在工业镍催化剂上苯气相加氢反应动力学

在常压下,应用内循环式无梯度反应器,研究了在国产工业镍催化剂上苯气相加氢的本征动力学.假设催化剂表面上存在两类不同的活性中心,氢及苯各自吸附在相邻的不同类型的活性中心上,设第一个氢原子加入苯环的步骤为反应速率控制步骤,据此以导出反应的动力学方程,与实验数据颇相符合,平均偏差6.1%.测得的本征反应活化能为13.1kcal/mol.苯的吸附热为9.84kcal/mol,与不存在化学反应时的测定结果相接近.     

C18 Unsaturated Fatty Acid Selectivity of Lipases During the Acidolysis Reaction Between Tripalmitin and Oleic,Linoleic, and Linolenic Acids

The C18 unsaturated fatty acid (UFA) selectivity of three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanuginosa, Lipozyme RM IM from Rhizomucor miehei, and Novozym 435 from Candida antarctica, was determined in acidolysis conducted in hexane. Tripalmitin with a mixture of equimolar quantities of C18 UFAs was used as the substrate. Significantly different incorporation rates were observed for C18 UFAs used (p < 0.05). The highest incorporation was obtained for all three C18 UFAs with Novozym 435 followed by Lipozyme RM IM and Lipozyme TL IM catalyzed acidolysis under default conditions (substrate mole ratio 1:1; temperature 50 °C; reaction time 6 h; enzyme dosage 10%). Incorporation of the equimolar quantities of C18 UFAs was in the order C18:3 > C18:2 > C18:1 which also reflects C18 UFAs preferences of the lipases. The effects of operating variables on incorporation or UFA selectivity of lipases were also investigated. Among the experimental parameters including the mole ratio of fatty acid to triolein, temperature, enzyme dosage, and time on incorporation, the effect of the substrate mole ratio on UFA selectivity was greater than those of the others.     

H2S分压对1-十二烯在NiMo/Al2O3催化剂上加氢反应的影响

在加氢裂化反应过程中，裂化产生的痕量烯烃会与H2S结合生成硫醇。为研究H2S对烯烃加氢及硫醇生成的影响，实验室采用微反以正-十二烯为模型化合物，考察了H2S存在下1-十二烯在NiMo/Al2O3催化剂上的加氢反应。结果表明，在一定范围内H2S分压的变化对1-十二烯的转化率没有明显影响，但对产品中异构烯烃的选择性有很大影响，并直接影响产物中十二碳硫醇的收率与分布。     

The Percentage of n-3 Highly Unsaturated Fatty Acids in Total HUFA as a Biomarker for Omega-3 Fatty Acid Status in Tissues

A blood biomarker of omega-3 fatty acid intake and tissue status could serve as a modifiable risk factor for cardiovascular disease. The percentage of omega-3 highly unsaturated fatty acid (HUFA ≥ 20 carbons and ≥3 double bonds) in the total HUFA pool (the n-3 HUFA score) was examined as a potential blood biomarker of omega-3 fatty acids in tissues. The fatty acid composition of total lipid extracts (TLE) and phospholipid (PL) fractions were determined for plasma and erythrocytes samples of human subjects (n = 20) and the n-3 HUFA score and the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were compared. Omega-3 fatty acids in blood and tissues of rats (n = 31) and pigs (n = 48) were also determined and the associations were compared. The n-3 HUFA score is more consistent across plasma and erythrocytes, with strong correlations between TLE and PL in plasma (r = 0.93) and erythrocytes (r = 0.94). The n-3 HUFA score was less variable and blood levels correlated strongly with various animal tissues. The n-3 HUFA score is a useful blood biomarker that does not require the isolation of the PL class thereby supporting high throughput analyses. The strength of association between the n-3 HUFA score and disease risk needs to be examined.     

载体及镍源对镍催化剂催化苯酐选择性加氢反应的影响

分别以SiO2、TiO2、TiO2-SiO2、TiO2-Al2O3和TiO2-ZrO2为载体,以硝酸镍为镍源,采用浸溃法制备出一系列镍基催化剂,考察了不同载体对镍催化剂催化苯酐选择性加氢合成苯酞性能的影响;并考察了以TiO2-ZrO2为载体,分别以硝酸镍、乙酸镍和柠檬酸镍为镍源制备的镍催化剂的加氢性能.通过BET、XRD、SEM等方法对催化剂进行了表征.结果表明,载体对镍催化剂上苯酐加氢反应的影响较大,其中复合氧化物TiO2-SiO2和TiO2-ZrO2负载的镍催化剂上Niu活性组分晶粒度较小,分散度较高,催化剂表现出很好的催化活性和苯酞选择性.此外,以不同镍源制备的Ni/TiO2-ZrO2催化剂性能差异较明显,由乙酸镍制备的催化剂上Niu物种粒度较大,活性较低,由硝酸镍和柠檬酸镍制备的催化剂表现出很高的催化活性和选择性,其中由柠檬酸镍制备的催化剂性能略高于硝酸镍,在实验反应条件下,苯酐转化率为97.1%,苯酞收率为92.9%.     

Role of Acetic Acid Added to the Reaction Media for the Enantio-differentiating Hydrogenation of Methyl Acetoacetate Over a Tartaric Acid-modified Nickel Catalyst

The role of acetic acid added to the reaction media for the enantio-differentiating hydrogenation of methyl acetoacetate over a (R,R)-tartaric acid-in-situ-modified nickel catalyst was studied from the viewpoint of the hydrogenation rate during repeated runs. The hydrogenation of methyl acetoacetate on the “enantio-differentiating sites” of a tartaric acid-modified nickel catalyst was specifically accelerated by the acetic acid added to the reaction media to increase the enantio-differentiating ability of the catalyst. In order to increase the enantio-differentiating ability, the addition of acetic acid to the reaction media was required in each run during the repeated use of the catalyst.     

Reaction Rates for the Partial Dehydration of Glucose to Organic Acids in Solid-Acid,Molecular-Sieving Catalyst Powders

Molecular-sieving catalysts have the potential to promote the production of oxygenated hydrocarbons from glucose. A kinetic model for the partial dehydration of glucose to organic acids by micro- and mesoporous aluminosilicate catalysts was developed. Kinetic parameters were estimated from glucose conversion and product yield versus time data at 150°C for HY-zeolite, aluminum-pillared montmorillonite, MCM-20 and MCM-41 catalyst powders of 0·5 mmol H⁺ g⁻¹ solid-acid activity. Rate constants for the partial dehydration of glucose to 5-hydroxymethylfurfural (HMF) and the rehydration and cleavage of HMF to formic acid and 4-oxopentanoic acid were maximized at catalyst pore diameters of 10–30 Å. The final organic acid product yields were low, less than 60% of theoretical for formic acid and 10% of theoretical for 4-oxopentanoic acid, due to significant coke formation. © 1997 SCI.     

A Highly Active and Recyclable Catalyst: Phosphine Dendrimer‐Stabilized Nickel Nanoparticles for the Suzuki Coupling Reaction

We report here the first dendritic phosphine‐stabilized nickel nanoparticles, which can be prepared from nickel(II) chloride, a third generation phosphine dendrimer and the surfactant tetraoctylammonium bromide (TOABr) by two‐phase reduction using sodium borohydride. The resulting nickel nanoparticles are found to be a highly active and recyclable catalyst for Suzuki coupling reactions, especially those extended to aryl chloride substrates, affording the biaryls in moderate to good yields.     

Analytical Problems in the Investigation of Unsaturated Acids Conversion II: Determination of Position Isomers,Conjugated Unsaturated Bonds and Composition of Fatty Acids

The paper discusses the methods of determination of the position of unsaturated bonds in a chain of acids, the determination of the sum of conjugated unsaturated bonds and the composition of the fatty acids. The position of unsaturated bonds in acids of modified oils may be determined most quickly by the method of pyrrolidide derivatives and determinations by the GLCMS method. The content of conjugated bonds had been determined by standardized method of UV spectrometry, and the composition of the fatty acids had been determined by gas chromatography.     

糠醛气相加氢动力学探讨

在直流流动积分反应器中 ,于常压下研究了Cu -Zn催化剂上糠醛气相加氢制糠醇反应的本征动力学方程 ,结果表明加氢对糠醛为 0 .37级 ,对氢气为 0 .84级     

Influence of Reaction Conditions on Diacid Formation During Au-Catalyzed Oxidation of Glycerol and Hydroxymethylfurfural

The selective oxidation of glycerol and 5-hydroxymethylfurfural (HMF) to diacids over supported gold catalysts (Au/C and Au/TiO₂) in liquid water at mild temperatures was a strong function of the added base such as NaOH. Use of hydrotalcite as a solid base in place of NaOH in the HMF reaction medium facilitated the production of diacid over Au/TiO₂, but extensive leaching of magnesium suggested that hydrotalcite was consumed stoichiometrically in the reaction. Production of diacids from glycerol oxidation over supported Au catalysts was promoted by operating in a continuous flow reactor and by increasing the catalyst loading in a semi-batch reactor. Trace inhibitors formed by conversion of the product monoacid are proposed to account for the generally low selectivity to diacids over gold catalysts.     

不同工艺条件下耐硫甲烷化催化剂的反应活性研究

考察了钼基耐硫甲烷化催化剂在不同反应温度下的催化活性,结果表明反应温度在560℃附近时甲烷化活性最高。在此温度下研究了空速、原料气中H2S、H2O、CO2、CH4、H2/CO等浓度对反应活性的影响,结果表明,原料气中H2S含量的增加有利于提高催化剂的甲烷化反应活性;H2O的加入促进了水煤气变换反应的进行但抑制了甲烷化反应,因此CO转化率虽没有下降但甲烷化效率却有所降低;添加CH4对甲烷化反应没有明显影响,而添加CO2则明显抑制了甲烷的生成。结合催化剂表征结果进一步对各因素的影响机理进行了分析,这为耐硫甲烷化工艺条件优化及催化剂设计提供了重要依据。     

载体制备方法对Ni催化剂催化间二硝基苯加氢反应的影响

以正硅酸乙酯为原料,采用溶胶-凝胶法,分别经乙醇超临界干燥和常规干燥制得SiO2气凝胶和干凝胶载体,并以La2O3为助剂,通过浸渍法制备了用于间二硝基苯液相加氢制间苯二胺反应的镍基催化剂,通过BET、XRD、TPR、H2-TPD和活性评价等方法对催化剂的物化性质和催化性能进行了研究.结果表明,虽然以SiO2气凝胶为载体制备的二元镍基催化剂的镍晶粒的粒度较小,但由于金属镍烧结导致它表面存在的活性位相对较少,对反应组分的吸附强度较弱,致使其活性低于SiO2干凝胶负载的二元镍基催化剂.添加La2O3助剂的三元镍基催化剂的活性总体上比二元催化剂要高,其中以SiO2干凝胶为载体制备的三元催化剂具有较高的活性比表面积和适宜的吸附强度,对间二硝基苯加氢反应表现出很高的催化活性,在2.6 MPa、373 K下反应1 h后,间二硝基苯转化率可达97.0%、间苯二胺产率达93.1%.     

Effects of Support on Carbon Formation and Gasification on Nickel during Carbon Monoxide Hydrogenation

Rates of carbon deposition during carbon monoxide hydrogenation at 325–450°C and of carbon removal by oxygen at 300–350°C on unsupported Ni, Ni/Al₂O₃, Ni/SiO₂, and Ni/TiO₂ were determined by in situ gravimetric measurements. Following an induction period, carbon deposits on these catalysts at very significant rates; the order of decreasing deposition rate is Ni/TiO₂, Ni/Al₂O₃, Ni, Ni/SiO₂. Rates of gasification of these deposits in oxygen decrease in the same order. The order of decreasing deposition rate is the same as for carbon monoxide dissociation and removal of carbidic carbon by reaction with hydrogen. Approximately 70–80% of the metal surface area for adsorption of oxygen is lost as a result of carbon formation. However, 90–99% of this surface area is restored by the treatment in oxygen. The results indicate that the first 1–2 monolayers of carbon deposited during reaction are responsible for deactivation; subsequent deposition presumably in the form of vermicular carbon is not responsible for loss of activity.     

Reaction of Hydrazoic Acid on γ- and β-Oxoolefinic Fatty Acids

9-Oxo-cis-octadecenoic acid (I) when treated with an excess of hydrazoic acid in the presence of BF₃-etherate as catalyst gave an isomeric mixture of amide derivative (III). On the other hand, 12-oxo-cis-9-octadecenoic acid (II) on the similar treatment afforded urea (IV) and isomeric amide (V) derivatives.     

Selective Hydrogenation of Ethyne in Ethene-Rich Streams on Palladium Catalysts. Part 1. Effect of Changes to the Catalyst During Reaction

The effect of various changes to the palladium catalyst during its stabilization in the course of the selective hydrogenation of ethyne-ethene mixtures (formation of hydride and carbide phases and of carbonaceous deposits) was reviewed. The deposits in the form of a carbonaceous overlayer on the palladium surface create sites at which selective ethyne hydrogenation to ethene can occur. The carbonaceous deposit on the support increases the selectivity to ethane formation by increasing the rate of ethene hydrogenation on support sites (spillover of hydrogen from metal to the support surface) and by decreasing the effective diffusivity of ethyne in the pores.     

不饱和脂肪酸锌皂类加工助剂对天然橡胶性能的影响

研究3类不饱和程度的脂肪酸锌皂类加工助剂在天然橡胶中的应用。结果表明：随着脂肪酸锌皂类不饱和度增大,胶料门尼粘度降低,抗硫化返原性能改善,炭黑等填料的分散性能提高,在一定程度上加快了硫化速度,对胶料物理性能影响不大。     

Further Studies on Oscillations over Nickel Wires During the Partial Oxidation of Methane

Oscillatory reactions over nickel wires during the partial oxidation of methane were investigated in a tubular continuous flow reactor made of quartz at atmospheric pressure. A modified thermocouple was designed to measure the temperature while the interposed nickel coil worked as a catalyst. Significant effects on the oscillations were observed by varying the system temperature and the feed gas composition, and by cutting off one of the reactant gases temporarily.     

反应条件对FO-35M催化剂加氢改质性能的影响

针对催化裂化汽油加氢过程辛烷值损失过大的问题,抚顺石化公司开发的FCC汽油加氢改质催化剂(FO-35M)具有降烯烃最大限度减少辛烷值损失作用。以某炼厂提供的FCC汽油中间馏分为原料,考察不同反应条件对该剂加氢改质性能的影响。结果表明反应温度、压力对FO-35M催化剂加氢改质性能影响显著,存在最佳范围;而空速对降烯烃有一定影响,氢油比影响最弱。在工业装置运行过程中,要综合考虑各种因素,选择适宜的反应温度、压力、空速,保证装置的长周期运行。