光催化-膜分离耦合技术的水处理应用研究进展

介绍光催化-膜分离耦合工艺,它是在传统光催化技术中粉末催化剂难分离回收和废水处理后水质不够理想的基础上进行研发的。总结了不同构型的光催化膜反应器的特点及其存在的局限性,并简述了新型光催化膜反应器工艺运行时需考虑的因素。分析表明悬浮型光催化膜反应器的光催化效率明显高于负载型光催化膜反应器;针对悬浮式光催化膜反应器面临的由压力驱动引起的高能量输入和膜污染问题,指出光催化与渗透气化或膜蒸馏联用工艺所具有的独特优势。认为光催化/膜分离耦合工艺在水处理领域具有重要前景,今后研究应集中在高活性光催化剂的开发、高抗氧化性和耐污染的膜制备及光催化膜反应器结构的优化上。     

悬浮型光催化-膜分离反应器研究进展

悬浮型光催化反应体系因比表面积大和传质快等优点而具有较高光催化效率,但催化剂的分离回收工艺复杂,提高了工业成本。利用膜分离技术与悬浮型反应器耦合,可较好的解决固液分离问题,提高工艺经济性,代表了悬浮型光催化反应器的发展方向。本文重点对国内悬浮型光催化-膜分离反应器的研究进展进行综述,展望了该技术的发展方向。     

太阳能光催化反应器的研究进展

为促进太阳能光催化反应器的研究和开发,从反应器中催化剂的存在形态、反应器的聚光形式以及应用3个方面对太阳能光催化反应器的研究现状进行了系统的综述,对催化剂悬浮型和固定膜型反应器以及聚光型和非聚光型反应器进行了比较,并分析了反应器在实际废水处理或者大批量处理中应用的可行性。     

固定式填充复合床光催化反应器设计影响因素的研究

设计了一种固定式填充复合床光催化反应器，以亚甲基兰为模型污染物，对负载型催化剂在反应器申的设置方式、反应器的外形结构、溶液的pH值和光源的光强等主要因素在设计过程申的影响进行了研究，为该类型光催化反应器工业放大设计提供了理论依据。     

新颖填充床光催化反应器的辐射能分布模拟

采用以玻璃弹簧为载体的新颖负载型光催化剂 ,设计实验测试该催化剂的辐射能分布状况 ,通过实验测量修正双通量模型的参数 ,并使用修正双通量模型进行计算 ,上述实验值与理论计算值吻合较好 ,说明修正双通量模型可准确模拟多相光催化反应器的辐射能传递行为 .最后 ,采用该模型描述了由此负载型催化剂构成的平板式填充床光催化反应器内的辐射能分布和吸收状况     

固定膜太阳能光催化反应器的研究现状与展望

通过对负载在颗粒状、玻璃棒类、玻璃纤维网、纸质材料和平板型载体上的固定膜催化剂的比较,提出以玻璃纤维网、纸质材料和平板型材料为载体的固定膜催化剂是太阳能光催化反应器研究的良好选择。概述了薄膜瀑布反应器、阶梯反应器和复合抛物面反应器3种新型固定膜太阳能光催化反应器,并指出了未来太阳能光催化技术的研究方向。     

耦合分离膜对悬浮型光催化纳滤膜反应器耦合工艺特性的影响研究

以阿特拉津(atrazine)模拟废水作为处理对象,采用3种不同种类和性质的纳滤膜与悬浮型光催化氧化过程进行耦合构成悬浮型光催化纳滤膜反应器的废水耦合处理工艺,比较耦合纳滤分离膜的种类和性质对光催化膜反应器处理atrazine模拟废水耦合工艺特性的影响.实验得出,由于对目标污染底物及主要光催化降解中间产物出色的选择性分离截留效果,将TS-60与光催化膜反应器进行耦合处理目标废水的处理效果最佳.     

光催化膜反应器用于亚甲基蓝的降解

研究了催化剂颗粒粒径对降解速率的影响,并将光催化反应和膜分离技术相结合,开发了光催化膜反应器。利用该反应器对亚甲基蓝进行降解的结果表明,亚甲基蓝可被很快地降解,而悬浮在反应液里的催化剂颗粒同时可被有效地分离回收并连续地在反应器里使用。     

多相光催化反应工程介绍

多相光催化反应工程是化学反应工程学科的新领域.对近年来国内外有关多相光催化反应器模拟和设计研究现状进行了总结,探讨了辐射能传递行为、反应动力学和反应的温度效应;阐述了多相光催化反应器的设计因数,包括光源、几何形状、制造材料、热交换、混合和流动特性以及催化剂的放置;介绍了气固相和气液固3相光催化反应器的类型并分析了优缺点.认为现今反应器的设计方法仍然是用经验和半经验近似处理,仍需进行大量的基础研究和开发工作,以促进多相光催化技术的应用.     

光催化反应器的设计与应用研究进展

光催化技术在污水处理领域的广泛应用,促使光催化反应器的设计及研发日趋加快.本文就光催化反应器及其发展史进行了概述,归纳总结了各类典型光催化反应器的优势与不足之处,着重讨论了目前研究比较普遍的管式和环式光催化反应器,以及膜组件耦合技术、磁化技术在光催化反应器设计领域的应用.分析表明,多技术联合光催化反应器的设计与研发是未...     

Mathematical simulations of the performance of trickle bed and slurry reactors for methanol synthesis

Three- and two-phase reactor models were developed to simulate the performance of trickle bed and slurry reactors for methanol synthesis. The combination of orthogonal collocation and quasi-linearization was used to solve the trickle bed reactor model incorporating resistance to interparticle and intraparticle diffusion and resistance to mass transfer between gas and liquid phases. Model parameters were estimated independently from either published correlations or literature data. The model predicts significant resistance to intraparticle diffusion on the performance of trickle bed reactors. However, comparisons between pilot size trickle bed and slurry reactors illustrate the superior performance of trickle bed reactors over the slurry reactors for methanol synthesis even with diffusion limitations.     

Measurement and enhancement of gas-liquid mass transfer in milliliter-scale slurry reactors

Due to the limited availability of chemical reactants in the early process development of pharmaceuticals and fine chemicals, and sometimes the high-cost of catalyst, it is increasingly popular to use milliliter-scale slurry reactors with reaction volumes of 20 ml or less to screen catalyst candidates for three-phase reactions. To ensure the success of catalyst screening, it is advantageous to run reactions under kinetically controlled conditions so that the activities of different catalysts can be compared. Because catalysts with small particle sizes are used in slurry reactors, the reactions are susceptible to gas-liquid mass transfer limitations. This work presents an efficient way of enhancing gas-liquid mass transfer in milliliter-scale reactors through the use of magnetically driven agitation with complex motion. In the reactor described here, gas-liquid mass transfer coefficients can be doubled over those obtained with the agitation technique used in commercial milliliter-scale units. In addition, the reactor can achieve the top range of mass transfer coefficients obtained in a full-scale reactor. This work also presents the first measurements of gas-liquid mass transfer coefficients in milliliter-scale reactors, which are two orders-of-magnitude smaller than systems for which mass transfer coefficients have been reported earlier. Both physical and chemical absorption techniques are used.     

浆态床反应器流体力学行为研究及工业应用

浆态床是一种重要的气-液-固三相反应器,具有结构简单,传热、传质性能好以及催化剂可在线补加和更换等优点,在学术研究和工业应用上备受关注。对浆态床反应器的流型、气含率、气泡行为、传质、传热等研究进行了总结,并对温度、压力、液体性质等参数对于流体力学性质的影响进行了分析。介绍了多级浆态床和构件式浆态床新型反应器,对浆态床在大化工、精细化工及环保等重要过程中的工业应用进行了总结,并对浆态床反应器的应用前景和研究趋势进行了展望。     

Modelling and design of thin-film slurry photocatalytic reactors for water purification

Photocatalytic oxidation processes are highly effective clean technologies for the degradation and mineralization of a wide variety of priority pollutants in water and wastewater. However, the application of heterogeneous photocatalysis for wastewater treatment on an industrial scale has been impeded by a lack of mathematical models that can be readily applied to reactor design and scale-up. As a results current photocatalytic reactors in research and development have been designed by empirical or semi-empirical methods only.In this paper, a simple and generic mathematical model for steady-state, continuous flow, thin-film, slurry (TFS) photocatalytic reactors for water purification using solar and UV lamps is presented. The model developed is applicable to TFS flat plate and annular photoreactors of (a) falling film design or (b) double-skin design, operating with three ideal flow conditions: (1) falling film laminar flow, (2) plug flow and (3) slit flow. The model is expressed in dimensionless form and scale-up of TFS photocatalytic reactors can be carried out by dimensional analysis. In addition, the model parameters can be estimated easily from real systems and model solutions can be obtained with little computational effort.Comparison of a number of ideal flow systems shows that both falling film laminar flow and plug flow operation modes give higher performance than the slit flow system. Slit flow operation mode results in lower conversions due to the non-correspondence of fluid-residence time and the transversal radiation field. The effect of optical thickness, on reactor performance and the evolution of radial profiles of a model pollutant with photoreactor length are presented for each of the operation modes. The falling film laminar flow system was found to be more efficient than the plug flow system when the reactor conversion is above 80%. For lower reactor conversion the plug flow system was found to be marginally more efficient than the falling film laminar flow system. A methodology for the optimal geometrical design of a highly efficient configuration of TFS photocatalytic reactors is also presented. The mathematical models presented may be used as a tool for the design, scale-up and optimization of these types of photocatalytic reactors.     

Novel Gas-Liquid-Solid Reactors

Multiphase reactors involving gas, liquid, and solid phases have several important applications in the chemical industry, particularly in catalytic processes. Some of the well-known examples are: hydrogenation and oxidation of organic compounds, hydro-processing coal-derived and petroleum oils, Fischer-Tropsch synthesis, and methanation reactions. Due to the presence of three phases, the problem of reactor design is often important to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process. The reactors are mainly of two types: (a) solid catalyst is suspended either by mechanical agitation or gas-induced agitation and (b) solid catalyst is in a fixed bed with concurrent or countercurrent feed of gas and liquid re-actants. The reactor types conventionally used in industry are: (a) mechanically agitated or bubble column slurry reactors and (b) trickle-bed or packed-bed bubble reactor. The various design and modeling aspects of these reactors have been reviewed by Satterfield [1], Chaudhari and Ramachandran [2], Shah [3,4], Ramachandran and Chaudhari [5], Shah et al. [6], and Herskowitz and Smith [7]. In several industrial processes these reactor designs are modified to achieve a certain specific objective, such as better heat or mass transfer, higher catalyst efficiency, better reactor performance and selectivity, etc. Similarly, specially designed reactors are often used for laboratory kinetic studies or to understand a certain phenomenon. Thus, novel multiphase reactors are becoming important from both academic and industrial viewpoints. Some of the recently introduced novel gas-liquid-solid reactor types are: (a) loop recycle slurry reactors, (b) basket-type reactors, (c) ebullated-bed reactors, (d) internal or external recycle reactors, (e) multistage slurry or packed-bed reactors, (f) column reactors with sieve trays or multiple agitators, (g) gas-induced agitated reactors, and (h) horizontal-packed-bed reactors. are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed. These novel reactor designs are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed.     

Novel Gas-Liquid-Solid Reactors

Multiphase reactors involving gas, liquid, and solid phases have several important applications in the chemical industry, particularly in catalytic processes. Some of the well-known examples are: hydrogenation and oxidation of organic compounds, hydro-processing coal-derived and petroleum oils, Fischer-Tropsch synthesis, and methanation reactions. Due to the presence of three phases, the problem of reactor design is often important to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process. The reactors are mainly of two types: (a) solid catalyst is suspended either by mechanical agitation or gas-induced agitation and (b) solid catalyst is in a fixed bed with concurrent or countercurrent feed of gas and liquid re-actants. The reactor types conventionally used in industry are: (a) mechanically agitated or bubble column slurry reactors and (b) trickle-bed or packed-bed bubble reactor. The various design and modeling aspects of these reactors have been reviewed by Satterfield [1], Chaudhari and Ramachandran [2], Shah [3,4], Ramachandran and Chaudhari [5], Shah et al. [6], and Herskowitz and Smith [7]. In several industrial processes these reactor designs are modified to achieve a certain specific objective, such as better heat or mass transfer, higher catalyst efficiency, better reactor performance and selectivity, etc. Similarly, specially designed reactors are often used for laboratory kinetic studies or to understand a certain phenomenon. Thus, novel multiphase reactors are becoming important from both academic and industrial viewpoints. Some of the recently introduced novel gas-liquid-solid reactor types are: (a) loop recycle slurry reactors, (b) basket-type reactors, (c) ebullated-bed reactors, (d) internal or external recycle reactors, (e) multistage slurry or packed-bed reactors, (f) column reactors with sieve trays or multiple agitators, (g) gas-induced agitated reactors, and (h) horizontal-packed-bed reactors. are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed. These novel reactor designs are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed.     

偶氮染料在气-液-固循环浆态光催化反应器中的降解脱氮

偶氮染料废水是一种集中量大的重要污染物,其中的偶氮键可被环境微生物降解生成具有毒性的芳香胺类化合物。本文从光量子效率、脱氮速率、脱氮能耗等方面,对比研究了一种新设计的气-液-固循环浆态光催化反应器和环隙式光催化反应器对偶氮染料降解脱氮的性能。结果表明,由于空气的引入,使气-液-固循环浆态光催化反应器的量子收率有一定程度下降,同时造成单位数量级脱氮能耗也有一定增大,但偶氮染料脱氮速率比在环隙式反应器中的情况有大幅度提高,表明气-液-固循环浆态反应器在偶氮染料废水光催化降解脱氮方面具有较大应用前景。     

Model‐Based Optimization of a Photocatalytic Reactor with Light‐Emitting Diodes

The complicated interplay between mass and photon transfer within a photocatalytic reactor calls for an integrated design approach. A model‐based optimization approach for LED‐based photocatalytic reactors is presented. First, a model that describes the distribution of reactants and photons within a photocatalytic reactor is developed. Then, several design variables related to the reactor dimensions and light sources are optimized simultaneously using the photocatalytic degradation of toluene as a model system. The results demonstrate how different formulations of the problem can be used to either minimize the reactor cost or to obtain a specified concentration profile within the reactor.