Batch reactors monitoring conversion

The decomposition of nitrous oxide (NjO) to nitrogen and oxygen is preformed in a 5.0 1 batch reactor at a constant temperature of 1,015 K, beginning with pure NjO at several initial pressures. The reactor pressure P(t) is monitored, and the times (tj/2) required to achieve 50% conversion of N2O are noted in Table 3-19. Use these results to verify that the N2O decomposition reaction is second order and determine the value of k at T = 1,015 K. 

Rewrite the design equation in terms of the measured variabte. When there is a net increase or decrease in the totai number of moles in a gas phase reaction, the reaction order may be determined from experiments performed with a constant-volume batch reactor by monitoring the total pressure as a function of time. The total pressure data should not be converted to conversion and then analyzed as conversion-time data just because the design equations are written in terms of the variable conversions. Rather, transform the design equation to the measured variable, which in this case is pressure. Consequently, we need to express the concentration in terms of total pressure and then substitute for the concemtation of A in Equation (E5-I.1),... 

Hardware sensors for the on-line monitoring of polymerization such as in batch reactors have been reviewed (Kammona et al. 1999). In Section 3.4 the use of ruggedized conversion sensors for fibre-optic near-infrared (NIR) spectroscopy during extrusion was described. In many ways, the requirements are simpler than for control of a batch reaction (as in a polymer-synthesis autoclave) since... 

For practical implementation, monitoring of CO and H2 pressure and temperature during the reaction is recommended, since the phase behavior changes with increase of the molar fraction of CO and [63]. Moreover, also conversion of the substrate and increasing the concentration of the product aldehyde affect the critical point. It is recommended, that batch reactors should be operated at higher pressures than flow reactors in order to maintain a monophasic system throughout the whole hydroformylation process [64]. 

Monitoring conversion in batch and semibatch reactors Multistep polymer reaction processes often move from step to step as preset monomer conversion levels are met for example, in the production of block copolymers or for grafting reactions, such as used in high impact polystyrene. Currently, chemical conversion is... 

Batch reactors operated adiabatically are often used to determine the reaction orders, activation energies, and specific reaction rates of exothermic reactions by monitoring the temperature-time trajectories for different initial conditions. In the steps that follow, we will derive the temperature-conversion relationship for adiabatic operation. 

The view-cell reactor is made of titanium and has two sapphire windows, a gas inlet valve and an outlet valve, as shown in Figure 3. The view cell is interfaced with a pressure transducer, a thermocouple, and a pressure relief valve. The pressure and temperature are computer-monitored during the reaction. 0.6 ml of 50 wt% H2O2/H2O (10.41 mmoles), 0.20ml of pyridine (2.47 mmoles), or some other base, was dissolved in 5 ml of acetonitrile or methanol, and was added to the reactor. 2.2 ml of supercritical CO2 was charged after lOOmg of propylene (2.38 mmoles) had been added to the reactor. The reactor was heated with a band heater at 40 - 70°C for 3, 6, 12, and 24 hr reaction periods. Following a batch conversion experiment, the amounts of products formed were determined by GC and GC/MS. 

This latter interpretation would mean that with the approach depicted in Fig. 10, the catalyst itself could be monitored. The authors reported that the silica-supported Nafion could not be observed in the beginning of their experiments and appeared in the spectra only after the catalyst interacted with octanol. This observation may indicate that the octyl groups promote the sticking of the catalyst particles onto the ATR probe, within the evanescent field. However, the example also shows that this approach may not be without problems, because it depends on the adsorption of the particles from the slurry reactor onto the ATR element. This process is accompanied by the adsorption of molecules on the catalyst surface and complicates the analysis. More important, as also indicated by the work of Mul et al. (74). this adsorption depends on the surface properties of the catalyst particles and the ATR element. These properties are prone to change as a function of conversion in a batch process and are therefore hardly predictable. 

The available data from emulsion polymerization systems have been obtained almost exclusively through manual, off-line analysis of monomer conversion, emulsifier concentration, particle size, molecular weight, etc. For batch systems this results in a large expenditure of time in order to sample with sufficient frequency to accurately observe the system kinetics. In continuous systems a large number of samples are required to observe interesting system dynamics such as multiple steady states or limit cycles. In addition, feedback control of any process variable other than temperature or pressure is impossible without specialized on-line sensors. This note describes the initial stages of development of two such sensors, (one for the monitoring of reactor conversion and the other for the continuous measurement of surface tension), and their implementation as part of a computer data acquisition system for the emulsion polymerization of methyl methacrylate. 

It is clear from the previous section that the rate of reaction depends on the concentrations of reactants. In reversible reactions, it depends additionally on the concentrations of products. Often in a laboratory experiment, one of the reactants is selected, and its concentration is monitored as a function of time or flow rate, depending on whether the reactor is batch or continuous. Then the results are expressed in terms of the conversion of that reactant (say A) defined as... 

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