The effects of CO2 addition on the partial oxidation of heptane for hydrogen generation

The effects of CO2 on the partial oxidation of heptane for hydrogen generation have been studied. Based on the experimental results and thermodynamic equilibrium calculations, the validity of CO2 addition to weaken the hot spots, and the feasibility of the autothermal operation are discussed.

Microwave-assisted hydrothermal synthesis of hydroxy-sodalite zeolite membrane

A high quality pure hydroxy-sodalite zeolite membrane was successfully synthesized on an alpha-Al2O3 support by a novel microwave-assisted hydrothermal synthesis (MARS) method. Influence of synthesis conditions, such as synthesis time, synthesis procedure, etc., on the formation of hydroxy-sodalite zeolite membrane by MAHS method was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and gas permeation measurements. The synthesis of hydroxy-sodalite zeolite membrane by MAHS method only needed 45 min and synthesis was more than 8 times faster than by the conventional hydrothermal synthesis (CHS) method. A pure hydroxy-sodalite zeolite membrane was easily synthesized by MAHS method, while a zeolite membrane, which consisted of NaX zeolite, NaA zeolite and hydroxy-sodalite zeolite, was usually synthesized by CHS method. The effect of preparation procedures had a dramatic impact on the formation of hydroxy-sodalite zeolite membrane and a single-stage synthesis procedure produced a pure hydroxy-sodalite zeolite membrane. The pure hydroxy-sodalite zeolite membrane synthesized by MARS method was found to be well inter-grown and the thickness of the membrane was 6-7 mum. Gas permeation results showed that the hydrogen/n-butane permselectivity of the hydroxy-sodalite zeolite membrane was larger than 1000. (C) 2004 Elsevier Inc. All rights reserved.

Synthesis and properties of A-type zeolite membranes by secondary growth method with vacuum seeding

A-type zeolite membranes were successfully synthesized on tubular alpha-Al2O3 supports by secondary growth method with vacuum seeding In the seeding process, a thin, uniform and continuous seeding layer was closely attached to the support surface by the pressure difference between the two sides of the support wall. The effects of seed particle size, suspension concentration, coating pressure difference and coating time on the membrane and its pervaporation properties were investigated. The as-synthesized membranes were characterized by XRD and SEM. The quality of the membranes was evaluated by the pervaporation dehydration of 95 wt. % isopropanol/water mixture at 343 K. High quality A-type zeolite membranes can be reproducibly prepared by the secondary growth method with vacuum seeding under the conditions: seed particle size of 500-1200 nm, suspension concentration of 4-8 g/l, coating pressure difference of 0.0100-0.0250 MPa and coating time of 45-180 s. (C) 2004 Elsevier B.V. All rights reserved.

长白山阔叶红松林生态系统碳动态及其对气候变化的响应

应用基于干物质生产理论的过程模型(Sim-CYCLE)估算了1982—2003年间长白山阔叶红松林生态系统总第一生产力(GPP)、净第一生产力(NPP)、净生态系统生产力(NEP)及其季节动态变化以及碳储量(WE)、植物碳储量(WP)和土壤碳储量(WS),并分析了这些指标在当前气候情景和碳平衡情况时的差异及其对未来气候变化情景的响应.结果表明:在当前气候情景下,长白山阔叶红松林GPP、NPP和NEP分别为14.9、8.7和2.7Mg C·hm-2·a-1,三者分别比实测值减少2.8Mg C·hm-2·a-1、增加1.4Mg C·hm-2·a-1和增加0.2Mg C·hm-2·a-1;长白山阔叶红松林6—8月的NEP占全年总量的90%以上,其中,7月最高(1.23MgC·hm-2·month-1);研究区WE、WP和WS分别为550.8、183.8和367.0Mg C·hm-2,其与实测值均具有较高的一致性.从当前气候情景下到达碳平衡前,长白山阔叶红松林碳储量均有不同程度的增加,GPP和NPP分别为17.7和7.3Mg C·hm-2·a-1,表明研究区碳"汇"的作用随着碳储量的增加逐渐减弱;温度增加2℃时,不利于长白山阔叶红松林GPP、NPP和NEP的增长,CO2浓度倍增则可有利地促进三者的增长,CO2浓度倍增、温度增加2℃对GPP、NPP和NEP增幅的影响与单纯CO2浓度倍增的影响相似,气候变化情景对长白山阔叶红松林碳储量的影响规律与对生产力幅度的影响相同,这可能是生态系统生产力影响碳积累所致.

Photocatalytic water reduction under visible light on a novel ZnIn2S4 catalyst synthesized by hydrothermal method

A novel ZnIn2S4 catalyst synthesized by hydrothermal method shows high and stable photocatalytic activity for water reduction under visible light illumination.

Activated carbons chemically modified by concentrated H2SO4 for the adsorption of the pollutants from wastewater and the dibenzothiophene from fuel oils

The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150-270 degreesC. The modified AC was characterized by N-2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 degreesC greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m(2)/g to 745 m(2)/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon-oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 degreesC. The mesoporous properties of the AC modified by concentrated H2SO4 were further tested by the adsorption of methylene blue and dibenzothiophene. The AC modified by concentrated H2SO4 at 250 degreesC has much higher adsorption capacities for large molecules (e.g., methylene blue and dibenzothiophene) than the unmodified AC but less adsorption capacities for small molecules (e.g., iodine). The adsorption results from aqueous solutions have been interpreted using Freundlich adsorption models.

Catalytic partial oxidation of n-heptane for hydrogen production

Partial oxidation of n-heptane (POH) for hydrogen generation was studied over several catalysts between 700 and 850degreesC. Modified Ni-based/gamma-Al2O3 catalyst exhibited not only good catalytic activity but also good carbon deposition resistance ability. Under the modified reaction conditions, 100% n-heptane conversion and 93% hydrogen selectivity can be obtained.

AgBiVMo oxide catalytic membrane for selective oxidation of propane to acrolein

A metal ions (Ag, Bi, V, Mo) modified sol-gel method was used to prepare a mesoporous Ag0.01Bi0.85V0.54Mo0.45O4 catalytic membrane which was used in the selective oxidation of propane to acrolein. By optimizing the preparation parameters, a thin and perfect catalytically active membrane was successfully prepared. SEM results showed that the membrane thickness is similar to5 mum. XRD results revealed that Ag0.01Bi0.85V0.54Mo0.45O4 with a Scheelite structure, which is catalytically active for the selective oxidation of propane to acrolein, was formed in the catalytic membrane only when AgBiVMoO concentrations were higher than 40%. Catalytic reaction results demonstrated that the selective oxidation of propane could be controlled to a certain degree, such as to acrolein, in the catalytic membrane reactor (CMR) compared to the fixed bed reactor (FBR). For example, a selectivity of 54.85% for acrolein in the liquid phase was obtained in the CMR, while only 8.31% was achieved in the FBR. (C) 2003 Elsevier B.V. All rights reserved.

Structure and oxygen permeability of a dual-phase membrane

The dual-phase membrane of La0.15Sr0.85Ga0.3Fe0.7O3-delta-Ba0.5Sr0.5Fe0.2Co0.8O3-delta (LSGF-BSCF) was prepared successfully. This membrane was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe micro-analyzer (EPMA). This membrane has a dense dual-phase structure: LSGF being the dense body of this membrane and BSCF as another phase running along the LSGF body. This structure is favorable for the oxygen permeation through the membrane. The oxygen permeation test shows that the oxygen permeation flux of LSGF-BSCF membrane (Jo(2) = 0.45 ml/min cm(2), at 915 degreesC) is much higher than that of LSGF membrane (Jo(2) = 0.05 ml/min cm(2)). Thickness dependence of oxygen permeation indicates that the oxygen permeation is controlled by the bulk diffusion. Compared to pure BSCF the dual-phase membrane of LSGF-BSCF is stable in reducing atmosphere. (C) 2003 Elsevier B.V. All rights reserved.

Oxidative dehydrogenation of propane in a dense tubular membrane reactor

Oxidative dehydrogenation of propane (ODP) to propylene was investigated in a dense tubular membrane reactor made of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) at 700degreesC and 750degreesC. The propylene selectivity in the membrane reactor (44.2%) is much higher than that in the fixed-bed reactor (15%) at the similar propane conversion (23-27%). Higher propylene selectivity in the membrane reactor was attributed to the lattice oxygen (O2-) supplied through the membrane.

Water reduction and oxidation on Pt-Ru/Y2Ta2O5N2 catalyst under visible light irradiation

Y2Ta2O5N2 is presented as a novel photocatalyst with high activity for water splitting under visible-light irradiation in the presence of appropriate sacrificial reagents; the activity for reduction to H-2 is increased by the incorporation of Pt or Ru as a co-catalyst, with a significant increase in production efficiency when both Pt and Ru are present.

accurate and self-consistent ocean color algorithm:simultaneous retrieval of aerosol optical properties and chlorphyll concentrations

A new algorithm has been developed for simultaneous retrieval of aerosol optical properties and chlorophyll concentrations in case I waters. This algorithm is based on an improved complete model for the inherent optical properties and accurate simulations of the radiative transfer process in the coupled atmosphere-ocean system. It has been tested against synthetic radiances generated for the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) channels and has been shown to be robust and accurate. A unique feature of this algorithm is that it uses the measured radiances in both near-IR and visible channels to find that combination of chlorophyll concentration and aerosol optical properties that minimizes the error across the spectrum. Thus the error in the retrieved quantities can be quantified.

人工湿地中降解有机污染物细菌的分离筛选

采用平板划线法从人工湿地污水处理系统底泥和污水中分离出 2 3株细菌 ,在实验室条件下检测了这些细菌对灭菌污水和自然污水CODcr的去除效果 ,结果表明其中 8株细菌 (DN -4、DN -5、DN- 6、DN -10、DN -11、DN -12、DN- 13、WS- 5 )对灭菌污水和自然污水的CODcr均有较高的去除率 ,胞外酶检测表明该 8株细菌均能产生淀粉酶和接触酶 ,这些细菌具有潜在的应用价值。

Synthesis and evaluation of Gd-DTPA-labeled arabinogalactans as potential MRI contrast agents

Arabinogalactan derivatives conjugated with gad olinium-diethylenetriaminepentaacetic acid (Gd-DTPA) by ethylenediamine (Gd-DTPA-CMAG-A(2)) or hexylamine (Gd-DTPA-CMAG-A(6)) have been synthesized and characterized by means of Fourier transform infrared spectra (FTIR), C-13 nuclear magnetic resonance (C-13 NMR), size exclusion chromatography (SEC), and inductively coupled plasma atomic emission spectrometry (ICP-AES).

Toxicological effects of cinnabar in rats by NMR-based metabolic profiling of urine and serum

Cinnabar, an important traditional Chinese mineral medicine, has been widely used as a Chinese patent medicine ingredient for sedative therapy. However, the pharmaceutical and toxicological effects of cinnabar, especially in the whole organism, were subjected to few investigations. In this study, an NMR-based metabolomics approach has been applied to investigate the toxicological effects of cinnabar after intragastrical administration (dosed at 0.5, 2 and 5 g/kg body weight) on male Wistar rats.