Batch reactions using

In the first few minutes of a batch reaction using 1-alkenes an extremely fast reaction therefore may take place, which is the direct hydroformylation of 1-alkene, but after an equilibration to the internal isomers has taken place the reaction slows down considerably. 

Research in this field started in the wake of the reports of SL-PC. Consisting of a catalyst-containing supported liquid layer for CF reactions in the gas phase, the concept was transferred to batch reactions, using a catalyst dissolved in a supported aqueous phase. This was first referred to as supported aqueous-phase catalysis (SAPC) by Davis in an article published in Nature in 1989. Later, the concept was extended, using a variety of names, but the essence has remained the same a supported catalyst-philic phase. 

Batch reactions using solvents carried out on a laboratory scale are directly amenable to scale up, since the conditions are defined. 

The monitoring of isocyanate reactions, including urethane formation in foams and binders, can be conveniently carried out using mid-IR fiber optic spectroscopy. Once the spectroscopic evolution of a particular reaction is understood, a simple measure of the degree of curing of a urethane material can be developed by using a ratio of peak areas for a characteristic peak arising from the precursor and one from the product. In case such as that of the simulated solid fuel discussed above, the small batch reactions used in the industry can be monitored in situ when this method is combined with the use of mid-IR fiber optics, which offer a combination of convenience and robust calibration. 

It is important to note that most reactions using homogeneous catalysts are run in the liquid phase in a batch-wise mode. Especially in academic research laboratories, homogeneous catalysis is attributed to batch reactions using organic solvents. However, in large-scale industrial processes, e.g., carbonyl-ation reactions, oxidations are performed in a continuous mode. 

Figure 6.3a shows the sharp change with time in the concentrations of the iodine-containing species in a stirred batch reaction. Using a more detailed model of the reaction (Hanna et al., 1982), Showalter calculated the concentrations of iodate, iodide, and iodine as functions of time. Figure 6.3b shows the results. Notice that the iodine concentration is amplified 350 times. This is the key to simplifying the reaction because we can now make the approximation that all the iodine is present as either iodide or iodate ... 

A Summary of PP-p-MS Polymers Prepared by Batch Reaction Using rac-Me2Si(2-Me-4-Ph-lnd)2ZrCl2/MAO Catalyst and p-MS/Hydrogen Chain Transfer Agent ... 

Harvey, A.P. and Mackley, M.R. (2002). Intensification of two-phase liquid batch reactions using continuous oscillatory baffled reactors. AIChE Annual Meeting, Indianapolis, USA, November. 

Santos et al. [158] reported a study on suspension polymerizations using Raman spectroscopy in the NIR region. The authors observed that the Raman spectra were affected by the PSD and showed that it was possible to monitor the evolution of monomer conversion during batch reactions using an external Raman probe. The Raman spectra were able to indicate abnormal process behavior during suspension polymerization reactions. 

SCH 51048 is a THF-based antifungal agent, which can be synthesized through the lipase-catalyzed desymmetrization of an adequate homoallylic diol. CAL-B have allowed the selective synthesis of the enantiopure (S)-monoacetate in 71% isolated yield at a 30 kg batch reaction using two equivalents of VinOAc in acetonitrile (MeCN) at 0°C after 6h (Figure 9.21) [176]. Complete conversion of the diol was observed, yielding byproduct diacetate in around 30%, which was separated by column chromatography. The desymmetrization of other 1,3-propanediol subunits has been... 

In general terms, if the reaction to the desired product has a higher order than the byproduct reaction, use a batch or plug-flow reactor. If the reaction to the desired product has a lower order than the byproduct reaction, use a continuous well-mixed reactor. 

The use of alkali or alkaline-earth sulfides cataly2es the reaction so that it is complete in a few hours at 150—160°C use of aluminum chloride as the catalyst gives a comparable reaction rate at 115°C. When an excess of sulfur is used, the product can be distilled out of the reactor, and the residue of sulfur forms part of the charge in the following batch reaction. The reaction is carried out in a stainless steel autoclave, and the yield is better than 98% based on either reactant. Phosphoms sulfochloride is used primarily in the manufacture of insecticides (53—55), such as Parathion. 

Sulfurization of unsaturated compounds and meicaptans is normally carried out at atmospheric pressure, in a mild or stainless steel, batch-reaction vessel equipped with an overhead condenser, nitrogen atmosphere, an agitator, heating media capable of 120—215°C temperatures and a scmbber (typically caustic bleach or diethanolamine) capable of handling hydrogen sulfide. If the reaction iavolves the use of H2S as a reactant or the olefin or mercaptan is a low boiling material, a stainless steel pressurized vessel is recommended. 

The Center for Chemical Process Safety (CCPS) has identified the need for a publication dealing with process safety issues unique to batch reaction systems. This book, Guidelines for Process Safety in Batch Reaction Systems, attempts to aid in the safe design, operation and maintenance of batch and semi-batch reaction systems. In this book the terms batch and semi-batch are used interchangeably for simplicity. The objectives of the book are to ... 

Frequently a piece of equipment is used in different processes during its lifecycle. This could result in process conditions that exceed the safe operating limits of the equipment. Equipment inspection may provide a poor prediction of the equipment s useful life and reliability, due to the change of material handled or change in process chemistry over the life of equipment. Batch operations are also characterized by frequent start-up and shut-down of equipment. This can lead to accelerated equipment aging and may lead to equipment failure. This chapter presents issues and concerns related to the safe design, operation, and maintenance of various pieces of equipment in batch reaction systems, and provides potential solutions. 

This chapter discusses safety issues reiated to the design and operation of key equipment used in the batch reaction systems. Some of the equipment covered inciudes ... 

Some of the types of equipment used in batch reaction systems are discussed in more detaii beiow. 

The following details establish reactor performance, considers the overall fractional yield, and predicts the concentration profiles with time of complex reactions in batch systems using the Runge-Kutta numerical method of analysis. 

From diese various estimates, die total batch cycle time t(, is used in batch reactor design to determine die productivity of die reactor. Batch reactors are used in operations dial are small and when multiproducts are required. Pilot plant trials for sales samples in a new market development are carried out in batch reactors. Use of batch reactors can be seen in pharmaceutical, fine chemicals, biochemical, and dye industries. This is because multi-product, changeable demand often requues a single unit to be used in various production campaigns. However, batch reactors are seldom employed on an industrial scale for gas phase reactions. This is due to die limited quantity produced, aldiough batch reactors can be readily employed for kinetic studies of gas phase reactions. Figure 5-4 illustrates die performance equations for batch reactors. 

Equations 5-110, 5-112, 5-113, and 5-114 are first order differential equations and the Runge-Kutta fourth order numerical method is used to determine the concentrations of A, B, C, and D, with time, with a time increment h = At = 0.5 min for a period of 10 minutes. The computer program BATCH57 determines the concentration profiles at an interval of 0.5 min for 10 minutes. Table 5-6 gives the results of the computer program and Figure 5-16 shows the concentration profiles of A, B, C, and D from the start of the batch reaction to the final time of 10 minutes. 

Assume that in Example 7-10, the overall cycle time for a batch reaction is 8 hrs. The cycle time will include 2 hrs for heat-up and 3 hrs for cool-down. The batch will be heated from 20°C to the reaction temperature of 60°C, then cooled to 35°C. Using a hot-water jacket temperature of 80°C, it took 15 min to heat the batch from 20°C and 30°C. Calculate the jacket temperatures required for heat-up and cool-down. 

Use continuous reactors if possible. It is usually easier to control continuous reactors than batch reactors. If a batch reaction system is required, minimize the amount of unreacted hazardous materials in the reactor. Figures 12-40 and 12-41 show typical examples. 

Some batch reactions have the potential for very high energy levels. If all the reactants (and sometimes catalysts) are put into a kettle before the reaction is initiated, some exothermic reactions may result in a runaway. The use of continuous or semi-batch reactors to limit the energy present and to reduce the risk of a runaway should be considered. The term semi-batch refers to a system where one reactant and, if necessary, a catalyst is initially charged to a batch reactor. A second reactant is subsequently fed to the reactor under conditions such that an upset in reacting conditions can be detected and the flow of the reactant stopped, thus limiting the total amount of potential energy in the reactor. 

Table 1. Direct Fluorination of Organic Compounds Using Batch Reaction Techniques...

This method is the most widely used because it gives a good picture of batch reactions performed in industry. Reactions are carried out in a thermostated flask fitted with constant speed stirrer, inert gaz inlet, sampling device, thermometer, distillation column, and condenser. 

However, considering practical limitations, that is, the availability of optically pure enantiomers, E values are more commonly determined on racemates by evaluating the enantiomeric excess values as a function of the extent of conversion in batch reactions. For irreversible reactions, the E value can be calculated from Equation 1 (when the enantiomeric excess ofthe product is known) or from Equation 2 (when the enantiomeric excess ofthe substrate is knovm) [la]. For reversible reactions, which may be the case in enzymatic resolution carried out in organic solvents (especially at extents of conversion higher than 40%), Equations 3 or 4, in which the reaction equilibrium constant has been introduced, should be used [lb]. 

Many semibatch reactions involve more than one phase and are thus classified as heterogeneous. Examples are aerobic fermentations, where oxygen is supplied continuously to a liquid substrate, and chemical vapor deposition reactors, where gaseous reactants are supplied continuously to a solid substrate. Typically, the overall reaction rate wiU be limited by the rate of interphase mass transfer. Such systems are treated using the methods of Chapters 10 and 11. Occasionally, the reaction will be kinetically limited so that the transferred component saturates the reaction phase. The system can then be treated as a batch reaction, with the concentration of the transferred component being dictated by its solubility. The early stages of a batch fermentation will behave in this fashion, but will shift to a mass transfer limitation as the cell mass and thus the oxygen demand increase. 

There are two uses for Equation (2.36). The first is to calculate the concentration of components at the end of a batch reaction cycle or at the outlet of a flow reactor. These equations are used for components that do not affect the reaction rate. They are valid for batch and flow systems of arbitrary complexity if the circumflexes in Equation (2.36) are retained. Whether or not there are spatial variations within the reactor makes no difference when d and b are averages over the entire reactor or over the exiting flow stream. All reactors satisfy global stoichiometry. 

Suppose the desired product is the single-step mixed acidol as shown above. A large excess of the diol is used, and batch reactions are conducted to determine experimentally the reaction time, which maximizes the yield of acidol. Devise a kinetic model for the system and explain how the parameters in this model can be fit to the experimental data. 

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