Reactors for kinetic studies

Typical batch reactors for kinetic studies of liquid-phase reactions at ambient and elevated pressures are shown in Figures 3.1 and 3.2, respectively. They are equipped with stirrer, heating or cooling arrangement, temperature sensor, reflux condenser, and sampling ports. 

Figure 3.1. Batch reactor for kinetic studies of oxidation at ambient pressure (from Blaine and Savage [1]).

Figure 3.2. Commercial batch reactor for kinetic studies at elevated pressures (courtesy Autoclave Engineers, Erie, PA, U.S. A., reproduced with permission).

The principal use of tubular reactors for kinetic studies is as catalytic fixed-bed reactors in heterogeneous catalysis. They are rarely used for quantitative studies of homogeneous reactions because these are difficult to confine sharply to reactors of this type (see farther below). 

In the laboratory either integral or differential (see Sec. 4-3) tubular units or stirred-tank reactors may be used. There are advantages in using stirred-tank reactors for kinetic studies. Steady-state operation with well-defined residence-time conditions and uniform concentrations in the fluid and on the solid catalyst are achieved. Isothermal behavior in the fluid phase is attainable. Stirred tanks have long been used for homogeneous liquid-phase reactors and slurry reactors, and recently reactors of this type have been developed for large catalyst pellets. Some of these are described in Sec. 12-3. When either a stirred-tank or a differential reactor is employed, the global rate is obtained directly, and the analysis procedure described above can be initiated immediately. 

Remarkably, the form of the steady-state PFR equations is identical to the form of the fully transient well-mixed batch reactor with no volume change. The only difference is that instead of the derivative with respect to real time, the PFR equations involve the derivative with respect to reduced time. This is a very significant result. It shows us why the steady-state PFR is also such a useful reactor for kinetic studies—its model equations are quite simple Whichever form of the equations used is simply a matter of preference they all mean the very same thing. 

Ray, A. K., and Beenackers, A., 1997, Novel swirl-flow reactor for kinetic studies of semiconductor photocatalysis. AIChEJ., 43(10) 2571-2578. 

The above example deals with a simple isothermal situation. In Chapters 1 and 2 it was suggested to operate reactors for kinetic studies, whenever possible, in an isothermal way. There are cases, however, in which isothermal operation is impossible, in spite of all precautions, for example, a homogeneous reaction like thermal cracking of hydrocarbons. In such a case it is inevitable that part of the reactor is used to bring the feed to the desired temperature. In contrast with catalytic reactors there is no clear-cut separation between prdieat and reaction section in such a case. If the rate is to be determined at a reference temperature, say T, and if the reaction volume is counted from the point where T, is reached, then the conversion in the preheat section that cannot be avoided is not accounted for. Similarly... 

DAGAUT P., CATHONNET M., ROUAN J.P., FOULATIER R., QUILGARS A., BOETTNER J.C., GAILLARD F., JAMES H., A jet-stirred reactor for kinetic studies of homogeneous gas-phase reactions at pressures up to ten atmospheres, J. Phys. E. Sci. Instrum., 19, 207 (1986). 

FIGURE 22 Reactor for kinetic studies 1- magnetic stirrer 2-reactor 3-cooler 4 centrifugal pump with rotation of 100-1100 r/min. 

The partial oxidation of methanol to produce formaldehyde is a common industrial reaction that has attracted the attention of those working in PI, from both the use of micro-reactors for kinetic studies (Cao et al., 2005) and safer operation (Patience et al., 2007). 

Semi-batch stirred tank reactor for kinetic studies on epimerization. The catalyst is fixed in a basket inside the autoclave. The H2 pressure is kept constant. 

Evaluation of the IRDE reactor for kinetic studies of electrochemical reactions... 

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