Reactive Separations - Assignment Example

REACTIVE SEPERATIONS Task Outline Introduction This will give an overview of the topic, defining the topic in question. The introduction will also give examples of other alternative views to the topic. It contains the thesis statement the purpose of the study. Reactive separation is the topic of this research. 2. Reactive Separation There are two types of reactive separation and they are listed here. The two types listed here are reactive distillation and reactive absorption. 3. Reactive Distillation. The definition of reactive distillation is defined, how the process is done, and its uses. In addition, there are also benefits and demerits of the process. 4. Reactive Absorption Reactive absorption is defined, what is involved in the he process, the pros and cons of the process. 5. Uses of Reactive Separations There are many uses of reactive separation that are discussed under this topic. 6. Demerits of Reactive Separations The reactive separation method does not have many demerits, but the few are discussed. 7. Applications of Reactive Absorption Reactive separation is used commercially and this is discussed, including various methods of chemical separation. 8. Conclusion This contains a summary of the issues discussed and suggestions for future research. Introduction Separation of chemicals of compounds is a done for a number of reasons. Sometimes it is for purification purposes and sometimes for extraction where a particular chemical is required from a compound. Filtering, distillation, evaporation, hand picking, chromatography, and crystallization are examples of methods used to separate chemicals and mixtures. Sometimes it is difficult to separate certain chemicals from a mixture. Reactive separation is beneficial in these circumstances, where a compound could be reacted to form a different compound that its chemicals can be easily separated. Reactive separation is defined as the process where a compound is reacted to form another compound that can be easily separated (Sundmacher and Kienle, 2006, p. 65). This sometimes involves adding a chemical to the compound causing a reaction. Reactive separation is useful in removing cyanide from gold mine streams, and removal of Methacrylate, phenols and acrylates from the industrial wastes. It is also helpful in converting dangerous chemicals to chemicals that are less harmful to the environment. Reactive separation is a process that has many uses and it also has various applications. Types of Reactive Separation There are two types of reactive separation; reactive distillation and reactive absorption. Reactive Distillation This is a process where reaction and distillation is done in one vessel (Maloney and Doherty, 2000, p. 3953). It is more beneficial to methods previously used where reaction and separation were performed separately. Some of the benefits include better heat control, increased conversion, improved selectivity, proper use of reaction heat, and it also makes difficult separations easy (Baur and Krishna, 2002, p. 448). The reaction zone being in its original place causes the vapor-liquid equilibrium, diffusion and chemical kinetics, and mass transfer rates to interact in a complex way (Bhale et al, 2004, p. 1). This is a major challenge in the synthesis and design of the reactive distillation systems. For this reason, it is important to further research on certain aspects such as nonlinear dynamics and control, process synthesis, column hardware, modeling and simulation. How sustainable the process of reactive distillation is depends on certain factors such as temperature in which distillation and reaction are performed, and the reactants and products volatilities (Maloney and Doherty, 2000, p. 3955). This may mean that it is not appropriate to use reactive distillation for every reaction. Therefore, care and consideration need to be thoroughly done when selecting candidates for reactive distillation. Functions of reactive distillation Some of the uses of reactive distillation are in processes such as etherification, esterification, polymerization, hydrodesulfurisation, and hydrogenation (Bhale et al, 2004, p. 1). The application of this process is useful in many industries that are involved with chemicals. Reactive distillation is a well-established technology that is used for the manufacture of linear alkyl benzenes, carbonates and phenols (Sundmacher and Kienle, 2006, p. 67). It is also useful in the production of derivatives of organosilicon and in the business of chiral chemicals. There are also certain hydrogenation reactions that require more than one reaction in the same vessel, which is an important development (Baur and Krishna, 2002, p. 451). The limitations of the reactive distillation process are that sometimes there is depletion of the reactants or the side products are formed at very high temperatures. Reactive Absorption Reactive absorption is the process where gases in liquid solutions and chemical reactions are absorbed (Kenig and Seferlis, 2009, p. 65). This is an important process that makes it possible for the production of chemicals such as nitric acid and sulfuric acid. In addition, reactive absorption is useful in the removal of harmful substances such as hydrogen sulfide from gas streams. Purification of gases to high purities is now possible because of the process of reactive absorption (Kenig and Seferlis, 2009, pp. 65-66). This process is better than the physical absorption process since it does not require a lot of solvent and produces better results at partial pressures. The reaction stoichiometry makes it only possible to combine chemical reactions and absorption in low gas-phase concentrations. Another factor that limits the efficiency of reactive absorption is the difficulty of solvent regeneration. Heat that is released by the exothermal reactions is also another problem that faces the process of reactive absorption (Sundmacher and Kienle, 2006, p. 71). This process of reactive absorption may sometimes involve both gas-phase reactions and liquid-phase reactions, or a steady-state liquid phase. Reactive absorption does not occur in the thermodynamic equilibrium and involves a complex rate control process. For this reason, rate-based models are required to describe the process instead of the equilibrium concept (Kenig and Seferlis, 2009, p. 66). Certain models have to be made in order to facilitate this process and they include the rate-based model and the equilibrium stage model. In the equilibrium stage model, it is assumed the liquid stream moves in the same thermodynamic equilibrium as the corresponding gas stream (Sundmacher and Kienle, 2006, p. 65). The rate-based stage model considers directly the actual rates of chemical reactions and mass and heat transfer. Functions of reactive absorption The reactive absorption process it makes it possible for the production of chemicals such as nitric acid and sulfuric acid. On the other hand, reactive absorption is useful in the removal of harmful substances such as hydrogen sulfide from gas streams. Purification of gases to high purities is now possible because of the process of reactive absorption (Kenig and Seferlis, 2009, pp. 65-66). Consequently, the process aids in the combination chemical reactions and absorption in low gas-phase concentrations Uses of Reactive Separations One of the benefits of the reactive separation processes is that they increase the speed at which chemicals are separated. It is faster than the previous process such as hand picking, distillation and evaporation. This is because reactive separation combines the processes of reaction and distillation or absorption into one vessel (Bhale et al, 2004, p. 1). It can be able to separate mixtures that were otherwise impossible to separate using the other methods of separating mixtures. An example of this is the removal of acid from water (Sundmacher and Kienle, 2006, p. 65). Other methods of separating mixtures are difficult to apply when trying to separate such a mixture. Distillation or hand picking are not appropriate methods of separating the mixture of acid and water. Nonetheless, evaporation and chromatography are not effective methods of separating the mixture. However, reactive distillation can be used to separate water from acetic acid. Acetic acid is an advantageous product in everyday life since it can be used in pharmaceuticals, in foods, solvents, medicinal, and explosives. It can also be used in vinegar; a product found in many homes (Bhale et al, 2004, p. 21). Acetic acid is a pollutant in water, and for this reason, it must be removed from the mixture. Therefore, reactive separation can be used to separate products that can be very useful in their own rights. The equipment used in the process of reactive separation is not expensive. This means that reactive separation is a process that reduces on costs whenever it is used as a process of separating mixtures (Baur and Krishna, 2002, p. 453). This is an interesting benefit since the equipment used in reactive separation save time and they are also cost effective. The equipment used in this process is a combination of two activities into one vessel (Algusane, 2006, p. 278). This is the activity of chemical separation, then the activity of distillation or absorption. The processes of reactive separation are also energy efficient since they do not consume a lot of energy (Bhale et al, 2004, p. 1). It can be summed up that reactive separation is a process that is fast, saves on energy and cost, and it is also energy efficient. The reactive separation process also has equipment that is easy to use. The byproducts of the processes are fewer there is also less waste compared to the other methods of separating mixtures. Products of the processes are of good quality and there is also heat reduction. Demerits of Reactive Separations The reactive column combines both the chemical reactor and the distillation column that causes suboptimal conditions in the reactive column (Algusane, 2006, p. 276). The design of such systems has been a complex task since the equipment harbors interactions of diffusion, mass transfer rates, chemical kinetics, and vapor-liquid interactions. There are some reactions that are not appropriate for this equipment used in the reactive separation process. Applications of Reactive Separation Esterification is an industrial application where the process of reactive separation is used. For, example, it is used in the production of MTBE and methyl acetate (Bhale et al, 2004, p. 2). Esterification and etherification are used for commercial purposes, and they are aided by the process of reactive separation. The esterification process can be used commercially with the aid of the reactive separation process to extract acetic acid from the water. This is beneficial since it leads to both the purification of water and the acetic acid can also be put to other uses. Versatile solvents such as butyl acetate can also be extracted using the reactive separation process (Sundmacher and Kienle, 2006, p. 68). This is done using the esterification process of n-butanol and acetic acid in the presence of a catalyst. Other industrial applications of the reactive separation process using the esterification process are the productions of amyl acetate, methyl acetate, ethyl acetate, and fatty acids. The reactive separation process is also useful in the production of butyl acetate and the production of oxalates (Bhale et al, 2004, pp. 1-2). In addition, it can be used in the hydrolysis of methyl acetate and alkyl halides. The process or reactive separation can also be used to separate isobutene from a mixture of hydrocarbon. The synthesis of alcoxy alkanol is also possible due to the process of reactive distillation. Another application of the reactive separation process is the hydrogenation of benzene and the hydrogenation of acetone (Sundmacher and Kienle, 2006, p. 65). Other applications include hydrodesulfurisation, hydroconversion, removal of acetylene from hydrocarbon streams, synthesis of iso-octane from isobutylene, production of cyclopentene, dehydrogenation, alkylation, and carbonylation. Conclusion Reactive separation is a useful process, and it has many applications in the field of separating mixtures. Other processes of separating mixtures such as chromatography, evaporation, hand picking, crystallization, and filtering are useful, but they have limitations. They cannot separate certain types of chemicals, and that is why it is necessary to appreciate the process of reactive separation. Reactive separation can be used to for the purposes of purification. Here water can be purified by removing impurities such as acetate acid. In addition, reactive separation can also be used to break down compound into a compound that can then be easily separated. The process has its benefits and it also has a few problems. It is easy to use, energy efficient, low on cost and it also releases quality products. Further research needs to be done in this process. These should include studies the process’ simulation and design, column hardware, process synthesis, control, and non-linear dynamics. Bibliography Algusane, T. Y. (2006). A Framework or the Synthesis Reactive Absorption Columns. Chem. Eng. And Process. 45(4), pp. 276-290. Baur R. and Krishna R. (2002). Hardware selection and design aspects for RD columns. A case study on the synthesis of TAME. Chem. Eng. and Processing, Vol. 41, No. 5, 445- 462. Bhale, N., Hiwale, R., Mihajani, S., and Mahjan, Y. (2004). Industrial Applications of Reactive Distillation: Recent Trends. International Journal of Chemical Reactor Engineering. Vol. 2. Kenig, E., and Seferlis, P. (2009). Modeling Reactive Absorption. Reactions and Separations. Malone, M.F., and Doherty, M.F. (2000). Reactive Distillation. Ind. Eng. Chem. Res., Vol. 39, No. 11, 3953-3957. Sundmacher, K., & Kienle, A. (2003). International Workshop on Reactive Distillation. Reactive distillation status and future directions. 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