丙烯水合醚化反应过程中丙酮生成机理的研究

 在与色－质联用仪相连的微反装置上，考察了Hβ沸石及改性的\r\nHβ沸石催化剂上丙烯水合醚化及异丙醇脱水的反应行为．丙烯水合醚\r\n化反应中有副产物丙酮生成，而异丙醇单独进料时产物中没有发现丙酮\r\n的生成．这表明丙酮并不是异丙醇氧化脱氢的结果，而是一个应予重视\r\n的不利于丙烯水合醚化的副反应．用同位素示踪反应对丙酮的生成机理\r\n进行了探讨，为研制抑制这一副反应的新催化剂提供了参考依据．     

UV辐照接枝制备酚酞基聚芳醚酮纳滤膜——链转移剂的作用

酚酞基聚芳醚酮(PEK-C)超滤膜的表面通过紫外辐照接枝丙烯酸(AA)可以制备对II价盐有很好截留率的亲水性纳滤膜. FTIR-ATR、表面接触角、SEM和AFM的研究结果表明, 在接枝单体溶液中加入异丙醇(i-PrOH)作为链转移剂并不影响AA在PEK-C超滤膜表面的接枝反应. 得到的改性膜同样具有优良的纳滤性能. 与不加i-PrOH的AA改性膜相比, 新合成的膜有较高的滤出液通量, 该膜对盐离子的截留率虽有所降低, 但可以通过增加接枝反应时间和辐照光源的强度来提高. i-PrOH的浓度对膜的分离性能的影响很大, 在低浓度时, 改性膜对离子的截留率会有所下降, 继续提高i-PrOH的浓度, 膜的截留率不再变化而滤出液通量会有成倍的增加, 表明链转移剂的存在可能会提高膜的接枝密度, 增加膜的表面电荷, 使膜对离子的截留率保持不变.     

Immobilization of In2O3 nanoparticles on the surface of reduced graphene oxide

This communication describes a new method for immobilizing indium oxide nanoparticles (∼20 nm) on the surface of reduced graphene oxide. Dispersion of graphene oxide with added In₂O₃ nanoparticles was treated in supercritical isopropanol, both a reducing agent of graphene oxide and a reaction medium. The resulting nanocomposite was characterized by different methods of physical and chemical analysis.     

Isopropanol reactivity on SiO2-supported heteropolyanions

Isopropanol on silica-supported heteropolyanions with the Keggin structure reacts mainly through dehydration, due to the presence of strongly acidic surface sites. The effect of preparation conditions of the catalysts on the reaction has been studied.     

三氟甲磺酸铜(Ⅱ)催化炔烃选择性转移氢化合成顺式烯烃

顺式烯烃是许多生物活性分子的基本结构单元, 在材料科学、 药物化学和农药等领域都有着广泛的应用. 我们以异丙醇为氢源, 研究了4,5-双二苯基膦-9,9-二甲基氧杂蒽配合三氟甲磺酸铜催化的炔烃选择性转移氢化反应, 实现了高选择性顺式烯烃(Z/E >99/1)的合成. 该反应体系不需要使用高压设备, 操作简便、 安全, 对氟、 氯和溴等卤素取代的炔烃表现出良好的底物兼容性. 最后, 进行了对比实验, 并提出了可能的反应机理.     

阀切换离子色谱法测定电厂烟气异丙醇吸收液中三氧化硫的含量

建立了一种阀切换离子色谱法检测烟气中SO_3的方法,通过检测异丙醇(80%)前处理过的样品中SO_4~(2-)含量来实现对SO_3含量的检测。采用异丙醇(80%)吸收液将样品中的SO_3转化为SO_4~(2-),利用阀切换的在线预处理方法除去高浓度异丙醇对SO_4~(2-)测定所造成的影响。结果表明,在0.5～10.0mg/L线性范围内,其相关系数R~2=0.999 3,相对标准偏差为2.7%(n=6),检出限为0.7×10~(-2) mg/L,所得样品的加标回收率为95.0%～105%。方法可用于燃煤电厂烟气中SO_3含量的检测。     

Preparation and pervaporation properties of crosslinked hyperbranched poly(amine-ester) membranes

Crosslinked hyperbranched poly(amine-ester) (HPAE) membranes were prepared by crosslinking its terminal hydroxyl groups with glutaraldehyde (GA). The crosslinked HPAE membranes showed high reactivity and good hydrophilicity. The crosslinking degree was investigated by Fourier transformation infrared spectra (FT-IR). Atom force microscope (AFM) and scanning electron microscope (SEM) reveals that the crosslinked HPAE films have smooth surfaces, dense and homogenous matrices. The swelling degree of the membrane was higher in water than that in isopropanol. From the permeation of pure water through the HPAE membrane, the effect of hydroxyl/aldehyde group ratio on the permeation flux and separation factor was investigated. The results indicated that the permeation flux increase was accompanied with the separation factor decrease if the water concentration increased in the feed solution.     

Nickel ferrite spinel as catalyst precursor in the dry reforming of methane:Synthesis,characterization and catalytic properties

Dry reforming of methane by CO2 using nickel ferrite as precursor of catalysts was investigated.Nickel ferrite crystalline particles were prepared by coprecipitation of nitrates with NaOH or ammonia followed by calcination,or by hydrothermal synthesis without calcination step.The textural and structural properties were determined by a number of analysis methods,including X-ray diffraction (XRD),Raman spectroscopy and X-ray photoelectron spectroscopy (XPS),among which X-ray diffraction (XRD) was at room and variable temperatures.All synthesized oxides showed the presence of micro or nanoparticles of NiFe2O4 inverse spinel,but Fe2O3 (hematite) was also present when ammonia was used for coprecipitation.The reducibility by hydrogen was studied by temperature-programmed reduction (TPR) and in situ XRD,which showed the influence of the preparation method.The surface area (BET),particle size (Rietveld refinement),as well as surface Ni/Fe atomic ratio (XPS) and the behavior upon reduction varied according to the synthesis method.The catalytic reactivity was investigated using isopropanol decomposition to determine the acid/base properties.The catalytic performance of methane reforming with CO2 was measured with and without the pre-treatment of catalysts under H2 in 650-800 C range.The catalytic conversions of methane and CO2 were quite low but they increased when the catalysts were pre-reduced.A significant contribution of reverse water gas shift reaction accounted for the low values of H2 /CO ratio.No coking was observed as shown by the reoxidation step performed after the catalytic reactions.The possible formation of nickel-iron alloy observed during the study of reducibility by hydrogen was invoked to account for the catalytic behavior.     

A novel liquid–liquid extraction and stable isotope dilution NCI‐GC‐MS method for quantitation of agmatine in postmortem brain cortex

The group of biologically important amines includes putrescine, spermidine and spermine, as well as agmatine, which is a guanidino‐amine. There is considerable evidence supporting a role of these amines in the etiology and pathology of mental disorders. We have previously developed a quantitative GC‐MS method for simultaneous measurement of three major polyamines to support our studies linking polyamines to mental disorders. However, a unique GC‐MS method is required for agmatine. To efficiently extract agmatine from postmortem brain tissues, we developed an isopropanol based liquid–liquid extraction protocol using potassium carbonate as a salting‐out agent which showed a much greater recovery than n‐butanol used in earlier methods. The GC‐MS analysis employed hexafluoroacetylacetone as derivatization reagent and was carried out using negative chemical ionization with total ion and selected ion monitoring. ¹⁵N₄‐Agmatine was synthesized from ¹⁵N₄‐L ‐arginine and used as internal standard in a conventional stable isotope dilution assay. This method accurately measures the level of agmatine from very small quantities (10–20 mg) of postmortem brain tissue, with a quantitation limit down to 1 ng/g of wet tissue. The limit of detection is 0.01 ng/g of wet tissue. Copyright © 2010 John Wiley & Sons, Ltd.     

Highly sensitive capillary electrophoresis-mass spectrometry for rapid screening and accurate quantitation of drugs of abuse in urine

The combination of capillary electrophoresis (CE) and mass spectrometry (MS) is particularly well adapted to bioanalysis due to its high separation efficiency, selectivity, and sensitivity; its short analytical time; and its low solvent and sample consumption. For clinical and forensic toxicology, a two-step analysis is usually performed: first, a screening step for compound identification, and second, confirmation and/or accurate quantitation in cases of presumed positive results. In this study, a fast and sensitive CE-MS workflow was developed for the screening and quantitation of drugs of abuse in urine samples. A CE with a time-of-flight MS (CE-TOF/MS) screening method was developed using a simple urine dilution and on-line sample preconcentration with pH-mediated stacking. The sample stacking allowed for a high loading capacity (20.5% of the capillary length), leading to limits of detection as low as 2 ng mL⁻¹ for drugs of abuse. Compound quantitation of positive samples was performed by CE-MS/MS with a triple quadrupole MS equipped with an adapted triple-tube sprayer and an electrospray ionization (ESI) source. The CE-ESI-MS/MS method was validated for two model compounds, cocaine (COC) and methadone (MTD), according to the Guidance of the Food and Drug Administration. The quantitative performance was evaluated for selectivity, response function, the lower limit of quantitation, trueness, precision, and accuracy. COC and MTD detection in urine samples was determined to be accurate over the range of 10–1000 ng mL⁻¹ and 21–1000 ng mL⁻¹, respectively.