磁性催化剂与磁稳定床反应器

将非晶态Ni加氢性能和磁性与磁稳定床反应器相结合,工业应用于已内酰胺加氢精制过程,实现了加氢反应过程的强化。在此基础上制备了系列磁性催化剂,包括金属氧化物催化剂、负载型双金属催化剂和强酸性磁性树脂催化剂等。上述磁性催化剂与磁稳定床反应器相结合,用于CO加氢、乙炔选择性加氢、烯烃叠合和醚化等反应,同样表现出反应过程强化的特点。本文结合我们自己的研究工作,对近年来磁稳定床反应器与磁性催化剂的研究进展进行了评述,并展望了未来磁性催化剂与磁稳定床反应器的发展趋势。     

磁稳定床反应器(英文)

介绍了磁稳定床反应器在国际上的首次工业应用,它集成了浆态床、固定床、移动床和流化床等反应器的优点. 通过调整线圈间距、在反应器内设置磁隔栅构件,实现了均匀磁场的放大; 绘制出磁稳定床反应器链式操作相图. 将非晶态Ni优异的加氢性能和磁性与磁稳定床反应器反应过程强化性能相结合,实现了在己内酰胺加氢精制过程的工业应用,并建成5套20～40万吨/年工业装置. 磁性催化剂与磁稳定床反应器相结合,强化了甲烷化、乙炔选择性加氢和烯烃叠合等反应过程,形成了新技术生长点.     

非晶态合金催化剂和磁稳定床反应工艺在石油化工技术中的推广应用

本文综述了中石化石科院开发非晶态合金催化剂和磁稳定床工艺的历程及其在石油化工技术中的推广应用. 将晶态催化剂的结构非晶化,极大地改善了广泛使用的Raney Ni催化剂的加氢性能. 通过加入原子半径大的稀土和碱抽提铝提高了非晶态合金催化剂的热稳定性和比表面积. 引入助剂以调节催化剂的加氢性能、耐酸性和磁性,从而研制出SRNA系列催化剂;开发出工业生产非晶态合金催化剂的关键技术和设备. 磁稳定床可以强化受传热和传质限制的反应过程,与磁性催化剂结合,形成磁稳定床反应工艺. 设计了调节磁场的磁隔?建立了可指导用于工业化的磁场和反应器的数学模型. 与釜式加氢工艺相比,将磁稳定床工艺用于己内酰胺加氢精制时,催化剂耗量降低70%, 反应器体积减少85%. 非晶态合金催化剂和磁稳定床反应工艺在国际上首次工业应用,大大推动了我国的加氢技术的发展,并产生了巨大的经济和社会效益. 最新研究表明,将该技术用于精制氢气中CO的甲烷化、蒸汽裂解乙烯选择性加氢和催化裂化轻汽油叠合醚化等反应时,其性能明显优于已有技术,显示出良好的工业应用前景.     

还原温度与时间对铁基催化剂浆态床F-T合成性能的影响

在浆态床反应器中考察了未还原催化剂以及在240℃和270℃的还原温度下还原时间对Fe/Cu/K/SiO2催化剂F-T合成反应性能的影响,采用Mssbauer谱研究了还原和反应后催化剂的物相组成。结果表明,在240℃延长还原时间或将还原温度升高到270℃均有利于催化剂的还原,270℃还原的催化剂的活性和稳定性明显高于未还原和240℃还原的催化剂,催化剂的运行稳定性与催化剂在反应过程中的流失量有密切关系。催化剂高温还原时烃产物分布倾向于生成低碳数的烃类,在相同的还原温度下,烃产物选择性随还原时间的延长向轻组分方向偏移。     

Performance of a magnetically stabilized bed reactor with immobilized yeast cells

This paper is focused on the possibility to apply the magnetic stabilization technique in bioprocessing. The feasibility of a continuous ethanol fermentation process with immobilizedSaccharomyces cerevisiae cells in a magnetically stabilized bed (MSB) was demonstrated. The fermentation processes were carried out in an external magnetic field, transverse to the fluid flow. The flexibility to change the bed expansion owing to the independent change of the fluid flow and the field intensity (the “magnetization FIRST” mode) permitted the creation of fixed beds with different particle arrangements, which affected the bed porosity, the effective fluid-particle contact area, and the mass transfer processes on the particle-fluid interface. As a result, higher ethanol concentration, ethanol production, and glucose uptake rates than in conventional packed bed reactor were reached.     

Hydrogen production by catalytic decomposition of methane using a Fe-based catalyst in a fluidized bed reactor

Catalytic decomposition of methane using a Fe-based catalyst for hydrogen production has been studied in this work. A Fe/Al2O3 catalyst previously developed by our research group has been tested in a fluidized bed reactor (FBR). A parametric study of the effects of some process variables,including reaction temperature and space velocity,is undertaken. The operating conditions strongly affect the catalyst performance. Methane conversion was increased by increasing the temperature and lowering the space velocity. Using temperatures between 700 and 900℃ and space velocities between 3 and 6LN/(gcat·h),a methane conversion in the range of 25%-40% for the gas exiting the reactor could be obtained during a 6 hrun. In addition,carbon was deposited in the form of nanofilaments (chain like nanofibers and multiwall nanotubes) with similar properties to those obtained in a fixed bed reactor.     

Investigation of coupling dehydrogenation and hydrogenation reactions in a fixed bed catalytic reactor with well-mixed catalyst pattern

The enhancement of ethylbenzene conversion by further displacement of the thermodynamic equilibrium via the influence of the dual-functionality of a well-mixed catalyst pattern has been investigated. A rigorous steady state mathematical model based on the dusty gas model is implemented for the simulation. The simulation results reveal that the introduction of the concept of the reaction coupling has significant effect on the displacement of the thermodynamic equilibrium and considerable enhancement of simultaneous production of styrene and cyclohexane. Almost 100% conversion of the ethylbenzene and benzene is achieved through the application of this approach. It is also found that considerable decrease in the reactor length is achieved by employing a reactor catalyst bed with different bed compositions. Effective operating regions with optimal conditions are observed. An effective reactor length criterion is used to evaluate the performance of the reactor under these optimal conditions. The effective reactor length is found to be sensitive and favored by high feed temperature and pressure. The sensitivity analysis shows that the key parameters of feed temperature, pressure, and the bed composition play an important role on the reactor performance. The results also show that almost 100% conversion of ethylbenzene and benzene at low temperature and shorter reactor length can be achieved by maintaining the reactor beds at different temperatures. This temperature switching policy may result in appreciable energy saving. Moreover, operating the reactor at low temperature protect the catalyst from the excessive temperatures which have destructive effects on the catalysts and the mechanical stability of the reactors. Also, the low temperature operation has significant contribution to the reduction of the operating cost.     

Fe3O4-Lignin@Pd-NPs: A highly efficient,magnetically recoverable and recyclable catalyst for Mizoroki-Heck reaction under solvent-free conditions

Palladium nanoparticles ( Pd-NPs ) were synthesized under green conditions in water by chemical reduction of PdCl₂ with NaOH and supported by Fe ₃ O ₄ -Lignin . Fe ₃ O ₄ -Lignin is an organic–inorganic hybrid core-shell was synthesized by sonication of a mixture of Fe ₃ O ₄ -NPs (20 nm) and alkali lignin. The new materials Fe ₃ O ₄ -Lignin and Fe ₃ O ₄ -Lignin@Pd-NPs were characterized by PXRD, SEM and FT-IR spectroscopy. The Fe ₃ O ₄ -Lignin@Pd-NPs was further confirmed by UV–Visible spectroscopy, TEM, EDX, HRICP-AES and TGA/DTA. The average size of Pd-NPs determined from PXRD was 5–10 nm. The amount of palladium loaded on Fe ₃ O ₄ -Lignin obtained from EDX analysis was 26.63% by mass. The amount of Fe and Pd present in the catalyst obtained from HRICP-AES was 11.88 (wt. %) and 10.90 (wt. %) respectively per gram of lignin. The catalytic potential of Fe ₃ O ₄ -Lignin@Pd-NPs was evaluated in Mizoroki-Heck C-C coupling reaction. During the optimization studies of reaction between iodobenzene and n-butyl acrylate in various solvents and under solvent-free but aerobic conditions using various inorganic and organic bases, the product n-butyl 3-phenylprop-2-enoate ( 1a ) obtained was as high as 95% in highly polar solvents as short as in 10 min and 99% under solvent-free conditions in 3 min at 140 °C using n-Pr₃N as base. The scope of the above catalyst was investigated in the Mizoroki-Heck reaction of various aryl/heterocyclic halides and n-butyl acrylate/styrene under optimized solvent-less conditions. The corresponding products were obtained in high yields (73–99%). The catalyst recovered by magnetic decantation was reused for five times in the C-C coupling reaction between iodobenzene and n-butyl acrylate which yielded 90–95% of the desired product, 1a .     

Effect of diluent and reaction parameter on selective oxidation of propane over MoVTeNb catalyst using nanoflow catalytic reactor

The selective oxidation of propane to acrylic acid over an MoVTeNb mixed oxide catalyst, dried and calcined before reaction has been studied using high-throughput instrumentation, which is called nanoflow catalytic reactor. The effects of catalyst dilution on the catalytic performance of the MoVTeNb mixed oxide catalyst in selective oxidation of propane to acrylic acid were also investigated. The effects of some reaction parameters, such as gas hourly space velocity （GHSV） and reaction temperature, for selective oxidation of propane to acrylic acid over diluted MoVTeNb catalyst have also been studied. The configuration of the nanoflow is shown to be suitable for screen catalytic performance, and its operating conditions were mimicked closely to conventional laboratory as well as to industrial conditions. The results obtained provided very good reproducibility and it showed that preparation methods as well as reaction parameters can play significant roles in catalytic performance of these catalysts.     

Efficient monooleoyl glycerol synthesis employing hybrid ultrasonic-infrared-wave promoted reactor: Concurrent catalytic and noncatalytic esterification kinetics

For the first time, intensification of monooleoyl glycerol (MOG) synthesis has been investigated in an ultrasonic-infrared-wave (USIRW) promoted batch reactor. Esterification of octadecanoic acid (ODA) with glycerol (Gl) has been conducted [using Amberlyst 36 wet catalyst] in three different reactors, namely traditional batch reactor (TBR), infrared wave promoted batch reactor (IRWPBR), and USIRW-promoted batch reactor (USIRWPBR) to assess the relative efficacy. The energy-efficient USIRWPBR remarkably intensifies the ODA-Gl esterification as manifested through superior ODA conversion (92.5 ± 1.25%) compared to that achieved in IRWPBR (79.8 ± 1.2%) and TBR (36.39 ± 1.25%). The most favorable reaction condition for optimum ODA conversion and maximum MOG yield was identified through statistical optimization over a selected parametric range, namely 3-5 Gl/ODA mole ratio, 0.004-0.006 g/mL Amberlyst 36 catalyst concentration, 300-700 rpm impeller speed, and 333-353 K reaction temperature. The present study also reports the formulation and validation of an innovative reaction kinetics, that is, concurrent noncatalytic and heterogeneously catalyzed (CNCHC) reaction mechanism in addition to the conventional heterogeneous kinetic models (LH and Eley-Rideal mechanisms). Under combined USIRW, the CNCHC esterification mechanism could best describe ODA-Gl esterification (R² = 0.98) compared to LH (R² = 0.97) and Eley-Rideal (R² = 0.88) mechanisms. The optimal product (MOG) was characterized by differential scanning calorimetry and thermogravimetric analysis to assess its crystallization property and thermal stability for possible application as plasticizer/fuel additives.     

Oxidative coupling of methane in a fixed bed reactor over perovskite catalyst： A simulation study using experimental kinetic model

The oxidative coupling of methane （OCM） to ethylene over a perovskite titanate catalyst in a fixed bed reactor was studied experimentally and numerically. The two-dimensional steady state model accounted for separate energy equations for the gas and solid phases coupled with an experimental kinetic model. A lumped kinetic model containing four main species CH4, O2, COx （CO2, CO）, and C2 （C2H4 and C2H6） was used with a plug flow reactor model as well. The results from the model agreed with the experimental data. The model was used to analyze the influence of temperature and feed gas composition on the conversion and selectivity of the reactor performance. The analytical results indicate that the conversion decreases, whereas, C2 selectivity increases by increasing gas hourly space velocity （GHSV） and the methane conversion also decreases by increasing the methane to oxygen ratio.     

Palladium magnetic nanoparticle‐polyethersulfone composite membrane as an efficient and versatile catalytic membrane reactor

Developing polymer catalytic membrane reactors is an aim due to its outstanding advantages. In this paper, a novel catalytic membrane containing palladium‐supported magnetic nanoparticles is introduced. Silica‐iron oxide core shell nanoparticles were first prepared and functionalized by phosphine ionic liquid functionalized poly(ethylene glycol). The modified magnetic nanoparticles were used as support for immobilization of palladium. The final palladium‐immobilized nanoparticles were used as active filler for the preparation of membrane reactor. The prepared membranes were characterized, and their activities were tested in carbon‐carbon bond formation and catalytic reduction. The catalytic membrane showed good performance in the mentioned reactions.     

Sulfamic acid immobilized on amino‐functionalized magnetic nanoparticles: A new and active magnetically recoverable catalyst for the synthesis of N‐heterocyclic compounds

Sulfamic acid immobilized on amino‐functionalized magnetic nanoparticles (MNPs/DETA‐SA) was successfully fabricated and characterized using various techniques. Diameters of approximately 15 nm for the MNPs/DETA‐SA were observed from scanning electron microscopy images. The as‐fabricated nanocomposite was applied as an efficient and magnetically reusable catalyst for the synthesis of 2,3‐dihydroquinazoline‐4(1H)‐one and polyhydroquinoline derivatives. All products were obtained in good to excellent yields. Recovery tests confirm that the catalyst can be readily recovered using an external magnet and reused many times without significant loss of its catalytic activity.