香茅精油、香茅醛、香茅醇对储粮霉菌和害虫抑制与熏杀效果的试验研究

分析结果表明，香茅精油含３１种化学成份．香茅精油与香茅醛、香茅醇单体对６种储粮曲霉与青霉均有抑菌作用，香茅醇抑菌效果优于香茅精油和香茅醛，０．０５１／ｃｍ￣３浓度香茅醇可抑制霉菌孢子萌发和菌丝生长。香茅精油与香茅醛、香茅醇单体对玉米象、印度谷螟，绿豆象成虫及赤拟谷盗、黄粉虫成虫和幼虫有明显熏杀作用；对玉米象幼虫和卵有抑制效果；其顺序为：香茅醛＞香茅精油＞香茅醇；０．０５ｍ１／ｃｍ￣３浓度的香茅醛能抑制玉米象幼虫和卵的发育。     

Changes in the selective hydrogenation of citral induced by copper addition to Ru/KL catalysts

Bimetallic Ru–Cu catalysts supported on KL zeolite have been prepared by coimpregnation with ionic precursors and characterized by several methods, such as temperature-programmed reduction, CO and hydrogen chemisorption, nitrogen adsorption, infrared spectroscopy of chemisorbed CO and microcalorimetry of CO adsorption. The catalytic behavior of the samples was analyzed in the selective hydrogenation of citral in the liquid phase, at 323 K and 5 MPa. The presence of bimetallic entities as well as of segregated copper species was recognized by the TPR measurements. The CO-FTIR and microcalorimetry results evidence that the higher the Cu/Ru atomic ratio the larger the surface heterogeneity, with formation of Cu^δ+ species. Bimetallic catalysts are more active than the monometallic ruthenium catalyst in the hydrogenation of citral, but this activity decreases with the increasing of copper concentration. In addition, selectivity towards citronellal decreases as the copper content increases, in opposite trend to the selectivity toward geraniol and nerol. For low copper loading (Cu/Ru ≈ 0.4) formation of a surface alloy is discussed. This surface structure is particularly active for hydrogenation of the conjugated CC double bond of citral. For Cu/Ru = 0.8 and Cu/Ru = 1.2 samples, three-dimensional islands of segregated copper seem to cover, in part, the surface alloy. This latter surface structure is less active than the preceding one for hydrogenation of the CC double bond, but more selective for hydrogenation of the CO group of citral.     

香茅腈的合成及其应用

概述了香茅腈的性质、香气特征和应用,综述了以柠檬桉油为起始原料,经肟化反应和脱水反应合成香茅腈的方法。该工艺具有原料来源丰富、便宜、反应条件温和等优点,有广阔的工业前景。     

Heterogeneous Catalytic Transformation of Citronellal to Menthol in a Single Step on Ir-Beta Zeolite Catalysts

The synthesis of menthol from citronellal was studied on bifunctional Ir/Beta zeolite catalysts, prepared via impregnation of Beta zeolite with different concentrations of Ir. The results show that Beta zeolites, impregnated with Ir, catalyze the one-pot full conversion of citronellal to menthol by consecutive acid-catalyzed cyclization and Ir-catalyzed hydrogenation. The best results (95% selectivity for the menthol isomers, of which 75% is the desired (±)-menthol) were recorded on 3% Ir/Beta zeolite catalyst. In contrast with earlier studies, 0.05 g Ir/Beta catalyst per mL of substrate leads to complete and selective substrate transformation. The textural properties, acidity and hydrogenation function were studied by liquid N₂ adsorption–desorption, FT-IR, XPS and hydrogen chemisorption techniques. To clarify the mechanism of the cyclization of citronellal, tests were also performed using zeolites with different acidity and loaded with other metals (Pt, Pd, Rh, Ru).     

Kaffir Lime Leaf (Citrus hystric DC.) Drying Using Tray and Heat Pump Dehumidified Drying

Desorption isotherms of mature kaffir lime leaves are determined and a nonlinear regression program was applied to the experimental data to fit with any of the four moisture sorption isotherm models. It was found that the modified Halsey model could fit the best. Tray and heat pump–dehumidified drying of kaffir lime leaves were conducted and it was found that the modified Page model was the most effective one. The drying constant was fitted to drying air temperature using the Arrhenius model. Effective moisture diffusivities were determined using the drying data. Heat pump–dehumidified drying reduced drying time and provided dried kaffir lime leaves with higher amount of citronellal than tray drying.