2019 Vol. 4, No. 4

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Research highlights
Selective production of diethyl maleate from lignin
Buxing Han
2019, 4(4): 343-344. doi: 10.1016/j.gee.2019.09.002
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Short Review
High energy batteries based on sulfur cathode
Jian Zhu, Jianli Zou, Hua Cheng, Yingying Gu, Zhouguang Lu
2019, 4(4): 345-359. doi: 10.1016/j.gee.2018.07.001
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Lithium-ion batteries (LIBs) have become an indispensable part of our daily life, however, the energy and power capability that LIBs can deliver are lagging far behind the ever-increasing demands of portable electronics and electric vehicles. Metal-sulfur batteries as one of the most promising alternatives to LIBs are receiving rapidly growing research interests due to the extremely high energy density and abundant resources of sulfur. In this short review, we will discuss the state-of-art development of high energy density battery technologies based on sulfur cathode in combination with different metal anodes, with focus on sodium, magnesium and aluminum anodes. We leave lithium-sulfur batteries out of discussion since there are already a large number of nicely organized review papers available. The operation mechanism of various anode materials and the variety of electrolytes used in sulfur batteries will be reviewed. Some perspectives on improving the performances and overcoming the remaining issues in sulfur batteries will be discussed. It is expected that this review will draw more attention to sulfur batteries from both the academic and industrial communities.
Review article
Electrolyte for lithium protection: From liquid to solid
Xiaohong Wu, Kecheng Pan, Mengmin Jia, Yufei Ren, Hongyan He, Lan Zhang, Suojiang Zhang
2019, 4(4): 360-374. doi: 10.1016/j.gee.2019.05.003
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Lithium battery with high energy density and enhanced safety is undoubtedly the ideal choice for consumer electronics and electric vehicles. Metal anode such as lithium has been considered as the most effective way to enhance the energy density as it provides ultra-high theoretical capacity and the lowest redox potential. However, due to the low coulombic efficiency as well as safety concerns originated from dendrite issue of lithium, its further commercial utilization is hindered. Dendrite growth is a common phenomenon in metal electrodeposition while the plating process of Li is more complicated than other metals for its high reactivity nature. As a matter of fact, the Li plating process is accompanied with the generation of solid electrolyte interphase (SEI) in which the electrolyte plays a vital role. In this paper, recent advances of electrolytes for Li protect application are reviewed, from liquid to gel polymer and solid state, on which we find that although tremendous progress has been accomplished, there are still great challenges before Li metal anode could be commercially used.
Research paper
High–Speed electron beam curing of thick electrode for high energy density Li-ion batteries
Zhijia Du, Christopher J. Janke, Jianlin Li, David L. Wood
2019, 4(4): 375-381. doi: 10.1016/j.gee.2019.04.001
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Electron beam curing is demonstrated as a promising method for high speed, low cost and environmentally friendly battery electrode manufacturing. This work reports transfer of this process to pilot scale equipment and evaluation of electrochemical performance in prototype 1.5 Ah pouch cells. Thick LiNi0.5Mn0.3Co0.2O2 (NMC532) composite electrodes with an areal loading of 25 mg cm−2 (∼4 mAh cm−2) are successfully cured at a line speed of 500 feet per minute at 275 keV. Compared to the NMC532 cathode processed via a conventional coating method, the electron beam cured electrodes show higher capacity fade in the first 100 cycles, but similar fade rate afterwards. Further improvement strategies are proposed and discussed. This work demonstrates that electron beam curing is a promising method for manufacturing thick battery electrodes at high speeds and low capital/operation cost.
Flexible quasi-solid-state dual-ion asymmetric supercapacitor based on Ni(OH)2 and Nb2O5 nanosheet arrays
Xiaolan Deng, Yuqi Jiang, Zengxi Wei, Minglei Mao, Ramyakrishna Pothu, Hongxia Wang, Caiyun Wang, Jinping Liu, Jianmin Ma
2019, 4(4): 382-390. doi: 10.1016/j.gee.2019.02.001
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Increasing the energy density, power density as well as widening the operation voltage are essential to electrochemical capacitors to meet the practical energy demands. Herein, a novel flexible quasi-solid-state dual-ion asymmetric supercapacitor (ASC) with Ni(OH)2 and Nb2O5 nanosheets directly grown on stainless steel mesh is developed. In the dual-ion ASC, Nb2O5 negative and Ni(OH)2 positive electrodes react with Li+ and OH− respectively in alkaline gel electrolyte to store energy, which is quite different from conventional alkali metal ion SCs and alkaline SCs. The as-assembled flexible device has an extended working voltage of 1.7 V and delivers a capacity of 5.37 mAh cm−2, a maximum energy density and power density of 0.52 mWh cm−3 and 170 mW cm−3, respectively. The device maintains around 60% capacity retention after long cycling up to 1000 cycles. Moreover, our device can light up a LED light efficiently upon fast charging. The proposed quasi-solid-state dual-ion ASC has potential applications in future portable electronics and flexible energy storage devices.
One-pot degradation of cellulose into carbon dots and organic acids in its homogeneous aqueous solution
Hui Su, Zhihao Bi, Yong Ni, Lifeng Yan
2019, 4(4): 391-399. doi: 10.1016/j.gee.2019.01.009
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As the abundant biopolymer, cellulose can be used as a feedstock for chemicals and materials. Effective conversion of cellulose by simple processes is a key point. Degradation of cellulose in its homogeneous solution is attractive for the molecular chains are free and spread. Here, microcrystalline cellulose was first dissolved in aqueous solution of NaOH and urea, and then hydrothermal reaction was carried out at various temperature and time. Fluorescence carbon dots (CDs) were generated accompanied with six organic acids: oxalic acid, formic acid, malonic acid, lactic acid, acetic acid, and fumaric acid. The yields of all organic acids and CDs, and the fluorescence quantum yield (QY) of CDs were studied at different reaction conditions. It was found that the maximum yield of organic acids and CDs are 80.1% and 6.03%, respectively, and the highest QY of the CDs is 10.9%. Fluorescence studies reveal that the as-prepared CDs has efficient selectivity and sensitivity toward iron ions in acidic condition, indicating it is a potential fluorescent sensor to the detection of Fe3+. Importantly, it provides a panorama to summary the degradation routes of cellulose in its homogeneous aqueous solution with both organic molecules and CDs as products.
Direct conversion of furfural to levulinic acid/ester in dimethoxymethane: Understanding the mechanism for polymerization
Yuewen Shao, Xun Hu, Zhanming Zhang, Kai Sun, Guanggang Gao, Tao Wei, Shu Zhang, Song Hu, Jun Xiang, Yi Wang
2019, 4(4): 400-413. doi: 10.1016/j.gee.2018.10.002
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This study investigated the conversion of furfural to 5-hydroxymethylfurfural (HMF) and further to levulinic acid/ester in dimethoxymethane under acidic conditions, with the particular focus on understanding the mechanism for polymer formation. The results showed that furfural could react with dimethoxymethane via electrophilic substitution reaction to form HMF or the ether/acetal of HMF, which were further converted to levulinic acid and methyl levulinate. The polymerization of furfural and the cross-polymerization between dimethoxymethane and the levulinic acid/ester produced were the main side reactions leading to the decreased yields of levulinic acid/ester. Comparing to the other solvent, methanol as the co-solvent helped to alleviate but not totally inhibited the occurrences of the polymerization, as the polymerization reactions via aldol condensation did not eliminate the CO functionalities. As a consequence, the polymerization reactions continued to proceed. Other co-solvent used such as guaiacol, dimethyl sulfoxide and acetone interfered with the transformation of furfural to HMF or aided the polymerization reactions. The polymer produced from the reactions between furfural and DMM was different from that produced from levulinic acid/ester. The former had a higher crystallinity, while the latter was more aliphatic. The DRIFTS and TG-MS studies showed that the polymer had the carboxylic group, methyl group and the aliphatic structure in the skeleton. The removal of these functionalities was accompanied by the aromatization of the polymer. The condensation of DMM with levulinic acid/ester was the key reason for the diminished production of levulinic acid/ester.
Biomass-derived porous carbon highly efficient for removal of Pb(II) and Cd(II)
Anqi Wang, Zhikeng Zheng, Ruiqi Li, Di Hu, Yiran Lu, Huixia Luo, Kai Yan
2019, 4(4): 414-423. doi: 10.1016/j.gee.2019.05.002
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The utilization of abundant and renewable biomass to fabricate advanced functional materials is considered a promising route for environmental applications. Herein, Lignin-based porous carbon with layered graphene-like structure (LPC) is successfully synthesized and applied to efficiently remove Pb(II) and Cd(II). The as-synthesized LPC materials are systematically characterized and these results show that LPC has a porous graphene-like structure, facilitating the diffusion and immobilization of heavy metal ions. The influence of different reaction parameters (solution pH, initial concentration of metal ions, contact time and adsorbent amount) on the adsorption performance is investigated in details. The results demonstrate that LPC can achieve superior adsorption capacities of 250.5 mg g−1 for Pb(II) and 126.4 mg g−1 for Cd(II), which are far superior to the previously reported adsorbents. Pseudo-second order kinetics model and Freundlich isotherm model describe the adsorption process well. Furthermore, the exhausted LPC can be regenerated easily and exhibits the removal efficiency of 96% and 92% for Pb(II) and Cd(II) after five continuous runs, respectively. This study shows a sustainable strategy for the design of porous carbon material from naïve biomass and highlights the great potential in wastewater treatment.
Highly efficient catalytic valorization of biomass-derived hexoses and furfuryl alcohol in the presence of polymer-based catalysts
Yangyang Zhang, Xinli Tong, Linhao Yu, Lingwu Meng, Pengfei Guo, Song Xue
2019, 4(4): 424-431. doi: 10.1016/j.gee.2019.01.006
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The catalytic transformation of furfuryl alcohol and hexose into value-added chemicals have been investigated with a series of polymer-based catalysts including poly(styrenesulfonic acid) (PSS), graphite oxide-doped poly(styrenesulfonic acid) (PSS-GO), and graphite-doped poly(styrenesulfonic acid) (PSS-C). It is found that the selective conversion of furfuryl alcohol to methyl levulinate (MLE) was successfully performed with PSS as the catalyst, in which a 96.4% yield is attained in methanol solvent. Moreover, the efficient dehydration of d-fructose to produce 5-hydroxymethylfurfural (HMF) has also been achieved using PSS-GO as the catalyst, where a 76.5% yield of HMF was obtained in N-methylpyrrodinone solvent. The effects of reaction temperature, time and solvent were investigated. Furthermore, the used catalysts have been respectively characterized by XRD, TG, FTIR, SEM and TEM techniques to reveal the physical properties and structures of these polymeric catalytic materials.
Scale-up of biomass conversion using 1-ethyl-3-methylimidazolium acetate as the solvent
Ling Liang, Jipeng Yan, Qian He, Tina Luong, Todd R. Pray, Blake A. Simmons, Ning Sun
2019, 4(4): 432-438. doi: 10.1016/j.gee.2018.07.002
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This scale-up study demonstrated the feasibility of an ionic liquid (IL) pretreatment process at 40 kg scale, using the IL 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) as the solvent. The pretreatment was followed by enzymatic hydrolysis through which the process efficiency for biomass conversion to monomeric sugars was determined. The results show that 43 wt% of switchgrass was dissolved in IL after 2 h of pretreatment at 160 °C with 15 wt% solid loading. A 120 h enzymatic hydrolysis of the pretreated switchgrass results in 96% glucan and 98% xylan conversion. [C2C1Im][OAc] pretreatment has been successfully scaled up to 40 kg with improved sugar titers and yields relative to bench scale (6 kg). The mass flow of the overall process was established and the major scale-up challenges of the process were identified.
New solvent blends for post-combustion CO2 capture
Hanna K. Knuutila, Rune Rennemo, Arlinda F. Ciftja
2019, 4(4): 439-452. doi: 10.1016/j.gee.2019.01.007
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In the current work five different solvent blends are experimentally studied and the reboiler duties are calculated using the so-called short-cut method. Tertiary amines, 2-(diethylamino)ethanol (DEEA), 3-(Diethylamino)-1,2-propanediol (DEA-12PD), 2-[2-(Diethylamino)ethoxy]ethanol (DEA-EO), 1-(2-Hydroxyethyl)piperidine (12HE-PP) are blended with 3-(Methylamino)propylamine (MAPA) and ethanolamine (MEA). The first results from simple solvent screening are given and the cyclic capacities are calculated based data at 40 °C and 80 °C. Then, five solvent systems are chosen for vapor–liquid equilibrium characterization. The vapor–liquid equilibrium data are then used to estimate cyclic capacities at more realistic temperatures, between 40 °C and 120 °C and by using a short-cut method proposed in the literature the reboiler duties of the characterized solvents are estimated. Finally, the potential of the studied systems is discussed. Several of the characterized blends showed reboiler duties around 2.5 .
Study of effective parameters for enhancement of methane gas production from natural gas hydrate reservoirs
Hamid Aghajari, Moien Habibi Moghaddam, Mehdi Zallaghi
2019, 4(4): 453-469. doi: 10.1016/j.gee.2018.04.002
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Natural gas hydrate resources have become the major source of energy in the second half of 21st century. Gas production and fluid behavior in natural gas hydrate reservoirs are different from conventional ones. There are three major methods for methane decomposition such as depressurization, thermal stimulation and inhibitor injection. However, CO2 substitution can also be introduced as an alternative method to inject in sediments containing gas hydrate. All these methods tend to imbalance equilibrium condition via temperature and pressure variation in order to fulfill hydrate decomposition process. This study aims to simulate depressurization method for gas production from a hydrate gas bearing layer. Hence, a sensitivity analysis of reservoir parameters includes porosity, permeability, hydrate saturation, hydrate thickness layer; pressure and temperature of single well hydrate model were investigated to determine how these parameters impact on gas production. Results show that depressurization is an efficient method for gas production from hydrate bearing sediments. Through sensitivity analysis, it has been concluded that if properties of a hydrate layer such as porosity and permeability become greater, methane production will be increased significantly. Moreover, results investigate that the rate of hydrate dissociate is strongly dependent on pressure reduction, and it has a reverse relationship with bottomhole pressure and reservoir temperature.
Novel synthesis of fly-ash-derived Cu-loaded SAPO-34 catalysts and their use in selective catalytic reduction of NO with NH3
Ge Li, Baodong Wang, Qi Sun, Wayne Qiang Xu, Ziran Ma, Hongyan Wang, Daojun Zhang, Jiali Zhou
2019, 4(4): 470-482. doi: 10.1016/j.gee.2019.03.003
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A combined acid–alkali hydrothermal method was used to prepare fly ash –derived SAPO-34 molecular sieves from a thermal power plant in Inner Mongolia (China). The specific surface area of the prepared fly-ash-derived SAPO-34 molecular sieves was 579 m2 g−1, the total pore volume was about 0.27 cm3 g−1, and the pore size was 0.56 nm; the molar ratios of Al2O3:P2O5:SiO2 were 1:0.86:0.45. Cu/SAPO-34 catalysts were prepared by impregnation of low-cost fly-ash-derived SAPO-34 molecular sieves as a support and tested in selective catalytic reduction with NH3 (NH3-SCR). Powder X-ray diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), X-ray fluorescence analysis (XRF) and scanning electron microscopy (SEM) were used for catalyst characterization and investigation of the relationships between the catalyst structure and the catalytic activity. The actual silica:alumina ratio of the molecular sieves did not increase with increasing Cu loading, indicating that increasing the Cu loading does not change the original structure of the SAPO-34 molecular sieves. The XRF and NMR results showed that replacement by Cu results in more Si islands. The molecular sieve acidity decreased because of the increased number of Si islands. The NH3-TPD results showed that for the Cu/SAPO-34 catalysts there was a low correlation between the low-temperature activity and the amount of acidic sites. SCR activity is closely related to the location of Cu. The 4.47Cu/SAPO-34 catalyst has the highest isolated Cu2+ showed the highest NH3-SCR activities (> 90%) at 250–350 °C. This work opens up new avenues for recycling fly ash formed in coal-fired power plants (reducing environmental pollution) and developing low-cost SCR catalysts for NO pollution control.

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