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Preferential Oxidation of CO in Excess Hydrogen over CuO-CeO_2 Catalyst Prepared by Chelating Method

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Journal of Natural Gas Chemistry 2007年第2期16卷 167-172页

作者： zhigang liu Renxian Zhou Xiaoming Zheng Institute of Catalysis Zhejiang University Hangzhou 310028 Zhejiang China

The CuO-CeO2 catalyst prepared by chelating method has a superior catalytic performance for the preferential oxidation of CO in rich hydrogen, compared with the CuO-CeO2 catalyst prepared by coprecipitation method. The CO conversions over these catalysts, at 120 ℃ and 120000 ml/（g-h） in the absence of CO2 and H2O, are 99.6% and 88.6%, respectively, and the selectivity of O2 over these catalysts is very close （i.e. 51.3% and 55.8%, respectively）. The influence of certain factors such as hydrogen concentration, carbon monoxide concentration, H2O, O2/CO ratios, and space velocity on the catalytic performance of CuO-CeO2 catalyst prepared by chelating method is also studied. The results show that the addition of hydrogen and H2O has a negative effect on the catalytic performance of CuO-CeO2 catalyst, however, the variation of space velocity and the O2/CO ratio causes a comparatively slight influence.

关键词： CuO-CeO2 chelating method preferential oxidation CO hydrogen

High sulfur-doped hard carbon anode from polystyrene with enhanced capacity and stability for potassium-ion storage

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Journal of Energy Chemistry 2022年第5期31卷 688-698页

作者： Xiaoyan Chen Xin-Bing Cheng zhigang liu Advanced Catalytic Engineering Research Center of the Ministry of Education College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082HunanChina Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Carbonaceous materials are regarded as a promising anode material for potassium ion batteries(PIBs)due to their high electronic conductivity, abundant resources and low cost. However, relatively low storage capacity and structural instability still hinder their practical application. Herein, high sulfur-doped hard carbon(SHC-3) with a sulfur up to 27.05 at% is synthesized from polystyrene and sulfur as precursors. As an anode for PIBs, the SHC-3 delivers a superb cycling stability and rate performance(298.1 mAh g^(-1)at 100 mA g^(-1) for 1000 cycles, a capacity retention of 95.2%;220.2 mAh g^(-1)at 500 mA g^(-1) after 5200 cycles). The potassium storage of SHC-3 exhibits excellent cyclic stability at both low and high *** and kinetic studies demonstrate that the larger interlayer spacing(0.382 nm) of the SHC-3 accelerates the diffusion of potassium ions and effectively alleviates the volume expansion, and thus maintains the structure stability during the process of potassization/de-potassization. Meanwhile, the density functional theory calculation shows that the doped sulfur atoms provide abundant active sites for the adsorption of potassium ions, thereby increasing the reversible capacity of PIBs. This work provides a new scheme for the design of carbonaceous anode materials with high capacity and long cycle life.

关键词： Hard carbon materials Sulfur doping Anode Potassium-ion storage DFT calculation

Influence of rare-earth metal doping on the catalytic performance of CuO-CeO_2 for the preferential oxidation of CO in excess hydrogen

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Journal of Natural Gas Chemistry 2008年第3期17卷 283-287页

作者： zhigang liu Renxian Zhou Xiaoming Zheng Institute of Catalysis Zhejiang University Hangzhou 310028 Zhejiang China School of Chemistry and Chemical Engineering Hunan University Changsha 410082 Hunan China

Doping of different rare-earth metals （Pr, Nd, Y and La） had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation （PROX） of CO in excess hydrogen. As for Pr, the doping enhanced the catalytic activity of CuO-CeO2 for PROX. For example, the CO conversion over the above catalyst for PROX was higher than 99% at 120 °C. Especially, the doping of Pr widened the temperature window by 20 °C over CuO-CeO2 with 99% CO conversion. For Nd, Y, and La, the doping depressed the catalytic activity of CuO-CeO2 for PROX. However, the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.

关键词： CuO-CeO2 rare-earth metal doping CO

Influence of preparation methods on CuO-CeO_2 catalysts in the preferential oxidation of CO in excess hydrogen

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Journal of Natural Gas Chemistry 2008年第2期17卷 125-129页

作者： zhigang liu Renxian Zhou Xiaoming Zheng School of Chemistry and Chemical Engineering Hunan University Changsha 410082 China Institute of Catalysis. Zhejiang University Hangzhou 310028 China

Influence of three different preparation methods, i.e. impregnation, coprecipitation, and inverse coprecipitation, on the preferential oxidation of CO in excess hydrogen （PROX） over CuO-CeO2 catalysts has been investigated and CuO-CeO2 catalysts are characterized using BET, XPS, XRD, UV Raman, and TPR techniques. The results show that the catalysts prepared by coprecipitation have smaller particle sizes, well-dispersed CuOx species, more oxygen vacancies, and are more active in the PROX than those prepared by the other methods. However. the inverse coprecipitation depresses the catalytic performance of CuO-CeO2 catalysts and causes the growth of CuO-CeO2 because of different pH value in the precipitation process.

关键词： CuO-CeO2 preparation method preferential oxidation CO fuel cell

Reversible Oxygen-Rich Functional Groups Grafted 3D Honeycomb-Like Carbon Anode for Super-Long Potassium Ion Batteries

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Nano-Micro Letters 2022年第9期14卷 132-146页

作者： Na Cheng Wang Zhou Jilei liu zhigang liu Bingan Lu School of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082People’s Republic of China School of Materials Science and Engineering Hunan UniversityChangsha 410082People’s Republic of China School of Physics and Electronics Hunan UniversityChangsha 410082People’s Republic of China

Studies have found that oxygen-rich-containing functional groups in carbon-based materials can be used as active sites for the storage performance of K^(+),but the basic storage mechanism is still ***,we construct and optimize 3D honeycomb-like carbon grafted with plentiful COOH/C=O functional groups(OFGC)as anodes for potassium ion *** OFGC electrode with steady structure and rich functional groups can effectively contribute to the capacity enhancement and the formation of stable solid electrolyte interphase(SEI)film,achieving a high reversible capacity of 230 mAh g^(-1) at 3000 mA g^(-1) after 10,000 cycles(almost no capacity decay)and an ultra-long cycle time over 18 months at 100 mA g^(-1).The study results revealed the reversible storage mechanism between K^(+)and COOH/C=O functional groups by forming C-O-K ***,the in situ electrochemical impedance spectroscopy proved the highly reversible and rapid de/intercalation kinetics of K+in the OFGC electrode,and the growth process of SEI *** particular,the full cells assembled by Prussian blue cathode exhibit a high energy density of 113 Wh kg^(-1) after 800 cycles(calculated by the total mass of anode and cathode),and get the light-emitting diodes lamp and ear thermometer running.

关键词： Honeycomb-like Super-long Carbon anode Potassium-ion batteries

Sulfur/nitrogen/oxygen tri-doped carbon nanospheres as an anode for potassium ion storage

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Journal of Energy Chemistry 2023年第2期77卷 338-347,I0009页

作者： Xiaoyan Chen Wang Zhou Jilei liu Yingpeng Wu zhigang liu Advanced Catalytic Engineering Research Center of the Ministry of Education College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082HunanChina State Key Laboratory of Chem/Bio-Sensing and Chemometrics Advanced Catalytic Engineering Research Center of the Ministry of EducationCollege of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082HunanChina College of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean EnergyHunan Province Key Laboratory for Advanced Carbon Materials and Applied TechnologyHunan UniversityChangsha 410082HunanChina

Carbonaceous materials are considered as ideal anode for potassium ion batteries(PIBs)due to their abundant resources and stable physical and chemical ***,improvements of reversible capacity and cycle performance are still needed,aiming to the practical ***,S/N/O tridoped carbon(SNOC)nanospheres are prepared by in-situ vulcanized *** S/N/O tridoped carbon matrix provides abundant active sites for potassium ion adsorption and effectively improves potassium storage ***,the SNOC nanospheres possess large carbon interlayer spacing and high specific surface area,which broaden the diffusion pathway of potassium ions and accelerate the electron transfer speed,resulting in excellent rate *** an anode for PIBs,SNOC shows attractive rate performance(438.5 mA h g^(-1) at 50 mA g^(-1) and 174.5 mA h g^(-1) at2000 mA g^(-1)),ultra-high reversible capacity(397.4 mA h g^(-1) at 100 mA g^(-1) after 700 cycles)and ultra-long cycling life(218.9 mA h g^(-1) at 2000 mA g^(-1) after 7300 cycles,123.1 mA h g^(-1) at3000 mA g^(-1) after 16500 cycles and full cell runs for 4000 cycles).Density functional theory calculation confirms that S/N/O tri-doping enhances the adsorption and diffusion of potassium ions,and in-situ Fourier-transform infrared explores explored the potassium storage mechanism of SNOC.

关键词： Potassium ion batteries S/N/O tri-doped Carbon nanospheres Anode

Covalent sulfur as stable anode for potassium ion battery

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Journal of Energy Chemistry 2021年第11期30卷 645-652,I0015页

作者： Na Cheng Patrick Xu Bingan Lu zhigang liu School of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082HunanChina College of Letter and Science University of CaliforniaBerkeleyCA 94720USA School of Physics and Electronics Hunan UniversityChangsha 410082HunanChina

The potassium bis(fluoro-sulfonyl)imide(KFSI)-based electrolyte has great application prospects in potassium ion batteries (PIBs). However, their development has been limited by the decomposition of electrolytes and the corrosion of Al foils (current collector) at high potential. Here, a N-doping, sulfur-rich chemically bonded porphyrin organic framework (SPOF) with a high potential plateau were synthesized as an anode to lower the redox potential of full cells and further inhibit the corrosion of Al foils. SPOF as anode delivers high reversible capacity (557 mAh g^(−1) at 50 mA g^(−1)), excellent cycling performance (94% capacity retention over 1000 cycles at 500 mA g^(−1)), and superior rate performance. Meanwhile, the ex-situ FTIR, Raman, and HRTEM revealed the stability of N-doping and the reversible covalent sulfur and S–S bonds changes during potassiation/depotassiation. In addition, full cells using SPOF anode and PTCDA cathode showed outstanding performance (high capacity of 300 mAh g^(−1) at 200 mA g^(−1)). And the Al current collector of the full cell was not corroded after 150 cycles. Yet, the Al foils with PTCDA as cathode were seriously corroded. This work provides a new strategy for realizing ultra-high reversible capacity and cyclic stability of PIBs, and also accelerates the process of early commercial application of PIBs.

关键词： Porphyrin organic framework Covalent sulfur Anode Potassium-ion batteries

Influence of doping nitrogen on the catalytic performance of carbon nanotubes encapsulating cobalt for selective oxidation of arylalkanes

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Particuology 2021年第5期19卷 85-91页

作者： Ganghua Xiang Xiaocan Wang Lushuang Zhang zhigang liu Advanced Catalytic Engineering Research Center of the Ministry of Education College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082HunanChina

Efficient selective oxidation of hydrocarbons to corresponding ketones has been a significant but challenging work in the past ***,a nitrogen-doped bamboo-like carbon nanotubes encapsulating cobalt catalyst(NCNTs-X)using citric acid,melamine and CoCl_(2)·6H_(2)O as precursors was synthesized by a simple pyrolysis method.A series of characterization techniques were employed to investigate the physicochemical properties of *** the results show that the as-prepared catalysts achieve a high catalytic performance for selective ethylbenzene oxidation(78.3% ethylbenzene conversion)using molecular oxygen as oxidant,especially giving a high selectivity(93.8% selectivity to acetophenone).According to the investigation of the structure-activity relationship of the catalysts,it can be deduced that the Co-N_(x) sites have an obvious positive effect on catalytic performance thanks to the synergistic effect between metallic cobalt and pyridinic N.

关键词： Bamboo-like carbon nanotubes Encapsulation Co-N_(x) Ethylbenzene Selective oxidation

Effect of Steam Dilution on the MILD Combustion Characteristics of Methane in a Model Combustor

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Journal of Thermal Science 2023年第2期32卷 822-836页

作者： ZHU Ziru XIONG Yan liu zhigang ZHANG Zhedian Key Laboratory of Advanced Energy and Power Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Moderate or Intense Low-oxygen Dilution(MILD)combustion has low emission potential in gas *** present work has investigated the performance of MILD combustion with parallel-jet burner arrangement in dry and steam-diluted *** combustion tests were conducted in atmospheric pressure at various equivalence ratios from LBO(Lean Blow Out)to near-stoichiometric conditions and steam-to-air mass ratios from 0 to 0.2.A simplified chemical reactors network(CRN)model based on MILD combustion concept has been established to study the effect of steam dilution on different pathways of NO *** experimental results show that under the same adiabatic flame temperature,the reaction zone gradually moves downstream with the increase of steam *** the high steam content(0.2 kg/kg),the reaction zone is widely distributed,and the distribution of reaction intensity in the reaction zone is more *** average lift-off height of reaction zone is proportional to the steam *** the steam content of 0.2 kg/kg,the average lift-off height reaches 2.5 times that of the dry conditions,which brings the risk of *** the adiabatic flame temperature of 1650–1900 K,the emissions of NOxare below 3×10–6(at 15%O2,dry)when the steam content varies from 0 to 0.2 kg/kg,which indicates the ultra-low emissions can be obtained under large changes in steam *** the inlet temperature of 381 K,as the steam content increases,the Prompt NO is dominant in the total NO *** dilution results in a smaller operating range with lower CO *** the steam content reaches 0.2 kg/kg,compared to the dry condition,the carbon monoxide emission increases *** addition,the LBO equivalence ratio of combustion with larger steam content is significantly higher.

关键词： MILD combustion steam dilution chemical reactors network(CRN) NOx emissions