糠醛转化为燃料化合物的双功能催化剂研究进展

以生物质为原料制备燃料化合物对减少化石能源的依赖和构建绿色能源结构具有重要意义。生物质平台化合物糠醛经多步串联反应可得到乙酰丙酸、乙酰丙酸酯、γ-戊内酯、2-甲基呋喃等高附加值燃料化合物,一锅法合成避免了中间产物的分离、缩短了工艺流程。近年来,高效催化糠醛一锅转化为燃料化合物的双、多功能催化剂得到快速发展。该文介绍了高效催化糠醛一锅转化为乙酰丙酸、乙酰丙酸酯、γ-戊内酯、2-甲基呋喃的反应机理和路线;归纳了不同产物所需高效双功能催化剂体系,并探讨了催化剂的活性位点、空间结构、溶剂、氢供体等因素对反应的影响;最后,提出双功能催化剂未来的发展方向。

基于ANN-QSPR算法的新型纯碳水化合物燃料性质预测方法

开发新型纯碳水化合物燃料作为新能源时,必须预测和筛选纯碳水化合物的物理性质,从而找到可能合适的化学物质,然而由实验来逐一确定大量分子的物理性质既耗时又昂贵。研究发现,运用人工智能网络—定量构效关系(ANN-QSPR)算法来建立纯碳水化合物物理性质的计算模型可以起到事半功倍的效果。基于DIPPR 801数据库中的纯组分性质和DragonX软件包计算了相应碳水化合物的分子描述符,所构建的模型结合了定量构效关系(QSPR)和两层前馈人工智能网络(ANN)。由此建立了多个全面而可靠的模型来预测新型纯碳水化合物燃料的各种物理性质,包括正常沸点、闪点、燃烧焓、蒸发焓、液体密度、表面张力、液体的黏度和熔点等。为了提高模型中数据集之间的一致性,还引入了主成分分析法(PCA),以进一步消除分子描述符值的维数。另外,通过共识建模进行交叉验证,减少了不确定性的影响,提高了模型的预测精度。

国外红外诱饵现状与发展趋势

从国外资料分析红外诱饵现状与发展趋势 。

Advanced Pt‐based intermetallic nanocrystals for the oxygen reduction reaction

Proton exchange membrane fuel cells(PEMFCs)are considered ideal energy‐conversion devices because of their environmentally friendly nature and high theoretical energy efficiency.However,cathodic polarization,which is a result of the sluggish oxygen reduction reaction(ORR)kinetics,is a significant source of energy loss and reduces fuel cell efficiency.Further,the need to use Pt in commercial Pt/C cathodes has restricted their large‐scale application in fuel cells because of its high cost and poor durability.Thus,improvements in the activity and durability of Pt‐based catalyst are required to reduce the amount of Pt required and,thus,costs,while increasing the ORR rate and fuel cell power density and promoting widespread PEMFC commercialization.In recent years,atomically ordered Pt‐based intermetallic nanocrystals have received tremendous attention owing to their excellent activity and stability for the ORR.Therefore,in this review,we first introduce the formation of intermetallic compounds from the perspective of thermodynamics and kinetics to lay a theoretical foundation for the design of these compounds.In addition,optimization strategies for Pt‐based ordered intermetallic catalysts are summarized in terms of the catalyst composition,size,and morphology.Finally,we conclude with a discussion of the current challenges and future prospects of Pt‐based ordered alloys.This review is designed to help readers gain insights into the recent developments in and rational design of Pt‐based intermetallic nanocrystals for the ORR and encourage research that will enable the commercialization of PEMFCs.

Selective Removal of Nitrogen-Containing Heterocyclic Compounds from Transportation Diesel Fuels with Reactive Adsorbent

This paper presents a new selective adsorbent to remove nitrogen-containing heterocyclic compounds from model and commercial transportation diesel fuels based on characteristic reaction designed to occur in the pores of substrate.This reactive adsorbent is composed of formaldehyde,phosphotungstic acid and Santa Barbara USA(SBA)-15.The experiment was based on assumed hydroxymethylation reaction of nitrogen-containing heterocyclic compounds with formaldehyde using phosphotungstic acid as catalyst in batch and fixed-bed systems.The nitrogen concentration in the model fuel was 237.33 ng.μl-1,carbazole and toluene were used as model nitrogen-containing heterocyclic compound and solvent,respectively.The effectiveness of reactive adsorbent for removal of nitrogen-containing heterocyclic compounds from commercial 0# diesel fuel containing 224.86 ng.μl-1 nitrogen was examined in a fixed-bed reactor at 70 ℃.The results showed that nitrogen in the model fuel was very low and the nitrogen concentration in the commercial diesel reduced to 2.44 ng.μl-1.The demand for transportation fuel with ultra-low nitrogen is satisfied.

Ferroelectric solid solution Li1-xTa1-xWxO3 as potential photocatalysts in microbial fuel cells:Effect of the W content

Microbial fuel cells(MFCs)are bio-electrochemical systems that can directly convert the chemical energy contained in an effluent into bioelectricity by the action of microorganisms.The performance of these devices is heavily impacted by the choice of the material that forms the cathode.This work focuses on the assessment of ferroelectric and photocatalytic materials as a new class of non-precious catalysts for MFC cathode construction.A series of cathodes based on mixed oxide solid solution of LiTaO_3with WO_3formulated as Li_(1-x)Ta_(1-x)W_xO_3(x=0,0.10,0.20 and0.25),were prepared and investigated in MFCs.The catalyst phases were synthesized,identified and characterized by DRX,PSD,MET and UV–Vis absorption spectroscopy.The cathodes were tested as photoelectrocatalysts in the presence and in the absence of visible light in devices fed with industrial wastewater.The results revealed that the catalytic activity of the cathodes strongly depends on the ratio of substitution of W^(6+)in the LiTaO_3matrix.The maximum power densities generated by the MFC working with this series of cathodes increased from60.45 mW·m^(-3)for x=0.00(LiTaO_3)to 107.2 mW·m^(-3)for x=0.10,showing that insertion of W^(6+)in the tantalate matrix can improve the photocatalytic activity of this material.Moreover,MFCs operating under optimal conditions were capable of reducing the load of chemical oxygen demand by 79%(COD_(initial)=1030 mg·L^(-1)).

Synthesis/design optimization of SOFC-PEM hybrid system under uncertainty

Solid oxide fuel cell–proton exchange membrane(SOFC–PEM) hybrid system is being foreseen as a valuable alternative for power generation. As this hybrid system is a conceptual design, many uncertainties involving input values should be considered at the early stage of process optimization. We present in this paper a generalized framework of multi-objective optimization under uncertainty for the synthesis/design optimization of the SOFC–PEM hybrid system. The framework is based on geometric, economic and electrochemical models and focuses on evaluating the effect of uncertainty in operating parameters on three conflicting objectives: electricity efficiency, SOFC current density and capital cost of system. The multi-objective optimization provides solutions in the form of a Pareto surface, with a range of possible synthesis/design solutions and a logical procedure for searching the global optimum solution for decision maker. Comparing the stochastic and deterministic Pareto surfaces of different objectives, we conclude that the objectives are considerably influenced by uncertainties because the two trade-off surfaces are different.

Review of Brazilian Activities Related to the Thorium Fuel Cycle and Production of Thorium Compounds at IPEN-CNEN/SP

The Brazilian＇s interest in the nuclear utilization of thorium has started in the 1950s as a consequence of the abundant occurrence ofmonazite sands. Since the 1960s, IPEN-CNEN/SP （lnstituto de Pesquisas Energ6ticas e Nucleares） has performed some developments related to the thorium fuel cycle. The production and purification of thorium compounds was carried out at IPEN for about 18 years and the main product was the thorium nitrate with high purity, having been produced over 170 metric tons of this material in the period, obtained through solvent extraction. The thorium nitrate was supplied to the domestic industry and used for gas portable lamps （Welsbach mantle）. Although the thorium compounds produced have not been employed in the nuclear area, several studies were conducted. Therefore, those activities and the accumulated experience are of strategic importance, on one hand, due to huge Brazilian thorium reserves, on the other hand, by the resurgence of the interest of thorium for the Generation IV advanced reactors. This paper presents a review of the Brazilian research and development activities related to thorium technology.

Municipal Waste Plastics Conversion into Aviation Fuel

Aviation fuel is in great demand globally. The increased demand and high price for energy sources are driving efforts to convert natural non-renewable organic compounds into useful hydrocarbon fuel materials such as in form of aviation fuel. Alternate sources to these non-renewable hydrocarbon fuels are important and necessary. Much of these alternative sources are focused on biomass however, there are strong benefits of deriving fuels from waste plastic materials. Thermal processes can be used to convert waste plastics into hydrocarbon fuels like aviation fuel, which have unlimited applications in airline industries, as well as in transportation and power generation industries. These thermal processes are used to break down the long carbon chains found in plastics into the shorter chains in a temperature range from 300-450 ℃. This method has been carried out in succession in previous experiments. This simple and economically viable process has been developed to convert the hydrocarbon polymers of waste plastics into the short and medium chain hydrocarbons of liquid fuels. Based on the initial characterization, a fractionated portion of the developed fuel shows properties similar to some of the commercially available aviation fuels.

Process Flow Model of Combined High Temperature Fuel Cell Operated with Mixture of Methane and Hydrogen

One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.

Waste Plastic Conversion into Hydrocarbon Fuel Materials

The increased demand and high price for energy sources are driving efforts to convert organic compounds into useful hydrocarbon fuels. Although much of this work has focused on biomass, there are strong benefits to deriving fuels from waste plastic material. Natural State Research Inc. （NSR） has invented a simple and economically viable process to decompose the hydrocarbon polymers of waste plastic into the shorter chain hydrocarbon of liquid fuel （patent pending）. The method and principle of the production/process will be discussed. Initial tests with several widely used polymers indicate a high potential for commercialization.

Simultaneous desulfurization and denitrogen of liquid fuels using two functionalized group ionic liquids

Deep desulfurization of liquid fuels is an important and challenging issue in worldwide petroleum refining industry.Extraction and catalytic oxidative desulfurization(ECODS)of liquid fuels using a series of ionic liquids(ILs)with two functionalized groups,such as[(CH2)2COOHmim]Cl/n Fe Cl3,[(CH2)2COOHmim]Cl/n Zn Cl2,and[Amim]Cl/n Fe Cl3,was studied.In the ECODS,the ILs were used as both extractant and catalyst and 30 wt%hydrogen peroxide(H2O2)solution as oxidant.The effects of molar ratios of[(CH2)2COOHmim]Cl(or[Amim]Cl)to Fe Cl3(or Zn Cl2)in ILs,H2O2/sulfur(O/S)molar ratio,reaction temperature,and the nature of sulfur compounds on sulfur removal were investigated.The natures of the functional groups(–COOH,–CH2–CH=CH2)in cations and the acid strength of anions play important roles in the ECODS and affect the reaction time,temperature,and desulfurization efficiency of different substrates.Also,nitrogen-containing compounds(pyridine,pyrrole,and quinoline)could be removed simultaneously in the ECODS and had different effects on dibenzothiophene removal.

Experimental Study on Hydrocarbon Fuel Thermal Stability

The.thermal stability characteristics of kerosine-type fuels are examined using a heated-tube apparatus which allows independent control of fuel pressure,fuel temperature,tube-wall temperature and fuel flow rate.This method is identified simply as a“constant wall temperature method”.It is different from a previous widely used method,which is identified as a“constant heat flux method”.It is a single-pass system.Rate of deposition on the tube walls are measured by weighing the test tube before and after each test. For a fuel temperature of 250℃,it is found that deposition rates increase continuously with increase in tube- wall temperature.This finding contradicts the results of previous studies which had led to the conclusion that deposition rates increase with increase in wall temperature up to a certain value(around 650 K)beyond which any further increase in wall temperature causes the rate of deposition to decline. The present results show clearly that the constant wall temperature method is more suitable for assessing the thermal stability of gas turbine fuels.

Fabrication and characterization of Ba Ce_(0.8)Y_(0.2)O_(2.9)-Ce_(0.85)Sm_(0.15)O_(1.925) composite electrolytes for IT-SOFCs

The Ba Ce0.8Y0.2O2.9-Ce0.85Sm0.15O1.925 composite electrolytes were prepared with Ba Ce0.8Y0.2O2.9(BCY) and Ce0.85Sm0.15O1.925(SDC). The SDC and BCY powders were mixed in the weight ratio of 95:5, 85:15, and 75:25, respectively(named as BS95, BS85, and BS75). Because of the composite effect between the SDC and BCY phases, the BS95 and BS85 exhibit improved conductivity compared with the pure SDC and BCY. The conductivity of BS95 is higher than that of BS85, indicating that the composite effect of BS95 is greater than that of BS85. Nevertheless, the composite effect in BS75 does not exist. Hence, we conclude that the composite effect in the BCY-SDC composites will decrease with the increase of the amount of BCY and even disappear when the amount of BCY exceeds a certain value. In our case, the optimum composition of the composite electrolyte is 95 wt% SDC and 5 wt% BCY. The BS95 has the highest conductivity(σ1t=0.07808 S cm-1, at 800 °C) and the fuel cell based on the BS95 shows the best performance(the maximum power density reaches as high as 526 mw cm-2 at 750 °C). The encouraging results suggest that the BCY-SDC composites are the very promising electrolyte materials for IT-SOFCs.