异丁烯为原料制备甲基丙烯酸甲酯的催化剂

The catalysts used for manufacturing methyl methacrylate (MMA) by two-step conversion of isobutylene via methacrolein (MAID were studied. The selective oxidation of isobutylene to MAL was carried out in a fixed-bed flow microreactor using a series of Mo-Bi-containing catalysts and the oxidative esterification of MAL to MMA was carried out in a slurry-bed reactor using a series of palladiumcontaining catalysts. By means of BET and XPS, the properties of the catalysts were characterized. It was found that the performance of Mo-Bi-Co-Fe-Ce-O catalyst was improved distinctly when Cs was added for the selective oxidation of isobutylene to MAL, and the Pd5Bi2PbFe/CaCO3 catalyst with the loading sequence of Pd, Pb and Bi, Fe showed the best performance for the oxidative esterification of MAL to MMA.     

Temperature-mediated control of the growth of an entangled carbon nanofiber layer on stainless steel micro-structured reactors

A well-adhered layer of carbon nanofibers (CNFs) was grown on stainless steel microreactors by decomposition of a hydrocarbon over microreactors previously coated with Ni dispersed on alumina. In a previous work, we reported that the growth temperature and hydrocarbon (methane or ethane) modulated the morphology and size of the grown carbon species. Using ethane, the carbon yield increased dramatically for temperatures exceeding 898 K. At these temperatures some carbon protrusions arise, which plug microreactor channels and render the microreactor unsuitable for use. For methane at all the tested temperatures or for ethane at the lowest temperatures (853 and 873 K), the microreactor channels were covered completely by a uniform mat of entangled CNFs ready for catalytic use. Here, we show that the growth temperature and hydrocarbon can also control the primary structure of CNFs, either rolled graphitic planes parallel to the axis (multi-wall carbon nanotubes) or graphitic planes forming an angle with respect to the axis (fishbone type).     

Synthesizing bromobutyl rubber by a microreactor system

Bromobutyl rubber (BIIR) is an important synthetic rubber with better vulcanizing behavior than traditional butyl rubber (IIR). It is hard to synthesize for the high reactant viscosity and strong corrosion caused by Br₂ and HBr. A microreactor platform was developed to solve the corrosion problem with cheap materials and obtain high quality BIIR based on microscaled mixing. The results showed that low reaction temperature and quickly eliminating HBr from the reacting solution were crucial to obtain high selectivity of demanded molecule structure and prevent polymer from decomposition. Owing to the corrosion resistance ability, a water assistant technology was successfully implemented in the microreactor system, which produced high quality BIIR with almost 100% selectivity and less reduced molecule weight. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1002–1009, 2017     

Effect of solvent and impurity on synthesis of ethyl lactate from fermentation-derived ammonium lactate

Fermentation-derived ammonium lactate was converted into ethyl lactate by decomposition in various organic solvents followed by esterification with ethanol over Amberlyst catalyst. The ammonium lactate was decomposed more efficiently in an organic solvent with high boiling point, where the produced lactic acid was stabilized well as a monomer without oligomerization. However, only the nonreactive phosphate-type solvent such as triethyl phosphate and tributyl phosphate showed a notable ethyl lactate yield in the subsequent esterification reaction compared with dimethyl sulfoxide and N-methyl pyrolidine. The lactic acid yield in ammonium lactate decomposition and the subsequent ethyl lactate yield were also highly dependent on solvent ratio to ammonium lactate, temperature and pressure in ammonium lactate decomposition reaction. The amino acid impurity contained in the fermented ammonium lactate as well as the unreacted ammonium lactate reduced the acid strength of Amberlyst-36, which resulted in the final ethyl lactate yield.     

Integrated system for microreactor gas chromatography

A compact unit has been constructed to control and to supply a microreactor apparatus. Features are an ozone generator, gas flow rotameters, solenoid-operated six-way gas valve and a combination temperature-and-ozone meter. The meter monitors and, by means of a built-in relay, controls reaction temperature. It also affords a visual indication of ozone concentration during reactions. Basic electronic circuits and common laboratory items simplify the unit’s construction. Some possible microreactions to which this integrated system may be applied are ozonizationpyrolysis, esterification, transesterification, saponification, reduction and halogenation. Presented at the AOCS Meeting, Chicago, October 1967. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Nanometric bimetallic sulfides prepared via thermal decomposition of Ni and Fe heteropolymolybdate emulsions

NiMo and FeMo nanometric particles were prepared by thermal decomposition of water in oil emulsions, where the aqueous phase was a solution of iron or nickel heteropolymolybdates. Decomposition experiments were carried out at 573 K and 70 Bar of hydrogen, with carbon disulfide added to the emulsions. Solids were characterized by X ray diffraction, confocal microscopy and BET surface area. Thiophene hydrodesulfurization was performed in a continuous flow microreactor at 553 K and 1.0 Bar. Particles with diameters between 370 and 560 nm were obtained, and thiophene HDS was in the order NiMoS > MoS ≈ FeMoS > NiS > FeS. The feasibility of using thermal decomposition of emulsions to obtain nanometric bimetallic sulfides particles was shown.     

MRA microeactions for lipid analysis

Many types of reactions have been performed on a microscale with the microreactor apparatus (MRA) system, which incorporates a modified soldering gun. Specific procedures developed for some typical reactions include bromination of olive methyl esters, silylation of castor methyl esters, homogeneous reduction of oleic acid, heterogeneous reduction of soybean methyl esters, several methods of methyl ester preparation from soybean fatty acids and saponification of soybean triglycerides followed by esterification. The reaction chamber of the MRA has been redesigned to increase its versatility and to reduce explosion hazards when diazomethane is used. Advantages of the MRA over other systems are less handling of sample, minimum hazards due to small sample size and direct injection of products into analytical instruments, such as a gas chromatograph or mass spectrometer. Presented at AOCS Meeting, Minneapolis, Minn., October 1969. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Lipase Immobilized Methacrylate Polymer Monolith Microreactor for Lipid Transformations and Online Analytics

This communication entails development of a facile continuous flow lipase immobilized poly(glycidyl methacrylate-co-ethylene dimethacrylate (poly(GMA-co-EDMA)) monolith microreactor for application in lipid transformations. Candida antarctica lipase B was covalently immobilized on poly(GMA-co-EDMA) monolith prepared in a 700-μm (internal diameter) silica capillary. The specific activity of the immobilized lipase was calculated to be 30 ± 0.03 U/mg, where U refers to μg p-nitrophenol generated/min from 3.5 mM p-nitrophenyl butyrate solution. The microreactor performance was further tested for synthesis of lauryl laurate via esterification. Conversions of up to 97 % were realized at a flow rate of 10 μL/min of a mixture of 0.1 M in both lauric acid and lauryl alcohol. These microreactors could be reused at least 15 times over a 1 month time period, stored at room temperature, with minimal to no reduction in the activity of the enzyme. We have also demonstrated microreactors to be useful for facile transesterification of castor oil triglycerides with online ESI–MS analytics key in lipidomics applications.     

Catalytic Performance of Activated Carbon Supported Tungsten Carbide for Hydrazine Decomposition

Activated carbon (AC) supported tungsten carbide was reported for the catalytic decomposition of hydrazine for the first time. It was found that the WC _x /AC-H catalyst prepared by a carbothermal hydrogen reduction process exhibited excellent catalytic performances both in the microreactor and in a 1 Newton hydrazine microthruster. The XRD, TEM and microcalorimetry results suggest that the formation of well crystallized W₂C phase, the restraining of the carbon deposition, as well as the prohibiting of the methanation should be responsible for the high activity and stability of the WC _x /AC-H catalyst in the hydrazine decomposition reaction.     

Properties of cellulose xanthate solutions prepared in an organic solvent

Conclusions 1. To compare the properties of cellulose xanthates made by xanthation of alkali cellulose in an organic solvent medium, in a quasi-liquid state and in carbon disulphide vapour, the change in the properties of xanthate solutions with time was studied.2. Solutions of quasi-liquid xanthate differ by increased viscosity and decreased ripeness, which involves increased structure-formation in the solution, because of the higher degree of polymerisation of the cellulose and the lower degree of esterification of the cellulose xanthate.3. The decomposition rate of quasi-liquid xanthate in the initial ripening period of the viscose is higher than the decomposition rate of standard xanthate because of the increased degree of esterification of the secondary hydroxyl groups of the cellulose macromolecules, and the complication of secondary esterification of cellulose xanthate in solution.All-Union Scientific Research Institute for Man-Made Fibres. Translated from Khimicheskie Volokna, No. 2, pp. 33–35, March–April, 1969.     

Gas-liquid flow mass transfer in a T-shape microreactor stimulated with 1.7 MHz ultrasound waves

This paper describes the application of ultrasound waves on hydrodynamics and mass transfer characteristics in the gas-liquid flow in a T-shape microreactor with a diameter of 800 μm.A 1.7 MHz piezoelectric transducer (PZT) was employed to induce the vibration in this microreactor.Liquid side volumetric mass transfer coefficients were measured by physical and chemical methods of CO2 absorption into water and NaOH solution.The approach of absorption of CO2 into a 1 mol· L-1 NaOH solution was used for analysis of interfacial areas.With the help of a photography system,the fluid flow patterns inside the microreactor were analyzed.The effects of superficial liquid velocity,initial concentration of NaOH,superficial CO2 gas velocity and length of microreactor on the mass transfer rate were investigated.The comparison between sonicated and plain microreactors (microreactor with and without ultrasound) shows that the ultrasound wave irradiation has a significant effect on kLa and interfacial area at various operational conditions.For the microreactor length of 12 cm,ultrasound waves improved kLa and interfacial area about 21％ and 22％,respectively.From this study,it can be concluded that ultrasound wave irradiation in microreactor has a great effect on the mass transfer rate.This study suggests a new enhancement technique to establish high interfacial area and kLa in microreactors.     

A mathematical model for computer simulation of a direct continuous esterification process between terephthalic acid and ethylene glycol

To study the effect of potassium titanium oxyoxalate on the esterification reaction of terephthalic acid (TPA) and ethylene glycol (EG) in the first tank reactor of TPA/EG continuous esterification, experiments at various addition rates of potassium titanium oxyoxalate were made in the pilot plant. Potassium titanium oxyoxalate accelerated the esterification reaction of TPA and EG. Also, reaction rate constants of the reaction scheme reported in a previous report were fitted with the experimental results, and the calculated values of physical properties of oligomers obtained from these reaction rate constants showed relatively good agreement with experimentally obtained physical properties of the oligomers. The effect of potassium titanium oxyoxalate on the reaction rate constants was expressed by a set of seven equations: Using the resultant reaction rate constants, the esterification reaction at various addition rates of potassium titanium oxyoxalate were stimulated and the following conclusions drawn:

• 1 Under low pressure close to atmospheric, when the amount of water in the reaction mixture is very low, the decomposition of potassium titanium oxyoxalate proceeds slowly and decomposition can be practically neglected.
• 2 Potassium titanium oxyoxalate accelerates the esterification reaction.
• 2 Potassium titanium oxyoxalate mainly accelerates the main reactions and its effects on side reactions are rather weak. As a result, the higher the addition rate of potassium titanium oxyoxalate, the lower the values of AV and DEG, as is preferable.

     

松香甘油酯与甲基丙烯酸-2-羟乙酯的反应研究

松香甘油酯中的共轭双键可以与甲基丙烯酸-2-羟乙酯(HEMA)发生Diels-Alder加成发应,同时松香甘油酯具有一定的酸值,其中未反应的松香可与HEMA进行酯化反应。研究了反应温度和物料配比对加成反应和酯化反应的影响,并对产物进行了红外光谱(FT-IR)分析和热重分析。实验结果表明,反应温度升高,加成反应和酯化反应的速率会加快,230℃是理想的反应温度;随着n(HEMA)∶n(松香甘油酯)比值的增加,产物的酸值和溴值下降,当n(HEMA)∶n(松香甘油酯)=3.0∶1时,溴值(65.2 g Br/100 g)和酸值(2.95 mg KOH/g)最低;FT-IR分析表明HEMA已经连接到松香甘油酯的分子上;热重分析表明加成物的初始分解温度提高了10℃,而最终分解温度下降了11.8℃。     

γ-Al_2O_3负载的Ni_xCo_(1-x)Co_2O_4催化剂N_2O催化分解性能

以K_2CO_3为沉淀剂,γ—Al_2O_3为载体,采用共沉淀法制备了负载质量分数为30%和具有Co_3O_4尖晶石结构的Ni_xCo_(1-x)Co_2O_4复合金属氧化物催化剂(x分别为0、0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9和1.0),确定了最适宜的x值。考察了焙烧温度对催化剂的影响,对制备的样品进行了XRD、BET、SEM和H_2-TPR等表征,在微反装置上对催化剂进行N_2O催化分解活性评价。结果表明,适宜的x值为0.5,焙烧温度为800℃。N_2O和O_2浓度是影响催化剂的N_2O催化分解转化率的主要因素,低浓度有利于提高N_2O催化分解转化率。掺杂还原性气体(如CO和NO)加速了N_2O催化分解反应,有利于提高催化剂的N_2O催化分解转化率。在模拟工业装置反应尾气[φ(N_2O)=12%、φ(O_2)=16.8%和其他混合气体]条件下,催化剂N_2O完全催化分解温度为612℃,满足实际工业生产装置运行要求(小于750℃)。     

On the Mechanism of the Oxidative Amination of Benzene with Ammonia to Aniline Over NiO/ZrO2 as Cataloreactant

The kinetics of the semi-batch oxidative synthesis of aniline under atmospheric pressure using DuPont’s NiO/ZrO₂ cataloreactant was studied in a microreactor flow set-up equipped with a calibrated online mass spectrometer. It was found that the reaction temperature is a crucial parameter for the selectivity to aniline. At 590 K, exclusively aniline was formed, whereas at higher temperatures the decomposition of benzene into C-1 fragments led to the formation of toluene and benzonitrile. TPO experiments carried out in the same reactor subsequent to isothermal aniline synthesis allowed us to derive the degree of coking and the degree of NiO reduction.     

Rapid Hydrogen Peroxide Decomposition Using a Microreactor

The rapid decomposition of hydrogen peroxide (H₂O₂) is often desired in the cleanup of excess H₂O₂ when it is used as an oxidant. Although the decomposition process has been studied in batch reactors, it has never been performed before in a fixed‐bed microreactor with residence time on the scale of seconds. With enhanced mass and heat transfer in microreactors, higher H₂O₂ decomposition efficiency compared to batch reactors was obtained. A variety of parameters including length of microchannels, flow rate, solvent composition, and gas pressure were examined carefully and a first‐order kinetic model was established. Within a few seconds, more than 70 % of the H₂O₂ was decomposed successfully. The challenge of catalyst passivation was discussed as well.     

Overall kinetics of hydrogen peroxide formation by direct combination of H2 and O2 in a microreactor

Direct combination (DC) of hydrogen and oxygen over a heterogeneous catalyst in a microreactor is a novel method of producing hydrogen peroxide with significant economic advantages over the currently dominant anthraquinone autoxidation method. A kinetic rate expression for this reaction is required for design and modeling of a microreactor for the DC process. Since the formation of H₂O₂ by the DC process involves four simultaneous reactions (synthesis of H₂O₂, synthesis of water, reduction of H₂O₂ by H₂ and decomposition of H₂O₂), the overall rate expression must take into account each of these reactions. In this work, we describe a reactor model that involves the four component reactions as well as mass transfer effects. The model is verified by comparing the predicted reactor performance with experimental data. In addition to providing a tool for reactor design, the model also confirms important assumptions regarding the mechanism of DC reaction.     

微反应器在化工行业中的应用

微反应器工艺技术应用在化工行业中是未来的—个重要发展趋势,微流体技术的出现为化工工艺的发展提供了策略。微反应器同普通的反应器相比具有过程强化、安全性提高、产品性能提高、易实现工业化生产等优势。纳米材料与微反应器技术相结合为进一步研究新型的纳米材料和新型反应器提供了巨大的机会和推动力。本文概述了微反应器的优点,并重点对微反应器在化工行业中制备纳米颗粒物质的应用进行了综述。     

Organocatalyzed Beckmann rearrangement of cyclohexanone oxime in a microreactor: Kinetic model and product inhibition

The kinetic study of Beckmann rearrangement of cyclohexanone oxime catalyzed by trifluoroacetic acid and acetonitrile in a microreactor is presented in this article. Parametric studies are conducted varying temperature, ratio of trifluoroacetic acid to acetonitrile, and concentration of cyclohexanone oxime. The inhibition effect of ?‐caprolactam in this reaction system is firstly reported. A comprehensive mathematic kinetic model considering the product inhibition effect of caprolactam has been developed in the temperature range of 368–391 K, which agrees well with the experimental results across a broad experimental parameter space. In addition, kinetic study indicates that the esterification of cyclohexanone oxime and transposition reaction of the intermediate are both supposed to be the rate‐determining steps, and in this catalyst system, the ratio of trifluoroacetic acid and acetonitrile mainly influences the reaction rate and the activation energy of the transposition step. The developed model could provide much reliable knowledge for industrial application. © 2017 American Institute of Chemical Engineers AIChE J, 64: 571–577, 2018     

γ-Al2O3负载铜锌氧化物催化剂的N2O催化分解性能

以γ-Al₂O₃为载体,采用共浸渍法合成了负载量为35%（以CuO与ZnO总质量计）的CuZn金属氧化物催化剂,分别考察了金属助剂（Co、Ni,、Mg、Fe、Mn、Ba和Ce）对催化剂的影响。采用XRD、BET和H₂-TPR等方法对制备的催化剂进行表征,在微反装置上对催化剂的N₂O催化分解活性进行评价。结果表明,合成的CuZn氧化物催化剂均具有CuxZn_1-xAl₂O₄的类Co₃O₄尖晶石结构;加入金属助剂使催化剂的比表面积不同程度得到提高,催化剂的N₂O催化分解反应活性不仅与Cu³⁺还原为Cu²⁺的温度有关,还与晶粒尺度大小和催化剂比表面积等有关;其中,含金属助剂Ni的催化剂具有相对较高的N2O催化分解反应活性,其N₂O完全转化温度为567 ℃。除含金属助剂Ba催化剂以外,加入其他金属助剂有利于N₂O催化分解反应进行。