以沥青为前驱体制备TiC/FeCrNi反应火焰喷涂复合涂层

以钛铁粉、CrFe粉、羰基镍粉和碳的前驱体(石油沥青)为原料,通过前驱体碳化复合技术制备了Ti-Fe-Cr-Ni-C反应喷涂复合粉末,并通过普通火焰喷涂成功地合成与沉积了TiC/FeCrNi复合涂层。采用XRD和SEM对喷涂粉末和涂层的相组成和显微结构进行了分析,同时对涂层耐磨性能进行了对比研究。研究结果表明:采用前驱体碳化复合技术制备的Ti-Fe-Cr-Ni-C反应喷涂复合粉末粒度均匀、无有害相生成;所制备的TiC/FeCrNi复合涂层由不同含量TiC颗粒分布于金属基体内部而形成的复合强化片层叠加而成,TiC颗粒呈纳米级;基体由(Fe,Cr)和Cr0.19Fe0.7Ni0.11两相组成;相同条件下,所获TiC/FeCrNi复合涂层磨损体积大约是常规火焰喷涂Ni60涂层的1/8。

Advances in the studies of the supported ruthenium catalysts for CO_(2)methanation

CO_(2)methanation has a potential in the large-scale utilization of carbon dioxide.It has also been considered to be useful for the renewable energy storage.The commercial pipeline for natural gas transportation can be directly applied for the methane product of CO_(2)methanation.The supported ruthenium(Ru)catalyst has been confirmed to be active and stable for CO_(2)methanation with its high ability in the dissociation of hydrogen and the strong binding of carbon monoxide.CO_(2)methanation over the supported Ru catalyst is structure sensitive.The size of the Ru catalyst and the support have significant effects on the activity and the mechanism.A significant challenge re-mained is the structural controllable preparation of the supported Ru catalyst toward a sufficiently high low-temperature activity.In this review,the recent progresses in the investigations of the supported Ru catalysts for CO_(2)methanation are summarized.The challenges and the future devel-opments are also discussed.

纳米SiC复合镀层制备工艺的研究

在A3钢板上制备了含有纳米SiC的镍基复合镀层 ,在MM 2 0 0摩擦磨损试验机上对镀层进行磨损试验 ,研究了阴极电流密度、镀液温度、SiC浓度和pH值等主要工艺参数对镀层耐磨性能的影响 ,以确定工艺参数范围 ,并采用正交试验方法分析得到最佳的工艺参数。结果表明 ,纳米SiC复合镀层的最佳工艺参数为 :电流密度 3A/dm2 ,温度 3 0℃ ,SiC含量 5g/L ,pH =3 .5。

Polycondensation of ammonium thiocyanate into novel porous g-C_3N_4 nanosheets as photocatalysts for enhanced hydrogen evolution under visible light irradiation

Porous graphitic carbon nitride（pg-C3N4） nanosheets have been prepared through a one-step ammonia thermopolymerization method.The effects of synthetic temperature on the structural,optical and photocatalytic properties of the samples have been investigated.Characterization results show that the heptazine-based conjugate heterocyclic structure was formed over 500℃,which is attributed to the inhibitory effect of ammonia from the decomposition of NH4SCN.Precise nanosheet morphology and an increased pore distribution with an enlarged surface area are observed for the samples obtained under high temperatures.Optical analysis results show that the bandgap of the samples widens and photoluminescene intensity is gradually quenched as the treating temperature is increased.The results demonstrate that a higher polymerization temperature improves the nanolayer structure,porosity and migration rate of the photo-induced carriers of the samples.The pg-C3N4 nanosheets prepared at 600℃ presents the highest photocatalytic activity for hydrogen evolution from water under visible-light irradiation.This study demonstrates a novel strategy for the synthesis and optimization of polymer semiconductor nanosheets with gratifying photocatalytic performance.

Determination of Structure and Polarity of Si C Single Crystal by X-Ray Diffraction Technique

Structure and polarity of the Si C single crystal have been analyzed with the four- circle X- ray diffraction method by a double- crystal diffractom eter.The hexagonal{ 10 15 } pole figure shows that this Si C sam ple has a6 H modification.The difference between the integrated intensities m easured byω scan in the triple- axis diffraction set- up finds some convincing evidence that the surface is either a Si- terminated face or C- terminated face.The experi- mental ratios of| F( 0 0 0 L) | 2 / | F( 0 0 0 L) | 2 are in good agreem entwith the calculated ones after the dispersion cor- rections to the atomic scattering factors( L=6 ,12 and18,respectively) .Thus,this m easurem ent technique is con- venient for the application of the materials with remarkable surface polarity.

Fabrication of 4H-SiC Merged PN-Schottky Diodes

The design, fabrication and characteristics of 4H SiC merged PN Schottky (MPS) diodes with Ni Schottky contact and junction termination extension (JTE) edge termination are reported. A multiple energy implantation Al in the surface of the n - drift region below the face to face Schottky metal formed pn junctions, which screen the Schottky contact from high electrical, post implantation annealing has been done at 1500℃ for 30min in the ultra high purity Ar ambient. The devices can block more than 600V reverse voltage and the lowest leakage current at -600V is 1×10 -3 A/cm 2, while the forward current density at 3V is more than 200A/cm 2 for 1000μm devices, 1000A/cm 2 at 3 5V for 300μm devices.

Preparation of MgO whisker from magnesite tailings and its application

Magnesium carbonate whisker as precursor was prepared from the low-grade magnesite tailings by the route of calcination, hydration, carbonation and thermal decomposition, and then MgO whisker was prepared by calcining the precursor. In addition, the effect of MgO whisker addition on sintering and thermal shock resistance of refractory was also investigated. The results show that the thermal decomposition product is MgCO3·3H2O and its morphology is remarkably influenced by the types of additives, and magnesium carbonate whisker with the length of 10-60 μm and length-diameter ratio of 10-20 is successfully prepared when a type of soluble magnesium salt is added. MgO whisker with the length of 10-40 μm is derived from precursor with the heating rate of 1 ℃/min. The thermal shock resistance of refractory is significantly improved by the addition of MgO whisker due to its effect on binding and preventing crack expanding, and the proper amount of whisker addition is around 3%.

Catalytic reduction of SO_2 by CO over CeO_2-TiO_2 mixed oxides

The structure and catalytic desulfurization characteristics of CeO2-TiO2 mixed oxides were investigated by means ofX-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and catalytic activity tests. According to the results, a CeO2-TiO2solid solution is formed when the mole ratio of cerium to titanium n（Ce）：n（Ti） is 5：5 or greater, and the most suitable n（Ce）：n（Ti） isdetermined as 7：3, over which the conversion rate of SO2 and the yield of sulfur at 500℃ reach 93% and 99%, respectively.According to the activity testing curve, Ce0.7Ti0.3O2 （n（Ce）：n（Ti）=7：3） without any pretreatment can be gradually activated by reagentgas after about 10 min, and reaches a steady activation status 60 min later. The XPS results of Ce0.7Ti0.3O2 after different time ofSO2＋CO reaction show that CeO2 is the active component that offers the redox couple Ce4＋/Ce3＋ and the labile oxygen vacancies, andTiO2 only functions as a catalyst structure stabilizer during the catalytic reaction process. After 48 h of catalytic reaction at 500℃,Ce0.7Ti0.3O2 still maintains a stable structure without being vulcanized, demonstrating its good anti-sulfur poisoning performance.

Highly Efficient Synthesis of Clean Biofuels from Biomass Using FeCuZnAIK Catalyst

Highly efficient synthesis of clean biofuels using the bio-syngas obtained from biomass gasi- fication was performed over Fel.5CulZnlAllK0.117 catalyst. The maximum biofuel yield from the bio-syngas reaches about 1.59 kg biofuels/（kgcat·rh） with a contribution of 0.57 kg alcohols/（kgcat·rh） and 1.02 kg liquid hydrocarbons/（kgcat·rh）. The alcohol products in the resulting biofuels were dominated by the C2＋ alcohols （mainly C2-C6 alcohols） with a content of 73.55%-89.98%. The selectivity .of the liquid hydrocarbons （C5＋） in the hydrocarbon products ranges from 60.37% to 70.94%. The synthesis biofuels also possess a higher heat value of 40.53-41.49 MJ/kg. The effects of the synthesis conditions, including temperature, pressure, and gas hourly space velocity, on the biofuel synthesis were investigated in detail. The catalyst features were characterized by inductively coupled plasma and atomic emission spectroscopy, X-ray diffraction, temperature programmed reduction, and the N2 adsorption-desorption isotherms measurements. The present biofuel synthesis with a higher biofuel yield and a higher selectivity of liquid hydrocarbons and C2＋ alcohols may be a potentially useful route to produce clean biofuels and chemicals from biomass.

Physiological Analysis of Two Arabidopsis thaliana Mutants in Response to CO2

[Objective] The 15urpose was to seek for the different phenotypes between wild type and Arabidopsis Mutants in response to CO2. [Method] The epidermis bioassays and seed germination test were carried out to analyze the physiological characteristics of two Arabidopsis mu- tants and their wild type. [Result] There existed distinct differences in stomata apertures, water loss and leaf temperature compared with wild type except for stomata density. In addition, seed germination test on the medium indicated that cdfl was insensitive to ABA, mannitol and NaCI, but cdsl performed contrary to cdil. [ Conclusion] There are some different physiological characteristics between wild type and mutants.

CO oxidation over Au/ZrLa-doped CeO_2 catalysts: Synergistic effect of zirconium and lanthanum

The physicochemical properties of nanosized Au catalysts supported on doped CeO2 and their cata‐lytic performance for the CO oxidation reaction were investigated. The Au/Zr‐doped CeO2 catalyst is much more active than undoped Au/CeO2, while Au/ZrLa‐doped CeO2 shows the highest activity. Characterization of the catalysts by X‐ray diffraction, transmission electron microscopy （TEM）, high‐resolution TEM, and the X‐ray absorption fine structure technique shows high homogeneity of the oxide supports and well‐dispersed nanosized Au nanoparticles. Raman spectroscopy, X‐ray photoelectron spectroscopy, and H2‐tempeature‐programmed reduction show that the surface oxygen species are the main factor for the catalytic activity in the CO oxidation reaction, while the supported Au species can improve the redox properties and create oxygen vacancy sites on the support. The oxidation state of Au is not the main factor governing the activity of Au/doped‐CeO2 catalysts. Additionally, the synergistic effect of Zr and La is discussed.

Progress in the Study on the Phase Equilibria of the CO2·H2O and CO2-HeO-NaCI Systems

To study the feasibility of CO2 geological sequestration,it is needed to understand the complicated mul- tiple-phase equilibrium and the densities of aqueous solution with CO2 and multi-ions under wide geological condi- tions(273.15—473.15K,0—60MPa),which are also essential for designing separation equipments in chemical or oil-related industries.For this purpose,studies on the relevant phase equilibria and densities are reviewed and ana- lyzed and the method to improve or modify the existing model is suggested in order to obtain more reliable pre- dictions in a wide temperature and pressure range.Besides,three different models(the electrolyte non random two-liquid(ELECNRTL),the electrolyte NRTL combining with Helgeson model(ENRTL-HG),Pitzer activity co- efficient model combining with Helgeson model(PITZ-HG))are used to calculate the vapor-liquid phase equilib- rium of CO2-H2O and CO2-H2O-NaCl systems.For CO2-H2O system,the calculation results agree with the experi- mental data very well at low and medium pressure(0—20MPa),but there are great discrepancies above 20MPa.For the water content at 473.15K,the calculated results agree with the experimental data quite well.For the CO2-H2O-NaCl system,the PITZ-HG model show better results than ELECNRTL and ENRTL-HG models at the NaCl concentration of 0.52mol·L -1 .Bur for the NaCl concentration of 3.997mol·L -1 ,using the ELECNRTL and ENRTL-HG models gives better results than using the PITZ-HG model.It is shown that available experimental data and the thermodynamic calculations can satisfy the needs of the calculation of the sequestration capacity in the temperature and pressure range for disposal of CO2 in deep saline aquifers.More experimental data and more accu- rate thermodynamic calculations are needed in high temperature and pressure ranges(above 398.15K and 31.5MPa).

Synthesis of Higher Alcohols from Syngas over Alkali Promoted K-Co-Mo Catalysts Supported on Multi-walled Carbon Nanotubes

A series of carbon nanotubes-supported K-Co-Mo catalysts were prepared by a sol-gel method combined with incipient wetness impregnation. The catalyst structures were characterized by X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy and H2-TPD, and its catalytic performance toward the synthesis of higher alcohols from syngas was investigated. The as-prepared catalyst particles had a low crystallization degree and high dispersion on the outer and inner surface of CNTs. The uniform mesoporous structure of CNTs increased the diffusion rate of reactants and products, thus promoting the reaction conversion. Furthermore, the incorporation of CNTs support led to a high capability of hydrogen absorption and spillover and promoted the formation of alkyl group, which served as the key intermediate for the alcohol formation and carbon chain growth. Benefiting from these characteristics, the CNTs supported Mo-based catalyst showed the excellent catalytic performance for the higher alcohols synthesis as compared to the unsupported catalyst and activated carbon supported catalyst.

Three Stage Equilibrium Model for Coal Gasification in Entrained Flow Gasifiers Based on Aspen Plus

A three stage equilibrium model is developed for coal gasification in the Texaco type coal gasifiersbased on Aspen Plus to calculate the composition of product gas, carbon conversion, and gasification teml^erature. The model is divided into three stages including pyrolysis and combustion stage, char gas reaction stage, and gas p.hase reaction stage. Part of the water produced in thepyrolysis and combust!on stag.e is assumed to be involved inthe second stage to react with the unburned carbon. Carbon conversion is then estimated in the second stage by steam participation ratio expressed as a function of temperature. And the gas product compositions are calculated from gas phase reactions in the third stage. The simulation results are consistent with published experimental data.

A Multilayer Study of pCO2 in the Surface Waters of the Yellow and South China Seas in Spring and the Sea-Air Carbon Dioxide Flux

A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface microlayer(SML) ,subsurface layer(SSL) and surface layer(SL) . The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order:pCO2 SML> pCO2 SSL> pCO2 SL. The highest values were found in March for all SML,SSL and SL,followed by those in April,and the lowest were in May. The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude,there was a significant negative correlation between it and latitude,i.e.,'high latitude low pCO2'. By using four calculation models,the carbon dioxide fluxes(FC O2) in spring in the Yellow and South China Seas,which were found to act as a 'sink' of atmospheric CO2,were preliminarily estimated on the basis of the pCO2 data in the SML to be -7.00×106 t C and -22.35×106 t C,respectively. It is suggested that the FC O2calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL.

Estimate of Global Sea-Air CO_2 Flux with Sea-State-Dependent Parameterization

Although the annual global sea-air CO2 flux has been estimated extensively with various wind-dependent-k parameterizations,uncertainty still exists in the estimates. The sea-state-dependent-k parameterization is expected to improve the uncertainty existing in these estimates. In the present study,the annual global sea-air CO2 flux is estimated with the sea-state-dependent-k parameterization proposed by Woolf(2005) ,using NOAA/NCEP reanalysis wind speed and hindcast wave data from 1998 to 2006,and a new estimate,-2.18 Gt C year-1,is obtained,which is comparable with previous estimates with biochemical methods. It is interesting to note that the averaged value of previous estimates with various wind-dependent-k parameterizations is almost identical to that of previous estimates with biochemical methods by various authors,and that the new estimate is quite consistent with these averaged estimates.

Effect of decomposition of catalyst precursor on Ni/CeO_2 activity for CO methanation

CO methanation on Ni/CeO2 has recently received increasing attention.However,the low-temperature activity and carbon resistance of Ni/CeO2 still need to be improved.In this study,plasma decomposition of nickel nitrate was performed at ca.150℃ and atmospheric pressure.This was followed by hydrogen reduction at 500 ℃ in the absence of plasma,and a highly dispersed Ni/CeO2 catalyst was obtained with improved CO adsorption and enhanced metal-support interaction.The plasma-decomposed catalyst showed significantly improved low-temperature activity with high methane selectivity(up to 100%)and enhanced carbon resistance for CO methanation.For example,at 250 ℃,the plasma-decomposed catalyst showed a CO conversion of 96.8% with high methane selectivity(almost 100%),whereas the CO conversion was only 14.7% for a thermally decomposed catalyst.

Copper-ceria solid solution with improved catalytic activity for hydrogenation of CO to CHOH

A copper-ceria solid solution and ceria-supported copper catalysts were prepared and used for the catalytic hydrogenation of CO2 to CH3OH.According to site-specific classification and quantitative analyses(X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,and CO adsorption),the interfaces of the prepared catalysts were classified as Cu incorporated into ceria(Cu-Ov-Cex),dispersed Cu O(D-Cu O-Ce O2),and bulk Cu O(B-Cu O-Ce O2)over the Ce O2 surface.These results,together with those of activity tests,showed that the Cu-Ov-Cex species was closely related to the CO2 hydrogenation activity and resulted in a much higher turnover frequency of CH3OH production than that observed with the D-Cu O-Ce O2 and B-Cu O-Ce O2 species.Thus,the copper-ceria solid solution exhibited improved activity due to the higher Cu-Ov-Cex fraction.

△P index with different gas compositions for instantaneous outburst prediction in coal mines

In this study we measured the △P(initial speed of gas emission) index with different gas concentrations of carbon dioxide(pure CO2,90% CO2+10% CH4,67% CO2+33% CH4,50% CO2+50% CH4,30% CO2+10% CH4 and pure CH4) of coal samples from the No.2 coal seam in the Yaojie Coal Mine,Gansu province,China.The effect of carbon dioxide concentration,gas composition,coal strength and particle size of coal samples on the △P index was investigated.The experimental results show that with gas of various compositions,the △P value of three samples were clearly different.The △P index of coal samples A,B and C(0.2～0.25 mm) were 4,6 and 7 with pure CH4 and 22,30 and 21 when pure CH4 was used.Carbon dioxide concentration affects the △P index markedly.The △P index increases with an increase in carbon dioxide concentration,especially for coal B.Hence,the △P index and K(another outburst index) values tested only with pure CH4 for prediction of the danger of outburst is not accurate.It is important to determine the initial speed of gas emission given the gas composition of the coal seam to be tested for exact outburst prediction.

MoS2-rGO hybrid architecture as durable support for cathode catalyst in proton exchange membrane fuel cells

Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting the durability of the fuel cells. Meanwhile, carbon corrosion would also weaken the linkage between Pt and the support material, which causes Pt agglomeration, and consequently, deterioration of the cell performance. To overcome the drawbacks of a Pt/C electrocatalyst, a hybrid support material comprising molybdenum disulfide and reduced graphene oxide is proposed and synthesized in this study to exploit the graphitic nature of graphene and the availability of the exposed edges of MoS2. TEM results show the uniform dispersion of Pt nanoparticles over the MoS2-rGO surface. Electrochemical measurements indicate higher ECSA retention and better ORR activity after 10000 potential cycles for Pt/MoS2-rGO as compared to Pt/C, demonstrating the improved durability for this hybrid support material.