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2015, Vol. 24, No. 5　Online: 2015-09-15


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Special issue: Congratulations on changes of JEC
Quick publication online on ScienceDirect.
Peer review process in charge by associate editors.
Reorganization of editorial board.
In this special issue, members of Editorial Board present their latest research results and insights.

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PERSPECTIVES

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The energy-chemistry nexus: A vision of the future from sustainability perspective Salvatore Abate, Gabriele Centi, Paola Lanzafame, Siglinda Perathoner 2015, 21(5): 535-547.  DOI: 10.1016/j.jechem.2015.08.005 摘要 ( 5082 )   The changing energy-chemistry nexus is discussed in this perspective paper about the future of sustainable energy and chemical production to identify the priorities and open issues on which focus research and development. Topics discussed regard (i) the new sustainable energy scenario, (ii) the role of energy storage (from smart grids to chemical storage of energy), (iii) the outlooks and role of solar (bio)refineries and solar fuels, (iv) how to integrate bioand solar-refineries to move to new economy, (v) the role of methanol at the crossover of new energy-chemistry nexus, (vi) the role of chemistry in this new scenario, (vii) the role of nanomaterials for a sustainable energy, (viii) the use of nanocarbons to design advanced energy conversion and storage devices, and (ix) possibilities and routes to exploit solar energy and methane (shale gas). The contribution provides a glimpse of the emerging directions and routes with some elements about their possible role in the future scenario, but does not provide a detailed analysis of the state of the art in these directions.

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5-Hydroxymethylfurfural: A key intermediate for efficient biomass conversion Yajie Zhang, Jian Zhang, Dangsheng Su 2015, 21(5): 548-551.  DOI: 10.1016/j.jechem.2015.09.005 摘要 ( 9430 )   Biomass has been widely accepted as a “zero-emission” energy carrier to take place fossil fuels, while its catalytic conversion is still limited by low efficiency of carbon atoms. Biomass conversion via 5hydroxymethylfurfural (HMF) as a platform chemical is highly attractive because almost all carbon atoms could be retained in the downstream chemicals under mild reaction conditions. Here we summarize recent fundamental researches and industrial progresses on all involved processes including biomass degradation to hexoses, HMF formation, hydrogenation and oxidation of HMF.

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Energy-efficient methods for production methane from natural gas hydrates Jun Chen, Yan-Hong Wang, Xue-Mei Lang, Shuan-Shi Fan 2015, 21(5): 552-558.  DOI: 10.1016/j.jechem.2015.08.014 摘要 ( 5343 )   Gas hydrates now are expected to be one of the most important future unconventional energy resources. In this paper, researches on gas hydrate exploitation in laboratory and field were reviewed and discussed from the aspects of energy efficiency. Different exploiting methods and different types of hydrate reservoir were selected to study their effects on energy efficiencies. Both laboratory studies and field tests have shown that the improved technologies can help to increase efficiency for gas hydrate exploitation. And it also showed the trend that gas hydrate exploitation started to change from permafrost to marine. Energy efficiency ratio (EER) and energy return on energy invested (EROI) were introduced as an indicator of efficiency for natural gas hydrate exploitation. An energy-efficient hydrate production process, called “Hydrate Chain Energy System (HCES)”, including treatment of flue gas, replacement of CH4 with CO2, separation of CO2 from CH4, and storage and transportation of CH4 in hydrate form, was proposed for future natural gas hydrate exploitation. In the meanwhile, some problems, such as mechanism of CO2 replacement, mechanism of CO2 separation, CH4 storage and transportation are also needed to be solved for increasing the energy efficiency of gas hydrate exploitation.

REVIEW

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Aligned carbon nanostructures based 3D electrodes for energy storage Fengliu Lou, De Chen 2015, 21(5): 559-586.  DOI: 10.1016/j.jechem.2015.08.013 摘要 ( 5944 )   Electrochemical energy storage systems with high specific energy and power as well as long cyclic stability attract increasing attention in new energy technologies. The principles for rational design of electrodes are discussed to reduce the activation, concentration, and resistance overpotentials and improve the active material efficiency in order to simultaneously achieve high specific energy and power. Three dimensional (3D) nanocomposites are currently considered as promising electrode materials due to their large surface area, reduced electronic and ionic diffusion distances, and synergistic effects. This paper reviews the most recent progress on the synthesis and application of 3D thin film nanoelectrode arrays based on aligned carbon nanotubes (ACNTs) directly grown on metal foils for energy storages and special attentions are paid on our own representative works. These novel 3D nanoelectrode arrays on metal foil exhibit improved electrochemical performances in terms of specific energy, specific power and cyclic stability due to their unique structures. In this active materials coated ACNTs over conductive substrate structures, each component is tailored to address a different demand. The electrochemical active material is used to store energy, while the ACNTs are employed to provide a large surface area to support the active material and nanocable arrays to facilitate the electron transport. The thin film of active materials can not only reduce ion transport resistance by shortening the diffusion length but also make the film elastic enough to tolerate significant volume changes during charge and discharge cycles. The conductive substrate is used as the current collector and the direct contact of the ACNT arrays with the substrate reduces significantly the contact resistance. The principles obtained from ACNT based electrodes are extended to aligned graphene based electrodes. Similar improvements have been achieved which confirms the reliability of the principles obtained. In addition, we also discuss and view the ongoing trends in development of aligned carbon nanostructures based electrodes for energy storage.

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Liquid organic hydrogen carriers Teng He, Qijun Pei, Ping Chen 2015, 21(5): 587-594.  DOI: 10.1016/j.jechem.2015.08.007 摘要 ( 5948 )   The development of efficient hydrogen storage materials is one of the biggest technical challenges for the coming “hydrogen economy”. The liquid organic hydrogen carriers (LOHCs) with high hydrogen contents, reversibilities and moderate dehydrogenation kinetics have been considered as an alternative option supplementing the extensively investigated inorganic hydride systems. In this review, LOHCs for long distance H 2 transport and for onboard application will be discussed with the focuses of the design and development of LOHCs and their hydrogenation & dehydrogenation catalyses.

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Catalytic transformation of cellulose and its derived carbohydrates into chemicals involving C-C bond cleavage Weiping Deng, Qinghong Zhang, Ye Wang 2015, 21(5): 595-607.  DOI: 10.1016/j.jechem.2015.08.016 摘要 ( 5836 )   The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a polymer of glucose and a lot research effort has been devoted to the conversion of cellulose to six-carbon platform compounds such as glucose and glucose derivatives through C-O bond activation. There also exist considerable studies on the catalytic cleavage of C-C bonds in biomass for the production of high-value chemicals, in particular polyols and organic acids such as ethylene glycol and lactic acid. This review article highlights recent advances in the development of new catalytic systems and new strategies for the selective cleavage of C-C bonds in cellulose and its derived carbohydrates under inert, reductive and oxidative atmospheres to produce C1 -C5 polyols and organic acids. The key factors that influence the catalytic performance will be clarified to provide insights for the design of more efficient catalysts for the transformation of cellulose with precise cleavage of C-C bonds to high-value chemicals. The reaction mechanisms will also be discussed to understand deeply how the selective cleavage of C-C bonds can be achieved in biomass.

ARTICLES

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Ball-milling MoS2/carbon black hybrid material for catalyzing hydrogen evolution reaction in acidic medium Jiayuan Li, Dunfeng Gao, Jing Wang, Shu Miao, Guoxiong Wang, Xinhe Bao 2015, 21(5): 608-613.  DOI: 10.1016/j.jechem.2015.08.003 摘要 ( 5381 )   Replacing platinum for catalyzing hydrogen evolution reaction (HER) in acidic medium remains great challenges. Herein, we prepared few-layered MoS2 by ball milling as an efficient catalyst for HER in acidic medium. The activity of as-prepared MoS2 had a strong dependence on the ball milling time. Furthermore, Ketjen Black EC 300J was added into the ball-milled MoS2 followed by a second ball milling, and the resultant MoS22/carbon black hybrid material showed a much higher HER activity than MoS2 and carbon black alone. The enhanced activity of the MoS2/carbon black hybrid material was attributed to the increased abundance of catalytic edge sites of MoS2 and excellent electrical coupling to the underlying carbon network.

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High-temperature liquid Sn-air energy storage cell HyungKuk Ju, Jaeyoung Lee 2015, 21(5): 614-619.  DOI: 10.1016/j.jechem.2015.08.006 摘要 ( 4226 )   A new type of a high temperature liquid metal-air energy storage cell based on solid oxide electrolyte has been successfully demonstrated at 750 ℃ by feeding metal Sn. In order to understanding the initial size effect of metal as a liquid fuel, we report here the impact of the thermal and electrochemical oxidation behavior of nano Sn (～100 nm), comparing with micro-sized (～5 μm) and macro-sized (～350 μm) Sn. The thermogravimetric analysis and the monitoring OCV test indicate that the distinct property of nano-sized Sn results in a favorable thermal oxidation behavior near the melting point and a promising power performance due to enhanced fuel transport to the anode. However, the accumulated Sn oxide at the reaction interface during a discharge test towards the limitation of further electrochemical oxidation.

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Carbon dioxide catalytic conversion to nano carbon material on the iron-nickel catalysts using CVD-IP method Jiaquan Hu, Zhanglong Guo, Wei Chu, Le Li， Tao Lin 2015, 21(5): 620-625.  DOI: 10.1016/j.jechem.2015.09.006 摘要 ( 5419 )   The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide (CO2), which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to explore efficient and sustainable approaches for the carbon-neutral pathway of CO2 utilization and recycling. In our recent works with this context, we developed successfully a novel “chemical vapor deposition integrated process (CVD-IP)” technology to converting robustly CO2 into the value-added solid-form carbon materials. The monometallic FeNi0-Al2O3 (FNi0) and bimetallic FeNix-Al2O3 (FNi2, FNi4, FNi8 and FNi20) samples were synthesized and effective for this new approach. The catalyst labeled FNi8 gave the better performance, exhibited the single pass solid carbon yield of 30%. These results illustrated alternative promising cases for the CO2 capture utilization storage (CCUS), by means of the CO2 catalytic conversion into the solid-form nano carbon materials.

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Synthesis and characterization of anatase TiO2 nanosheet arrays on FTO substrate Dong Zhong, Qike Jiang, Baokun Huang, Wen-Hua Zhang, Can Li 2015, 21(5): 626-631.  DOI: 10.1016/j.jechem.2015.08.002 摘要 ( 8969 )   We have exploited a green approach to prepare layered titanate Na2-xHxTi2O5·H2O nanosheet arrays on FTO substrate by hydrothermal hydrolysis of titanium(IV) isopropoxide (TTIP) with aids of Na2 EDTA and TEOA as co-coordination agents, which were then treated by HNO3 to replace Na+ by H+, followed by a calcination at 450 ℃ to topotactically transform into anatase TiO2 nanosheet arrays. SEM, TEM, XRD, and Raman spectroscopy have been employed to characterize the nanosheet films. The TiO2 nanosheet arrays were further applied as electron transport materials of CH3NH3PbI3 perovskite solar cells, achieving power conversion efficiency of 6.99%.

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Selective esterification of glycerol with acetic acid to diacetin using antimony pentoxide as reusable catalyst Wenfei Hu, Yan Zhang, Yizheng Huang, Jiaxi Wang, Jin Gao, Jie Xu 2015, 21(5): 632-636.  DOI: 10.1016/j.jechem.2015.08.001 摘要 ( 6878 )   Glycerol can be obtained as a by-product during biodiesel manufacture. It is important to convert glycerol to value-added products. Glycerol esterification with acetic acid is one of the most promising approaches for glycerol utilization. It is usually difficult to obtain diacetin with good activity and selectivity. In this work, glycerol esterification with acetic acid over different metal oxides, such as Bi2O3, Sb2O3, SnO2, TiO2, Nb2O5 and Sb2O5, was investigated. It was found that in the six investigated metal oxides, only Sb2O5 resulted in good activity and selectivity to diacetin. Under the optimized conditions, the glycerol conversion reached 96.8%, and the selectivity to diacetin reached 54.2%, while the selectivity to monoacetin and triacetin was 33.2% and 12.6%, respectively. The catalysts were characterized with FT-IR spectra of adsorbed pyridine, which indicated that in the six investigated metal oxides, only Sb2O5 possessed Br nsted acid sites strong enough to protonate adsorbed pyridine. The good catalytic activity and selectivity to diacetin might be mainly attributable to the Br nsted acid sites of Sb2O5 . Reusability tests showed that with Sb2O5 as catalyst, after six reaction cycles, no significant change in the glycerol conversion and the selectivity to diacetin was observed.

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Sputtered nano-cobalt on H-USY zeolite for selectively converting syngas to gasoline Peng Lu, Jian Sun, Pengfei Zhu, Takayuki Abe, Ruiqin Yang, Akira Taguchi, Tharapong Vitidsant, Noritatsu Tsubaki 2015, 21(5): 637-641.  DOI: 10.1016/j.jechem.2015.08.004 摘要 ( 6914 )   Selectively converting CO and H2 to gasoline product (isoparaffin and olefin) in one step still remains a great challenge. We demonstrate effective H-USY zeolite supported nano-cobalt bifunctional catalysts for this catalytic reaction, which are prepared by the novel physical sputtering process. Particles of the sputtered cobalt exist in nano-level and are well-dispersed on acid USY zeolite. Easy activation of the loaded nano-cobalt is also achieved in a low-temperature hydrogen reduction atmosphere. In the tandem catalytic reaction, the sputtered bifunctional Co/USY catalyst exhibits a much higher CO conversion and higher isoparaffin selectivity than the conventional impregnated one. Compared with H-Mor, H-Beta and other zeolites supported catalysts, H-USY zeolite supported cobalt catalyst shows the clearest promotional effect on the activity of FischerTropsch synthesis. The described synthesis herein provides a new pathway to solve the problem caused by the strong metal-support interaction (MSI) in heterogeneous catalysis.

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Interlayer expansion of the layered zeolite precursor COK-5 with Sn(acac)2Cl2 Chaoqun Bian, Qinming Wu, Jian Zhang, Shuxiang Pan, Liang Wang, Xiangju Meng, Feng-Shou Xiao 2015, 21(5): 642-645.  DOI: 10.1016/j.jechem.2015.09.002 摘要 ( 4216 )   In the interlayer expansion of the layered zeolite precursor COK-5, a Sn, salt, bis(2,4-pentanedionate)dichlorotin [Sn(acac)2Cl2], instead of a silylating agent was used to link the layers at 180 ℃. The obtained material, which is designed as Sn-COE-5, shows a shift of the first XRD reflection, which is very similar to that of COK-5 interlayer expanded with dichlorodimethylsilane (DCDMS), indicating an increase in interlayer distance. X-ray diffraction (XRD), N2 sorption isotherms, inductively coupled plasma (ICP), and X-ray photo-electron spectroscopy (XPS) support the incorporation of isolated Sn sites in the sample. In the conversion of glucose to levulinic acid, Sn-COE-5 exhibits much higher activity than COK-5, which is due to the presence of Lewis acidic sites in the Sn-COE-5.

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The nature of active sites in Pt-ReOX/TiO2 catalysts for selective hydrogenation of carboxylic acids to alcohols Alexey Suknev, Vladimir Zaikovskii, Vasily Kaichev, Eugenii Paukshtis, Ekaterina Sadovskaya, Bair Bal'zhinimaev 2015, 21(5): 646-654.  DOI: 10.1016/j.jechem.2015.09.003 摘要 ( 4220 )   The highly dispersed Pt-ReOX (x ≤ 1) sites ca. 0.5 nm in size were formed via a successive and strong interaction of the Re precursor with titania and then of the Pt complex with deposited low-valent rhenium oxide clusters. The size, charge and chemical composition were characterized by means of HRTEM/STEM with EDX mapping, XPS, and FTIRS. These sites with Re/Pt = 2 were shown to be highly active and selective in the hydrogenation of carboxylic acid to alcohol under very mild conditions (T= 130 ℃, P = 50 bar). The reaction rate constant for the hydrogenation of hexanoic acid increased linearly with the Pt content. As for the homogeneous pincer-type Ru-organic complexes, the active Pt-ReOX sites can dissociate heterolytically the molecular hydrogen with the formation of hydroxyl groups and Pt hydride for hydrogenation of the carboxylic group. Indeed, TOF of 20 h-1 and selectivity of 98%-99% are approaching the values typical of homogeneous catalysts. The first order kinetics described well the experimental data obtained in a wide range of reaction conditions.

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Improved activity of Ni/MgAl2O4 for CO2 methanation by the plasma decomposition Zhigang Fan, Kaihang Sun, Ning Rui, Binran Zhao, Chang-jun Liu 2015, 21(5): 655-659.  DOI: 10.1016/j.jechem.2015.09.004 摘要 ( 9873 )   CO2 methanation has been a hot topic because of its important application in the spacecraft and potential utilization of carbon dioxide. Nickel catalyst is active for this reaction. However, its activity still needs to be improved. Dielectric barrier discharge (DBD) plasma, initiated at ambient condition and operated at ～150 ℃, has been employed in this work for decomposition of nickel precursor to prepare Ni/MgAl2O4. The plasma decomposition results in high dispersion, unique structure, enhanced reducibility of Ni particles and promoted catalyst-support interaction. An improved activity of CO2 methanation with a higher yield of methane has been achieved over the plasma decomposed catalyst, compared to the catalyst prepared thermally. For example, the methane yield of the plasma prepared catalyst is 71.8% at 300 ℃ but it is 62.9% over the thermal prepared catalyst. The catalyst characterization confirmed that CO2 methanation over the DBD plasma prepared catalyst follows pathway of CO methanation.

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Seed-mediated synthesis of dendritic platinum nanostructures with high catalytic activity for aqueous-phase hydrogenation of acetophenone Yuan Yuan, Yusuf Valentino Kaneti, Minsu Liu, Fangzhu Jin, Danielle Frances Kennedy, Xuchuan Jiang, Jun Huang, Aibing Yu 2015, 21(5): 660-668.  DOI: 10.1016/j.jechem.2015.09.001 摘要 ( 5363 )   This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum (Pt) nanoparticles (NPs) at low temperatures of 55-60 ℃ in water, using L-ascorbic acid as a reducing agent and sodium citrate as a capping agent. It is found that the dendritic Pt NPs (10-150 nm) are composed of tiny Pt nanocrystals, which nucleate and grow through the introduced smaller Pt seeds with diameters of 3-5 nm. Further investigation shows that the dendritic Pt nanostructures display excellent catalytic performance in an aqueous-phase aromatic ketone hydrogenation reaction, including: (i) acetophenone conversion rate of > 90%, with smaller dendritic Pt NPs (10-46 nm) offering a higher conversion efficiency; (ii) high chemoselectivity toward carbonyl group (90.6%-91.5%), e.g., the selectivity to 1-phenylethanol is ～90.1% with nearly 100% acetophenone conversion for 10 nm dendritic Pt NPs within 60 min, under mild reaction conditions (20 ℃, 1.5 bar H2 pressure, and 1.5 mol% catalyst). The high catalytic activity, selectivity and stability of the dendritic Pt nanostructures under the organic solvent-free conditions make them promising for many potential applications in green catalytic conversion of hydrophilic biomass derived compounds.

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Base-free aerobic oxidation of glycerol on TiO2-supported bimetallic Au-Pt catalysts Yihong Shen, Yuming Li, Haichao Liu 2015, 21(5): 669-673.  DOI: 10.1016/j.jechem.2015.08.015 摘要 ( 4917 )   The aerobic oxidation of glycerol provides an economically viable route to glyceraldehyde, dihydroxyacetone and glyceric acid with versatile applications, for which monometallic Pt, Au and Pd and bimetallic Au-Pt, AuPd and Pt-Pd catalysts on TiO2 were examined under base-free conditions. Pt exhibited a superior activity relative to Pd, and Au-Pd and Pt-Pd while Au was essentially inactive. The presence of Au on the Au-Pt/TiO2 catalysts led to their higher activities (normalized per Pt atom) in a wide range of Au/Pt atomic ratios (i.e. 1/3-7/1), and the one with the Au/Pt ratio of 3/1 exhibited the highest activity. Such promoting effect is ascribed to the increased electron density on Pt via the electron transfer from Au to Pt, as characterized by the temperature-programmed desorption of CO and infra-red spectroscopy for CO adsorption. Meanwhile, the presence of Au on Au-Pt/TiO2, most like due to the observed electron transfer, changed the product selectivity, and facilitated the oxidation of the secondary hydroxyl groups in glycerol, leading to the favorable formation of dihydroxyacetone over glyceraldehyde and glyceric acid that were derived from the oxidation of the primary hydroxyl groups. The synergetic effect between Au and Pt demonstrates the feasibility in the efficient oxidation of glycerol to the targeted products, for example, by rational tuning of the electronic properties of metal catalysts.