氮中二氧化氮气体标准物质的研制

采用称量法制备并计算定值,研制(10～5000)μmol.mol-1氮中二氧化氮气体标准物质。考察了气体标准物质随贮存时间和钢瓶压力变化的稳定性,将制备的气体标准物质与GBW 08180进行比对验证,结果表明研制的气体标准物质定值的扩展不确定度优于3%(k=3),有效期限为12个月。     

Trifluoromethyl chlorosulfonate, CF3OSO2Cl: gas phase and crystal structure, conformation and vibrational analysis studied by experimental and theoretical methods

The geometric structure and conformational properties of trifluoromethyl chlorosulfonate (chlorosulfuric acid trifluoromethyl ester), CF(3)OSO(2)Cl, have been determined by X-ray crystallography, gas electron diffraction (GED), and vibrational spectroscopy (IR(gas), IR(matrix), and Raman(liquid)). These experimental investigations were supplemented by quantum chemical calculations (B3LYP with 6-311G* and 6-311+G(3df) basis sets). All experimental methods result in a single conformer with gauche orientation of the CF(3) group relative to the S[bond]Cl. The dihedral angle delta(COSCl) is determined to be 91.7(3) degrees in the crystal and 94(3) degrees in the gas phase. This dihedral angle corresponds to a near-eclipsed orientation of the O[bond]C relative to one of the S[double bond]O bonds (delta(CO[bond]SO) = -23.0(3) degrees and -21(3) degrees in the crystal and gas phase, respectively).     

等离子体辅助煤气化及影响因素

应用等离子体辅助煤气化反应装置对大同煤进行了实验研究，考察了供气量、供粉速率、发生器输入功率、水蒸气压力以及添加不同质量分数的CaCO3 和CaO对煤气化反应的影响，并对不同条件下产品气体的组成进行了分析。实验结果表明，装置的最佳工艺参数为供煤速率150 g/min、供气量18 m3/h、等离子体发生器输出功率100 kW、水蒸气出口压力0.3 MPa。加入添加剂CaCO3和CaO的质量分数分别为10%和5%时，催化效果最好。根据CaCO3和CaO的实验数据可知，在等离子体辅助煤气化过程中CaCO3起催化作用为主，CO2还原为辅。     

Unsteady-state direct partial oxidation of methane to synthesis gas in a fixed-bed reactor using AFeO3 (A = La, Nd, Eu) perovskite-type oxides as oxygen storage

Direct partial oxidation of methane to synthesis gas on AFeO(3) (A = La, Nd, Eu) oxides by a novel sequential redox cyclic reaction in the absence of gaseous oxygen was investigated over a fixed-bed reactor. These oxides were prepared by the sol-gel method and characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. XRD analysis showed that all AFeO(3) (A = La, Nd, Eu) oxides, calcined at 1173 K, are single-phase perovskites. The CH(4)-TPSR/MS and continuous reaction experiments indicated that the AFeO(3) (A = La, Nd, Eu) oxides provide mostly oxygen species, as the sole oxidant originated from lattice oxygen instead of gaseous oxygen, which can oxidize CH(4) to synthesis gas with high selectivity in the absence of gaseous oxygen. In terms of material economics and the amount of oxygen species for synthesis gas formation, the LaFeO(3) sample exhibits the best performance among these tested AFeO(3) oxides for synthesis gas production. The pulse experiments at different temperatures showed that the rate of oxygen migration during the CH(4) reaction with LaFeO(3) is strongly affected by the reaction temperature, and increases with rising temperature, which is favorable to much more CH(4) selective oxidation at high temperature. The two types of oxygen species are identified by experiments of continuous reactions and pulses, and confirmed by XPS. Methane can be converted selectively to synthesis gas by consumption of lattice oxygen, and general carbonaceous deposits on the catalyst surface do not occur under the appropriate reaction conditions by sequential redox cycles. The performance of selective oxidation of CH(4) to synthesis gas can be recovered by reoxidation using gaseous molecular oxygen; the LaFeO(3) oxide maintains relatively high catalytic activity and structural stability in redox atmospheres.     

First-principles study of methanol adsorption on heteroatom-doped phosphorene

First-principles calculations were firstly employed to investigate the adsorption of methanol on pristine and X-doped phosphorene (X=B, C, N and O). The N and O doping improved the adsorption of phosphorene with CH₃OH gas molecule, while B and C doping were almost not beneficial.     

生物质在流化床中的空气-水蒸气气化研究

以流化床为反应器，对生物质的空气-水蒸气气化特性进行了研究。考察了一些主要参变量，如温度 (700 ℃～900 ℃)、水蒸气/生物质比(0～4.04)、空气当量比(0.19～0.27)以及生物质粒度(0.2 mm～0.9 mm)等对气化结果的影响。在实验研究的条件范围内，生物质产气率在1.43 m3/kg～2.57 m3/kg范围内变化，产气的低热值在6 741 kJ/m3～9 143 kJ/m3范围内变化。实验结果表明：较高的气化温度有利于氢的产生；但气化温度过高会使气体热值下降；与常规的空气气化相比，水蒸气的加入使生物质气化产气率显著提高，但水蒸气加入量过多使气化温度下降，产气率和产气热值降低；生物质颗粒粒度的大小对产气组分的分布和产气率均有影响，较小颗粒的生物质会产生较多的CH4、CO和较少的CO2。     

应用水汽相变促进湿法脱硫净烟气中PM_(2.5)和SO_3酸雾脱除的研究

在石灰石-石膏法脱硫净烟气中分别采用添加适量蒸汽和湿空气方式建立PM_(2.5)和SO_3酸雾凝结长大所需的过饱和水汽环境,在测试分析湿法脱硫净烟气中PM_(2.5)及SO_3酸雾物性的基础上,考察了蒸汽及湿空气添加量、脱硫净烟气温度等的影响。结果表明,湿法脱硫净烟气中PM2.5除含有燃煤飞灰外,含Ca SO_4、Ca SO_3及未反应的Ca CO_3等组分;由于SO_3酸雾基本处于亚微米级粒径范围,湿法烟气脱硫(WFGD)系统对SO_3酸雾的脱除率仅为35%-55%;添加适量蒸汽及湿空气方式均可促进湿法脱硫净烟气中PM_(2.5)和SO_3酸雾脱除,最终排放浓度随蒸汽或湿空气添加量的增加而降低,其中,添加蒸汽方式适合于脱硫净烟气温度较低(≤50-55℃)的场合,在脱硫净烟气温度较高(≥55-60℃)时,利用添加湿空气方式替代添加蒸汽更具技术经济优势。     

Sn掺杂MoO_3的制备、表征及气敏性能

以仲钼酸铵和四氯化锡为原料,采用水热法制备了不同Sn掺杂比例的MoO_3;利用X射线衍射(XRD),扫描电子显微镜(SEM)和Brunauer-Emmett Teller(BET)测试等手段对材料进行了物相、形貌结构和孔径表征;测试了其对乙醇、二氯甲烷、甲醇、甲醛、甲酸、四氯化碳、氨气和丙酮等气体的传感性能.结果表明,Sn掺杂未改变MoO_3的结构;290℃为气体传感测试的最佳测试温度;掺杂后的MoO_3对乙醇气体的灵敏度和响应时间均优于纯相MoO_3,Sn掺杂摩尔比为5%时效果最好,500 mg/m~3测试条件下对乙醇的灵敏度为19.64,响应时间为1.1 s.     

Coordination mode of nitrate in uranyl(VI) complexes: a first-principles molecular dynamics study

According to Car-Parrinello molecular dynamics simulations for [UO(2)(NO(3))(3)](-), [UO(2)(NO(3))(4)](2-), and [UO(2)(OH(2))(4-)(NO(3))](+) complexes in the gas phase and in aqueous solution, the nitrate coordination mode to uranyl depends on the interplay between ligand-metal attractions, interligand repulsions, and solvation. In the trinitrate, the eta(2)-coordination is clearly favored in water and in the gas phase, leading to a coordination number (CN) of 6. According to pointwise thermodynamic integration involving constrained molecular dynamics simulations, a change in free energy of +6 kcal/mol is predicted for eta(2)- to eta(1)-transition of one of the three nitrate ligands in the gas phase. In the gas phase, the mononitrate-hydrate complex also prefers a eta(2)-binding mode but with a CN of 5, one H(2)O molecule being in the second shell. This contrasts with the aqueous solution where the nitrate binds in a eta(1)-fashion and uranyl coordinates to four H2O ligands. A driving force of ca. -3 kcal/mol is predicted for the eta(2)- to eta(1)- transition in water. This structural preference is interpreted in terms of steric arguments and differential solvation of terminal vs uranyl-coordinated O atoms of the nitrate ligands. The [UO(2)(NO(3))(4)](2-) complex with two eta(2)- and two eta(1)- coordinated nitrates, observed in the solid state, is stable for 1-2 ps in the gas phase and in solution. In the studied series, the modulation of uranyl-ligand distances upon immersion of the complex in water is found to depend on the nature of the ligand and the composition of the complex.     

Production of poly-3-hydroxyalkanoates from CO and H2 by a novel photosynthetic bacterium

A novel process is described to efficiently photoconvert low-grade organic materials such as waste biomass into natural biological plastics. When heterogeneous forms of dry biomass are thermally gasified, relatively homogeneous synthesis gas mixtures composed primarily of carbon monoxide and hydrogen are produced. Unique strains of photosynthetic bacteria were isolated that nearly quantitatively photoassimilate the carbon monoxide and hydrogen components of synthesis gas into new cell mass. Under unbalanced culture conditions when cellular growth is limited by shortages of nitrogen, calcium, magnesium, iron, or essential vitamins, up to 28% of the new cell mass is found as granules of poly-3-hydroxyalkanoate (PHA), a highmolecular-weight thermoplastic that can be solvent-extracted. The dominant monomeric unit of PHAs is 3-hydroxybutyrate (3HB), which is polymerized into the homopolymeric poly-3-hydroxybutyrate (PHB). PHB is marketed as a biodegradable plastic with physical properties similar to polystyrene. When a green alga was cocultured with the photosynthetic bacterium in light-dark (day-night) cycles, the bacteria synthesized a polymer of poly-3-hydroxybutyrate-3-hydroxyvalerate (PHB-V) with a composition of 70% 3HB and 30% 3-hydroxyvalerate (3HV) to an extent of 18% of the new cell mass. PHB-V is commercially marketed as Biopol and has physical properties similar to polypropylene or polyethylene. Our results demonstrate that a strain of photosynthetic bacteria capable of photoassimilating synthesis gas or producer gas is a potential candidate for large-scale production of biological polyesters.     

Development of an automated measurement system using a diffusion scrubber and high-performance liquid chromatography for the monitoring of formaldehyde and acetaldehyde in automotive exhaust gas.

An automated measurement system for monitoring formaldehyde (HCHO) and acetaldehyde (CH3CHO) in automotive exhaust gas by using a diffusion scrubber in combination with high-performance liquid chromatography (HPLC) was developed. HCHO and CH3CHO are effectively collected by the diffusion scrubber, which consists of a hydrophobic porous PTFE tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine is used as the scrubbing solution for trapping HCHO and CH3CHO, which are derivatized to formaldehyde 2,4-dinitrophenylhydrazone (DNPH-HCHO) and acetaldehyde 2,4-dinitrophenylhydrazone (DNPH-CH3CHO), respectively, with phosphoric acid as an acid catalyst. After the collection of the gas sample, the sample solution in the diffusion scrubber is injected into the HPLC system and DNPH-HCHO and DNPH-CH3CHO are separated and determined. All measurement operations are sequenced by a programmable controller and an automated continuous measurement can be performed at 10 min intervals. The collection efficiencies of HCHO and CH3CHO were higher than 97% at a gas flow rate of 0.21 min-1. The detection limit (3 sigma of the blank value) was 0.001 ppm v/v for HCHO and CH3CHO for a 1.61 gas sample volume. No interference of co-existing nitrogen dioxide (NO2) in the collection of HCHO and CH3CHO was observed. The average concentration of HCHO in the exhaust gas from methanol-fueled vehicles was 77.3 ppm v/v (n = 5) in the cold-phase mode when engines were first started. In the hot-phase mode, the average concentration of HCHO was 3.3 ppm v/v (n = 15). The concentrations of HCHO measured by this automated measurement system were in good agreement with those obtained using the impinger-HPLC method.     

Silanetriols in the gas phase: single molecules vs. hydrogen-bonded dimers

The first gas phase structure of a silanetriol, tert-butylsilane-triol [(t)BuSi(OH)(3)], determined by gas electron diffraction (GED), is reported. Quantum chemical calculations have been performed to elucidate potential intermolecular interactions between silanetriol molecules in the gas phase. The results are set into contrast to solid state structures of (t)BuSi(OH)(3) and related compounds.     

A Study on the Effects of Carrier Gases on the Structure and Morphology of Carbon Nanotubes Prepared by Pyrolysis of Ferrocene and C2H2 Mixture

Carbon nanotubes （CNTs） were prepared using different carrier gases, with ferrocene as the catalyst precusor and acetylene as the carbon source. The effects of ammonia and nitrogen as carrier gases on the structure and morphology of CNTs were investigated. Transmission electron microscope （TEM）, high-resolution electron microscope （HRTEM）, scanning electron microscope （SEM） and X-ray diffraction （XRD） were employed to characterize the products and the catalyst. Experiment results show that the CNTs grown in N2 gas exhibited cylindrical and tubular structure, while a bamboo-like structure was observed for the CNTs grown in NH3 gas. Moreover, vertically aligned CNTs were obtained on an A12O3 disk when NH3 was used as the carrier gas. The carrier gas also exerted influence on the shape of the catalyst. Based on the theory of active centers of catalysis and combined with the particle shape of the catalyst, a growth model for the vertically aligned CNTs on the substrate is given.     

Selective gas sorption property of an interdigitated 3-D metal-organic framework with 1-D channels

An interdigitated 3-D metal-organic framework, [Cd(3)(OH)(2)L(4)(H(2)O)(2)], with 1-D channels was prepared using 4-aminophenyl-1H-tetrazole (HL) and Cd(II) ions, where the host framework shows selective gas sorption behavior that is based on the different nature of the interactions between the gas and the framework rather than on the size-exclusion effect of the micropores.     

催化热解生物质制取富氢气体的研究

在实验室自制的固定床反应器上, 考察了秸秆和锯屑的热解行为, 研究了热解产物分布特别是富氢气体的体积分数和产率, 着重研究了（5种金属氧化物和2种碳酸盐催化剂）的催化效果。结果表明,温度从500 ℃提高到850 ℃, 秸秆和锯屑的热解气产率分别从29.0%提高到40.6%, 35.0％提高到46.5%, 而对应的富氢气体的体积分数分别从41.2％提高到48.2%, 40.6％提高到47.0%；在5种金属氧化物中，Cr2O3显示了最好的催化效果，在750 ℃时对应的热解气产率与不使用催化剂相比提高了10％，富氢气体的体积分数提高了13％；催化剂（CaCO3和Na2CO3）占生物质的质量分数对热解气和富氢气体产率有明显的影响，当质量分数从0增加到30％时， 热解气和富氢气体产率增加较明显，而后其值的增加可以忽略， 因此推荐使用的催化剂质量分数为30％。     

Modifying the fullerene surface using endohedral noble gas atoms: density functional theory based molecular dynamics study of C70O3

We have performed a series of ab initio molecular orbital and molecular dynamics calculations to ascertain the influence of an endohedral noble gas atom on the reactivity of the surface of the model system C(70)O(3). Our simulations show that the minimum energy pathways for the ozone ring-opening reaction are influenced by the presence of the endohedral atom. The effect is isomer dependent, with the enthalpy of the reaction increasing for a,b-C(70)O(3) and decreasing for e,e-C(70)O(3) when doped with the heavy noble gas atoms Xe and Rn.     

射流冷却下过氧化二叔丁基瞬时热解反应的研究

采用射流冷却和高温瞬时热解技术研究了过氧化二叔丁基(DTBP)热解产物的质量分布和飞行时间谱。DTBP解离率与热解温度的关系表明,1300K时DTBP全部解离。以Ar为载气时,DTBP热解产物CH₃COCH₃的飞行时间谱上出现双峰,而以He或N₂为载气时只出现单峰,表明在射流冷却下可能有部分CH₃COCH₃分子与Ar生成了范德华分子CH₃COCH₃·Arn·此外,还讨论了射流冷却下DTBP瞬时热解的机理。     

Comparison of three methods for natural gas dehydration

This paper compares three methods for natural gas dehydration that are widely applied in industry:(1) absorption by triethylene glycol, (2) adsorption on solid desiccants and (3) condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.     

Photochemistry of 5-phenyl-1-pentene in the gas phase

The photochemistry of the title compound has been studied in the gas phase using 254-nm irradiation. In addition to meta cycloadducts analogous to those observed in solution, population of S1(vib) in the gas phase gives several products, the relative amounts of which depend on quencher gas pressure but not on excitation wavelength. For example, in the absence of butane, the major photoproduct is compound 5. This product is formed by a [1,5] hydrogen shift in the primary photoproduct, compound 4. Compound 4 is an intramolecular meta cycloadduct that is generated in the gas phase with sufficient excess vibrational energy to undergo rearrangement unless quencher gas is present. Likewise, there is evidence that two other meta cycloadducts (2 and 3) are also formed with appreciable vibrational energy in the absence of a quencher gas. A unique intramolecular ortho cycloadduct is also formed from 1 but only within a narrow range of quencher gas pressures. This is a two-photon product, with the initial cycloadduct (11) ring opening to a cyclooctatriene (12) that photochemically closes to 6. The pressure dependence of this ortho cycloaddition may be due to a requirement for vibrational deactivation of 11 (Scheme 5) or a precursor species (Scheme 6). The overall chemistry is outlined in Scheme 7.