated by controlling catalyst loading, reaction pressure and time, and very high turnover number (turnover frequency) was obtained: 3350 (35 h −1 ) with 0.01 mol% silver catalyst under 0.1 MPa, and up to 13360 (139 h −1 ) with 0.005 mol% silver catalyst under 2.0 MPa at room temperature. The strategy was ingeniously regulated, and synchronously afforded a wide range of β-oxopropylcarbamate and 1,3-oxazolidin-2-one motifs in excellent yields and selectivity together with unprecedented high turnover number (TON) and turnover frequency (TOF) value.
研究领域:
化学
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材料科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 11
·期 9
·3241-3250
·
IF 6.119
Ming Jiang,Xiaopeng Chen,Linlin Wang,Jiezhen Liang,Xiaojie Wei
Selective hydrogenolysis of aryl ethers to produce aromatic compounds is a key strategy for lignin valorization. The use of non-noble-metal catalysts to realize the cleavage of C–O ether bonds under mild conditions has been of considerable research interest recently. We herein report the synthesis of a nitrogen-doped porous-carbon-skeleton-supported Ni–CeO2 catalyst (Ni–CeO2/CN). The synergistic effect between Ni and CeO2 species led to the Ni–CeO2/CN catalyst having a high activity and selectivity for the cleavage of C–O ether bonds at a low reaction temperature. In particular, the Ni–CeO2/CN catalyst showed excellent effectiveness in the hydrogenolysis of benzyl phenyl ether (α-O-4 bonds), and the full conversion was achieved after 2 h at a temperature of 60 °C, with phenol and toluene as the sole reaction products. In addition, the conversion of more robust β-O-4 ether bonds in 2-phenoxy-1-phenylethanol reached up to 100% with the yield of ethylbenzene and phenol at 150 °C for 2.5 h being 60.2% and 68.3%, respectively. The reusability-experiment results indicate that Ni–CeO2/CN maintained a high catalytic activity in five reaction runs, making this a promising route for C–O ether bond cleavage under mild conditions.
研究领域:
催化化学
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生物质转化
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材料科学
✓ 已验证
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2017
·
IF 3.752
Xiang-Xue Liu,Zhi-Min Zong,Wei-Tu Li,Xiang Li,Zhan-Ku Li,Sheng-Kang Wang,Xian-Yong Wei
A novel and highly active magnetic solid superbase (MSSB) with extraordinary recovery and recycling properties was prepared by impregnating Mg 2 Si onto mesoporous silica coated magnetite via one-pot preparation and successfully applied in the catalytic hydroconversion (CHC) of sawdust at 220 °C. Detailed molecular compositions of the soluble portions from non-catalytic hydroconversion (SP NCHC ) and CHC (SP CHC ) were characterized with a Fourier transform infrared spectrometer and gas chromatograph/mass spectrometer (GC/MS). As a result, the yield of SP CHC is significantly higher than that of SP NCHC and most of the GC/MS-detectable compounds in SP CHC are guaiacols , while SP NCHC is rich in guaiacols and esters, indicating that MSSB effectively catalyzed the cleavage of C O bridged bonds in sawdust. The mechanism for catalytically hydrocracking C O bridged bonds over MSSB is proposed using benzyloxybenzene and oxybis(methylene)dibenzene as model compounds. MSSB can be easily separated by using an external magnetic field and the recovered MSSB proved to be still highly active for catalyzing the hydrocracking of C O bridged bonds in sawdust.
研究领域:
化学工程
·
生物质转化
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 60
·37932-37941
·
IF 3.361
Ge Guo,Wenzhi Li,Tauseef Ahmed,DuoDuo Hu,Ru Cui,Baikai Zhang,Xia Zhang
Non-noble bimetallic NiMo supported on zeolitic imidazolate framework-derived porous carbon (NiMo@FDC) catalyst for lignin depolymerization has been successfully developed. The synergism between Ni and Mo species in NiMo@FDC catalyst could promote the catalytic cleavage of C–O linkages in Kraft lignin. At a low reaction temperature of 240 °C and under 4 MPa H2, the lignin liquefaction yield was 98.85 wt% and minimum coke yield was 1 wt%, particularly when using 10%NiMo@FDC catalyst. Additionally, at a high reaction temperature of 300 °C and under 2 MPa H2, there was an overall yield of 86 wt% of liquid product and 42 wt% of petroleum ether soluble product. The higher heating value (HHV) increased from 27.65 MJ kg−1 to 34.11 MJ kg−1. In the cycling experiment, the bifunctional catalyst also demonstrated reversability and stability. The synergy of Ni hydrogenation sites and Mo coupled adsorption sites identified a possible mechanism path, which could offer considerable potential for lignin depolymerization.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 39
·18744-18750
·
IF 3.925
Dawang Chu,Hui Zhou,Zhicheng Luo
Selective conversion of glycerol to lactic acid requires the synergistic activation of C–H, C–O, and O–H. Herein, we report an inexpensive Fe–Cr/TiO2 catalyst that achieves lactic acid formation with a high selectivity of 60.5%. By changing the Fe/Cr ratios and reduction temperatures, the structures of Vő and Vő-OH were altered, which determined the overall oxidation–dehydration–isomerization process. The in situ ATR-IR experiments confirmed the activation of glycerol by adsorbing the primary −OH, and a series of control experiments verified that Fe was responsible for the cleavage of C–H and O–H, while CrOx catalyzed the activation of C–O and C–H. This work designs a hydrothermal catalyst with multifunctional ability, which may guide the rational catalyst design for the selective oxidation of glycerol to lactic acid.
研究领域:
催化化学
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材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2022
·
IF 8.129
Wang Li,Wen-Ying Li,Xing-Bao Wang,Jie Feng
During direct coal liquefaction , selective C al –O bond cleavage is critical for phenol production. In this study, anisole and benzyl phenyl ether were chosen as the oxygen-containing model compounds. Radical-induced sites of benzyl phenyl ether were investigated using the Fukui function and energy barrier calculation. The promotion routes of the C al –O bond cleavage in anisole and benzyl phenyl ether by radicals were illustrated. The formation of o -benzyl phenol was regarded as a sign of benzyl radical-induced pyrolysis based on the most optimal path. The competitive process between the optimal path and β-bond scission path was analyzed from the rate constant perspective. Radical-induced pyrolysis made remarkable differences in product selectivity for benzyl phenyl ether. Similarly, the cleavage of the C al –C al bond can also be promoted using two methods of radical induction, which is referred to as a radical chain process. In contrast to benzyl phenyl ethers, the induced pyrolysis of the C al –C al bond in bibenzyl is more likely to occur via β-bond scission after the H of CH 2 is abstracted by a radical. The findings of this research would provide a theoretical foundation for comprehending the radical mechanism of direct coal liquefaction.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
Solid Fuel Chemistry
·
2022
·Vol. 56
·期 1
·37-44
·
IF 0.829
Wang Ruiyu,Sun Bingkang,Zhu Jiliang,Fan Xing
Abstract Nano γ-Al 2 O 3 support was prepared by sol-gel method, and the Mg 2 Si/γ-Al 2 O 3 catalyst was prepared by impregnation method from Mg 2 Si and the γ-Al 2 O 3 support. The catalyst was characterized by X-ray diffraction, N 2 adsorption-desorption, scanning electron microscopy and CO 2 temperature-programmed desorption analysis. The catalytic hydrocracking of lignite-related modelcompounds, 1-methoxynaphthalene (1-MON) and bibenzyl ether (BE), was investigated. Mg 2 Si was well distributed on the surface and in the voids of γ-Al 2 O 3 support. The Mg 2 Si/γ-Al 2 O 3 catalyst had high specific surface area, large amount of mesopores, strong basicity, and exhibited high catalytic efficiency in hydrocracking of 1-MON and BE due to the synergic effect between Mg 2 Si and γ-Al 2 O 3 . Under an initial hydrogen pressure of 3 MPa and reaction time of 60 min, the conversion of 1-MON and BE reached 100% when the reaction temperatures were 225 and 175°C, respectively. The selectivities for naphthalene and toluene were close to 100%, only traces of the hydrogenated products were detected. After 4 cycle tests, the catalytic activity of Mg 2 Si/γ-Al 2 O 3 catalystdropped to 50%.
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2017
·
IF 3.204
Chen Zhu,Jing-Pei Cao,Xiao-Yan Zhao,Tao Xie,Jie Ren,Xian-Yong Wei
Selective cleavage of C O bonds in benzyl phenyl ether (BPE) as a typical lignin α-O-4 ether to produce aromatics is a challenging and attractive topic. Herein, the earth-abundant first-row transition metals, such as Co, Ni and Cu were supported on activated carbon (Co/AC, Ni/AC and Cu/AC) to identify their ability for cleaving C O bond of BPE. Among these catalysts, Ni/AC exhibit highest activity for cleavage of C O bond. The reaction with BPE was carried out at pretty mild condition of 140 °C and 2 MPa H 2 , which is highly selective afforded toluene and phenol as the major products with the optimum yields of 88.5 and 86.5%, respectively. Based on the test, the reaction pathways were proposed. A abundant of dissociated H· atoms on Ni(0) sites forms surface active Ni H species; Ni(0) activates and facilitates cleavage of the C O bond in BPE to form benzyl (C 6 H 5 C·) and phenoxy radicals (C 6 H 5 O·); H· atoms spill from active species Ni H recombined together with C 6 H 5 C· and C 6 H 5 O· forming the products of toluene and phenol, respectively.
研究领域:
化学
·
催化科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）