Over the past several decades, the number of electric vehicles (EVs) has continued to increase. Projections estimate that worldwide, more than 125 million EVs will be on the road by 2030. At the ...heart of these advanced vehicles is the lithium-ion (Li-ion) battery which provides the required energy storage. This paper presents and compares key components of Li-ion batteries and describes associated battery management systems, as well as approaches to improve the overall battery efficiency, capacity, and lifespan. Material and thermal characteristics are identified as critical to battery performance. The positive and negative electrode materials, electrolytes and the physical implementation of Li-ion batteries are discussed. In addition, current research on novel high energy density batteries is presented, as well as opportunities to repurpose and recycle the batteries.
Although plastic is considered an indispensable commodity, plastic pollution is a major concern around the world due to its rapid accumulation rate, complexity, and lack of management. Some political ...policies, such as the Chinese import ban on plastic waste, force us to think about a long-term solution to eliminate plastic wastes. Converting waste plastics into liquid and gaseous fuels is considered a promising technique to eliminate the harm to the environment and decrease the dependence on fossil fuels, and recycling waste plastic by converting it into monomers is another effective solution to the plastic pollution problem. This paper presents the critical situation of plastic pollution, various methods of plastic depolymerization based on different kinds of polymers defined in the Society of the Plastics Industry (SPI) Resin Identification Coding System, and the opportunities and challenges in the future.
Electric machines are critical components of the drivetrains of electric vehicles. Over the past few years the majority of traction drive systems have converged toward containing some form of a ...permanent magnet machine. There is increasing tendency toward the improvement of power density and efficiency of traction machines, thereby giving rise to innovative designs and improvements of basic machine topologies and the emergence of new classes of machines. This paper provides an overview of present trends toward high specific power density machines for traction drive systems. The focus will be on current technology and the trends that are likely to be pursued in the near future to achieve the high specific power goals set for the industry. The paper discusses machines that are applied in both hybrid and battery electric drivetrains without distinction and does not discuss the associated power electronic inverters. Future electric machine trends that are likely to occur are also projected.
Steam reformation of hydrogen sulfide AuYeung, Nicholas; Yokochi, Alexandre F.T.
International journal of hydrogen energy,
05/2013, Letnik:
38, Številka:
15
Journal Article
Recenzirano
A modified version of the Sulfur–Iodine cycle, here called the Sulfur–Sulfur Cycle, offers an all-fluid route to thermochemical hydrogen and avoids implications of the corrosive HI–H2O azeotropic ...mixture:(1)4I2(l) + 4SO2(l) + 8H2O(l) ↔ 4H2SO4(l) + 8HI(l) (120 °C)(2)8HI(l) + H2SO4(l) ↔ H2S(g) + 4H2O(l) + 4I2(l) (120 °C)(3)3H2SO4(g) ↔ 3H2O(g)+3SO2(g) + 1½O2(g) (850 °C)(4)H2S(g) + 2H2O(g) ↔ SO2(g) + 3H2(g) (900–1500 °C)
The key step in the Sulfur–Sulfur cycle is the steam reformation of hydrogen sulfide, which is highly endothermic and has a positive Gibbs free energy change. The steam reformation of hydrogen sulfide was investigated under favorable circumstances (excessive dilution with steam and inert carrier) over a variety of catalytic and non-catalytic settings in a quartz tube. Successful results were obtained by pretreating a molybdenum wire with H2S at high temperature. Apparent Arrhenius parameters for both thermal splitting and steam reformation of hydrogen sulfide were determined.
► Steam reformation of H2S was successfully carried out at temperatures between 700 and 900 °C. ► Increasing the ratio of H2O to H2S increases H2 and SO2 production. ► Apparent Arrhenius parameters were estimated based upon kinetic data.
•Reduction of CO2 in wet ionic liquid solution can be achieved in a microscale-based electrochemical reactor.•A mathematical model is developed to simulate the CO2 reduction process.•The mathematical ...model well explains the experimental data.•All reaction rate constants can be obtained via numerical optimization of the mathematical model.
A microscale-based electrochemical reactor was introduced for the reduction of CO2 into CH4, CH3OH, H2, HCOOH and HCHO with the presence of ionic liquid BMIM-BF4 (1-butyl-3-methylimidazolium tetrafluoroborate). Reduction of CO2 was studied under various experimental conditions controlled by factors such as solvent concentration, microreactor height, and mean residence time of fluids in the microreactor. A mathematical model reflecting geometry and flow conditions inside the microreactor was developed to simulate the chemical reaction process. The parameters of the mathematical model were determined using an optimization process in which the best fit between the experimental data and the model prediction was achieved. The model describes the reactions containing substrate reactants (CO2 and H2O) and final products (CH4, CH3OH, H2, HCOOH, and HCHO), which were measured throughout CO2 reduction process experiments.
Non-thermal plasma as a tool in chemical reaction engineering has been studied for many years. The temperature of electrons in non-thermal plasma far exceeds other particles, which leads to its high ...efficiency. Besides the well-studied destruction of volatile organic compounds (VOCs), the reaction environment generated by non-thermal plasma is also suitable for the activation of many significant gas-phase chemical reactions, e.g., as methane coupling, reduction of carbon dioxide, ammonia synthesis, nitrogen fixation, as well as some liquid phase chemical reactions such as the treatment of contaminated water. Material synthesis is another target field of non-thermal plasma. Plasma in micro scale with several enhanced properties makes it an even more promising tool for plasma-chemical processing. This work summarizes different types of non-thermal plasmas and their performance in commonly studied chemical reactions. The advantages gained by generating non-thermal plasma in micro scale with constricted spaces, reduced timescales, and micro-/nano-structured electrodes are also discussed.
Display omitted
•Non-thermal plasma is suitable for activating many chemical reactions because of its high efficiency and stability.•Various reactions activated by non-thermal plasma are summarized, especially the energy-consuming ones.•Better control of the energetic electrons can benefit the performance of the non-thermal plasma.•Microplasma, multiple discharges, and suitable electrode materials and structures are analyzed for their improvements in the control of energetic electrons and challenges towards industrialization.•Non-thermal plasma is a promising tool in chemical reaction engineering, especially in the background of global carbon emissions reduction.
The efficient synthesis of the C19−C26 subunit of amphidinolide B1 and B2 has been completed using a boron-mediated aldol reaction. The synthesis of the C19−C26 subunit of amphidinolide B3 has also ...been accomplished through an unexpected anti aldol reaction using a titanium-mediated process. In addition, the first reported examples of a stereochemical discrepancy between the Evans' boron-mediated oxazolidinone and the Crimmins' titanium-mediated oxazolidinethione aldol reactions are disclosed. A working hypothesis is put forth to explain the results.
Display omitted
► Explored diffusion in wet silica gels relevant to biological encapsulation. ► Used a variety of tracers and gel compositions. ► Tracer size, not gel hydrophobicity, is the primary ...determinant of diffusion. ► Gels can be tailored to the bio-component without significantly altering diffusion. ► Diffusion adequate to support viable photoautotrophic organisms.
Divalent nickel (Ni2+), Cu(II)EDTA, methyl orange, and dichromate were used to investigate diffusion from hydrated silica sol–gel monoliths. The objective was to examine diffusion of compounds on a size regime relevant to supporting biological components encapsulated within silica gel prepared in a biologically compatible process space with no post-gelation treatments. With an initial sample set, gels prepared from tetraethoxysilane were explored in a factorial design with Ni2+ as the tracer, varying water content during hydrolysis, acid catalyst present during hydrolysis, and the final concentration of silica. A second sample set explored diffusion of all four tracers in gels prepared with aqueous silica precursors and a variety of organically modified siloxanes. Excluding six outliers which displayed significant syneresis, the mean diffusion constant (Dgel) across the entire process space of sample set 1 was 2.42×10−10m2s−1; approximately 24% of the diffusion coefficient of Ni2+ in unconfined aqueous solution. In sample set 2, the tracer size and not gel hydrophobicity was the primary determinant of changes in diffusion rates. A strong linear inverse correlation was found between tracer size and the magnitude of Dgel. Based on correlation with the tracers used in this investigation, the characteristic 1-h diffusion distance for carbonate species relevant to supporting active phototrophic organisms was approximately 1.5mm. These results support the notion that silica sol–gel formulations may be optimized for a given biological entity of interest with manageable impact to the diffusion of small ions and molecules.
In this study, a directly irradiated, milli-scale chemical reactor with a simple nickel catalyst was designed for dry reforming of methane for syngas. A milli-scale reactor was used to facilitate ...rapid heating, which is conducive to combating thermal transience caused by intermittent solar energy, as well as reducing startup times. Milli-scale reactors also allow for a distributed and modular process to produce chemicals on a more local scale. In this setup, the catalyst involved in the reaction is located directly in the focal area of the solar simulator, resulting in rapid heating. The effects of mean residence time and temperature on conversion and energy efficiency were tested. The process, which is intended to store thermal energy as chemical enthalpy, achieved 10% thermal-to-chemical energy conversion efficiency at a mean residence time of 0.028 s, temperature of 1000 °C, and molar feed ratio of 1:1 CO2:CH4. A significant portion of the thermal energy input into the reactor was directed toward sensible heating of the feed gas. Thus, this technology has potential to achieve solar-to-chemical efficiency with the integration of recuperative heat exchange.
Tanikolide seco-acid 2 and tanikolide dimer 3, the latter a novel and selective SIRT2 inhibitor, were isolated from the Madagascar marine cyanobacterium Lyngbya majuscula. The structure of 2, ...isolated as the pure R enantiomer, was elucidated by X-ray experiment in conjunction with NMR and optical rotation data, whereas the depside molecular structure of 3 was initially thought to be a meso compound as established by NMR, MS, and chiral HPLC analyses. Subsequent total synthesis of the three tanikolide dimer stereoisomers 4, 5, and ent-5, followed by chiral GC−MS comparisons with the natural product, showed it to be exclusively the R,R-isomer 5. Tanikolide dimer 3 (= 5) inhibited SIRT2 with an IC50 = 176 nM in one assay format and 2.4 μM in another. Stereochemical determination of symmetrical dimers such as compound 3 pose intriguing and subtle questions in structure elucidation and, as shown in the current work, are perhaps best answered in conjunction with total synthesis.
PDF
