Raney-Ni催化下菜籽油生物柴油催化转移加氢的研究

在水环境下,以异丙醇为供氢体和Raney-Ni为催化剂,对菜籽油经酯交换得到的生物柴油进行催化转移加氢研究.通过定时取样分析生物柴油的碘值变化和组分含量,研究了生物柴油中亚麻酸甲酯(C18∶3)、亚油酸甲酯(C18∶2)和油酸甲酯(C18∶1)催化转移加氢选择性和反应动力学,以及加氢过程中不饱和脂肪酸甲酯的顺反异构情况.结果表明:在水环境下生物柴油催化转移加氢反应可用拟一级动力学模型来描述;C18∶3和C18∶2的加氢选择性较高,反应速率常数是C18∶1的6倍,但产物主要为反式油酸甲酯(t-C18∶1),而且顺式油酸甲酯(c-C18∶1)进一步加氢变成硬脂酸甲酯(C18∶0)的速率远远高于t-C18∶1.     

1-(3-氨丙基)-2-甲基咪唑的催化合成、表征及应用

环氧树脂用的咪唑类固化剂多为固体和假性液体(低温下易析出的低熔点固体),工业应用不便。为了制得常温及低温下均呈液体的便于工业应用的咪唑固化剂,以1-氰乙基-2-甲基咪唑作为基本原料,骨架镍为催化剂,液氨为副反应抑制剂,乙醇作为溶剂,加压催化氢化合成液体咪唑固化剂1-(3-氨丙基)-2-甲基咪唑,考察氢气压力、液氨用量和催化剂循环使用次数对产率的影响,并通过元素分析、核磁共振氢谱和红外光谱对产物进行确证。结果表明,优化的反应条件为:反应温度100℃,氢气压力5 MPa,m(1-氰乙基-2-甲基咪唑)∶m[骨架镍(湿重)]∶m(液氨)∶m(乙醇)=139∶27.8∶42.5∶278,此条件下,产率可达96%。产物低至-35℃也不凝固,能良好地固化环氧树脂,表现出优异的工业适用性和固化性。     

Kinetics of hydrogenation of D-glucose to sorbitol

The kinetics of the heterogeneous reaction between hydrogen and aqueous solutions of D -glucose to produce sorbitol were studied in a high pressure Parr reactor. Raney-Ni was used as catalyst. The reaction between hydrogen and D -glucose was found to be very slow. In the agitated slurry reactor the diffusional aspects were completely eliminated and the reaction followed homogeneous kinetics. It was found to be first order with respect to both hydrogen and D -glucose. The values of the pseudo-first-order rate constants were found to be 1.5 × 10^?4 and 6.4 × 10^?4s^?1 at 398 and 435 K, respectively. The activation energy was found to be 64.8 kJ mol^?1.     

催化加氢法制备邻氨基苯乙醚

本文针对传统合成邻氨基苯乙醚工艺方法中的缺点,对催化氢化法制备邻氨基苯乙醚的工艺进行了研究。即用Raney Ni为催化剂,对邻硝基苯乙醚进行催化加氢还原,制备了邻氨基苯乙醚。考查了温度、催化剂用量及反应物浓度等工艺条件对反应的影响。结果表明,在较佳条件下反应,产品收率可达90%,纯度可达99%以上。     

用Raney镍和钯碳催化剂制备植物甾烷醇

以植物甾醇为原料,分别以Raney镍和钯碳为催化剂,以反应温度、氢气压力、反应时间、转速、催化剂添加量等因素进行正交试验优化植物甾醇氢化工艺参数。以Raney镍为催化剂,最优工艺条件为:反应温度135℃,氢气压力2.5 MPa,反应时间5.0 h,转速700 r/min,催化剂添加量40%。该条件下,植物甾醇的氢化率为94.18%,羟基值(KOH)为124.79 mg/g。以钯碳为催化剂,最优工艺条件为:反应温度130℃,氢气压力2.6 MPa,反应时间4.5 h,转速580 r/min,催化剂添加量1.5%。该条件下,植物甾醇的氢化率为93.65%,羟基值(KOH)为125.04 mg/g。     

Impedance measurements of air-oxidized and H2-annealed Raney-Ni catalysts for alkaline fuel cells

The catalytic properties and the long-term performance of Raney-NiTi2 catalysts being used in H₂ electrodes of alkaline H₂---O₂ fuel cells can be significantly improved by slow air oxidation and subsequent annealing in an H₂ atmosphere at 300°C. Individual reaction steps are investigated by means of impedance measurements. Theoretical estimations, on the basis of a simple equivalent circuit of a supported electrode, result in a frequency-response relationship which is in very good agreement with the experimental data referring to the relevant frequency range of 10⁻³−10⁻¹ Hz. A method to evaluate the impedance spectra is described in some detail. Calculated and measured impedance data are in good agreement, thus indicating the validity of the charge transfer resistance, the diffusion resistance, as well as the chemisorption capacity and the double-layer capacity. Experiments on the influence of catalyst annealing in an H₂ atmosphere at 350°C show a strong increase in the charge transfer resistance and an obvious decrease in the diffusion resistance, depending on the annealing time. A similar influence on the chemisorption capacity and the double-layer capacity is not observed.     

多相态甲基环己烷催化脱氢反应过程的研究

从系统动态能量平衡的角度对以Raney-Ni为催化剂的甲基环己烷在"多相态"模式下的脱氢反应过程进行了研究,考察了反应温度(453～573 K)、反应液用量(0.2～4.0 mL)和催化剂用量(2～10 g)对甲基环己烷脱氢转化率的影响.反应过程中生成的气体通过冷凝回流装置不断地从反应体系中分离溢出,通过对Raney-Ni催化剂表面温度和冷凝回滴液量的控制,使整个反应体系始终介于"液-固"和"气-固"的中间状态,实现反应体系的"液(由反应物系的冷凝回滴实现)、气(通过催化剂表面高温气化反应物系实现)、固(即固体催化剂)"的三相共存.研究表明,在多相态的反应体系中存在一个最佳的能量平衡点,它所对应的反应物在催化剂表面的停留时间,既能保证反应液与催化剂充分有效地接触,又能使反应物在发生脱氢反应后立即被气化脱离催化剂,抑制逆反应的发生,从而有效地提高甲基环己烷的脱氢转化率.在523 K,0.5 mL甲基环己烷和8 g Raney-Ni的反应条件下,甲基环己烷的脱氢转化率达到65%.     

木糖Raney—Ni催化加氢宏观动力学研究

在改装的高压釜中，测定两种粒径Ｒａｎｅｙ－Ｎｉ催化剂用于木糖水溶液加氢反应的动力学规律。反应温度３８３Ｋ、氢压范围１．０－６．０ＭＰａ，借助模型计算对反应过程进行分析，并讨论了实验结果     

Kinetics of 9-ethylcarbazole hydrogenation over Raney-Ni catalyst for hydrogen storage

Hydrogen storage in form of liquid organic hydrides, e.g. 9-ethylcarbazole, is a relatively novel method. In the present work, the hydrogenation kinetics of 9-ethylcarbazole over Raney-Ni catalyst was studied by investigating the influences of the reaction temperature, pressure and catalyst concentration on the mass transfer-reaction processes. The results show that the kinetics of reaction is controlled by the chemical process on the catalyst surfaces. The hydrogenation reaction followed first-order kinetics with an apparent activation energy of 65.17 KJ/mol. The apparent kinetics model of the hydrogenation was established.     

Kinetic analysis of dehydrogenation reaction of cyclohexane catalyzed by Raney-Ni under multiphase reaction conditions

The kinetics of dehydrogenation reaction of cyclohexane catalyzed by Raney-Ni under “wet–dry” multiphase reaction conditions was studied in this paper. The influences of the heating temperature, feeding amount of cyclohexane and catalyst dosage on conversion of cyclohexane, apparent rate constant of reaction and retardation constant for aromatic product were investigated systematically. The experimental studies indicate that the control of the dynamic energy balance of reaction system is very important, there exists an optimal energy balance point in “wet–dry” multiphase reaction system, which depends on the combined action of heating temperature, feeding amount of cyclohexane and catalyst dosage. It was found that, with 0.5 ml cyclohexane feeding amount and 7 g catalyst dosage, at 320 °C the reaction system approached its optimal energy balance point, and the dehydrogenation conversion of cyclohexane reached its highest value of 72.7%.