红外光谱技术探究Ⅰ类琥珀形成的化学过程

琥珀是由远古裸子类和被子类植物分泌的树脂历经数百万年乃至几千万年的沉积石化过程所形成的石化树脂。根据石化树脂的化学组成,琥珀被分为五种类型:Ⅰ类、Ⅱ类、Ⅲ类、Ⅳ类和Ⅴ类。其中,Ⅰ类琥珀是含有半日花烷型二萜化合物的萜类树脂所形成的石化树脂;而形成过程中的半石化树脂被归类为Ⅰ类柯巴树脂。在漫长的沉积石化过程中,萜类树脂中的半日花烷型二萜化合物,因含有碳碳双键、羟基、羧基等活性官能团,会发生一系列的聚合反应、交联反应、酯化反应和异构化反应等,并逐渐形成了石化程度不同的半石化树脂和石化树脂;石化不足时,形成半石化树脂中的柯巴树脂;石化充分时,形成石化树脂中的琥珀;石化彻底时,形成石化树脂中的硬琥珀。以上述三个石化阶段为研究对象,借助红外光谱技术,跟踪碳碳双键、羧基、酯基等吸收峰的变化,验证半石化树脂和石化树脂的阶段性演化特征,推演出Ⅰ类琥珀形成的化学过程。经红外测试结果的分析与比对研究,主要结论如下:(1)Ⅰ类柯巴树脂,因石化不足,聚合反应、交联反应和异构化反应不足,酯化反应尚未发生,并含有大量碳碳双键和羧基,故其结构特性不稳定;(2)Ⅰ类琥珀,因石化充分,进行了较为充分的聚合反应、交联反应和异构化反应等,但酯化反应仍在进行,形成了含有少量碳碳双键和羧基的稳定结构;(3)Ⅰ类硬琥珀,因石化彻底,进行了较为彻底的聚合反应、交联反应、酯化反应和异构化反应,形成了几乎不含活性官能团的更加稳定的结构形式。

Effect of graphitization degree of fuel cell gas diffusion layers on their heat management:Modeling and experiments

Serving as gas diffusion layers(GDLs),the thermal conductivity of carbon paper(CP)plays a significant role in the heat transfer management in fuel cells.In the present study,the effect of graphitization degree of CP on its through plane thermal conductivity and in-plane thermal conductivity is investigated.The relationship between heat treatment temperatures(1800,2000,2200,2400 and 2500℃)and graphitization degree is also investigated by SEM,XRD and Raman measurements.A model for CP under different graphitization degree is suggested considering the thermal conductivity difference of carbon fiber and matrix carbon.The experimental and simulation results are compared.The results show that the graphitization degree has a significant impact on the through-plane thermal conductivity and in plane thermal conductivity.

Raman spectroscopy investigation of structural and textural change in C/C composites during braking

The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar （RL） pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy. The full width at half maximum （FWHM） of the D-band indicates the amount of defects in the in-plane lattice, while the G-to-D band intensity （peak area） ratios （lC/ID） is used to evaluate the degree of graphitization. The results show that the FWHM of D-band of sample with RL pyrocarbon changes greatly from 36 cm-1 to 168 cm 1 after braking tests, which indicates that a large number of lattice defects are produced on its wear surface. However, the graphitization degree of resin-derived carbon sample rises significantly, because the IC/1D increases from 0.427 to 0.928. Braking tests under normal loading conditions, involving high temperature and high pressure, produce a lot of lattice defects on the wear surface, and induce the graphitization of the surface. Sample with RL pyrocarbon having a low hardness is easy to deform, and has the most lattice defects on the wear surface after braking. While raw materials with resin-derived carbon have the lowest graphitization degree which rises greatly during braking.

Green fuel from coal via Fischer-Tropsch process： scenario of optimal condition of process and modelling

Extracting, transportation and the using from fossil fuels can damage to the hydrosphere, the biosphere and the Earth＇s atmosphere. But humans always need to this valuable substance. The production of oil derivatives by means of forest waste and coal through the Fischer-Tropsch process is an appropriate solution for the cleanliness of all parts of the environment. For the production of favorite products by the synthesis of Fischer-Tropsch, the performance of the catalyst under different operating conditions should be predictable. For this reason, in this paper, eight mathematical models were determined for the selectivity of five products of methane, light hydrocarbons, gasoline, diesel and wax based on three factors of reduction temperature, time on stream, and He/CO ratio inlet gas on iron-based catalyst. The results showed that the reduction temperature factor had the most effective on the selectivity of hydrocarbon products, exception diesel, so that the increase of the reduction temperature led to increase of the selectivity of methane, light hydrocarbons, gasoline and reduce of the degree of selectivity of the wax and vice versa. For the diesel selectivity, factor of the He/CO ratio inlet gas was the most effective than other factors.

Catalytic graphitization of polyacrylonitrile-based carbon fibers coated with Prussian blue

Prussian blue(PB) was used as catalyst to improve the extent of graphitization of polyacrylonitrile(PAN)-based carbon fibers.PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coating(PB content) was controlled by adjusting the electrodeposition time.PAN-based carbon fibers with PB coating were heat-treated and the extent of graphitization was measured by X-ray diffractometry and Raman spectroscopy.The results indicate that the extent of graphitization of PAN-based carbon fibers is enhanced in the presence of the coating.When the PB-coated carbon fibers were heat-treated at 1 900 ℃,interlayer spacing(d002) and crystallite size(Lc) reach 0.336 8 and 21.2 nm respectively.Contrarily,the values of d002 and Lc are 0.341 4 and 7.4 nm respectively when the bare carbon fibers were heat-treated at 2 800 ℃.Compared with the bare carbon fibers,PB can make the heat treatment temperature(HTT) drop more than 500 ℃ in order to reach the same extent of graphitization.Furthermore,the research results show that PB content also has a certain influence on the extent of graphitization at the same HTT.

Effect of Metal Contamination on the Performance of Catalyst for Deep Catalytic Cracking Process

The effect of different metal contamination levels of catalysts for Deep Catalytic Cracking(DCC) on the distribution and selectivity of DCC products was investigated in a FCC pilot unit. The pilot test results showed that the effects of the metal contamination level of catalyst on the propylene yield,the coke yield,the LPG yield,the gasoline yield,the selectivity of low carbon olefins,and coke selectivity was significant,and that the influence of metal contamination level on the conversion and dry gas yield was minor.

Moisture-triggered actuator and detector with high-performance: interface engineering of graphene oxide/ethyl cellulose

Actuators that can directly convert other forms of environmental energy into mechanical work offer great application prospects in intriguing energy applications and smart devices. But to-date, low cohesion strength of the interface and humidity responsive actuators primarily limit their applications. Herein, by experimentally optimizing interface of bimorph structure, we build graphene oxide/ethyl cellulose bidirectional bending actuators — a case of bimorphs with fast and reversible shape changes in response to environmental humidity gradients. Meanwhile, we employ the actuator as the engine to drive piezoelectric detector. In this case, graphene oxide and ethyl cellulose are combined with chemical bonds, successfully building a bimorph with binary synergy strengthening and toughening. The excellent hygroscopicity of graphene oxide accompanied with huge volume expansion triggers giant moisture responsiveness greater than 90 degrees. Moreover, the open circuit voltage of piezoelectric detector holds a peak value around 0.1 V and exhibits excellent reversibility. We anticipate that humidity-responsive actuator and detector hold promise for the application and expansion of smart devices in varieties of multifunctional nanosystems.