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Chemical Engineering vocabulary · Reactions and Reactors

Rate-limiting step

Meaning in chemical engineering, with examples

nounAdvanced term

In chemical engineering, rate-limiting step means: The slowest step in a series of steps, such as reaction, diffusion or heat removal, which controls how fast the whole process can go.

In Turkish: hız belirleyen basamak, hız sınırlayıcı adım

How it is used

Used in kinetics, catalysis and troubleshooting. Engineers ask whether a process is limited by kinetics, mass transfer or heat transfer, because only speeding up the rate-limiting step will help.

Example sentences

  1. Gas-liquid mass transfer is the rate-limiting step, so a faster agitator will help more than extra catalyst.

  2. In the plant, heat removal, not chemistry, became the rate-limiting step.

Common collocations

  • identify the rate-limiting step
  • rate-determining step
  • kinetically limited
  • mass-transfer limited
  • reaction rateHow fast reactants are used up or products are formed, usually given as moles per unit volume per unit time. It depends on temperature, concentration and catalyst.
  • mass transferThe movement of a component from one place or phase to another because of a difference in concentration, for example from a gas into a liquid or from a liquid into a solid.
  • diffusionThe movement of molecules from an area of high concentration to an area of low concentration caused by their random motion, without any bulk flow.
  • activation energyThe minimum energy that reacting molecules need for a reaction to happen. A high value means the rate is very sensitive to temperature; a catalyst lowers it.

More terms: Reactions and Reactors

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