FUEL
·
2018
·
IF 4.908
Yang Zhou,Lu Li,Lijun Jin,Jian Zhou,Zhiwei Shi,Yang Li,Haoquan Hu
Coal pyrolysis is generally considered to initiate by cleavage of weak covalent bonds bridged between aromatic rings. The C–C covalent bonds are predominant bridged linkages among the framework of coal, which have a critical influence on coal pyrolysis reaction but lack of direct online observation. Five representative coal-related model compounds containing C–C bridged bonds, polypropylene (PP), polyvinylpyrrolidone (PVP), poly-4-vinylpyridine (P4VP), polystyrene (PS) and poly-4-vinylphenol, were selected to pyrolyze in an in-situ pyrolysis vacuum ultraviolet photoionization mass spectrometry (Py-VUV-PIMS). The soft ionized mass spectral detection can provide product distribution and evolved information of original products and intermediates, which are the key evidence to understand the initiation, recombination and reaction routes during pyrolysis process. Online analysis of pyrolysis reaction was found to be priority with cracking of C–C bond in the five polymer samples, and homologous free radicals and original products, which mainly include monomers, dimers and their alkyl and alkenyl radicals, were detected. The results reveal the cleavage temperature of C–C covalent bond is deeply related to its chemical environment, and obvious conjugation effect and steric effect for the bridged linkage were observed. In addition, the effect of hydrogen bond was also observed during the pyrolysis of model compounds containing hydroxyl groups, and intramolecular or intermolecular hydrogen bonding reduced the temperature at which C–C bridged bonds break. The analogous fracture mode and pyrolysis behavior of coal-related model compounds, which are beneficial to understand the reaction route and mechanism of coal pyrolysis, were discussed based on the experimental observations and theoretical calculation.
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Asian Journal of Organic Chemistry
·
2018
·Vol. 7
·期 10
·2039-2044
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IF 2.496
Qian-Qian Huang,Wei-Qiang Yu,Xiao-Lin Luo,Jin Gao,Jie Xu
Graphical An alternative method for glycerol hydrogenolysis to CH 4 and ethylene glycol that proceeds through preferential C−C bonds cleavage catalyzed by highly-dispersed Ru catalysts with tunable particle sizes via carbothermal reduction has been reported. An alternative method for the conversion of crude glycerol was proposed to produce renewable energy methane and high-value chemical ethylene glycol through preferential cleavage of C−C bonds, catalyzed by highly dispersed Ru-based catalysts prepared by carbothermal reduction. It was found that the Ru particles size could be tuned by adjusting the reduction temperature, and the size firstly decreased then increased with raising of the temperature of carbothermal reduction. This resulted in the opposite tendency of catalytic performance against the Ru particle sizes in hydrogenolysis of glycerol, in which the glycerol conversion and yield of C−C bond cleavage increased firstly and then decreased. Ru catalysts carbothermal reduced at 450 °C possessed highly dispersed Ru nanoparticles with uniform particle sizes about 1.0 nm that showed high hydrogenation activity and selectivity of C−C bond cleavage as well as good stability that could be recycled in aqueous phase hydrogenolysis of glycerol.
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Scientific Reports
·
2017
·Vol. 7
·期 1
·1-10
·
IF 4.259
Feng Shanglei,Yang Yingguo,Li Li,Zhang Dongsheng,Yang Xinmei,Xia Huihao,Yan Long,Tsang Derek K. L.,Huai Ping,Zhou Xingtai
An in-situ real-time synchrotron-based grazing incidence X-ray diffraction was systematically used to investigate the crystal structural evolution of carbon fiber reinforced carbon matrix (C/C) composite impregnated with FLiNaK molten salt during the heat-treatment process. It was found that the crystallographic thermal expansion and contraction rate of interlayer spacing d
002 in C/C composite with FLiNaK salt impregnation is smaller than that in the virgin sample, indicating the suppression on interlayer spacing from FLiNaK salt impregnated. Meanwhile the crystallite size L
C002 of C/C composite with FLiNaK salt impregnation is larger than the virgin one after whole heat treatment process, indicating that FLiNaK salt impregnation could facilitate the crystallization of C/C composite after heat treatment process. This improved crystallization in C/C composite with FLiNaK salt impregnation suggests the synthetic action of the salt squeeze effect on crooked carbon layer and the release of internal residual stress after heating-cooling process. Thus, the present study not only contribute to reveal the interaction mechanism between C/C composite and FLiNaK salt in high temperature environment, but also promote the design of safer and more reliable C/C composite materials for the next generation molten salt reactor.
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PubMed
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
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2024
·
IF 5.6
Zhen Huang,Penghao Sun,He Liu,Chunyu Ren,Xiangyu Lin,Minggui Shen,Zhaoshuang Li,Xu Xu
To obtain high-valued aromatic products, it is paramount to cleave the C α −C β bonds in lignin under mild conditions selectively. Nevertheless, this task remains daunting due to the formidable dissociation energies and steric hindrance associated with these bonds. Herein, a facile, efficient and cost-effective strategy for selectively breaking the C α −C β bond in lignin with visible-light irradiation and room temperature is proposed, facilitated by the utilization of the ferric-doped mesoporous graphitic carbon nitride (Fe/mpg-CN) photocatalyst. Collective contributed by the reduced band gap and photoluminescence, combined with intensified visible-light absorption and enhanced photocurrent, the effectiveness in photocatalytic activity of Fe/mpg-CN is offered. Specifically, a high conversion rate (98 %) of the lignin model compound (2-phenoxy-1-phenylethanol), coupled with an excellent selectivity of 98 % in cleaving the C α −C β bonds is achieved by Fe/mpg-CN. Photogenerated holes are indicated as the main active species through comprehensive mechanistic investigations. Additionally, the successful photocatalytic depolymerization of the complex dimer model compound (conversion rate ∼ 96 %) and pine kraft lignin further corroborate the satisfying photocatalytic activity and selectivity of Fe/mpg-CN. This study introduces a promising and viable strategy for the selective breaking of lignin through photocatalysis, offering significant implications for the sustainable production of valuable aromatic compounds.
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ACS Catalysis
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2024
·
IF 11.3
Weijie Geng,Di Zhang,Ni Zhen,Jianxin Du,Jing Dong,Chengpeng Liu,Shi-Lu Chen,Yingnan Chi,Changwen Hu
The electrochemical coupling of biomass platform molecules to biofuels provides a promising method for addressing energy crises and environmental issues. However, achieving high yields of C–C coupling products under ambient conditions remains a challenge. Herein, we present a highly efficient electrocatalyst, [Cu(pz)]3[PW12O40] (Cu-PW12), fabricated by combining a Cu-pz complex (pz = pyrazine), a redox catalytic center, with Keggin-type PW12O40, and an electron sponge. Cu-PW12 exhibits remarkable catalytic activity for the electroreductive C–C coupling of furfural (FF), a bulk and low-cost biomass platform chemical, to produce a jet fuel precursor, hydrofuroin (HDF). Under neutral and ambient conditions, over 99% of FF is converted and the selectivity of HDF reaches 91.2%. Furthermore, experimental and theoretical studies, including control experiments, kinetic isotope studies, electrochemical and spectral analyses, and DFT calculations, reveal a synergistic catalysis effect between Cu center and PW12. The introduction of PW12 not only facilitates electron transfer, improving FF conversion, but also changes the rate-determining step, favoring the formation of HDF. Under turnover conditions, the Cu-PW12 catalyst is initially reduced and then FF is reduced by the Cu center to ketyl radical after protonation on the electrode surface. Finally, the self-coupling of two ketyl radicals in solution leads to the generation of HDF.
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Journal of Energy Chemistry
·
2024
·
IF 14
Hongqiang Yang,Jianfeng Zheng,Guoyu Wang,Yifei Gao,Yatao Yang,Jia Li,Xiaojin Han,Yan Cui,Zhanggen Huang
Photoelectrocatalytic coupling CO 2 and volatile organic compounds (VOCs) is a promising green strategy for the synergistic conversion of the two carbon-containing resources to C 2 products. The catalytic efficiency is always at the mercy of chemical inertness of CO 2 and the competitive hydrogen evolution of H 2 O. Herein, a modified g-C 3 N 4 /ZnAl-LDH Z-scheme heterojunction catalyst with dual reaction site was rationally designed and precisely constructed. The Faraday efficiency of ethanol reached 68.67% with a corresponding formation rate of 227.3 μmol g −1 h −1 . As revealed by in-situ characterizations and density functional theory calculations, CO 2 and HCHO were absorbed at Zn site and N site, respectively. Then, *CO generated from CO 2 and HCHO was converted to *CH 3 O and *CHO on the dual-active-site heterojunction. The detailed reaction mechanism experiments indicated that C–C coupling only occurred between *CO and *CH 3 O in electrocatalysis process. Apart from the “*CO + *CH 3 O” path, another “*CO + *CHO” coupling path was also detected in photoelectrocatalytic process. The selectivity of ethanol was significantly enhanced due to the synthesis of dual-site catalyst and the dual-path coupling path between CO 2 and HCHO simultaneously driven by light and electricity.
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高影响因子
ANALYTICA CHIMICA ACTA
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2018
·
IF 5.123
Tengfei Xu,Zifeng Pi,Fengrui Song,Shu Liu,Zhiqiang Liu
Unsaturated lipids exhibit different physiological significances due to the different locations of the carbon–carbon double bond (C=C). Identifying lipid isomers with mass-based methods remains challenging. Xia's group has been successfully employed Paternò–Büchi (PB) reaction, a photochemical reaction with UV irradiation , coupled with tandem mass spectrometry (MS/MS) to identify and quantify unsaturated lipids in complex mixtures. However, the existing PB reagents possess certain demerits. In this regard, a new PB reagent that is compatible with various lipidomic analysis platforms must be screened. In this study, we comprehensively evaluated the conditions of the PB reaction and screened benzophenone as a new PB reagent. Benzophenone possesses unique advantages, such as a relative high PB yield; the PB products could be readily distinguished from the reacted lipids based on the added high molecular weight (182 Da); and the benzophenone does not affect the lipids appearance interval for reversed-phase column separation. Furthermore, we optimized the reaction conditions by using benzophenone as a PB reagent and summarized the molecular formulas of the diagnostic ions according to the fragment rules. The proposed PB method has been implemented in shotgun and LC–MS lipidomics. To our best knowledge, this work is the first to report the integrated PB reaction with LC–MS lipidomics for identification of lipid isomers.
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Catalysis Science & Technology
·
2015
·Vol. 6
·期 6
·1693-1700
·
IF 5.426
Zhixin Zhang,Yehong Wang,Min Wang,Jianmin Lu,Chaofeng Zhang,Lihua Li,Jingyang Jiang,Feng Wang
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.
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高影响因子
Nanoscale
·
2016
·Vol. 8
·期 8
·4681-4687
·
IF 7.76
Zexing Wu,Jie Wang,Lili Han,Ruoqian Lin,Hongfang Liu,Huolin L. Xin,Deli Wang
Investigating active, stable, and low-cost materials for the oxygen reduction reaction is one of the key challenges in fuel-cell research. In this work, we describe the formation of N-doped carbon shell coated Co@CoO nanoparticles supported on Vulcan XC-72 carbon materials (Co@CoO@N–C/C) based on a simple supramolecular gel-assisted method. The double-shelled Co@CoO@N–C/C core–shell nanoparticles exhibit superior electrocatalytic activities for the oxygen reduction reaction compared to N-doped carbon and cobalt oxides, demonstrating the synergistic effect of the hybrid nanomaterials. Notably, the Co@CoO@N–C/C nanoparticles give rise to a comparable four-electron selectivity, long-term stability, and high methanol tolerance; all show a multi-fold improvement over the commercial Pt/C catalyst. The progress is of great importance in exploring advanced non-precious metal-based electrocatalysts for fuel cell applications.
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CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Su Wang,Qifang Sun,Chen Li,Dongge Wang,Yue Ma,Hongzhou Zhang,Xixi Shi,Lianqi Zhang,Dawei Song
Given the high combustion or explosion potential of liquid electrolyte, polymer electrolytes have attracted intensive attention due to high safety, compatible interface and flexible processability. However, the related low ionic mobility remains an issue for related wide application. Herein, a crosslinked polymer electrolyte (abbreviated as PMEP) comprising abundant oxygen-contained groups (C-O-C/C=O) is developed. With the crosslinking agent of ethoxylated trimethylolpropane triacrylate (ETPTA), a high transference number ( t Li + =0.69) is obtained since C-O/C=O are conducive to the transfer of Li ions. Specifically, C=O group exists in individual monomers in order to be applicable to high voltage cathode, therefore, a criss-cross network containing abundant sites conducive to ion transport is constructed and rapid ion transfer as well as enhanced mechanical strength can be realized even in high potential system. With the coordination effect of C-O and C=O, PMEP exhibits rapid Li ion transfer and a wide electrochemical stability window of 5.1 V. As for Li//Li symmetrical cell, a stable voltage profile with slight polarization of 60 mV is displayed for over 550 h at 1 mA cm −2 . After assembled with LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode, a high discharge specific capacity of 190.6 mAh g −1 is delivered and the capacity retention reaches 86 % at 0.1C for 100 cycles. This work provides a promising method for designing high-performance polymer electrolytes for lithium metal batteries.
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高影响因子
Journal of Energy Chemistry
·
2024
·
IF 14
Xiaoyue Zhang,Yong Yang,Yingjie Hu,Lijun Xiong,Tianyu Wang,Panjie Li,Jinyou Shen
Photothermal catalytic CO 2 conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat. However, the C–C coupling initiated by photothermal catalysis is still a big challenge. Herein, a three-dimensional (3D) hierarchical W 18 O 49 /WTe 2 hollow nanosphere is constructed through in-situ embodying of oxygen vacancy and tellurium on the scaffold of WO 3 . The light absorption towards near-infrared spectral region and CO 2 adsorption are enhanced by the formation of half-metal WTe 2 and the unique hierarchical hollow architecture. Combining with the generation of oxygen vacancy with strengthened CO 2 capture, the photothermal effect on the samples can be sufficiently exploited for activating the CO 2 molecules. In particular, the close contact between W 18 O 49 and WTe 2 largely promotes the photoinduced charge separation and mass transfer, and thus the *CHO intermediate formation and fixedness are facilitated. As a result, the C–C coupling can be evoked between tungsten and tellurium atoms on WTe 2 . The ethylene production by optimized W 18 O 49 /WTe 2 reaches 147.6 μmol g − 1 with the selectivity of 80%. The in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations are performed to unveil the presence and significance of aldehyde intermediate groups in C–C coupling. The half-metallic WTe 2 cocatalyst proposes a new approach for efficient CO 2 conversion with solar energy, and may especially create a new platform for the generation of multi-carbon products.
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Journal of Cleaner Production
·
2020
·
IF 7.246
Shanshan Shao,Xinggang Hu,Wenbin Dong,Xiaohua Li,Huiyan Zhang,Rui Xiao,Yixi Cai
Aldol condensation of biomass-derives coupled with hydrogenation is a promising route for the production of renewable aviation fuel. In this study, a bifunctional catalyst was prepared to integrate the aldol condensation of cyclopentanone and hydroprocessing for aviation fuel in one pot. Due to its strong mild-basic sites, Mg–Al–O performed the best with the total yield of dimer and trimer of 80.4%. Nickel was screened out to be favorable for hydrogenation. Considering the unsatisfactory porous structure of Ni/Mg–Al–O, the bifunctional catalyst was prepared with activated carbon (AC) as carrier. With Ni loading of 20 wt%, the maximum yield of targeted alkanes reached 81.1% over Ni/Mg–Al–O/AC. The calcination and reduction temperature in the preparation process were both optimized at 550 °C. In the reusability test, the yield of targeted alkanes reduced to 31.6% in the 5th run. To attenuate the hydration effect, n-pentane was introduced as solvent, and the bifunctional Ni/Mg–Al–O/AC performed stably in 5 runs. By the design of bifunctional catalyst based on the theoretical basis to realize the integration of C–C coupling and hydrogenation in one pot, it will promote the development of aviation fuel from biomass in a more sustainable and green way.
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