煤矸石催化气化耦合气化灰提铝过程中K2CO3和Na2CO3作用的对比研究

以煤矸石为研究对象，对比研究了Na₂CO₃与K₂CO₃对煤矸石催化气化反应性及催化气化灰中Al的溶出行为的影响。同时，采用X射线衍射分析（XRD）和热重分析（TGA）研究了不同催化剂及温度作用下矸石中矿物质的热转变过程。结果表明，与K₂CO₃相比，煤矸石中的高岭石更容易与Na₂CO₃反应生成钠霞石，而酸浸可实现钠霞石中铝和硅元素的有效分离。此外，Na₂CO₃作为催化剂时，所得气化灰经盐酸浸取后铝的浸出率可达到94.2%。而K₂CO₃作催化剂时，其铝的浸出率只有83.7%。因此，对矸石催化气化耦合气化灰的铝提取来说，Na₂CO₃催化剂具有更好的选择性。     

离子排斥色谱法同时测定2,3-丁二醇发酵液中的葡萄糖和木糖及各种代谢产物

针对2,3-丁二醇发酵体系,以高交联度磺化苯乙烯-二乙烯基苯共聚物多孔微球为固定相的Aminex HPX-87H离子色谱柱为分析柱,利用示差折光检测器对该体系中的6种代谢产物(2,3-丁二醇、3-羟基丁酮、乙醇、乙酸、甲酸和乳酸)以及2种残留底物葡萄糖和木糖进行了分离.在65 ℃柱温下,以5 mmol/L H2SO4作为流动相,发酵液样品中底物葡萄糖和木糖及2,3-丁二醇等各种代谢产物的线性相关系数均在0.9990～0.9999之间,回收率为98.8%～103.2%,精密度为0.3%～2.1%.在最佳色谱条件下,能够同时测定2,3-丁二醇发酵体系中的残留底物和各种代谢产物的含量,适合于实时定量监测2,3-丁二醇发酵过程.     

纳米Ag,CeO2和Ag-CeO2的合成及在CO催化氧化中的应用

系统合成了不同粒径的CeO2和Ag纳米粒子及Ag-CeO2纳米复合粒子,并对其进行了结构表征和CO催化氧化性能测试.结果表明,Ag纳米粒子的催化活性较低,以其为催化剂时CO的最大催化转化率仅为40%,且粒径越小越容易失活;在CeO2纳米粒子催化下,CO的催化转化率可达到100%,但催化反应的温度较高(约350℃);与CeO2和Ag相比,Ag-CeO2的催化性能明显增强,CO在较低的温度(150℃)下可实现完全转化.程序升温还原(Temperature-programmed reduction,TPR)分析结果表明,纳米复合材料中Ag和CeO2之间的相互作用是产生优异催化性能的关键原因.     

LaCoO3对H2S选择氧化性能的影响

使用溶胶-凝胶法制备了LaCoO₃催化剂,采用XRD、BET和XPS等方式对催化剂进行了表征,考察了该催化剂制备过程中煅烧温度、表面活性剂PEG-6000和PEG-20000含量对其H₂S选择氧化制硫磺反应催化活性的影响。结果表明,表面活性剂PEG-6000及PEG-20000的添加能明显提高LaCoO₃的催化活性。0.02 mol La（NO₃）₃+0.02mol Co（NO₃）₂溶液中添加0.30 g PEG-20000、煅烧温度为650℃时所制备的LaCoO₃催化活性最好;在最佳反应温度260℃下,H₂S的转化率达到96.10%,硫选择性为93.77%。     

基于H2O2的自燃离子液体研究进展

基于H₂O₂的自燃离子液体是目前绿色自燃推进剂领域的一个重要研究方向。本文对H₂O₂—离子液体的自燃体系进行了综述,富B-H类和硫氰酸阴离子类离子液体能与H₂O₂直接自燃,在加入碘铜酸盐等促进剂后达到更好的点火效果;此外二氰胺根阴离子类、二甲基硼磷酸根阴离子类和醋酸根阴离子类等离子液体不能与H₂O₂直接自燃,但加入促进剂后能达到良好点火效果。进一步介绍了各类自燃离子液体的合成方法和理化性质,提出基于H₂O₂—离子液体自燃推进剂的研究重点应着眼于以下三方面：更高能量密度离子液体的设计合成、高活性促进剂的研制开发以及强化点火的内在机制。     

CO在纳米CeO2负载的Pd-Cu催化剂上的低温催化氧化

用溶胶-凝胶法制得了平均晶粒度为15nm的CeO2粉体,并用浸渍法制备了Pd-Cu/纳米CeO2催化剂;通过XRD、SEM和HRTEM等表征手段研究了纳米CeO2粉体和Pd-Cu/纳米CeO2催化剂的性能;考察了催化剂对CO的低温催化氧化活性.结果表明纳米CeO2粉体负载的Pd-Cu催化剂对CO的低温催化氧化活性明显优于一般CeO2颗粒负载的Pd-Cu催化剂,其CO完全氧化的最低温度比Pd-Cu/热分解法CeO2催化剂低约70℃,比Pd-Cu/工业CeO2催化剂低约130℃.因此,纳米CeO2粉体作载体可极大地提高Pd-Cu催化剂的CO氧化性能.     

Ni-Fe/La2O2CO3催化乙醇水蒸气重整制氢的研究

采用La2(CO3)3空气焙烧法制备了La2O2CO3载体、采用浸渍法制备了Ni,Fe不同比例的Ni-Fe双金属催化剂及Ni/La2O2CO3,Fe/La2 O2 CO3催化剂,考察了各催化剂从300～700℃催化乙醇水蒸气重整反应的性能,并用BET,XRD,TPR等技术对催化剂进行表征。结果表明,相对单一金属催化剂,Ni-Fe双金属催化剂均表现出更高的活性,这可能是因为高分散的Ni,Fe和LaFeyNi1-yO3的共存作用。其中Ni含量为10%,Fe含量为5%时的Ni-Fe/La2O2CO3表现出最高的活性,400℃时乙醇的转化率为100%,H2的选择性最高达到94.1%,而CO的选择性则低至1.2%。     

MoO3/Al2O3催化氧化选择性合成亚砜

采用浸渍法制备了不同负载量的MoO3/Al2O3催化剂,讨论了MoO3,Al2O3和MoO3/Al2O3负载的催化剂作用下,利用H2O2进行硫醚氧化制亚砜的反应.结果显示MoO3/Al2O3催化剂负载量为20%时催化活性最高,原料转化率达100%,且没有副产物生成.将该方法应用到兰索拉唑前体的氧化反应中,收率达到80%.催化剂重复使用6次不失活.     

PO43-掺杂Bi2O2CO3/Bi0的制备及其可见光催化性能

构建氧空位以及附着金属单质Bi(Bi⁰)是增强半导体材料光吸收性能、促进半导体光生载流子分离的有效方法。通过简单的共沉淀法及氢气热还原成功制备了PO₄^3-掺杂Bi₂O₂CO₃附着Bi⁰(Bi-P-BOC)的可见光催化剂,并对其在可见光下催化降解氧氟沙星(OFX)的性能及机理进行了研究。材料表征结果表明BOC随着PO₄^3-的均匀掺杂,可见光吸收能力增强,表面缺陷增多,比表面积增大。而随着氢气热还原,BOC表面形成Bi⁰的同时也原位构建了大量的氧空位。可见光催化性能测试表明,Bi-P-BOC可以在180 min内降解约85%的OFX,降解速率为0.013 0 min^-1,是BOC降解速率的8倍。Bi-P-BOC光催化降解机理表明其具有更好的可见光吸收能力,Bi⁰以及氧空位的存在促进了光生载流子的分离,h⁺是其...     

离子色谱法连续测定乳制品中的NO2-和NO3-

采用AS18,4 mm×250 mm色谱柱,以32 mmol/L的KOH作为淋洗液,建立了一种用具有电导检测器的离子色谱连续测定乳制品中NO-2和NO-3的方法.该法处理简单、快速,定量结果准确. NO-2和NO-3的检出限(3S/N)分别为0.001和0.004 mg/L,标准曲线相关系数分别为0.999 7和0.999 6,添加水平上的回收率均在90.0%～103.4%之间.     

Comparative analysis of the organic acid content of vinegar by capillary electrophoresis and ion-exclusion chromatography with conductimetric detection

Summary Ion-exclusion chromatography (IEC) and capillary electrophoresis (CE) have been compared for determination of organic acids in samples of Sherry wine vinegar. The accuracy of each technique was evaluated by use of the standard addition method. There were no differences between the techniques at a significance level of 5%, except for determination of malic acid by CE. Both analytical methods were used to analyse sixteen samples of Sherry wine vinegar supplied by different producers. The regression coefficients (r ²) for analysis by IEC and CE exceeded 0.94 for all acids. Results from both methods were in good agreement and the methods are sufficiently selective and sensitive to be applied directly to sherry wine vinegars.     

Trace anion determination in concentrated hydrofluoric acid solutions by two-dimensional ion chromatography I. Matrix elimination by ion-exclusion chromatography

Since years, ion exclusion chromatography (ICE) has been the standard method to separate strong acid analyte anions from concentrated weak acid matrices such as hydrofluoric acid (HF). In this work, the commercially available IonPac ICE-AS 1 column was used to separate trace levels of chloride, nitrate, sulfate and phosphate from HF solutions at 20% (w/w). The efficiency of the separation was studied in more detail using techniques such as ion chromatography (IC), inductively coupled plasma optical emission spectrometry (ICP-OES) and ICP-mass spectrometry (ICP-MS). For 20% (w/w) HF solutions and at a water carrier flow-rate of 0.50 ml/min, the cut window was set from 8.5 to 14.5 min. Under these conditions, analyte recoveries of better than 90% were obtained for chloride, nitrate and sulfate, but only about 75% for phosphate. The HF rejection efficiency was better than 99.9%. It was found that the ICP techniques, measuring total element levels and not species, yielded significantly higher recoveries for phosphorus and sulfur compared to IC. Evidence will be given that part of the added phosphorus (approximately 15% for an addition of 10 mg PO4/kg) is present as mono-fluorophosphoric acid (H2FPO3). In the case of sulfate, the difference between IC and ICP-MS could be attributed to an important matrix effect from the residual HF concentration.     

Determination of organic acids in air by capillary electrophoresis and ion-exclusion chromatography

Summary A capillary electrophoretic (CE) method for the determination of organic acids in the low ppm range is described. The buffer consisted of 5 mM 2,6-pyridinedicarboxylic acid and 0.5 mM cetyltrimethylammonium bromide, pH 5.6. The former served as background electrolyte for indirect UV detection at 200 nm, whereas the latter was used to reverse electroosmotic flow. In <5 min 8 low molecular mass organic acids (oxalic, formic, malonic, glutaric, glycolic, acetic, lactic and propanoic) and two inorganic acids (hydrochloric and sulphuric) were separated. Detection limits for anions tested were 0.04 mg L⁻¹ (lactic acid) to 0.6 mg L⁻¹ (malonic acid). The method was applied to the determination of organic acids in air samples. The CE results when compared with ion-exclusion chromatography (IEC) agreed well. The use of electrokinetic injection in CE proved beneficial for preconcentration of organic acids in real samples. Using electrokinetic injection, preconcentration factors ranging from 14 (hydrochloric acid) to 3 (propanoic acid) were obtained. Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

Determination of volatile fatty acids in landfill leachates by ion-exclusion chromatography

An ion-exclusion chromatographic method with on-line desalinization for the determination of volatile fatty acids in landfill leachates is described. Highly sensitive conductivity detection of the organic acids was achieved by using dilute p-hydroxybenzoic acid solution as an eluent. Interference with mineral acids was reduced by treatment with barium chloride solution prior to desalinization. A silver-loaded cation-exchange guard column for the desalinization was installed in series with the analytical column to avoid the contamination of organic acids. This method features detection limits of 0.01 mg L(-1) formic acid, 0.02 mg L(-1) acetic acid, 0.05 mg L(-1) propionic acid, and 0.1 mg L(-1) butyric acid, respectively, with an injection of 20 microL sample. Application of the on-line desalinization LC method is illustrated for leachate samples from a Japanese sanitary landfill.     

Aluminum(III) triflate-catalyzed selective oxidation of glycerol to formic acid with hydrogen peroxide

Glycerol is a by-product of biodiesel production and is an important readily available platform chemical. Valorization of glycerol into value-added chemicals has gained immense attention. Herein, we carried out the conversion of glycerol to formic acid and glycolic acid using H₂O₂ as an oxidant and metal (III) triflate-based catalytic systems. Aluminum(III) triflate was found to be the most efficient catalyst for the selective oxidation of glycerol to formic acid. A correlation between the catalytic activity of the metal cations and their hydrolysis constants (K_h) and water exchange rate constants was observed. At 70 °C, a formic acid yield of up to 72% could be attained within 12 h. The catalyst could be recycled at least five times with a high conversion rate, and hence can also be used for the selective oxidation of other biomass platform molecules. Reaction kinetics and ¹H NMR studies showed that the oxidation of glycerol (to formic acid) involved glycerol hydrolysis pathways with glyceric acid and glycolic acid as the main intermediate products. Both the [Al(OH)_x]ⁿ⁺ Lewis acid species and CF₃SO₃H Brønsted acid, which were generated by the in-situ hydrolysis of Al(OTf)₃, were responsible for glycerol conversion. The easy availability, high efficiency, and good recyclability of Al(OTf)₃ render it suitable for the selective oxidation of glycerol to high value-added products.     

Size and diffusion effects on the oxidation of formic acid and ethanol on platinum nanoparticles

Formic acid and ethanol oxidations on spherical platinum nanoparticles dispersed on carbon with different loadings have been studied. The increasing loading of the catalyst leads to a lower diffusion flux of reactants in the internal parts of the catalyst layer, resulting in a lower apparent activity. In some cases, as in ethanol oxidation, it may also affect the diffusion of the products. As a practical consequence, the structure of the supporting layer and the catalyst loading should be optimized so that the maximum catalyst utilization is obtained. Finally, these diffusion effects may mask some important catalytic activity increase of the nanoparticles. In the case of formic acid, a significant increase in the activity is obtained for very small nanoparticles.     

高效离子抑制色谱法和高效离子交换色谱法检测琥珀酸去甲文拉法辛中琥珀酸的含量

建立了用于琥珀酸去甲文拉法辛中琥珀酸含量测定的高效离子抑制色谱和高效离子交换色谱方法。离子抑制色谱法采用Rezex ROA-organic Acid H+(8%)色谱柱,以2.50×10^-3mol/L硫酸溶液为流动相等度洗脱,流速为0.5 mL/min,进样10 μ L,检测波长为210 nm,琥珀酸的含量按峰面积外标法计算;离子交换色谱法采用IonPac^® AS11-HC色谱柱,以氢氧化钾为淋洗液等度洗脱,流速为1.0 mL/min,进样10 μ L,带DIONEX AERS^® 500 4-mm抑制器的电导检测器检测,琥珀酸含量按峰面积外标法计算。两种方法对3批琥珀酸去甲文拉法辛中琥珀酸质量分数的测定结果分别为:28.8%、28.9%、28.9%和28.2%、28.6%、28.6%。离子抑制色谱法和离子交换色谱法在琥珀酸去甲文拉法辛中琥珀酸的含量测定结果上没有明显不同,可根据实际情况选择。     

Mesoporous silica-supported V-substituted heteropoly acid for efficient selective conversion of glycerol to formic acid

V-substituted polymolybdenum phosphoric acid (PV_xMo) supported on mesoporous silica was prepared and investigated as a catalyst for the oxidation of glycerol to formic acid in a batch operation. Different synthetic methods for PV_xMo supported on mesoporous silica were compared. Detailed characterizations of the final products were carried out by N₂ adsorption and desorption, XRD, HR-TEM, SEM, ICP-OES, XANES, NH₃-TPD, and FTIR to identify the chemical properties and the porous structure of silica-supported PV_xMo, as well as the strong interactions between PV_xMo with the silica skeleton. These critical properties explain the bifunctionality of silica-supported PV_xMo as a catalyst for the selective oxidation of glycerol to formic acid with standing stability.     

Concave Pt-Cu-Fe ternary nanocubes:One-pot synthesis and their electrocatalytic activity of methanol and formic acid oxidation

Concave nanostructures may be developed to improve the specific mass activity of a catalyst for formic acid and methanol electro-oxidation. In this work, we report the elctrocatalytic oxidation of methanol and formic acid in acid medium over concave Pt-Cu-Fe ternary nanocubes (NCs), obtained by the galvanic exchange of Pt and Fe on Cu NCs. The concave Pt-Cu-Fe NCs exhibited improved electrooxidation performance contrasted to Pt-Cu NCs and purchased commercial Pt/C as demonstrated by their improved durability, lower onset potential, and more preferable anti-poisoning properties. These properties are believed to originate from the tailored concave structure of the catalyst and possible synergetic effects among the components of the Pt-Cu-Fe NCs.     

甲酸为氢源的甘油催化选择氢解

以甲酸作为氢源, 采用铜基复合金属氧化物催化剂, 催化氢解甘油制备1,2-丙二醇, 其中液相甲酸的高选择性分解是实现甘油氢解的必要和关键步骤. 活性测试表明, 高分散的铜和ZrO₂载体间的协同作用对甲酸分解和甘油到1,2-丙二醇的转化至关重要, 20%Cu/ZrO₂催化剂的活性最佳. 由于避免使用相对昂贵的化石燃料氢, 因而该催化体系在生物质的高值利用方面具有潜在的应用前景.