氟碳法合成CF4反应器结构及工艺条件优化的研究

针对氟碳法合成CF₄因反应剧烈、放热量大而存在的安全隐患及反应收率较低的问题,以氟碳反应器为研究对象,对影响反应器安全高效性的内部结构和影响反应收率的工艺参数进行了研究。根据现有反应器的结构缺陷对其进行改进,研究新型反应器的安全生产条件。结果表明,新型反应器可以在不使用抑爆剂的条件下实现安全高效生产,极大地降低了能耗和设备成本。通过单因素试验,研究了反应温度、反应压力和氟气流量对反应收率的影响。基于单因素试验结果和因素间的交互作用,进行了两因素三水平三重复试验和方差分析,以提升反应收率为目标对工艺参数进行优化,筛选出最优的工艺参数组合。以筛选出的最优工艺参数组合进行验证性试验,结果表明使用该工艺参数组合的反应收率为94.87%,单台反应器的CF₄产能为13.73kg·h^-1、每小时电耗为242.63kW·h,具有极高的经济价值。     

微通道中硝基胍的连续流合成工艺研究

以硫酸胍和硝硫混酸为原料,在微通道中进行管式流动硝化反应,形成了硝基胍的连续流合成工艺。研究了混酸浓度、反应温度、停留时间、物料摩尔比等工艺参数对合成反应的影响。获得的优化工艺参数为：90%HNO3:98%H2SO4=2:1(v/v),反应物与硝酸摩尔配比为1:1.2,反应温度为60 ℃,停留时间为30 s,此时硫酸胍的转化率为87.9%,硝基胍收率为86.1 %。与传统间歇釜式合成工艺相比,连续流工艺实现了硝基胍合成反应的稳定进行,消除了过程反应热的积累和温度波动,解决了硝基胍的合成安全性问题,缩短了反应时间,提高了产率,减少了废酸排放量。     

微反应器内邻氨基苯甲酸甲酯的连续重氮化工艺

邻氨基苯甲酸甲酯（MA）的重氮盐是一种典型的重氮化合物,因其具有高化学选择性可高效合成结构复杂分子被广泛应用于现代有机合成领域。传统半间歇合成工艺中的固有缺陷以及MA重氮盐的潜在爆炸性,限制了其在工业规模上的应用。本文基于此提出了在“心形结构”的高通量微通道反应器内合成MA重氮盐的连续流工艺。在单因素实验的基础上,采用Box-Behnken design（BBD）中心组合原理构建响应面模型对工艺进行优化,研究了不同反应条件之间交互效应对反应的影响并与实验室规模的半间歇合成工艺进行了比较。结果表明,微反应器内连续重氮化合成工艺对降低因素交互效应、提高工艺可控性、抑制平行副反应有显著的效果。经优化后的最佳工艺条件为n(MA)∶n(亚硝酸钠)∶n(盐酸)=1∶1.15∶2.67,反应温度为34.62℃,停留时间为45.07s,在此条件下MA重氮盐收率可达92%,相比于半间歇合成工艺提高了10%。这种新的合成方式可有效解决传统半间歇工艺中重氮化合成体系对温度的高敏感性,避免了反应温度控制困难、高潜在热失控风险带来的安全隐患。     

在微结构反应器中制备双酚A环氧丙烯酸树脂

为了解决釜式反应器制备双酚A环氧丙烯酸树脂(EA)过程中存在温度控制难、反应周期长和稳定性差等问题,采用具有高效传热和传质能力的微结构反应器来合成EA。研究了反应温度、流速、停留时间、催化剂种类及用量、管径对反应的影响,优化出最佳制备工艺。采用傅里叶红外光谱(FT-IR)对产物EA结构进行了表征。结果表明:应用微结构反应器可以成功制备EA。最佳制备条件如下:反应温度140 ℃,流速3.05 mL/min,停留时间4 min,管径1 mm,催化剂选用三苯基膦且用量为双酚A环氧树脂(EP)质量的2%。在最佳制备条件下,丙烯酸和环氧基的转化率分别为99.1%和96.3%。固化涂膜的附着力、铅笔硬度和耐磨性等,均达到了使用要求。     

微通道中硝基胍的连续流合成

以硫酸胍和硝硫混酸为原料,在微通道中进行管式流动硝化反应。考察了混酸浓度、反应温度、停留时间、物料比对反应的影响。获得的优化工艺参数为:V(质量分数80%HNO_3)∶V(质量分数98%H_2SO_4)=2∶1,n(硫酸胍)∶n(硝酸)=1∶1.2,反应温度为60℃,停留时间为30 s,此时硫酸胍的转化率为87.9%,硝基胍收率为86.1%。与传统间歇釜式合成工艺相比,连续流工艺实现了硝基胍合成反应的稳定进行,消除了过程反应热的积累和温度波动,缩短反应时间。     

溶聚丁苯橡胶生产技术专利综述

介绍了近60年来溶聚丁苯橡胶生产技术专利的申请量变化趋势及主要申请企业,重点总结了与溶聚丁苯橡胶生产相关的工艺、聚合反应器结构、链结构调控等方面的专利技术。目前溶聚丁苯橡胶的釜式聚合工艺较为成熟并广泛使用,管式反应器聚合工艺和挤出反应聚合工艺仍待进一步开发;连续釜式聚合工艺应通过优化聚合釜结构和聚合工艺来提高运行的平稳性和产品质量;通过调控聚合工艺将不同聚合物的链段特性集合到一条聚合物链上,可以得到性能优异的产品。对溶聚丁苯橡胶生产技术的发展方向提出了建议。     

响应面法优化微通道反应器中巴柳氮的合成工艺

以N-对氨基苯甲酰-β-丙氨酸为原料，利用Box-Behnken设计-响应面法优化微通道反应器中巴柳氮合成工艺，采用Box-Behnken设计试验优化重氮化反应停留时间、水杨酸量以及偶合反应停留时间对巴柳氮产率的影响，并对合成工艺进行优化。结果表明，微通道反应器内巴柳氮反应最优条件为：重氮化反应停留时间为21.15s、水杨酸量0.24mol、偶合反应停留时间172.64s,巴柳氮产率为89.01%,与模型预测值仅相差0.35%。该工艺可为巴柳氮工业化生产改进提供一定的参考。     

微通道反应器内合成高纯度碘化钾

利用微通道反应器,研究了氢碘酸、甲酸溶液及氢氧化钾合成碘化钾的反应,考察了反应温度、原料配比、停留时间对碘化钾产率的影响。获得了较优的反应工艺条件,反应温度为85℃、停留时间为30 s、m(氢碘酸)∶m(甲酸)=54%、m(氢氧化钾)∶m(水)=31%。在该优化工艺条件下,碘化钾的产率为97%,产品纯度达到99%。实验结果表明,该方法具有反应时间短、产品收率高、绿色环保等优点。     

气相SO3磺化甲苯工艺研究进展

本文综述了气相三氧化硫磺化甲苯制取对甲苯磺酸的反应机理及工艺条件,阐述了设备及工艺条件等诸多因素对反应的影响。指出气相SO3磺化甲苯具有反应速度快,强放热,反应体系粘度大的特点,为了得到高质量的对甲苯磺酸,减少副产物的生成,需要在设备和工艺两方面做研究。一方面,反应器是磺化反应的核心,应具有快速均匀混合和良好的质热传递性能;另一方面,工艺条件应根据反应的特点进一步优化。     

湿式氧化法治理棉浆黑液中试及反应器工艺设计原理

本文对湿式氧化治理棉浆黑液过程,进行了试验研究,考察了湿式氧化 COD 的宏观反应动力学和传质特性。通过对传质和反应的理论分析,为中试提出了单泡罩鼓泡环流厨应器型式。采用氧化—苛化—循环回用的工艺路线,在5.4～5.9 MPa、240～250℃、黑液平均停留时间为0.7小时的条件下,氧化结果获得 COD 转化率为42～48%,去色率大于95%,总碱回收率达90%以上。氧化液循环回用符合生产要求,反应器结构合理,操作稳定,能满足工艺和反应的要求。     

Analysis and optimal design of an ethylene oxide reactor

In this work, a recently proposed multi-level reactor design methodology (Peschel et al., 2010) is extended and applied for the optimal design of an ethylene oxide reactor. In a first step, the optimal reaction route is calculated taking various process intensification concepts into account. The potential of each reaction concept can be efficiently quantified, which is the economic basis for the design of advanced reactors. Based on these results, a promising concept is further investigated and a technical reactor is designed. As an extension to the design method, reactor design criteria for external and internal heat and mass transfer limitations are directly included in the optimization approach in order to design the catalyst packing. The derived reactor concept is investigated with a detailed 2D reactor model accounting for radial concentration and temperature gradients in addition to a radial velocity profile.The example considered in this work is the production of ethylene oxide which is one of the most important bulk chemicals. Due to the high ethylene costs, the selectivity is the main factor for the economics of the process. A membrane reactor with an advanced cooling strategy is proposed as best technical reactor. With this reactor design it is possible to increase the selectivity of the ethylene epoxidation by approximately 3% compared to an optimized reference case.     

Experimental investigation of fast-mode liquid modulation in a trickle-bed reactor

Unsteady-state operation of trickle-bed reactors (TBRs) is a promising technique to improve reactor performances especially when mass transfer phenomena are rate controlling. Among the different techniques, fast-mode modulation of the liquid flow rate seems to be one of the most successful. In fact cycling the liquid flow rate at very low frequencies can induce the reactor to work at the high-interaction regime where mass and heat transfer phenomena are strongly enhanced. Fast-mode periodic operation, then, can be considered an extension of the natural high-interaction regime at a mean range of gas and liquid flow rate normally associated with trickling regime in steady-state conditions.Experimental tests have been performed in a TBR employing α-methyl styrene hydrogenation on Pd/C catalyst in unsteady-state conditions by “on-off” fast-mode liquid modulation. Results have been compared with the steady-state experiments at the corresponding average liquid flow rate, revealing a conversion rate improvement up to 60%. All experiments have been performed in isothermal conditions, so conversion improvement can be ascribed only to mass transfer increase and not to thermal effects. The variation of gas and liquid flow rates and liquid cycle parameters presented several important implications about the optimal working conditions.     

Deep desulfurization of diesel oil: kinetic studies and process-improvement by the use of a two-phase reactor with pre-saturator

Desulfurization of liquid fuels is usually obtained by heterogeneous catalyzed hydrodesulfurization (HDS). Improvement of this process is needed, particularly with respect to future low residual S-contents of about . Up to now HDS of diesel oil is performed in a trickle bed reactor equipped with an expensive H₂-recycle, although the H₂-supply is far beyond the amount chemically consumed, at least for deep HDS of an already hydrotreated feed. In addition, scale up of trickle bed reactors is in general problematic. In this work kinetic studies and above all a new HDS-concept using a two-phase reactor is presented. Thereby the oil is externally pre-saturated with H₂ and only the liquid phase is passed over the catalytic fixed bed. The H₂-recycle is then redundant, the intrinsic reaction rate can be utilized, and scale-up problems do not occur. In addition, this concept can also be used for HDS of oils with a higher content of sulfur and/or unsaturated hydrocarbons by installing a liquid recycle.     

Fluidised bed membrane reactor for ultrapure hydrogen production via methane steam reforming: Experimental demonstration and model validation

Hydrogen is emerging as a future alternative for mobile and stationary energy carriers in addition to its use in chemical and petrochemical applications. A novel multifunctional reactor concept has been developed for the production of ultrapure hydrogen from light hydrocarbons such as methane for online use in downstream polymer electrolyte membrane fuel cells. A high degree of process intensification can be achieved by integrating perm-selective hydrogen membranes for selective hydrogen removal to shift the methane steam reforming and water-gas-shift equilibriums in the favourable direction and perm-selective oxygen membranes for selective oxygen addition to supply the required reaction energy via partial oxidation of part of the methane feed and enable pure CO₂ capture without costly post-treatment. This can be achieved in a proposed novel multifunctional bi-membrane bi-section fluidised bed reactor [Patil, C.S., van Sint Annaland, M., Kuipers, J.A.M., 2005. Design of a novel autothermal membrane assisted fluidized bed reactor for the production of ultrapure hydrogen from methane. Industrial and Engineering Chemistry Research 44, 9502-9512]. In this paper, an experimental proof of principle for the steam reforming/water-gas-shift section of the proposed novel fluidised bed membrane reactor is presented. A fluidised bed membrane reactor for steam reforming of methane/water-gas-shift on a commercial noble metal-based catalyst has been designed and constructed using 10 H₂ perm-selective Pd membranes for a fuel cell power output in the range of 50-100 W. It has been experimentally demonstrated that by the insertion of the membranes in the fluidised bed, the thermodynamic equilibrium constraints can indeed be overcome, i.e., increased CH₄ conversion, decreased CO selectivity and higher product yield (H₂ produced/CH₄ reacted). Experiments at different superficial gas velocities and also at different temperatures and pressures (carried out in the regime without kinetic limitations) revealed enhanced reactor performance at higher temperatures and pressures (3-4 bar). With a phenomenological two-phase reactor model for the fluidised bed membrane reactor, incorporating a separately developed lumped flux expression for the H₂ permeation rate through the used Pd-based membranes, the measured data from the fluidised bed membrane reactor could be well described, provided that axial gas back-mixing in the membrane-assisted fluidised bed reactor is negligible. This indicates that the membrane reactor behaviour approached that of an ideal isothermal plug flow reactor with maximum H₂ permeation.     

A sensitivity analysis and multi-objective optimization to enhance ethylene production by oxidative dehydrogenation of ethane in a membrane-assisted reactor

Owing to the importance of process intensification in the natural gas associated processes, the present contribution aims to investigate the production of an important natural gas downstream product in an improved system. Accordingly, a membrane-assisted reactor for the oxidative dehydrogenation of ethane is presented. The presented system includes a membrane for axial oxygen dosing into the reaction side. Such a strategy would lead to optimum oxygen distribution along the reactor length and prevention of hot spot formation as well. A feasibility study is conducted by developing a validated mathematical model composed of mass and energy balance equations. The effects of various operating variables are investigated by a rigorous sensitivity analysis. Then, by applying the genetic algorithm, a multi-objective optimization procedure is implemented to obtain the optimum operating condition. Considerable increase in the ethane conversion and ethylene yield are the advancements of membrane-assisted oxidative dehydrogenation reactor working under the optimum condition. More than 30% increase in the ethane conversion is obtained. Furthermore, the ethylene yield is enhanced up to 0.45.     

New generalized strategy for improving sorption-enhanced reaction process

The generalized principle of temperature-induced equilibrium shift was applied to improve the sorption-enhanced reaction (SER) process by controlling the subsection-wall temperature. The other auxiliary subsection-controlling parameters include the number of subsections, the subsection-packing ratio of adsorbent and catalyst, and the side-feed/removal position of the reactants/products. In this paper, a four-step one-bed with three-subsections SER process for steam-methane reforming was taken as an example for hydrogen production, where higher temperature (about 450-490°C) was adopted for subsections-I (inlet zone of the adsorptive reactor) and -II (middle zone of the adsorptive reactor) and lower temperature (about 400-450°C) for subsection-III (outlet zone of the adsorptive reactor), lower packing ratio of adsorbent and catalyst for subsections-I and -III and higher ratio for subsection-II. The feasibility and effectiveness of the subsection-controlling strategy for improving the SER process is analyzed by numerical simulation based on the basic data from literature. A product gas with above 85% hydrogen purity and traces of CO₂ (less than ) and CO (less than ) was continuously produced by using a long adsorptive reactor with three-subsections and can be directly used in fuel cell applications. The results show that subsection-controlling strategy is an easy and efficient way. The remarkable characteristics of this new process are: (1) the concentrations of CO and CO₂ decrease greatly in the product gas due to the principle of temperature-induced equilibrium-shift, (2) the hydrogen productivity (mole of hydrogen/kg of solid per cycle; CO is less than ) is over twice as large as in the normal SER process, (3) the length of unused bed for adsorption is apparently reduced, and (4) the regeneration of adsorbent can be performed by steam at normal atmospheric pressure.     

Catalytic combustion assisted methane steam reforming in a catalytic plate reactor

A theoretical study of methane steam reforming coupled with methane catalytic combustion in a catalytic plate reactor (CPR) based on a two-dimensional model is presented. Plates with coated catalyst layers of order of micrometers at distances of order of millimetres offer a high degree of compactness and minimise heat and mass transport resistances. Choosing similar operating conditions in terms of inlet composition and temperature as in industrial reformer allows a direct comparison of CPRs with the latter. It is shown that short distance between heat source and heat sink increases the efficiency of heat exchange. Transverse temperature gradients do not exceed across the wall and across the gas-phase, in contrast to difference in temperature of outside wall and mean gas phase temperature inside the tube usually observed in conventional reformers. The effectiveness factors for the reforming chemical reactions are about one order of magnitude higher than in conventional processes. Minimisation of heat and mass transfer resistances results in reduction of reactor volume and catalyst weight by two orders of magnitude as compared to industrial reformer. Alteration of distance between plates in the range 1- does not result in significant difference in reactor performance, if made at constant inlet flowrates. However, if such modifications are made at constant inlet velocities, conversion and temperature profiles are considerably affected. Similar effects are observed when catalyst layer thicknesses are increased.     

A new reactor coupling heterogeneous Fenton‐like catalytic oxidation with membrane separation for degradation of organic pollutants

BACKGROUND: There is growing interest in employing heterogeneous Fenton‐like catalysts in slurry to obtain higher activity. However, fine size particles create problems associated with recovery from the treated water. Therefore, it is highly desirable to develop a novel Fenton‐like process that not only has high degradation efficiency of organic pollutants, but also allows for easily reusing the catalysts. RESULT: A new reactor was investigated by coupling the heterogeneous Fenton‐like oxidation with membrane separation. Results showed that the FeY catalyst could be almost filtrated by a submerged micro‐filtration membrane in the reactor to continuously activate H₂O₂. For a FeY dose of 1 g L^?1 and a residence time of 120 min, the degradation efficiency of AO II reached 97%. CONCLUSIONS: In the new reactor, degradation of AO II occurred continuously and efficiently without an additional FeY separation process. The treatment capacity of this FeY catalyst for wastewater containing 100 mg L^?1 AO II in the reactor was estimated to be 82 times that of a reactor in which the catalyst could not be reused. The distinguishing technical feature of this reactor was the reuse of the Fenton‐like catalyst. Copyright © 2011 Society of Chemical Industry     

生物膜反应器SBBR的动力学研究

采用序批式生物膜反应器(SBBR)处理经Fenton预处理后的偶氮染料活性嫩黄K-6G模拟染料废水。试验结果表明:该反应器的COD去除效果稳定,平均去除率达63%,且具有一定抗冲击负荷能力;好氧段COD降解过程服从扩散控制下的生物膜反应动力学模型:rA=1.69(S-55.2),其中包含扩散作用的膜表面反应速率常数k1A为1.69 m/d,生化反应速率常数k1Vf为47 867～95 733 d-1。     

用于分布式制氢的甲烷蒸汽重整膜反应器的数值模拟

采用反应-分离集成的膜反应器进行分布式制氢,对简化工艺、降低能耗、提升技术经济性至关重要。本文采用数学模型对甲烷蒸汽重整制氢过程膜反应器进行模拟,系统分析了渗透侧操作策略、反应压力、反应温度、钯基膜性能、催化剂性能对反应器行为的影响;并以1m³/h甲烷最大程度转化为目标进行分布式制氢案例分析,详细比较膜反应器技术与“常规反应器+膜分离”工艺技术。结果表明,膜反应器在反应压力30atm（1atm=101325Pa）、反应温度500℃下操作可实现紧凑设计,比“常规反应器+膜分离”工艺技术具有明显优势,但是亟需研发更佳活性（10倍）的钯基膜和催化剂以实现显著的过程强化。模拟结果可为不同规模分布式制氢膜反应器的操作与设计及进一步的性能强化提供指导。