Modified electronic structure and enhanced hydroxyl adsorption make quaternary Pt-based nanosheets efficient anode electrocatalysts for formic acid-/alcohol-air fuel cells

Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet challenging.Herein,using visible light,a class of quaternary Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)ultrathin nanosheets is fabricated and used as high-performance anode electrocatalysts for formic acid-/alcohol-air fuel cells.The modified electronic structure of Pt,enhanced hydroxyl adsorption,and abundant exterior defects afford Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C high intrinsic anodic electrocatalytic activity to boost the power densities of direct formic acid-/methanol-/ethanol-/ethylene glycol-/glycerol-air fuel cells,and the corresponding peak power density of Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C is respectively 129.7,142.3,105.4,124.3,and 128.0 mW cm^(-2),considerably outperforming Pt/C.Operando in situ Fourier transform infrared reflection spectroscopy reveals that formic acid oxidation on Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C occurs via a CO_(2)-free direct pathway.Density functional theory calculations show that the presence of Ag,Bi,and Te in Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)suppresses CO^(*)formation while optimizing dehydrogenation steps and synergistic effect and modified Pt effectively enhance H_(2)O dissociation to improve electrocatalytic performance.This synthesis strategy can be extended to 43 other types of ultrathin multimetallic nanosheets(from ternary to octonary nanosheets),and efficiently capture precious metals(i.e.,Pd,Pt,Rh,Ru,Au,and Ag)from different water sources.

Cold plasma-activated Cu-Co catalysts with CN vacancies for enhancing CO_(2)electroreduction to low-carbon alcohol

Electrocatalytic CO_(2)reduction reaction to low-carbon alcohol is a challenging task,especially high selectivity for ethanol,which is mainly limited by the regulation of reaction intermediates and subsequent C–C coupling.A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H_(2)cold plasma toward a high-efficiency CO_(2)RR into low-carbon alcohol.The Cu-Co PBA-V_(CN)(Prussian blue analogues with CN vacancies)electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8%(methanol:39.2%,ethanol:44.6%)at-0.9 V vs.RHE,excellent durability(100 h)and a small onset potential of-0.21 V.ATR-SEIRAS(attenuated total internal reflection surface enhanced infrared absorption spectroscopy)and DFT(density functional theory)reveal that the steric hindrance of V_(CN)can enhance the CO generation from*COOH,and the C–C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms.This work provides a strategy for the design and preparation of electrocatalysts for CO_(2)RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.

A Hybrid Membrane of Poly(vinyl alcohol) and Phosphotungstic Acid for Fuel Cells

Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA)were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most ofthe acid embedded are stable in the PVA matrix when the membrane is immerged in water or methanol solution atroom temperature. Conductivity of the composite membranes scatters around 10-3 S.cm-1 at room temperature.The methanol crossover through the membranes is about an order of magnitude lower than that through Nafion117 membrane.

低碳醇汽油发动机燃烧分析实验平台设计及教学应用

为探究低碳醇掺混汽油的醇基燃料在缸内具体的燃烧状态和燃烧过程,该文基于自然吸气式气道喷射汽油发动机搭建实验平台,并改进了燃烧分析功能。基于实验平台开展了3种燃料(92号汽油、甲醇比例85%的甲醇汽油、50%异丙醇掺混的92号汽油)的缸内燃烧实验,分析了醇基燃料燃烧状和在发动机中的燃烧性能。实验平台可完成动力性、经济性分析等测试项目,并可对缸压、放热率以及燃料自燃性质进行测量分析。

基于YC4D柴油机的醇氢燃料喷射控制策略研究

将YC4D柴油机组改造成醇氢-柴油双燃料发动机,根据其曲轴与凸轮轴的相位关系设计醇氢燃料喷射控制系统及其控制策略,并在柴油机组上燃料喷射的控制策略.结果表明:在该柴油机组上基于数齿同步的燃料喷射控制策略运行可靠,转速误差小于0.13%,脉宽误差小于2%,均满足应用需求.

咪唑二氰胺离子液体掺混糠醇的自燃及推进性能

利用落滴法对比了三种咪唑二氰胺离子液体分别掺混糠醇的自燃特性,使用高速摄相机和红外摄相机同步获得了燃料自燃过程的宏观、微观及红外图像;从液面下方拍摄了液滴与液池的混合反应过程。实验观察到了典型的三阶段自燃现象:铺展混合、气相产物生成及火核出现-火焰传播,使用着火延迟时间对燃料的自燃活性进行了定量表征,并计算了糠醇比例对混合燃料推进性能的影响。结果表明,糠醇添加可以显著降低混合燃料黏度,促进燃料与氧化剂的混合,加速自燃过程高温气雾产物的出现。混合燃料的着火延迟时间随糠醇添加比例非单调变化,着火延迟最短的掺混比随液滴速度的增加而增大;混合燃料推进性能受糠醇添加的影响较小。本研究可为自燃离子液体推进剂的开发及利用提供参考。

醇基燃料热值检测试验中盛样装置的研究

为防止醇基燃料在热值检测试验中的样品挥发,从而引起检测结果精密度差,通过采用恒温室全自动量热仪对醇基燃料的热值进行测定,分别采用药用胶囊、聚乙烯安剖瓶和生料带封口燃烧皿对样品进行密封测量,通过大量实验,计算三种试验数据的相对标准偏差,分析三种盛样方法的优缺点,从而研究出醇基燃料在取样和检测过程中能有效防止样品挥发且容易获得的一种盛样装置,为醇基燃料热值的准确检测提供基础保障,助推醇基燃料的广泛使用。

基于梯度下降算法和动量因子的醇基燃料锅炉燃烧温度非线性控制方法

醇基燃料锅炉燃烧温度与控制参数之间的关系不是简单的线性关系,增加了控制的难度,提出基于梯度下降算法和动量因子的醇基燃料锅炉燃烧温度非线性控制方法。建立醇基燃料锅炉的气流三维流动方程,确定燃烧速率、实际温度与期望温度之间的差值以及差值变化率等温度非线性控制参数。搭建燃烧温度控制的模糊神经PID控制器,采用梯度下降算法和动量因子对PID神经网络的权值展开训练,将所得温度非线性控制参数输入训练后的模糊神经PID控制器,实现醇基燃料锅炉燃烧温度非线性控制。实验结果表明,所提方法对于燃烧速率、实际温度与期望温度之间的差值以及差值变化率计算结果精准,温度控制精度高,温度变化率低,燃料能源利用率高,实际应用效果好。

Synergistic effect between few layer graphene and carbon nanotube supports for palladium catalyzing electrochemical oxidation of alcohols

Few layer graphene （FLG）, multi-walled carbon nanotubes （CNTs） and a nanotube-graphene composite （CNT-FLG） were used as supports for palladium nanoparticles. The catalysts, which were characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, were used as anodes in the electrooxidation of ethanol, ethylene glycol and glycerol in half cells and in passive direct ethanol fuel cells. Upon Pd deposition, a stronger interaction was found to occur between the metal and the nanotube-graphene composite and the particle size was significantly smaller in this material （6.3 nm）, comparing with nanotubes and graphene alone （8 and 8.4 nm, respectively）. Cyclic voltammetry experiments conducted with Pd/CNT, Pd/FLG and Pd/CNT-FLG in 10 wt% ethanol and 2 M KOH solution, showed high specific currents of 1.48, 2.29 and 2.51 mA-/zgp-d, respectively. Moreover, the results obtained for ethylene glycol and glycerol oxidation highlighted the excellent electrocatalytic activity of Pd/CNT-FLG in terms of peak current density （up to 3.70 mAgd for ethylene glycol and 1.84 mAfor glycerol, respectively）. Accordingly, Pd/CNT-FLG can be considered as the best performing one among the electrocatalysts ever reported for ethylene glycol oxidation, especially considering the low metal loading used in this work. Direct ethanol fuel cells at room temperature were studied by obtaining power density curves and undertaking galvanostatic experiments. The power density outputs using Pd/CNT, Pd/FLG and Pd/CNT-FLG were 12.1, 16.3 and 18.4 mW.cm-2, respectively. A remarkable activity for ethanol electrooxidation was shown by Pd/CNT-FLG anode catalyst. In a constant current experiment, the direct ethanol fuel cell containing Pd/CNT-FLG could continuously deliver 20 mA.cm-2 for 9.5 h during the conversion of ethanol into acetate of 30%, and the energy released from the cell was about 574 J.

Active sites contribution from nanostructured interface of palladium and cerium oxide with enhanced catalytic performance for alcohols oxidation in alkaline solution

Nanostructured interface is significant for the electrocatalysis process. Here we comparatively studied the electrooxidation of alcohols catalyzed by nanostructured palladium or palladium-cerium oxide. Two kinds of active sites were observed in palladium-cerium oxide system, attributing to the co-action of Pd-cerium oxide interface and Pd sites alone, by CO stripping technique, a structure-sensitive process generally employed to probe the active sites. Active sites resulting from the nanostructured interfacial contact of Pd and cerium oxide were confirmed by high resolution transmission electron microscopy and electrochemical CO stripping approaches. Electrochemical measurements of cyclic voltammetry and chronometry results demonstrated that Pd-cerium oxide catalysts exhibited much higher catalytic performances for alcohols oxidation than Pd alone in terms of activity, stability and anti-poisoning ability.The improved performance was probably attributed to the nanostructured active interface in which the catalytic ability from each component can be maximized through the synergistic action of bi-functional mechanism and electronic effect. The calculated catalytic efficiency of such active sites was many times higher than that of the Pd active sites alone. The present work showed the significance of valid nanostructured interface design and fabrication in the advanced catalysis system.

Functionalised Poly(Vinyl Alcohol)/Graphene Oxide as Polymer Composite Electrolyte Membranes

Crosslinked poly(vinyl alcohol)(PVA)based composite films were prepared as polyelectrolyte membranes for low temperature direct ethanol fuel cells(DEFC).The membranes were functionalised by means of the addition of graphene oxide(GO)and sulfonated graphene oxide(SGO)and crosslinked with sulfosuccinic acid(SSA).The chemical structure was corroborated and suitable thermal properties were found.Although the addition of GO and SGO slightly decreased the proton conductivity of the membranes,a significant reduction of the ethanol solution swelling and crossover was encountered,more relevant for those functionalised with SGO.In general,the composite membranes were stable under simulated service conditions.The addition of GO and SGO particles permitted to buffer the loss and almost retain similar proton conductivity than prior to immersion.These membranes are alternative polyelectrolytes,which overcome current concerns of actual commercial membranes such as the high cost or the crossover phenomenon.

Influence of the Molecular Weight on PVA/GO Composite Membranes for Fuel Cell Applications

Composite polymer electrolyte membranes were prepared with poly(vinyl alcohol)(PVA).Two different molecular weight(Mw),67·103 and 130·103 g·mol−1 were selected,cross-linked with sulfosuccinic acid(SSA)and doped graphene oxide(GO).The effects on the membranes obtained from these polymers were characterized in order to evaluate the fuel cell performance.Electron microscopy showed a proper nanoparticle distribution in the polymer matrix.The chemical structure was evaluated by Fourier transform infrared spectroscopy.The absence of a crystalline structure and the enhancement on the thermal stability with the addition of 1%of GO was demonstrated by thermal characterization.Total transference number and protonic conductivity were correlated to the performance of a hydrogen fuel cell.Overall,a power increase in the composite membranes with lower molecular weight was observed.Shorter polymer chains may improve protonic conductivity and consequently the fuel cell performance.

百吨级生物质混合醇系统能耗和温室气体排放分析

以农林废弃生物质气化合成混合醇工艺为对象,利用混合生命周期评估方法对百吨级系统进行环境影响分析。通过构建系统的工艺模型和收集生命周期资源消耗及排放清单,研究农林业、收储运和制取等各阶段的投入和排放特性,对棉秆、玉米秸秆、木屑和枝丫柴4种原料制取系统的环境影响特性进行分析,并与5万吨级系统进行比较。结果表明:百吨级系统生命周期化石能源消耗和温室气体排放分别在589~734 kJ/MJ混合醇和63.2~80.8 g CO_(2)eq/MJ混合醇范围内,制取阶段的电力消耗是最主要的影响因素,其次为系统设备设施投入,玉米秸秆混合醇的环境影响最大,这与原料碳含量低及混合醇收率低有关。

钨盐催化糠醇高效转化制乙酰丙酸己酯

乙酰丙酸长链酯是一类具有潜力的生物质基液体燃料,但其催化合成并未受到广泛关注。为开发乙酰丙酸长链酯的高效合成工艺,以HL(乙酰丙酸正己酯)为代表性的长链酯,通过糠醇醇解法研究其催化合成。结果表明,WCl_(6)是催化糠醇与正己醇醇解制HL的优选均相催化剂。当WCl_(6)加入量为糠醇物质的量的5%,糠醇与正己醇物质的量之比为1∶9时,在140℃下反应90 min,HL的收率最高可达76%。该催化反应体系可循环利用多次,而且也能实现糠醇与其他多种六碳醇有效醇解制乙酰丙酸六碳酯。此研究可为今后生物质合成可再生燃料提供参考。

醇基燃料的发展与应用

醇基燃料是以甲醇等醇类物质为主体原料并掺杂少量扩散剂、稳定剂等添加剂的新型环保燃料。本文综述了醇基燃料的发展和应用,并对醇基燃料的发展进行展望。

生物柴油在船用低速机上的燃烧分析研究

To study the applicability of biodiesel in marine engines,this research investigated the performance,combustion characteristics,and emission characteristics of biodiesel(B100),diesel,and a 50%volume blend of the two fuels(B50)in a marine engine.This study was conducted on a 4-cylinder,520 mm-bore,two-stroke,low-speed marine engine with a common rail fuel and exhaust gas charge system.The three fuels were tested at different loads from 25%–100%with a step size of 25%.Results showed that the fuel consumption of pure biodiesel increased by about 13.5%and 3.8%relative to that of diesel at 25%and 100%loads,respectively,and by about 6%at 50%and 75%loads.In-cylinder combustion pressure was slightly reduced when the engine ran on biofuel,and black carbon emissions from biodiesel were reduced by an average of 54.7%.Compared with those from diesel,the carbon CO and total hydrocarbon emissions from B100 were reduced by 11.3%and 39%,respectively.Nitroxide emissions were elevated for B100 and B50 under all loading conditions.The properties of B50 blended diesel lie between those of B100 and diesel.In terms of combustion characteristics and emissions,biodiesel can be used without changing the engine parameters and can effectively reduce pollution,such as black carbon and carbon monoxide.

新型环保醇基汽油抗水性能研究及其对燃料性能的影响

文章主要研究与论述了醇基汽油的配方调合技术,及不同的甲醇、乙醇加入量对醇基汽油抗水性、透光率密度的影响,以及进行了醇基汽油综合配方燃料性能的考察研究。由于醇基汽油在储存与运输上避免不了与水接触,使其分层而不能储存与使用,所以在本试验中得出醇基汽油的最大抗水性能,同时经过初步的醇基汽油性能指标试验验证,均符合国家燃用油标准,并最终能够指导醇基汽油的工业化生产,促进醇基汽油燃料汽车产业健康、有序发展。

生物质能醇基燃料合成技术研究

研究生物质能醇基燃料的合成工艺,对于研发新型高效低成本醇基燃料、实现国家双碳指标、降低石油消耗量以减少空气污染等具有重要意义。依据室内试验平台,系统分析不同已发表文献的醇基燃料的合成工艺以及化学试剂的添加关系,并合成新型醇基燃料,配方为:77%甲醇+18%增热剂+3%降凝剂+2%助燃剂。研究中以甲醇作为主体燃料,能够降低成本,同时还添加具有良好燃烧性能的异丙醇、丙烯醇、二叔丁基对甲酚、甲基叔丁基醚,不仅具有调整高性能醇基燃料的碳、氢、氧之间比例、促进充分燃烧和增加燃烧热值等效果,而且还能改善高性能醇基燃料体系中的互溶性,防止分层,使得高性能醇基燃料燃烧更加充分。

醇基液体燃料安全防控和消防救援对策研究

本文通过对多起醇基液体燃料安全生产事故典型案例进行研究,分析了醇基液体燃料的危险特点和主要应用场所的危险特性,总结了当前生产生活中使用醇基液体燃料存在的突出问题和经验教训,从而针对醇基液体燃料的安全防控和消防救援工作,提出相关对策和建议。

以纤维素类物质为原料发酵生产燃料乙醇的研究进展

燃料乙醇是清洁汽油的主要代替物。其生产方法根据原料区分有 :糖蜜类、谷物淀粉类和纤维素类。以植物秸秆、木材等纤维素类物质为原料生产乙醇是最具挑战性的课题 ,目前用纤维素类物质制造乙醇的关键问题是纤维素原料的预处理和高效的发酵工艺。文中就综述了纤维素类物质的发酵机制、发酵工艺和发酵方式 ,对进一步实现工业化提供一些借鉴。