丙烯气相水合反应过程的热力学分析

根据所提出的高压复杂物系化学平衡组成的计算方法，对丙烯气相水合反应进行了热力学分析。计算了反应条件对各反应组分平衡组成的影响。得到了丙烯和水的平衡转化率、异丙醇（ＩＰＡ）及异丙醚（ＩＰＥ）的平衡组成随温度、压力、进料中水／烯比及原料中异丙醇含量的变化规律，确定了该反应体系在热力学上的最优操作条件，为催化剂的筛选提供了依据。     

Comparative Study of the Acidity of Sulphated Zirconia Supported on Alumina Prepared by Sol-Gel and Impregnation Methods

Sulphated and unsulphated alumina-zirconia with atomic ratio Zr/Al = 0.5 were prepared by sol-gel and impregnation methods. The solid prepared by the sol-gel method exhibits the higher specific surface area. The Kelvin probe shows that the value of unsulphated sample is around 400 mV. This value grows up to 1100 mV for sample prepared by impregnation of aerogel alumina by sulphated propoxide zirconium and up to 1450 mV for sulphated alumina-zirconia aerogel catalyst. The modification of the work function is probably due to the charge transfer from the zirconium and aluminium to an oxygen species, responsible for the increase of Lewis acidity. XPS results show that the aluminium and zirconium exist in oxide form as Al₂O₃ and ZrO₂. The sulphur is present as sulphate species in the solids bonded to the Al—Zr—O framework. Furthermore, the oxygen species exist in different types created by the introduction of sulphur in the bulk of solids.Compared to the impregnated catalyst the sol-gel sulphated alumina zirconia exhibits higher activity in the isopropanol dehydration reaction in the temperature range 423 K–523 K.     

Blended chitosan and polyvinyl alcohol membranes for the pervaporation dehydration of isopropanol

Homogeneous membranes were prepared by casting the solution of blended chitosan and polyvinyl alcohol (PVA) on a glass plate. The percent weight of chitosan in the membrane was varied from 0 to 100%. The membrane thickness was in the range of 15–30 μm. The membranes were heat treated at 150 °C for an hour. After that the membranes were crosslinked by glutaraldehyde and sulfuric acid in acetone aqueous solution. The membranes were tested at 30–60 °C for dehydration performance of 50–95% isopropanol aqueous solutions. At around 90% of isopropanol in the feed mixture, permeate flux increased whereas the percent of water in permeate tended to decrease when the feed temperature increased for all membranes, except that the water content in permeate from the membrane containing 75 wt.% chitosan remained constant. The swelling degree in water and the total flux increased with increasing chitosan content in membranes. The effect of temperature on permeate flux followed the Arrhenius relationship. The permeate flux decreased when isopropanol in the feed increased for all membranes. However, water content in permeate and isopropanol concentration in the feed formed complex relationship for different chitosan content membranes. Sorption did not appear to have significant effects on separation. The membrane containing chitosan 75% performed the best. For a feed solution containing 90% isopropanol at 60 °C, the permeate flux was 644 g/m² h with water content of nearly 100% in the permeate. At 55% isopropanol in the feed at 60 °C, the permeate flux was 3812 g/m² h. In the range of 55–95% of isopropanol in the feed, the water content in permeate was more than 99.5%. This membrane showed very excellent performance with good mechanical strength. It is promising to develop this membrane for industrial uses.     

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．     

磺化聚乙烯中空纤维离子交换膜渗透汽化分离异丙醇/水混合液研究

离子交换膜作为醇/水和其他有机水溶液的渗透汽化分离膜有很好的选择性^[1-3]。其中尤以磺化聚乙烯离子交换膜最为显著。用磺化聚乙烯离子膜分离恒沸组成的异丙醇/水和乙醇/水(85:15wt%)混合物^[4]、近恒沸组成的二氧六环/水混合物^[5],透过物中水含量大于99%,而且保持了较高的渗透通量。但上述实验均使用的平板型膜,大型平板膜组件的加工制造昂贵而困难,况且膜在分离运行过程中会随料液浓度的变化发生溶胀与收缩,使固定的平面膜起皱在收缩时又可能被拉破。为了提高单位组件内的膜面积(中空纤维组件的膜装填密度为平板式的60-100倍),发展中空纤维型膜及其组件势在必行。本文首次报道磺化聚乙烯中空纤维阳离子交换膜对异丙醇/水的渗透汽化性能。     

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.     

Preparation of Magnesia-Silica Oxides: Effect of Mg/Si Ratio and Sulfate on Acidity

Mg−Si binary oxides were prepared by the sol-gel method, using magnesium diethoxide and tetraethoxysilane as starting materials. Mg−Si mixed oxides were prepared at pH3 and 9 at nominal concentrations of 1.3, 4.0, and 6.7 mole% MgO. Density and strength of the acid sites were determined by pyridine thermal programmed desorption. Comparable Lewis acidity was found in pH3 and 9 preparations. However, when the samples were sulfated with sulfuric acid, strong Bronsted acidity was developed, reaching a maximum at 6.7 mole% MgO. The strong acidity of sulfated samples was corroborated using the isopropanol decomposition reaction as catalytic test. Similar conversions are obtained at 100°C on sulfated samples, whereas 260°C are required for non-sulfated ones.     

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。     

Cesium Fluoride on Calcium Oxide as a Strongly Basic Catalyst. Synthesis of Flavones and Tobacco Alkaloids

Niobium containing aluminophosphate materials with AEL structure were prepared by the hydrothermal method. The chemical composition of the hydrogel was: 1 DIPA: 1 Al₂O₃: (1-x) P₂O₅: x Nb₂O₅: 80 H₂O, with x=0.025, 0.050, 0.075 and 0.100. The crystallization was carried out at temperature of 170°C for 72 h. The materials obtained were characterized by XRF, DRX, FTIR, TG and measurements of acidity. The characterization of the catalytic active sites were carried out in the isopropanol dehydration at temperature of 400°C, and WHSV of 1.6, 3.2, 4.8, 6.4 and 8.0 h^-1 . The samples showed good catalytic activity with selectivity to propene. This revised version was published online in June 2006 with corrections to the Cover Date.     

Sol-gel preparation of In2O3-Al2O3 supports with controlled textural and structural properties

Alumina supports with a very narrow pore size distribution were obtained with indium-doped alumina prepared by the sol-gel method. The formation of aluminum in pentahedral coordination was identified by ²⁷Al NMR-MAS-spectroscopy. A good correlation was obtained with the Al^V NMR-MAS intensity signal and the activity in isopropanol dehydration. The insertion of In³⁺ substituting some Al³⁺ in the alumina network was suggested.