TABLE OF CONTENTS This chapter treats the effects of temperature on the three types of ideal reactors: batch, piston flow, and continuous-flow stirred tank. Three major questions in reactor design are addressed. What is the optimal temperature for a reaction? How can this temperature be achieved or at least approximated in practice? How can results from the laboratory or pilot plant be scaled up?
Most reaction rates are sensitive to temperature, and most laboratory studies regard temperature as an important means of improving reaction yield or selectivity. Our treatment has so far ignored this point. The reactors have been iso-thermal, and the operating temperature, as reflected by the rate constant, has been arbitrarily assigned. In reality, temperature effects should be considered, even for isothermal reactors, since the operating temperature must be specified as part of the design. For nonisothermal reactors, where the temperature varies from point to point within the reactor, the temperature dependence directly enters the design calculations.
The rate constant for elementary reactions is almost always expressed as
| (5.1) |  |
where m = 0, 1/2, or 1 depending on the specific theoretical model being used. The quantity E is activation energy, although the specific theories interpret this energy term in different ways. The quantity T act = E/ R g has units of temperature (invariably K) and is called the activation temperature. The activation temperature should not be interpreted as an actual temperature. It...
