Rare earths (Ce, Y, Pr) modified Pd/La2O3-ZrO2-Al2O3 catalysts usedin lean-burn natural gas fueled vehicles

14%REO-2.5%LaO-33.5%ZrO-50%AlO(RE = Ce, Y, Pr) composites were prepared by a coprecipitation method. The Pd catalysts were obtained by an aqueous solution of Pd(NO)loaded on the rare earths modified composites with an initial wet impregnated method. The experiment results show that catalytic activity of the rare earths modified Pd/LaO-ZrO-AlOcatalysts is better than bare sample for methane oxidation. The structural characterization results reveal that the rare earths modified Pd catalysts increase amounts of surface active oxygen species by X-ray photoelectron spectroscopy(XPS) analysis and improve the dispersion of active component from H2-temperature programmed reduction(H2-TPR) measurement compared with bare sample. Especially,Pd/14%YO-2.5%LaO-33.5%ZrO-50%AlOsample exhibits highly active stability, it is related to the Pd particles highly dispersion,which was observed by transmission electron microscope(TEM) images.

Characteristics of a coherent jet enshrouded in a supersonic fuel gas

Based on a current coherent jet,this study proposes a supersonic combustion(SC)coherent jet in which the main oxygen jet is surrounded by a supersonic fuel gas.The characteristics of the proposed coherent jet are analyzed using experimental methods and numerical simulations in the high-temperature environment of electric arc furnace(EAF)steelmaking.The SC coherent jet achieved stable combustion in the EAF steelmaking environment.The simulated combustion temperature of the supersonic shrouding methane gas was 2930 K,slightly below the theoretical combustion temperature of methane–oxygen gas.The high speed and temperature of the supersonic flame effectively weakened the interaction between the main oxygen jet and the external ambient gas,inhibiting the radial expansion of the main oxygen jet and maintaining its high speed and low turbulence over a long distance.These features improved the impact capacity of the coherent jet and strengthened the stirring intensity in the EAF bath.

Energy Giant Expands Gas Output to Meet Growing Demand for Cleaner Fuel

China National Petroleum Corporation(CNPC),Asia’s biggest oil and gas producer,will increase its investment in natural gas exploration and production,pipeline construction and gas sales in the coming decade,betting big on the country’s thirst for the clean fuel.The stateowned company,which currently allocates 70

Process conditions for preparing methanol from cornstalk gas

The low-heat-value cornstalk gas produced in the down-flow fixed bed gasifier was tentatively used for methanol synthesis. The cornstalk gas was purified and the technical procedures such as deoxygenation, desulfurization, catalytic cracking of tar, purification and hydrogenation were studied. The catalytic experiments of methanol synthesis with cornstalk syngas were carried out in a tubular-flow integral and isothermal reactor. The effect of reaction temperature, pressure, catalysttypes, catalyst particle size, syngas flow at entering end and composition of syngas was investigated. The optimum process conditions and yield of methanol from cornstalk syngas were obtained. The experimental results indicated that the proper catalyst of the synthetic reaction was C301 and the optimum catalyst size （φ） was 0.833 mm×0.351 mm. The optimum operating temperature and pressure were found to be 235℃ and 5 Mpa, respectively. The suitable syngas flow 0.9-1.10 mol/h at entering end was selected and the best composition of syngas were CO 10.49%, CO2 8.8%, N2 37.32%, CnHm 0.95% and H2 40.49%. The best methanol yield is 0.418 g/g cornstalk. The study provided the technical support for the industrial test of methanol production from biomass （cornstalk）gas.

Atomic layer deposition of ultrathin layered TiO_2 on Pt/C cathode catalyst for extended durability in polymer electrolyte fuel cells

This study shows the preparation of a TiO2 coated Pt/C（TiO2/Pt/C） by atomic layer deposition（ALD）,and the examination of the possibility for TiO2/Pt/C to be used as a durable cathode catalyst in polymer electrolyte fuel cells（PEFCs）. Cyclic voltammetry results revealed that TiO2/Pt/C catalyst which has 2 nm protective layer showed similar activity for the oxygen reduction reaction compared to Pt/C catalysts and they also had good durability. TiO2/Pt/C prepared by 10 ALD cycles degraded 70% after 2000 Accelerated degradation test, while Pt/C corroded 92% in the same conditions. TiO2 ultrathin layer by ALD is able to achieve a good balance between the durability and activity, leading to TiO2/Pt/C as a promising cathode catalyst for PEFCs. The mechanism of the TiO2 protective layer used to prevent the degradation of Pt/C is discussed.

Pd/activated carbon sorbents for mid-temperature capture of mercury from coal-derived fuel gas

Higher concentrations of Hg can be emitted from coal pyrolysis or gasification than from coal combustion, especially elemental Hg. Highly efficient Hg removal technology from coal-derived fuel gas is thus of great importance. Based on the very excellent Hg removal ability of Pd and the high adsorption abilities of activated carbon（AC） for H2 S and Hg, a series of Pd/AC sorbents was prepared by using pore volume impregnation, and their performance in capturing Hg and H2 S from coal-derived fuel gas was investigated using a laboratory-scale fixed-bed reactor. The effects of loading amount, reaction temperature and reaction atmosphere on Hg removal from coal-derived fuel gas were studied. The sorbents were characterized by N2 adsorption, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The results indicated that the efficiency of Hg removal increased with the increasing of Pd loading amount, but the effective utilization rate of the active component Pd decreased significantly at the same time. High temperature had a negative influence on the Hg removal. The efficiency of Hg removal in the N2-H2S-H2-CO-Hg atmosphere（simulated coal gas） was higher than that in N2-H2S-Hg and N2-Hg atmospheres, which showed that H2 and CO, with their reducing capacity, could benefit promote the removal of Hg. The XPS results suggested that there were two different ways of capturing Hg over sorbents in N2-H2S-Hg and N2-Hg atmospheres.

Numerical simulation and experimental measurement of transport phenomena for coherent jet with CH4 ＋ N2 mixed fuel gas

Coherent jet technology has been widely used in EAF steelmaking process because of the longer potential core length and stronger impacting power of the supersonic oxygen jet. However, more oxygen and fuel gas are consumed to achieve excel- lent characteristics of coherent jets, which causes the increase in steelmaking cost. Computational fluid dynamics simulation and experimental measurement of the coherent jets with CH4 ＋ N2 mixed fuel gas were carried out aiming at reducing the consumption of fuel gas. The numerical simulation results showed good agreement with the experimental data. As a result, high proportion of N2 negatively affects the combustion of CH4, which is not good for the protection of oxygen jets. While the gas composition is 75% CH4 ＋ 25% N2, the N2 addition to the CH4 leads to an expanding of CH4 combustion zone, and the energy generated by the combustion reaction could be delivered to the molten bath more efficiently, which is one control scheme with high performance-price ratio.

NATURAL GAS AS AN ALTERNATIVE FUEL

Research in Early Days In early 1950s to 1960s, China began to study natural gas as an alternative fuel according to the State Science & Technology Commission’s requirment of widely utilizing natural gas. A testing station for natural gas vehicles was established in Sichuan province

Sensitivity analysis of a methanol and power polygeneration system fueled with coke oven gas and coal gas

The sensitivity analysis of a polygeneration energy system fueled with duo fuel of coke oven gas and coal gas is performed in the study,and the focus is put on the relations among syngas composition,conversation rate and performance.The impacts of the system configuration together with the fuel composition on the performance are investigated and discussed from the point of cascading utilization of fuel chemical energy.First,the main parameters affecting the performance are derived along with the analysis of the system configuration and the syngas composition.After the performance is being simulated by means of the Aspen Plus process simulator of version 11.1,the variation of the performance due to the composition of syngas and the conversion rate of chemical subsystem is obtained and discussed.It is obtained from the result that the proper conversion rate of the chemical subsystem according to the specific syngas composition results in better performance.And the syngas composition affects the optimal conversion rate of the chemical subsystem,the optimal point of which is around the stoichiometric composition for methanol production(CO/H_(2)=0.5).In all,the polygeneration system fueled with coke oven gas and coal gas,which can realize the reasonable conversion of syngas to power and chemical product according to the syngas composition,is a promising method for coal energy conversion and utilization.

Gas leakage monitoring with scanned-wavelength direct absorption spectroscopy

A natural gas leakage detector based on scanned-wavelength direct absorption spectroscopy is described. The sensor employs a multi-channel scanned-wavelength direct absorption strategy.It has the potential to simultaneously monitor methane and hydrogen sulfide in open path environment.Traditionally,scanned-wavelength direct absorption spectroscopy is the technique choice for natural gas leakage applications because of its simplicity,accuracy,and stability.We perform the gas sensor using direct-absorption wavelength scans with isolated features at 1-kHz repetition rate and the center wavelength is stabilized at the center of the 2v_3 band R（3） line of methane（1.65μm） and the（v_1＋v_2＋v_3） combination band of hydrogen sulfide（1.57μm）,respectively.The influence of light intensity fluctuations can be eliminated by using scanned-wavelength direct absorption spectroscopy.Because of the fast wavelength scanning,the sensor has a response time of less than 0.1 s.The sensor can be configured to sense leakages in path-integrated concentrations of,for example,100-ppm·m hydrogen sulfide and 10-ppm·m methane.

Gas separation using porous cement membrane

Gas separation is a key issue in various industrial fields. Hydrogen has the potential for application in clean fuel technologies. Therefore, the separation and purification of hydrogen is an important research subject. CO2 capture and storage have important roles in ＂green chemistry＂. As an effective clean technology, gas separation using inorganic membranes has attracted much attention in the last several decades. Membrane processes have many applications in the field of gas separation. Cement is one type of inorganic material, with the advantages of a lower cost and a longer lifespan. An experimental setup has been created and improved to measure twenty different cement membranes. The purpose of this work was to investigate the influence of gas molecule properties on the material transport and to explore the influence of operating conditions and membrane composition on separation efficiency. The influences of the above parameters are determined, the best conditions and membrane type are found, it is shown that cementitious material has the ability to separate gas mixtures, and the gas transport mechanism is studied.

Two-phase flow distributors for fuel cell flow channels

All existing proton exchange membrane （PEM） fuel cell gas flow fields have been designed on the basis of single-phase gas flow distribution. The presence of liquid water in the flow causes non-uniform gas distribution, leading to poor cell performance. This paper demonstrates that a gas flow restrictor/distributor, as is commonly used in two-phase flow to stabilize multiphase transport lines and multiphase reactors, can improve the gas flow distribution by significantly reducing gas real-distribution caused by either non-uniform water formation in parallel flow channels or flow instability associated with negative-slope pressure drop characteristic of two-phase horizontal flow systems.

Effect of methane-hydrogen mixtures on flow and combustion of coherent jets

Coherent jets are widely used in electric are furnace （EAF） steelmaking to increase the oxygen utilization and chemical reaction rates. However, the influence of fuel gas combustion on jet behavior is not fully understood yet. The flow and combustion characteristics of a coherent jet were thus investigated at steelmaking temperature using Fluent software, and a detailed chemical kinetic reaction mecha- nism was used in the combustion reaction model. The axial velocity and total temperature of the supersonic jet were measured via hot state experiments. The simulation results were compared with the experimental data and the empirical jet model proposed by Ito and Muchi and good consistency was obtained. The research results indicated that the potential core length of the coherent jet can be prolonged by optimizing the combustion effect of the fuel gas. Besides, the behavior of the supersonic jet in the subsonic section was also investigated, as it is an important factor for controlling the position of the oxygen lance. The investigation indicated that the attenuation of the coherent jet is more notable than that of the conventional jet in the subsonic section.